18.5: Nursing Care During the Fourth Stage of Labor
By the end of this section, you will be able to:
- Obtain assessment data on the person who has completed the first three stages of labor and birth
- Explain the nursing actions when caring for a person during the fourth stage of labor
- Monitor parent-newborn attachment
- Provide education to the person who has given birth and the family related to the fourth stage of labor
Assessment during the Fourth Stage of Labor
The delivery of the placenta initiates the fourth stage of labor . This stage ends after 1 to 4 hours or until the birthing person is clinically stable. During this stage, the nurse will closely monitor the birthing person’s vital signs, uterine tone, lochia, and recovery from any anesthesia for complications and encourage parent-newborn bonding and breast-feeding. The nurse will also assist the health-care provider during the repair of any lacerations.
Vital Signs
During the first hour following delivery, the nurse will monitor the birthing person’s vital signs every 15 minutes, followed by every 30 minutes during the second hour (Table 18.12) summarizes the assessment data to be collected. The nurse should compare the vital signs to predelivery vital signs and look for subtle changes to report to the physician (Hutchison et al., 2023).
| Assessment Data | Fourth Stage of Labor | Expected Findings |
|---|---|---|
| Vital signs |
Every 15 minutes for the first hour, every 30 minutes for the second hour, every hour for the third and fourth hours
Temperature Within the first hour of delivery, as needed after the first hour |
Vital signs will return to baseline following the 1-hour recovery. |
| Uterus | Monitor location, size, and consistency every 15 minutes for the first hour, every 30 minutes for the second hour, every hour for the third and fourth hours | The uterus will remain firm, midline, and approximately at the level of the umbilicus. |
| Lochia | Monitor amount, color, and consistency every 15 minutes for the first hour, every 30 minutes for the second hour, every hour for the third and fourth hours | The lochia will remain rubra in color, will not contain large clots, and will remain consistent or decreased in quantity. |
| Perineum | Monitor for edema, ecchymoses, and discomfort every 15 minutes for the first hour, every 30 minutes for the second hour, every hour for the third and fourth hours | The perineum will remain free from infection. |
| Pain | Hourly, or more frequently as needed | Pain will be managed with pain medications when required. |
| Recovery from anesthesia | Monitor every 15 minutes for a return of sensation and movement in the lower extremities | Birthing person will return to normal sensation and movement. |
| Emotional response | Continuous | Birthing person will discuss feelings and concerns with health-care providers and family. |
Involution
During the fourth stage of labor, it is critical for the nurse to assess uterine tone, size, and location, as well as any vaginal bleeding. The nurse should assess and monitor for uterine involution , the process by which the uterus begins to return to its prepregnant size, using regular fundal massage (Milton, 2024). Involution follows a predictable rate. During the first hours after childbirth, the fundus should be at the level of the umbilicus, and that level should not rise over the first couple of hours following delivery. A rise in uterine height warrants further assessment and notification of the provider.
The vaginal discharge composed of blood, mucus, and tissue during the postpartum period is called lochia . Assessing lochia is a critical aspect of postpartum care for people who have recently given birth. Monitoring its characteristics helps health-care providers to ensure that the birthing person’s recovery is progressing normally and to identify any potential complications.
Assessing lochia provides valuable information about the birthing person’s postpartum recovery. By closely monitoring and promptly reporting any abnormal findings, nurses can ensure the birthing person’s well-being and address any potential issues as they arise. This assessment is an essential component of postpartum care and helps in promoting a safe and healthy recovery for the new parent.
How to Assess Lochia
- Frequency: Lochia is assessed at regular intervals (sample protocol: every 15 minutes in the first hour of the fourth stage of labor, hourly for the next 1 to 4 hours, then every 4 hours for 24 to 48 hours.
- Explanation and privacy: Explain the assessment procedure to the birthing person, ensuring they understand what to expect. Maintain the birthing person’s privacy and dignity throughout the assessment, using drapes or blankets as needed.
- Position: Ensure the birthing person is in a comfortable and appropriate position (legs apart and knees bent) for assessment, such as lying on their back or sitting up at less than 45 degrees.
- Use gloves: Wear disposable gloves to minimize the risk of infection when handling lochia.
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Inspection: Inspect the perineal pad, underpad, or any material used to collect lochia.
Note the color, amount, consistency, and odor of the discharge.-
Color: Lochia progresses through different color phases:
- Lochia rubra: This is the initial discharge and is typically bright red, resembling menstrual blood. Lochia rubra is expected for the first 4 days.
- Lochia serosa: This is the second phase and is typically pink or brownish in color. Lochia serosa is expected for up to another 10 days.
- Lochia alba: This is the third phase and is typically whitish or yellowish and may continue for several weeks.
- The transition from rubra to serosa to alba indicates the normal healing process of the site where the placenta was attached in the uterus.
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Amount:
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Visually estimate the amount of lochia by assessing whether it is:
- (a) Scant: A small amount, less than 1 inch on a perineal pad.
- (b) Light: Approximately 1 to 4 inches on a pad.
- (c) Moderate: Approximately 4 to 6 inches on a pad.
- (d) Heavy: Saturating a pad within 1 hour or less.
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Weigh the lochia on all materials (quantification of blood loss* [QBL])
- (a) Using a scale, weigh the soiled perineal pads, underpads, and linen.
- (b) Subtract the dry weight of all materials (perineal pad, underpad, and linen) from the soiled weight. This equals the weight of the lochia in grams.
- (c) Convert the weight in grams to milliliters (1 g = 1 mL).
- (d) Add the mL of lochia to the QBL at the delivery (and any previous lochia in the postpartum period).
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Visually estimate the amount of lochia by assessing whether it is:
- Consistency: Note the consistency of lochia; it should be similar to that of mucus or watery. Clots may be present but should not be larger than a quarter.
- Odor: Assess the odor of lochia. Lochia typically has a mild, musky odor. Any foul or unpleasant smell may indicate infection.
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Color: Lochia progresses through different color phases:
- Abnormal findings: Report any abnormal findings, such as heavy bleeding (hemorrhage), foul odor, or large clots, to the health-care provider immediately, as these can be signs of complications.
- Documentation: Document the findings of the lochia assessment accurately in the birthing person’s medical record, including color, amount, consistency, and odor.
Perineum
The delivery of the newborn may result in lacerations or edema of the perineum. Lacerations are repaired by the provider, ensuring skin approximation. The nurse will assess the perineum for edema, bruising, laceration approximation, and pain when assessing vital signs and when indicated (Milton, 2024). Excessive pain may indicate the development of a hematoma. (See Chapter 20 Postpartum Care and Chapter 21 Postpartum Complications for more information.)
Nursing Actions in the Fourth Stage of Labor
In addition to assessing the patient who just delivered, nursing care during the fourth stage of labor includes assisting the health-care provider, monitoring the physiologic and psychologic responses of the birthing person, and assisting with breast-feeding. During this period, the nurse also continues to monitor the birthing person for complications.
Assisting the Health-Care Provider
During the fourth stage of labor, the nurse assists the health-care provider as needed and provides updates on any deviations from normal. Nursing actions may include cleaning the perineum, massaging the fundus, and providing any assistance and supplies for perineal repairs (Milton, 2024). The nurse also informs the HCP of any deviations from normal.
Lidocaine
Patients requiring suturing for a perineal laceration or repair of an episiotomy may require lidocaine . Lidocaine is a local anesthetic that is administered under the skin and to the area under the wound edge to relieve the pain associated with the repair. Lidocaine temporarily numbs the area and allows the health-care provider time to complete the repair while the patient remains comfortable.
Lidocaine ( Xylocaine )
- Indications: pain relief during repair of postpartum perineal tears
- Mechanism of Action: Lidocaine provides local anesthesia by nerve blockade at various sites in the body by stabilizing the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action.
- Adverse Effects: dizziness, tinnitus, confusion, tachycardia, anxiety, chest pain, dyspnea, hives
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Contraindications:
- known hypersensitivity to lidocaine or other local anesthetics of the amide type
- complete heart block
- hypovolemia
- Patient Education:
- Classification: Local anesthetics
- Route/Dosage : 10 to 15 mL of lidocaine 1 percent along the edges of the perineal tear or episiotomy
(Vallerand & Sanoski, 2002)
Monitoring the Physical Response during the Fourth Stage of Labor
Following the delivery of the newborn, the nurse should obtain vital signs of the birthing person every 15 minutes for the first hour and every 30 minutes for the second hour. During this period, the nurse will also assess the birthing person’s fundus, ensuring that it is contracting and that the birthing person’s lochia is small to moderate. The nurse also monitors the birthing person’s bladder immediately after delivery because of any IV fluid intake during labor. A full bladder interferes with uterine involution, increasing the risk of PPH (Milton, 2024). The nurse will need to assist the birthing person to void when needed. It is important for the nurse to monitor the birthing person’s level of pain and to provide comfort measure s or analgesia.
Monitoring the Emotional Response during the Fourth Stage of Labor
The emotional changes that occur for the birthing person during the fourth stage of labor reflect the physical challenges and changes that the birthing person’s body has undergone. Immediately following birth, some birthing persons may feel shocked or disconnected from reality; others may feel wide awake and euphoric. As the intensity of labor wears off, the birthing person may become exhausted and interested in sleeping or resting. The role of the nurse is to support the emotional needs of the birthing person and reassure them that their feelings are normal, all while encouraging bonding with the newborn (Milton, 2024).
Promoting Breast-Feeding
In most cases, the newborn will be placed skin-to-skin with the birthing person. This allows for bonding between the birthing person and the newborn and the initiation of early breast-feeding. Following the birth of the newborn, the nurse may need to educate the birthing person on the importance of breast-feeding and the newborn’s feeding cues. The nurse can support the birthing person by keeping the newborn at the bedside for physical and emotional closeness, and to recognize feeding cues more easily (WHO, 2024). The nurse can assist the birthing person with proper positioning of the infant and attaining a proper latch during feeding. Early assistance with breast-feeding can increase the success of long-term breast-feeding (Couto, 2020). (See Chapter 22 Immediate Care of the Newborn for more information on breast-feeding.)
Toronto Metropolitan Maternity Series: Labor and Delivery includes four games that examine the role of the nurse in preconception and prenatal care. These games promote the application of knowledge and skills related to assessment and intervention, highlight the important components of a comprehensive postpartum assessment, and introduce the nurse to the care of the newborn.
Monitoring for Complications during the Fourth Stage of Labor
The nurse should perform frequent assessments of the uterine fundus, including tone, location, and position. The fundus should be firm and well contracted, with the uterus located midline. Initially, the fundus will be located between the umbilicus and the symphysis pubis, slowly rising to the level of the umbilicus during the first hour after birth.
Fundal massage is performed at regular intervals to assess and maintain the firmness of the uterus. If the uterus becomes boggy at any point, additional fundal massage may be warranted. Any deviation of the fundus to the right or left of the midline requires further assessment and may require additional interventions to promote involution of the uterus. The nurse must continually assess for bladder distention, a common contributor to uterine atony , lack of muscle tone in the uterus following birth, a leading cause of postpartum hemorrhage .
The birthing person’s lochia should be frequently assessed during the fourth stage (Figure 18.7). An increase in lochia is one of the hallmark signs of potential postpartum hemorrhage. When observed, the cause should be investigated and corrected immediately. As previously mentioned, quantitative measurements of blood loss should be obtained, and treatment of postpartum hemorrhage should be a priority for nurses following every delivery (Milton, 2024).
Monitoring Parent-Newborn Attachment
The nurse can continue to encourage skin-to-skin contact between the newborn and the birthing person and support person throughout the fourth stage of labor. The nurse educates the birthing person and support person on the importance of skin-to-skin. The nurse evaluates the interactions between the birthing person and newborn and the support person and newborn. Lack of parental interaction, such as minimal holding, touching, and discussing the infant, has been linked with an increase in risk for abuse and neglect of the newborn (Safari et al., 2022).
Patient Education during the Fourth Stage of Labor
The fourth stage of labor is a time of great importance for patient teaching. The nurse should include teaching about care of the birthing person and the newborn. Fundal massage can be very uncomfortable, and birthing persons may push the nurse away. Educating the birthing person on the importance and need for fundal massage, including a decreased risk of PPH, can improve the birthing person’s acceptance of the intervention. The nurse should educate the birthing person and their partner or support person on the benefits of early skin-to-skin contact with the newborn (Safari et al., 2022) by mentioning how it
- promotes calm and relaxation for both parent and newborn;
- regulates the newborn’s heart rate and breathing, helping with the transition to extrauterine life;
- stimulates digestion and an interest in feeding;
- regulates the newborn’s temperature;
- protects against infection via colonization of the newborn’s skin with the birthing person’s bacteria; and
- stimulates maternal hormones to support breast-feeding and parenting.
Cultural Considerations about Privacy
The needs and expectations when having a baby vary based on the patient’s social, religious, and cultural background. The health-care team should make every effort to understand, respect, and implement the cultural requests of the patient when appropriate. Privacy among cultures may vary, with some patients requesting no male providers or staff at the bedside. The nurse should notify the health-care team of the patient’s requests and provide staff that meet the patient’s needs. When it is not possible to meet the privacy needs of the patient, the nurse should have a discussion with the patient on how to maximize the patient’s privacy.


3.5: Using Advanced Search
Unlike a basic search, advanced search gives you more control over how you structure your search and what that search finds. This can be particularly helpful when doing in-depth research. In most finding tools, you can find a link to advanced search near the default search box.
Advanced search may seem more complicated with more than one search box and various drop-down menus or check boxes, but these can better help you craft a more specific search to help you find relevant resources.
Advanced search features
Most finding tools allow you to do a simple search or use more advanced features. In subject-focused indexes, these features can be highly specialized. Search features you are likely to find in an article index include:
- limiting to only peer-reviewed articles
- full-text or abstract only
- specifying a date range to search within
- restricting to languages you understand
- document type (book chapter, article, etc.)
You can also do more complex searching in advanced search with booleans, field searching, and subject searching.
Booleans in advanced search
Advanced search can help you structure complex Boolean searches more easily. Typically, the advanced search interface starts by displaying two rows of search boxes, but you can add more rows as well. Each row acts to group terms together, with an implied set of parentheses around your search terms. Between the rows, you can select AND, OR, or NOT to choose which Boolean operator is applied between the groups. You can place Booleans alongside your keywords within these search boxes, as well as using the Booleans outside of the search boxes. This can be particularly useful if you are new to using Booleans, as advanced search helps you group your keywords on different rows. You can think of this as showing your work while doing math problems until you’re familiar enough with the processes to be able to perform mental math. This is demonstrated in the figure below.
The example above shows you how to perform a search for ( cinema OR movies OR film ) AND ( french OR france ) AND criticism using advanced search in an article index. We have grouped the related terms together on their own rows using OR. We also connected the three rows with the Boolean operator AND. Even though there are no parentheses displayed around the search boxes, the terms are nested because they are grouped in different rows.
Some finding tools’ advanced search interface lets you choose how your words are processed. Here are some options you might encounter for that.
- The default option in most finding tools, contains/anywhere , finds items that contain your keywords in any order anywhere in the item’s information (not necessarily together in the order you wrote them). Use the default option if you don’t remember the exact title or wording of the item you want to find.
- Use is (exact) or exact phrase only when you’re certain you remember the exact wording of a title, author, or other elements of the item you’re trying to find. This lets you do phrase searching without using quotation marks.
- Use starts with if you know how a title or phrase begins but you aren’t sure what the full title of the book is. You’ll mostly find this in Quick Search.
These options may appear and function differently depending on which finding tool you use. They may present as drop-down menus, radio buttons, checkboxes, or more.


9.2: Introduction to Physical Development in Middle Adulthood
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What you’ll learn to do: explain the physiological changes during middle adulthood and their physical and psychological consequences
Hippocrates (author of the famous “Hippocratic oath”) was of the opinion that “walking is the best medicine.” This was his learned opinion in 400 BCE and there is now considerable, and increasing, evidence that he may have been correct.
As we will see, there are simple physiological changes that accompany middle adulthood. These are somewhat inevitable, but the importance of physical activity at this age range would be difficult to overstate looking at the evidence. Exercise does not necessarily mean running marathons, it may simply mean a commitment to using your legs in a brisk fashion for thirty minutes. “Use it or lose it” is a good mantra for this stage of development—the technical term for the the loss of muscle tissue and function as we age is sarcopenia. From age 30, the body loses 3-8% of its muscle mass per decade, and this accelerates after the age of 60 (Volpi et al, 2010). Diet and exercise can ameliorate both the extent and lifestyle consequences of these kinds of processes. In this section, we will examine some of the changes associated with middle adulthood and consider how they impact human life.
Contributors and Attributions
CC licensed content, Original
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Introduction to Physical Development in Middle Adulthood.
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7.6: Spermatophyta - Seed Plants
Seed plants consist of approximately 1,000 species of non-angiosperms ( gymnosperms ) and about 250,000 species of angiosperms . They have a sporic life-cycle with sporophyte predominance, and seeds. The gametophyte is reduced to cells inside the ovule or pollen grain. Males have a minimum number of cells being three and females being four. The antheridia are absent and in flowering plants (Angiospermae) and Gnetopsida the archegonia are also reduced. The sporophyte will always start as an embryo located inside the nutrition tissue, endosperm\(_1\) which is the female gametophyte or in endosperm\(_2\) (see the next chapter). Spermatophyta have axillary buds (buds in leaf axils). Like ferns, they are megaphyllous and homoiohydric, and have a secondary thickening. Higher groups of seed plants lost flagellate spermatozoa and developed pollen tubes. The classes of Spermatophyta are Ginkgoopsida, Cycadopsida, Pinopsida, Gnetopsida, and Angiospermae.
Ginkgoopsida is just one species; ginkgo or maidenhair tree ( Ginkgo biloba ). This plant is long extinct in the wild but is grown on Chinese temple grounds as a decorative tree. Ginkgo is a large tree bearing distinctive triangle-shaped leaf with dichotomous venation. This plant is also dioecious (as an exception among plants, Ginkgo has sexual chromosomes like birds and mammals) and the pollen is transported by wind to female (ovulate) trees. The pollen grains of the ginkgo plants produce two multi-flagellate spermatozoa; the edible seed is fruit-like and becomes ripe after lying on the ground for a long time. Maidenhair tree has symbiotic cyanobacteria in cells. As ginkgo probably went through the population bottleneck, there are very few, almost no, phytophagous insects that can damage ginkgo leaves. The only fungus which is capable to eat them, Bartheletia , is also a living fossil.
Cycadopsida —cycads is a class with few genera and about 300 species that grow mostly in tropics. Only one species grows naturally in the United States, Zamia pumil a, and can be found in Florida and Georgia. Cycads are palm-like plants with large, pinnate leaves. Their wood is rich of parenchyma since stem has anomalous secondary thickening. They are all dioecious and its cone is large and protected by prickles and woody plates. The ovules of these plants are attached to modified leaves ( megasporophylls ) that are gathered in upright cones. Like ginkgo, they have multi-flagellate spermatozoa, archegonia and large oocyte. Cycad seeds are distributed by animals. Life cycle is extremely slow.
Pinopsida —conifers are the most widely known and economically important among gymnosperms. Conifers consist of approximately 630 species. Most of them are temperate evergreen trees, but some are deciduous, such as larch ( Larix ). The stem has a large amount of xylem, a small cork, and minute pith. The ovules are attached to specialized leaves, seed scales , and are compacted in cones with bract scales (Figure \(\PageIndex{1}\)). Some conifers, like junipers ( Juniperus ) and yews ( Taxus ), lack woody cones; these plants have fleshy scales. Seeds are distributed by wind and animals.
In all, conifer life cycle takes up to two years. Conifers do not have flagellate spermatozoa; their non-motile male gametes (spermatia) move inside long, fast-growing pollen tube. Among families of conifers, Pinaceae (pine family) have resin and needle-like leaves; Pinus have them in shortened shoots, brachyblasts , and their large cones have woody scales. Cupressaceae (cypress family) do not have resin, produce small cones that have a fused bract and seed scales, have dimorphic leaves, and some of their genera (like “living fossil” Metasequoia from China) are deciduous in an unusual way: they drop whole branches, not individual leaves.
Gnetopsida —gnetophytes are sometimes called chlamydosperms. They are a small class with only three genera that are not at all similar: Ephedra , Welwitschia , and Gnetum . While these plants morphologically remind of angiosperms, they are molecularly related more to other gymnosperms. Ephedra are horsetail-like desert leafless shrubs, Gnetum are tropical trees, and Welwitschia are plants which have a life form that is really hard to tell (Figure \(\PageIndex{2}\)).
Ephedra has archegonia, but in Gnetum and Welwitschia they are reduced. On the other hand, Ephedra and Gnetum have double fertilization the process when two brother male gametes fertilize two sister female cells : both male nuclei fuse with cells of the one female gametophyte (endosperm\(_1\)): with egg cell and another haploid cell, sister to the egg. Double fertilization in gnetophytes results in two competing embryos, and only one of them will survive in future seed.
Both Gnetum and Welwitschia have vessels (like angiosperms). Gnetum also has angiosperm-like opposite leaves with pterodromous venation, like, for example, coffee tree (however, this probably is a result of modification of dichotomous venation). Ovules of chlamydosperms are solitary and covered with an additional outer integument; the male gametes are spermatia moving inside pollen tube.
Welwitschia is probably most outstanding among gnetophytes. There is only one species that occurs in the Namibian desert. The best way to describe this plant is an “overgrown seedling.” It has a small trunk with two wide leaves that have parallelodromous venation. The secondary thickening is anomalous, wood has vessels. Plant is insect-pollinated, and its winged seeds are dispersed by the wind. Fertilization is not double, but, along with pollen tubes, involves the most crazy structures: prothallial tubes which grow from female gametophyte and meet with pollen tubes to make zygote.
Life cycles determine the basic diversity of plants, they designate plant phyla. Let us compare three types of life cycles again (Figure \(\PageIndex{3}\)) and again (Figure \(\PageIndex{4}\)). What is visible on all these schemes, as well as on all similar schemes from above, is growing complexity of cycle, growing reduction of haploid stage, and growing self-similarity within the cycle.


15.5: Summary
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The pressure from a force, \(\vec F\), exerted over a surface with area, \(A\), is a scalar quantity defined as:
\[\begin{aligned} P=\frac{F_{\perp}}{A} \end{aligned}\]
where \(F_{⊥}\) is the component of the force perpendicular to the surface.
If a force is exerted on the particles in a fluid (e.g. gravity), a pressure will exist everywhere in the fluid. If the fluid is placed in a container, that pressure leads to an external force on all surfaces of the container.
If two fluids at different pressures exist on either side of an interface/object, the net force on that interface/object from the pressures of the fluids will be proportional to the difference in pressure of the fluids on either side.
A fluid is in hydrostatic equilibrium if the sum of the forces on any fluid element is zero. In the presence of gravity, this always leads to a vertical pressure gradient
\[\begin{aligned}\frac{dP}{dy}=-\rho g \end{aligned}\]
where \(ρ\) is the density of the fluid, \(g\) is the magnitude of the Earth’s gravitational field, and the \(y\) axis is positive upwards.
If the fluid is incompressible, then the difference in pressure between two points at heights \(y_{1}\) and \(y_{2}\) is given by:
\[\begin{aligned} P(y_{2})-P(y_{1})=-\rho g(y_{2}-y_{1}) \end{aligned}\]
Pascal’s Principle states that if an external pressure, \(P\), is applied to one location in a fluid, then the pressure everywhere in the fluid increases by \(P\).
If an object is immersed in a fluid, it will experience a force of buoyancy that is in the opposite direction to the gravitational field in that fluid. The magnitude of the buoyancy force is given by Archimedes’ Principle:
\[\begin{aligned} F_{B}=\rho Vg \end{aligned}\]
where, \(ρ\), is the density of the fluid and, \(V\), is the volume of the fluid displaced by the object (i.e. the volume of the part of the object that is immersed in the fluid).
We can distinguish between laminar and turbulent flow of fluids. In laminar flow, individual particles in the fluid follow well-defined streamlines. In turbulent flow, individual particle follow complicated paths that usually involve Eddy currents. In general, it is much easier to model the laminar flow of fluids.
The equation of continuity states that the mass flow rate of a fluid through a closed system must be the same everywhere in the system (no fluid can appear or disappear). For laminar flow of a fluid with density, \(ρ\), flowing at speed, \(v\), through a pipe with cross section, \(A\), the mass flow rate is a constant:
\[\begin{aligned} \rho Av=\text{constant} \end{aligned}\]
A fluid is said to be incompressible if it has constant density. For a fluid of constant density, the volume flow rate, \(Q\), must be constant everywhere in a closed system:
\[\begin{aligned} Q=Av=\text{constant} \end{aligned}\]
Bernoulli’s Principle, which is based on the conservation of mechanical energy, states that the following quantity is a constant:
\[\begin{aligned} P+\frac{1}{2}\rho v^{2}+\rho gy=\text{constant} \end{aligned}\]
for the laminar flow of a fluid with no viscosity. \(P\) is the internal pressure of the fluid, \(v\) its speed, and \(y\) the height of the fluid relative to a fixed coordinate system. In particular, Bernoulli’s Principle implies that, for a constant height, the internal pressure of a fluid must decrease if its speed increases.
Viscosity, \(η\), for the laminar flow of a fluid can be modeled as the result of the internal friction force between layers of the fluid. Because of viscosity, a fluid cannot flow in a horizontal pipe unless there is a difference in pressure across the pipe. Similarly, there will be no horizontal pressure gradient through a fluid unless the fluid is flowing. In general, the volume flow rate, \(Q\), of an incompressible fluid through a pipe with resistance, \(R\), is given by:
\[\begin{aligned} Q=\frac{\Delta P}{R} \end{aligned}\]
For the laminar flow of a fluid with viscosity, \(η\), through a horizontal cylindrical pipe of length, \(L\), and radius, \(r\), the flow rate is given by Poiseuille’s equation:
\[\begin{aligned}Q=\frac{\pi r^{4}}{8ηL}\Delta P \end{aligned}\]
Important Equations
In the presence of gravity:
\[\begin{aligned} \frac{dP}{dy}&=-\rho g \\[4pt] P(y_{2})-P(y_{1})&=-\rho g(y_{2}-y_{1}) \\[4pt] F_{B}&=\rho Vg \end{aligned}\]
Equation of continuity:
\[\begin{aligned} \rho Av&=\text{constant} \\[4pt] Q&=Av=\text{constant}\quad\text{(if incompressible)} \end{aligned}\]
Bernoulli:
\[\begin{aligned} P+\frac{1}{2}\rho v^{2}+\rho gy=\text{constant}\end{aligned}\]
Viscosity:
\[\begin{aligned} Q&=\frac{\Delta P}{R} \\[4pt] Q&=\frac{\pi r^{4}}{8ηL}\Delta P\quad\text{(Poiseuille)} \end{aligned}\]
Important Definitions
Definition
Pressure : A measurement of force per unit area. SI units: \([\text{Pa}]\). Common variable(s): \(P\).
Definition
Viscosity : A measurement of a fluid’s resistance to flow. SI units: \([\text{Pas}]\). Common variable(s): \(η\).
Definition
Flow rate : Measurement of a fluid’s motion, in volume per unit time. SI units: \([\text{m}^{3}\text{s}^{−1}]\). Common variable(s): \(Q\).


18.2: Desultory Thoughts Upon the Utility of encouraging a degree of Self-Complacency especially in Female Bosoms
Self-estimation, kept within due bounds,
However oddly the assertion sounds,
May, of the fairest efforts be the root,
May yield the embow’ring shade–the mellow fruit;
May stimulate to most exalted deeds,
Direct the soul where blooming honor leads;
May give her there, to act a noble part,
To virtuous pleasures yield the willing heart.
Self-estimation will debasement shun,
And, in the path of wisdom, joy to run;
An unbecoming act in fears to do,
And still, its exaltation keeps in view.
“To rev’rence self,” a Bard long since directed,
And, on each moral truth HE well reflected;
But, lost to conscious worth, to decent pride,
Compass nor helm there is, our course to guide:
Nor may we anchor cast, for rudely tost
In an unfathom’d sea, each motive’s lost,
Wildly amid contending waves we’re beat,
And rocks and quick sands, shoals and depths we meet;
‘Till, dash’d in pieces, or, till found’ring, we
One common wreck of all our prospects see!
Nor, do we mourn, for we were lost to fame,
And never hap’d to reach a tow’ring name;
Ne’er taught to “rev’rence self,” or to aspire,
Our bosoms never caught ambition’s fire;
An indolence of virtue still prevail’d,
Nor the sweet gale of praise was e’er inhal’d;
Rous’d by a new stimulus, no kindling glow.
No soothing emulations gentle flow,
We judg’d that nature, not to us inclin’d,
In narrow bounds our progress had confin’d,
And, that our forms, to say the very best,
Only, not frightful, were by all confest.
I think, to teach young minds to aspire, ought to be the ground work of education: many a laudable achievement is lost, from a persuasion that our efforts are unequal to the arduous attainment. Ambition is a noble principle, which properly directed, may be productive of the most valuable consequences. It is amazing to what heights the mind by exertion may tow’r: I would, therefore, have my pupils believe, that every thing in the compass of mortality, was placed within their grasp, and that, the avidity of application, the intenseness of study, were only requisite to endow them with every external grace, and mental accomplishment. Thus I should impel them to progress on, if I could not lead them to the heights I would wish them to attain. It is too common with parents to expatiate in their hearing, upon all the foibles of their children, and to let their virtues pass, in appearance, unregarded: this they do, least they should, (were they to commend) swell their little hearts to pride, and implant in their tender minds, undue conceptions of their own importance. Those, for example, who have the care of a beautiful female, they assiduously guard every avenue, they arrest the stream of due admiration, and endeavour to divest her of all idea of the bounties of nature: what is the consequence? She grows up, and of course mixes with those who are less interested: strangers will be sincere; she encounters the tongue of the flatterer, he will exaggerate, she finds herself possessed of accomplishments which have been studiously concealed from her, she throws the reins upon the neck of fancy, and gives every encomiast full credit for his most extravagant eulogy. Her natural connexions, her home is rendered disagreeable, and she hastes to the scenes, whence arise the sweet perfume of adulation, and when she can obtain the regard due to a merit, which she supposes altogether uncommon. Those who have made her acquainted with the dear secret, she considers as her best friends; and it is more than probable, that she will soon fall a sacrifice to some worthless character, whose interest may lead him to the most hyperbolical lengths in the round of flattery. Now, I should be solicitous that my daughter should possess for me the fondest love, as well as that respect which gives birth to duty; in order to promote this wish of my soul, from my lips she should be accustomed to hear the most pleasing truths, and, as in the course of my instructions, I should doubtless find myself but too often impelled to wound the delicacy of youthful sensibility. I would therefore, be careful to avail myself of this exuberating balance: I would, from the early dawn of reason, address her as a rational being; hence, I apprehend, the most valuable consequences would result: in some such language as this, she might from time to time be accosted. A pleasing form is undoubtedly advantageous, nature, my dear, hath furnished you with an agreeable person, your glass, was I to be silent, would inform you that you are pretty, your appearance will sufficiently recommend you to a stranger, the flatterer will give a more than mortal finishing to every feature; but, it must be your part, my sweet girl, to render yourself worthy respect from higher motives: you must learn “to reverence yourself,” that is, your intellectual existence; you must join my efforts, in endeavouring to adorn your mind, for, it is from the proper furnishing of that, you will become indeed a valuable person, you will, as I said, give birth to the most favorable impressions at first sight: but, how mortifying should this be all, if, upon a more extensive knowledge you should be discovered to possess no one mental charm, to be fit only at best, to be hung up as a pleasing picture among the paintings of some spacious hall. The flatterer, indeed, will still pursue you, but it will be from interested views, and he will smile at your undoing! Now, then, my best Love, is the time for you to lay in such a fund of useful knowledge, as shall continue, and augment every kind sentiment in regard to you, as shall set you above the snares of the artful betrayer.
Thus, that sweet form, shall serve but as a polished casket, which will contain a most beautiful gem, highly finished, and calculated for advantage, as well as ornament. Was she, I say, habituated thus to reflect, she would be taught to aspire; she would learn to estimate every accomplishment, according to its proper value; and, when the voice of adulation should assail her ear, as she had early been initiated into its true meaning, and from youth been accustomed to the language of praise; her attention would not be captivated, the Siren’s song would not borrow the aid of novelty, her young mind would not be enervated or intoxicated, by a delicious surprise, she would possess her soul in serenity and by that means, rise superior to the deep-laid schemes which, too commonly, encompass the steps of beauty.
Neither should those to whom nature had been parsimonious, be tortured by me with degrading comparisons; every advantage I would expatiate upon, and there are few who possess not some personal charms; I would teach them to gloss over their imperfections, inasmuch as, I do think, an agreeable form, a very necessary introduction to society, and of course it behoves us to render our appearance as pleasing as possible: I would, I must repeat, by all means guard them against a low estimation of self. I would leave no charm undiscovered or unmarked, for the penetrating eye of the pretended admirer, to make unto himself a merit by holding up to her view; thus, I would destroy the weapons of flattery, or render them useless, by leaving not the least room for their operation.
A young lady, growing up with the idea, that she possesses few, or no personal attractions, and that her mental abilities are of an inferior kind, imbibing at the same time, a most melancholly idea of a female, descending down the vale of life in an unprotected state; taught also to regard her character ridiculously contemptible, will, too probably, throw herself away upon the first who approaches her with tenders of love, however indifferent may be her chance for happiness, least if she omits the present day of grace, she may never be so happy as to meet a second offer, and must then inevitably be stigmatized with that dreaded title, an Old Maid, must rank with a class whom she has been accustomed to regard as burthens upon society, and objects whom she might with impunity turn into ridicule! Certainly love, friendship and esteem, ought to take place of marriage, but, the woman thus circumstanced, will seldom regard these previous requisites to felicity, if she can but insure the honors, which she, in idea, associates with a matrimonial connection–to prevent which great evil, I would early impress under proper regulations, a reverence of self; I would endeavour to rear to worth, and a consciousness thereof: I would be solicitous to inspire the glow of virtue, with that elevation of soul, that dignity, which is ever attendant upon self-approbation, arising from the genuine source of innate rectitude. I must be excused for thus insisting upon my hypothesis, as I am, from observation, persuaded, that many have suffered materially all their life long, from a depression of soul, early inculcated, in compliance to a false maxim, which hath supposed pride would thereby be eradicated. I know there is a contrary extreme, and I would, in almost all cases, prefer the happy medium. However, if these fugitive hints may induce some abler pen to improve thereon, the exemplification will give pleasure to the heart of CONSTANTIA.
October 22, 1784.


20.6B: Structure and Function of Antibodies
An antibody is a Y-shaped protein produced by B cells to identify and neutralize antigens in the body.
- Describe antibody structure and function
Key Points
- An antibody, also known as an immunoglobulin, is a large Y-shaped protein produced by B- cells and used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.
- Each tip of the “Y” of an antibody contains a paratope (a structure analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision.
- Though the general structure of antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with different antigen binding sites to exist. This region is known as the hypervariable region.
- Five isotypes of antibodies are found in different locations and perform different specific functions.
- The base of the Y plays a role in modulating immune cell activity. This region is called the Fc region, and phagocytes may bind to it to initiate phagocytosis.
- Antibodies that bind to surface antigens on a bacterium attract the first component of the complement cascade with their Fc region and initiate activation of the classical complement system.
Key Terms
- epitope : Part of a biomolecule (such as a protein) that is the target of an immune response.
- paratope : Part of the molecule of an antibody that binds to an antigen.
- isotype : A marker corresponding to an antigen found in all members of a subclass of a specific class of immunoglobulins.
An antibody (formally called immunoglobulin) is a large Y-shaped glycoprotein produced by B-cells and used by the immune system to identify and neutralize pathogens. Antibodies are produced by B cells, and are either secreted into circulation or remain expressed on the surface of the B cell.
Structure of Antibodies
The antibody recognizes a unique part of an antigen (foreign object). Each tip of the “Y” of an antibody contains a paratope (a structure analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can neutralize its target directly or tag it for attack by other parts of the immune system.
Antibody : Each antibody binds to a specific antigen, an interaction similar to a lock and key.
Antibodies are glycoproteins belonging to the immunoglobulin superfamily, typically made of basic structural units each with two large heavy chains and two small light chains. Most antibodies exist as a monomer, in which they have a single “Y” shaped sub-unit, but some antibodies can exist as dimers (two subunits) or pentamers (five subunits). The paratope is considered a hypervariable region and has the same specificity and antigen-binding affinity as the B cell receptor of the B cell that created the antibody. In some isotypes, the tail end of the antibody is called the constant region and faces away from the “Y-shaped” paratobe ends, functioning as an Fc tail to which phagocytes can bind.
Isotypes
Five different isotypes of antibodies each perform different functions and are generally found in different parts of the body.
- IgA: A dimer secreted into mucosal surfaces, such as the gut, respiratory tract, and urogenital tract, that prevents mucosal invasion into the body by pathogens. It is resistant to the proteolytic enzymes found in the gastrointestinal mucosae.
- IgD: Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. It has been shown to activate basophils and mast cells to produce antimicrobial factors.
- IgE: Found in circulation and binds to allergens, triggering histamine release from mast cells and basophils. Also protects against parasitic worms.
- IgG: Has four different forms and provides the majority of antibody-based immunity against invading pathogens as the best opsonin of any type of antibody. This is because it expresses a tail for Fc receptors on phagocytes to bind to, which activates phagocytosis. It is the only antibody capable of crossing the placenta to give passive immunity to fetus, and can activate the classical complement system.
- IgM: Expressed on the surface of B cells (monomer) and in a secreted pentamer with very high avidity. Eliminates pathogens in the early stages of B cell-mediated (humoral) immunity before there is sufficient IgG. Like IgG, it can also activate the classical complement system.
Function of Antibodies
Circulating antibodies are produced by clonal B cells that specifically respond to only one antigen. Antibodies contribute to immunity in three ways: preventing pathogens from entering or damaging cells by binding to them (neutralization); stimulating removal of pathogens by macrophages and other cells by coating the pathogen (opsonization); and triggering destruction of pathogens by stimulating other immune responses such as the complement pathway. The complement system starts a long cascade of protein productions that either opsonize a pathogen for phagocytosis or lyse it directly by forming a membrane attack complex. During opsonization, the antibody expresses the tail for an Fc receptor on a macrophage, neutrophil, or natural killer cell. The immune cell will then bind to the antibody’s Fc tail instead of the pathogen itself, which speeds up the process of finding pathogens to phagocytize. Additionally, because antibodies have two or more paratopes, they can sometimes link pathogens together, making phagocytosis more efficient.


3.2.3: Elements of Culture
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Values and Beliefs
The first, and perhaps most crucial, elements of culture we will discuss are its values and beliefs. Values are a culture’s standard for discerning what is good and just in society. Values are deeply embedded and critical for transmitting and teaching a culture’s beliefs.Beliefs are the tenets or convictions that people hold to be true. Individuals in a society have specific beliefs, but they also share collective values. To illustrate the difference, Americans commonly believe in the American Dream—that anyone who works hard enough will be successful and wealthy. Underlying this belief is the American value that wealth is good and important.
Values help shape a society by suggesting what is good and bad, beautiful and ugly, sought or avoided. Consider the value that the United States places upon youth. Children represent innocence and purity, while a youthful adult appearance signifies sexuality. Shaped by this value, individuals spend millions of dollars each year on cosmetic products and surgeries to look young and beautiful. The United States also has an individualistic culture, meaning people place a high value on individuality and independence. In contrast, many other cultures are collectivist, meaning the welfare of the group and group relationships are a primary value.
Living up to a culture’s values can be difficult. It’s easy to value good health, but it’s hard to quit smoking. Marital monogamy is valued, but many spouses engage in infidelity. Cultural diversity and equal opportunities for all people are valued in the United States, yet the country’s highest political offices have been dominated by white men.
Values often suggest how people should behave, but they don’t accurately reflect how people do behave. Values portray an ideal culture, the standards society would like to embrace and live up to. But ideal culture differs from real culture, the way society actually is, based on what occurs and exists. In an ideal culture, there would be no traffic accidents, murders, poverty, or racial tension. But in real culture, police officers, lawmakers, educators, and social workers constantly strive to prevent or repair those accidents, crimes, and injustices. American teenagers are encouraged to value celibacy. However, the number of unplanned pregnancies among teens reveals that not only is the ideal hard to live up to, but the value alone is not enough to spare teenagers the potential consequences of having sex.
One way societies strive to put values into action is through rewards, sanctions, and punishments. When people observe the norms of society and uphold its values, they are often rewarded. A boy who helps an elderly woman board a bus may receive a smile and a “thank you.” A business manager who raises profit margins may receive a quarterly bonus. People sanction certain behaviors by giving their support, approval, or permission, or by instilling formal actions of disapproval and nonsupport. Sanctions are a form of social control, a way to encourage conformity to cultural norms. Sometimes people conform to norms in anticipation or expectation of positive sanctions: good grades, for instance, may mean praise from parents and teachers. From a criminal justice perspective, properly used social control is also inexpensive crime control. Utilizing social control approaches pushes most people to conform to societal rules, regardless of whether authority figures (such as law enforcement) are present.
When people go against a society’s values, they are punished. A boy who shoves an elderly woman aside to board the bus first may receive frowns or even a scolding from other passengers. A business manager who drives away customers will likely be fired. Breaking norms and rejecting values can lead to cultural sanctions such as earning a negative label—lazy, no-good bum—or to legal sanctions, such as traffic tickets, fines, or imprisonment.
Values are not static; they vary across time and between groups as people evaluate, debate, and change collective societal beliefs. Values also vary from culture to culture. For example, cultures differ in their values about what kinds of physical closeness are appropriate in public. It’s rare to see two male friends or coworkers holding hands in the United States where that behavior often symbolizes romantic feelings. But in many nations, masculine physical intimacy is considered natural in public. This difference in cultural values came to light when people reacted to photos of former president George W. Bush holding hands with the Crown Prince of Saudi Arabia in 2005. A simple gesture, such as hand-holding, carries great symbolic differences across cultures.
In many parts of Africa and the Middle East, it is considered normal for men to hold hands in friendship. How would Americans react to these two soldiers? (Photo courtesy of Geordie Mott/Wikimedia Commons)
Norms
So far, the examples in this chapter have often described how people are expected to behave in certain situations—for example, when buying food or boarding a bus. These examples describe the visible and invisible rules of conduct through which societies are structured, or what sociologists call norms. Norms define how to behave in accordance with what a society has defined as good, right, and important, and most members of the society adhere to them.
Formal norms are established, written rules. They are behaviors worked out and agreed upon in order to suit and serve the most people. Laws are formal norms, but so are employee manuals, college entrance exam requirements, and “no running” signs at swimming pools. Formal norms are the most specific and clearly stated of the various types of norms, and they are the most strictly enforced. But even formal norms are enforced to varying degrees and are reflected in cultural values.
For example, money is highly valued in the United States, so monetary crimes are punished. It’s against the law to rob a bank, and banks go to great lengths to prevent such crimes. People safeguard valuable possessions and install antitheft devices to protect homes and cars. A less strictly enforced social norm is driving while intoxicated. While it’s against the law to drive drunk, drinking is for the most part an acceptable social behavior. And though there are laws to punish drunk driving, there are few systems in place to prevent the crime. These examples show a range of enforcement in formal norms.
There are plenty of formal norms, but the list of informal norms—casual behaviors that are generally and widely conformed to—is longer. People learn informal norms by observation, imitation, and general socialization. Some informal norms are taught directly—“Kiss your Aunt Edna” or “Use your napkin”—while others are learned by observation, including observations of the consequences when someone else violates a norm. But although informal norms define personal interactions, they extend into other systems as well. In the United States, there are informal norms regarding behavior at fast food restaurants. Customers line up to order their food and leave when they are done. They don’t sit down at a table with strangers, sing loudly as they prepare their condiments, or nap in a booth. Most people don’t commit even benign breaches of informal norms. Informal norms dictate appropriate behaviors without the need of written rules.
BREACHING EXPERIMENTS
Sociologist Harold Garfinkel (1917–2011) studied people’s customs in order to find out how societal rules and norms not only influenced behavior but also shaped social order. He believed that members of society together create a social order (Weber 2011). His resulting book, Studies in Ethnomethodology , published in 1967, discusses people’s assumptions about the social makeup of their communities.
One of Garfinkel's research methods was known as a “breaching experiment,” in which the researcher behaves in a socially awkward manner in order to test the sociological concepts of social norms and conformity. The participants are not aware an experiment is in progress. If the breach is successful, however, these “innocent bystanders” will respond in some way. For example, if the experimenter is, say, a man in a business suit, and he skips down the sidewalk or hops on one foot, the passersby are likely to stare at him with surprised expressions on their faces. But the experimenter does not simply “act weird” in public. Rather, the point is to deviate from a specific social norm in a small way, to subtly break some form of social etiquette, and see what happens.
To conduct his ethnomethodology, Garfinkel deliberately imposed strange behaviors on unknowing people. Then he observed their responses. He suspected that odd behaviors would shatter conventional expectations, but he wasn’t sure how. For example, he set up a simple game of tic-tac-toe. One player was asked beforehand to mark Xs and Os not in the boxes but on the lines dividing the spaces instead. The other player, in the dark about the study, was flabbergasted and did not know how to continue. The second player's reactions of outrage, anger, puzzlement, or other emotions illustrated the existence of cultural norms that constitute social life. These cultural norms play an important role. They let us know how to behave around each other and how to feel comfortable in our community.
There are many rules about speaking with strangers in public. It’s OK to tell a woman you like her shoes. It’s not OK to ask if you can try them on. It’s OK to stand in line behind someone at the ATM. It’s not OK to look over his shoulder as he makes his transaction. It’s OK to sit beside someone on a crowded bus. It’s weird to sit beside a stranger in a half-empty bus.
For some breaches, the researcher directly engages with innocent bystanders. An experimenter might strike up a conversation in a public bathroom, where it’s common to respect each other’s privacy so fiercely as to ignore other people’s presence. In a grocery store, an experimenter might take a food item out of another person’s grocery cart, saying, “That looks good! I think I’ll try it.” An experimenter might sit down at a table with others in a fast food restaurant or follow someone around a museum and study the same paintings. In those cases, the bystanders are pressured to respond, and their discomfort illustrates how much we depend on social norms. Breaching experiments uncover and explore the many unwritten social rules we live by.
Norms may be further classified as either mores or folkways. Mores (mor-ays) are norms that embody the moral views and principles of a group. Violating them can have serious consequences. The strongest mores are legally protected with laws or other formal norms. In the United States, for instance, murder is considered immoral, and it’s punishable by law (a formal norm). But more often, mores are judged and guarded by public sentiment (an informal norm). People who violate mores are seen as shameful. They can even be shunned or banned from some groups. The mores of the U.S. school system require that a student’s writing be in the student’s own words or use special forms (such as quotation marks and a whole system of citation) for crediting other writers. Writing another person’s words as if they are one’s own has a name—plagiarism. The consequences for violating this norm are severe and usually result in expulsion.
Unlike mores, folkways are norms without any moral underpinnings. Rather, folkways direct appropriate behavior in the day-to-day practices and expressions of a culture. They indicate whether to shake hands or kiss on the cheek when greeting another person. They specify whether to wear a tie and blazer or a T-shirt and sandals to an event. In Canada, women can smile and say hello to men on the street. In Egypt, that’s not acceptable. In regions in the southern United States, bumping into an acquaintance means stopping to chat. It’s considered rude not to, no matter how busy one is. In other regions, people guard their privacy and value time efficiency. A simple nod of the head is enough. Other accepted folkways in the United States may include holding the door open for a stranger or giving someone a gift on their birthday. The rules regarding these folkways may change from culture to culture.
Many folkways are actions we take for granted. People need to act without thinking in order to get seamlessly through daily routines; they can’t stop and analyze every action (Sumner 1906). Those who experience culture shock may find that it subsides as they learn the new culture’s folkways and are able to move through their daily routines more smoothly. Folkways might be small manners, learned by observation and imitated, but they are by no means trivial. Like mores and laws, these norms help people negotiate their daily lives within a given culture.
Symbols and Language
Humans, consciously and subconsciously, are always striving to make sense of their surrounding world. Symbols—such as gestures, signs, objects, signals, and words—help people understand that world. They provide clues to understanding experiences by conveying recognizable meanings that are shared by societies.
The world is filled with symbols. Sports uniforms, company logos, and traffic signs are symbols. In some cultures, a gold ring is a symbol of marriage. Some symbols are highly functional; stop signs, for instance, provide useful instruction. As physical objects, they belong to material culture, but because they function as symbols, they also convey nonmaterial cultural meanings. Some symbols are valuable only in what they represent. Trophies, blue ribbons, or gold medals, for example, serve no other purpose than to represent accomplishments. But many objects have both material and nonmaterial symbolic value.
A police officer’s badge and uniform are symbols of authority and law enforcement. The sight of an officer in uniform or a squad car triggers reassurance in some citizens, and annoyance, fear, or anger in others.
It’s easy to take symbols for granted. Few people challenge or even think about stick figure signs on the doors of public bathrooms. But those figures are more than just symbols that tell men and women which bathrooms to use. They also uphold the value, in the United States, that public restrooms should be gender exclusive. Even though stalls are relatively private, most places don’t offer unisex bathrooms.
Some road signs are universal. But how would you interpret the signage on the right? (Photo (a) courtesy of Andrew Bain/flickr; Photo (b) courtesy of HonzaSoukup/flickr)
Symbols often get noticed when they are out of context. Used unconventionally, they convey strong messages. A stop sign on the door of a corporation makes a political statement, as does a camouflage military jacket worn in an antiwar protest. Together, the semaphore signals for “N” and “D” represent nuclear disarmament—and form the well-known peace sign (Westcott 2008). Today, some college students have taken to wearing pajamas and bedroom slippers to class, clothing that was formerly associated only with privacy and bedtime. Though students might deny it, the outfit defies traditional cultural norms and makes a statement.
Even the destruction of symbols is symbolic. Effigies representing public figures are burned to demonstrate anger at certain leaders. In 1989, crowds tore down the Berlin Wall, a decades-old symbol of the division between East and West Germany, communism, and capitalism.
While different cultures have varying systems of symbols, one symbol is common to all: language. Language is a symbolic system through which people communicate and through which culture is transmitted. Some languages contain a system of symbols used for written communication, while others rely on only spoken communication and nonverbal actions.
Societies often share a single language, and many languages contain the same basic elements. An alphabet is a written system made of symbolic shapes that refer to spoken sound. Taken together, these symbols convey specific meanings. The English alphabet uses a combination of twenty-six letters to create words; these twenty-six letters make up over 600,000 recognized English words (OED Online 2011).
Rules for speaking and writing vary even within cultures, most notably by region. Do you refer to a can of carbonated liquid as “soda,” pop,” or “Coke”? Is a household entertainment room a “family room,” “rec room,” or “den”? When leaving a restaurant, do you ask your server for a “check,” the “ticket,” or your “bill”?
Language is constantly evolving as societies create new ideas. In this age of technology, people have adapted almost instantly to new nouns such as “e-mail” and “Internet,” and verbs such as “downloading,” “texting,” and “blogging.” Twenty years ago, the general public would have considered these nonsense words.
Even while it constantly evolves, language continues to shape our reality. This insight was established in the 1920s by two linguists, Edward Sapir and Benjamin Whorf. They believed that reality is culturally determined, and that any interpretation of reality is based on a society’s language. To prove this point, the sociologists argued that every language has words or expressions specific to that language. In the United States, for example, the number thirteen is associated with bad luck. In Japan, however, the number four is considered unlucky, since it is pronounced similarly to the Japanese word for “death.”
The Sapir-Whorf hypothesis is based on the idea that people experience their world through their language, and that they therefore understand their world through the culture embedded in their language. The hypothesis, which has also been called linguistic relativity, states that language shapes thought (Swoyer 2003). Studies have shown, for instance, that unless people have access to the word “ambivalent,” they don’t recognize an experience of uncertainty from having conflicting positive and negative feelings about one issue. Essentially, the hypothesis argues, if a person can’t describe the experience, the person is not having the experience.
In addition to using language, people communicate without words. Nonverbal communication is symbolic, and, as in the case of language, much of it is learned through one’s culture. Some gestures are nearly universal: smiles often represent joy, and crying often represents sadness. Other nonverbal symbols vary across cultural contexts in their meaning. A thumbs-up, for example, indicates positive reinforcement in the United States, whereas in Russia and Australia, it is an offensive curse (Passero 2002). Other gestures vary in meaning depending on the situation and the person. A wave of the hand can mean many things, depending on how it’s done and for whom. It may mean “hello,” “goodbye,” “no thank you,” or “I’m royalty.” Winks convey a variety of messages, including “We have a secret,” “I’m only kidding,” or “I’m attracted to you.” From a distance, a person can understand the emotional gist of two people in conversation just by watching their body language and facial expressions. Furrowed brows and folded arms indicate a serious topic, possibly an argument. Smiles, with heads lifted and arms open, suggest a lighthearted, friendly chat.
IS THE UNITED STATES BILINGUAL?
In 1991, when she was six years old, Lucy Alvarez attended a school that allowed for the use of both English and Spanish. Lucy’s teacher was bilingual, the librarian offered bilingual books, and many of the school staff spoke both Spanish and English. Lucy and many of her classmates who spoke only Spanish at home were lucky. According to the U.S. Census, 13.8 percent of U.S. residents speak a non-English language at home. That’s a significant figure, but not enough to ensure that Lucy would be encouraged to use her native language in school (Mount 2010).
Lucy’s parents, who moved to Texas from Mexico, struggled under the pressure to speak English. Lucy might easily have gotten lost and left behind if she’d felt the same pressure in school. In 2008, researchers from Johns Hopkins University conducted a series of studies on the effects of bilingual education (Slavin et al. 2008). They found that students taught in both their native tongue and English make better progress than those taught only in English.
Technically, the United States has no official language. But many believe English to be the rightful language of the United States, and over thirty states have passed laws specifying English as the official tongue. Proponents of English-only laws suggest that a national ruling will save money on translation, printing, and human resource costs, including funding for bilingual teachers. They argue that setting English as the official language will encourage non-English speakers to learn English faster and adapt to the culture of the United States more easily (Mount 2010).
Groups such as the American Civil Liberties Union (ACLU) oppose making English the official language and claim that it violates the rights of non-English speakers. English-only laws, they believe, deny the reality of our nation’s diversity and unfairly target Latinos and Asians. They point to the fact that much of the debate on this topic has risen since 1970, a time when the United States experienced new waves of immigration from Asia and Mexico.
Today, a lot of product information gets written in multiple languages. Enter a store like Home Depot and you’ll find signs in both English and Spanish. Buy a children’s product, and the safety warnings could be presented in multiple languages. While marketers are financially motivated to reach the largest number of consumers possible, this trend also may help people acclimate to a culture of bilingualism.
Studies show that most U.S. immigrants eventually abandon their native tongues and become fluent in English. Bilingual education helps with that transition. Today, Lucy Alvarez is an ambitious and high-achieving college student. Fluent in both English and Spanish, Lucy is studying law enforcement—a field that seeks bilingual employees. The same bilingualism that contributed to her success in grade school will help her thrive professionally as a law officer serving her community.
Nowadays, many signs—on streets and in stores—include both English and Spanish. What effect does this have on members of society? What effect does it have on our culture? (Photo courtesy of istolethetv/flickr)
Summary
A culture consists of many elements, such as the values and beliefs of its society. Culture is also governed by norms, including laws, mores, and folkways. The symbols and language of a society are key to developing and conveying culture.
Section Quiz
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A nation’s flag is:
- A symbol
- A value
- A culture
- A folkway
- Answer
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A
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The existence of social norms, both formal and informal, is one of the main things that inform ___________, otherwise known as a way to encourage social conformity.
- values
- sanctions
- social control
- mores
- Answer
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C
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The biggest difference between mores and folkways is that
- mores are primarily linked to morality, whereas folkways are primarily linked to being commonplace within a culture
- mores are absolute, whereas folkways are temporary
- mores refer to material culture, whereas folkways refer to nonmaterial culture
- mores refer to nonmaterial culture, whereas folkways refer to material culture
- Answer
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A
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The notion that people cannot feel or experience something that they do not have a word for can be explained by:
- linguistics
- Sapir-Whorf
- Ethnographic imagery
- bilingualism
- Answer
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B
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Cultural sanctions can also be viewed as ways that society:
- Establishes leaders
- Determines language
- Regulates behavior
- Determines laws
- Answer
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C
Short Answer
What do you think of the Sapir-Whorf hypothesis? Do you agree or disagree with it? Cite examples or research to support your point of view.
How do you think your culture would exist if there were no such thing as a social “norm”? Do you think chaos would ensue or relative peace could be kept? Explain.
Further Research
The science-fiction novel, Babel-17 , by Samuel R. Delaney was based upon the principles of the Sapir-Whorf hypothesis. Read an excerpt from the novel here: http://openstaxcollege.org/l/Babel-17
References
- Mount, Steve. 2010. “Constitutional Topic: Official Language.” USConstitution.net , last modified January 24. Retrieved January 3, 2012 ( http://www.usconstitution.net/consttop_lang.html ).
- OED Online . 2011. Oxford University Press. Retrieved May 5, 2011 ( http://www.oed.com/view/Entry/260911 ).
- Passero, Kathy. 2002. “Global Travel Expert Roger Axtell Explains Why.” Biography July:70–73,97–98.
- Slavin, R. E., A. Cheung, C. Groff, and C. Lake. 2008. “Effective Reading Programs for Middle and High Schools: A Best-Evidence Synthesis.” Reading Research Quarterly 43(3):290–322.
- Sumner, William G. 1906. Folkways: A Study of the Sociological Importance of Usages, Manners, Customs, Mores, and Morals . New York: Ginn and Co.
- Swoyer, Chris. 2003. “The Linguistic Relativity Hypothesis.” In The Stanford Encyclopedia of Philosophy , edited by E. N. Zalta, Winter. Retrieved May 5, 2011 ( http://plato.stanford.edu/archives/w...pplement2.html ).
- Vaughan, R. M. 2007. “Cairo’s Man Show.” Utne Reader March–April:94–95.
- Weber, Bruce. 2001. “Harold Garfinkel, a Common-Sense Sociologist, Dies at 93.” The New York Times , May 3. Retrieved February 10, 2012 ( http://www.nytimes.com/2011/05/04/us...nkel.html?_r=2 ).
- Westcott, Kathryn. 2008. “World’s Best-Known Protest Symbol Turns 50.” BBC News , March 20. Retrieved January 3, 2012 ( http://news.bbc.co.uk/2/hi/uk_news/m...ne/7292252.stm ).
Glossary
- beliefs
- tenets or convictions that people hold to be true
- folkways
- direct, appropriate behavior in the day-to-day practices and expressions of a culture
- formal norms
- established, written rules
- ideal culture
- the standards a society would like to embrace and live up to
- informal norms
- casual behaviors that are generally and widely conformed to
- language
- a symbolic system of communication
- mores
- the moral views and principles of a group
- norms
- the visible and invisible rules of conduct through which societies are structured
- real culture
- the way society really is based on what actually occurs and exists
- sanctions
- a way to authorize or formally disapprove of certain behaviors
- Sapir-Whorf hypothesis
- the way that people understand the world based on their form of language
- social control
- a way to encourage conformity to cultural norms
- symbols
- gestures or objects that have meanings associated with them that are recognized by people who share a culture
- values
- a culture’s standard for discerning what is good and just in society


7.2.13: Crossword (Usable with Best Practices)
Query \(\PageIndex{1}\)
Overall Usability
Usable with Best Practices:
- The activity requires minimal adjustments by content authors.
Important Reminders
Use best practices for content authoring, including:
- Add a correctly structured heading at the beginning of the activity
- Use good color contrast for meaningful visual information in images
- Do not use the Overall solution word option.
In Text overrides and translations, for the Crossword grid description, include, "Crossword grid. Use arrow keys to navigate and the keyboard to enter characters. Or navigate with Tab to type the answers in fill in the blank style fields instead of the grid."
Visible Indication of Focus
The activity buttons and form fields have a visible indication of focus.
Color Contrast
The color contrast of meaningful visual elements and text with backgrounds must be ensured manually by the content author.
Keyboard Usability
The activity is usable with the keyboard.
No Keyboard Traps
There are no keyboard traps.
Magnification
Content magnifies up to 200% using browser settings without loss of content or functionality. The crossword does not magnify up to 400%, but the fill in the blank style option to use the activity does magnify up to 400% and does not require horizontal scrolling.
Usability with Screen Reading Software
The activity is usable with screen reading software.


2.10: How Social Media Platforms Intersect With News
Take a moment to think about the last news item you read, heard, or watched. How did you encounter it? Were you looking for it or did it come looking for you? Were you visiting a news site online to see what’s happening? Catch it on the radio while driving to work? Did you hear about it from a friend or teacher? Was it something that caught your eye when skimming a news app on your phone? Or while checking your favorite social media platform?
Information networks that don’t create news are increasingly important discovery and distribution routes. Content created by news organizations spreads through social media when people share links and as the organizations promote their own content through Facebook, Snapchat, and elsewhere. This has benefits – news can reach people where they are and acquaintances can amplify the reach of a news story through a network of trust – but the downsides include organizations having to share dwindling ad revenue with the platforms and being at the whim of companies that can change their algorithms at any time without warning or consultation.
But social media is where news is at. A survey conducted by Pew Research in 2018 found two-thirds of American adults report getting news through social media, with Facebook and YouTube leading other platforms.
Another study by Project Information Literacy involving nearly 6,000 college students at 11 institutions found nearly 90 percent of students got news through social media, second only to hearing about it from friends face-to-face or through online channels. A large majority said journalism is necessary for democracy but most find it hard to keep up and half weren’t confident they could identify whether a news story was fake or not. Over a third doubted the credibility of all news.
Alternative News, Alternative Facts
But it’s not all about how journalism travels. Social platforms enable the creation of new information channels that challenge the dominance of traditional news organizations. That’s not all bad. New players can provide valuable alternative viewpoints and cover news ignored by the mainstream, but it also enables the creation and spread of misinformation, disinformation, and propaganda. The incentives built into social networks promote the use of emotional appeals and reward “influencers” who engage large audiences by any means necessary. The more outrageous, the more they are richly rewarded. While reputations matter in these new information channels, they are not dependent on old-school journalistic values or practices. For example, a conspiracy theory about murders of South African farmers that circulated in white supremacist circles for years broke into the mainstream when a claim by a “citizen journalist” on YouTube was repeated by Tucker Carlson and then by the president in a Tweet.
Social platforms, meeting with new criticism, want to avoid taking responsibility for what appears on their platforms. While they will take material down if it violates their terms of use or is illegal (child pornography or copyright violations, for example), they rely on a provision of the Telecommunications Act of 1996 that immunizes internet providers.
No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider.
Of course, this law predates the social platforms we use today and their meteoric rise to the top of the list of the world’s most valuable corporations. Lawmakers in 1996 had no way of knowing billions of people would be using and contributing material through the internet, that we would be accessing volumes of information through our phones. They might have had reservations if they imagined a world where 300 hours of video would be uploaded to a single website every minute, that messages could rocket around the world instantly, that governments could be toppled or could undermine one another covertly through disinformation campaigns. Section 230 of the Act gave entrepreneurs the freedom to create new things. It also let them off the hook for the problems we’re dealing with today. The consequences of this laissez-faire attitude are becoming more clear by the day, and platforms are scrambling to balance the ability of anyone to publish and share anything with the political and social fallout.
If you want to understand information, it’s important to understand how information networks operate. Profiles of major social platforms will be presented in Part Three of this book.


1.2: Pre-Lab 1
(5 points)
Last Name: _______________________ First Name: _______________________
Instructions:
Fill in the table below with the appropriate terms. Note: For this lab only, you may use any anatomical structure of the human body to fill in the table.
For the remaining pages of the prelab, label the designated planes, regions, and directions.
(1 point)
| Name of a structure | is | directional term | to | Name of the second structure |
|---|---|---|---|---|
| forearm | is | proximal | to | hand |
| head | is | superior | to | |
| is | inferior | to | tibia | |
| breast | is | anterior | to | |
| is | distal | to | upper arm | |
| brain | is | medial | to | |
| is | lateral | to | trunk |
Label the planes of the body. (1 point)
Label all nine regions of the abdomen. (1 point)
Label the anatomical directions designated by the lines and arrows. (1 point)
Label the regions of the body. (1 point)


6.2.1: Reasoning about Solving Equations (Part 1)
Lesson
Let's see how a balanced hanger is like an equation and moving its weight is like solving the equation.
Exercise \(\PageIndex{1}\): Hanger Diagrams
In the two diagrams, all the triangles weigh the same and all the squares weigh the same.
For each diagram, come up with . . .
- One thing that must be true
- One thing that could be true
- One thing that cannot possibly be true
Exercise \(\PageIndex{2}\): Hanger and Equation Matching
On each balanced hanger, figures with the same letter have the same weight.
-
Match each hanger to an equation. Complete the equation by writing \(x\), \(y\), \(z\), or \(w\) in the empty box.
- \(2 ?+3=5\)
- \(3 ?+2=3\)
- \(6=2?+3\)
- \(7=3?+1\)
- Find the solution to each equation. Use the hanger to explain what the solution means.
Exercise \(\PageIndex{3}\): Use Hangers to Understand Equation Solving
Here are some balanced hangers where each piece is labeled with its weight. For each diagram:
- Write an equation.
- Explain how to figure out the weight of a piece labeled with a letter by reasoning about the diagram.
- Explain how to figure out the weight of a piece labeled with a letter by reasoning about the equation.
Summary
In this lesson, we worked with two ways to show that two amounts are equal: a balanced hanger and an equation. We can use a balanced hanger to think about steps to finding an unknown amount in an associated equation.
The hanger shows a total weight of 7 units on one side that is balanced with 3 equal, unknown weights and a 1-unit weight on the other. An equation that represents the relationship is \(7=3x+1\).
We can remove a weight of 1 unit from each side and the hanger will stay balanced. This is the same as subtracting 1 from each side of the equation.
An equation for the new balanced hanger is \(6=3x\).
So the hanger will balance with \(\frac{1}{3}\) of the weight on each side: \(\frac{1}{3}\cdot 6=\frac{1}{3}\cdot 3x\).
The two sides of the hanger balance with these weights: 6 1-unit weights on one side and 3 weights of unknown size on the other side.
Here is a concise way to write the steps above:
\(\begin{array}{lr}{7=3x+1}&{}\\{6=3x}&{\text{after subtracting 1 from each side}}\\{2=x}&{\text{after multiplying each side by }\frac{1}{3}}\end{array}\)
Practice
Exercise \(\PageIndex{4}\)
There is a proportional relationship between the volume of a sample of helium in liters and the mass of that sample in grams. If the mass of a sample is 5 grams, its volume is 28 liters. (5, 28) is shown on the graph below.
- What is the constant of proportionality in this relationship?
- In this situation, what is the meaning of the number you found in part a?
- Add at least three more points to the graph above, and label with their coordinates.
- Write an equation that shows the relationship between the mass of a sample of helium and its volume. Use \(m\) for mass and \(v\) for volume.
(From Unit 2.4.2)
Exercise \(\PageIndex{5}\)
Explain how the parts of the balanced hanger compare to the parts of the equation.
\(7=2x+3\)
Exercise \(\PageIndex{6}\)
For the hanger below:
- Write an equation to represent the hanger.
- Draw more hangers to show each step you would take to find \(x\). Explain your reasoning.
- Write an equation to describe each hanger you drew. Describe how each equation matches its hanger.


3.3: Beating between Tones
Perhaps you have heard two slightly mistuned musical instruments play pure tones whose frequencies are close but not equal. If so, you have sensed a beating phenomenon wherein a pure tone seems to wax and wane. This waxing and waning tone is, in fact, a tone whose frequency is the average of the two mismatched frequencies, amplitude modulated by a tone whose “beat” frequency is half the difference between the two mismatched frequencies. The effect is illustrated in the Figure. Let's see if we can derive a mathematical model for the beating of tones.
We begin with two pure tones whose frequencies are \(ω_0+ν\) and \(ω_0−ν\) (for example, \(ω_0=2π×10^3\mathrm{rad}/\mathrm{sec}\) and \(ν=2π \mathrm{rad}/\mathrm{sec}\)). The average frequency is \(ω_0\), and the difference frequency is \(2ν\). What you hear is the sum of the two tones:
\[x(t)=A_1\cos[(ω_0+ν)t+φ_1]+A_2\cos[(ω_0−ν)t+φ_2] \nonumber \]
The first tone has amplitude \(A_1\) and phase \(φ_1\); the second has amplitude \(A_2\) and phase \(φ_2\). We will assume that the two amplitudes are equal to \(A\). Furthermore, whatever the phases, we may write them as
\[φ_1=φ+ψ;\mathrm{and};φ_2=φ−ψ \nonumber \]
\[φ=\frac 1 2 (φ_1+φ_2);\mathrm{and}ψ=\frac 1 2 (φ_1−φ_2) \nonumber \]
Recall our trick for representing \(x(t)\) as a complex phasor:
\[x(t)=A\mathrm{Re}\{e{j[(ω_0+ν)t+φ+ψ]},+,e^{j[(ω_0−ν)t+φ−ψ]}\} \nonumber \]
\[=A\mathrm{Re}\{e^{j(ω_0t+φ)},[e^{j(νt+ψ)}+e^{−j(νt+ψ)]}\} \nonumber \]
\[=2A\mathrm{Re}\{e^{j(ω_0t+φ)},\cos(νt+ψ)\} \nonumber \]
\[=2A\cos(ω_0t+φ)\cos(νt+ψ) \nonumber \]
This is an amplitude modulated wave, wherein a low frequency signal with beat frequency \(ν\) rad/sec modulates a high frequency signal with carrier frequency \(ω_0\) rad/sec. Over short periods of time, the modulating term \(\cos{νt+ψ}\) remains essentially constant while the carrier term \(\cos{ω_0t+φ}\) turns out many cycles of its tone. For example, if \(t\) runs from 0 to \(\frac {2π} {10ν}\) (about 0.1 seconds in our example), then the modulating wave turns out just 1/10 cycle while the carrier turns out \(10νω_Δ\) cycles (about 100 in our example). Every time \(νt\) changes by \(2π\) radians, then the modulating term goes from a maximum (a wax) through a minimum (a wane) and back to a maximum. This cycle takes
\[νt=2π⇔t=\frac {2π} {ν} \mathrm{seconds} \nonumber \]
which is 1 second in our example. In this 1 second the carrier turns out 1000 cycles.
Find out the frequency of A above middle C on a piano. Assume two pianos are mistuned by \(±1\mathrm{Hz}(±2π/mathrm{rad/sec})\). Find their beat frequency \(ν\) and their carrier frequency \(ω_0\).
(MATLAB) Write a MATLAB program to compute and plot
\(A\cos[(ω_0+ν)t+φ_1],A\cos[(ω_0−ν)t+φ_2]\), and their sum. Then compute and plot \(2A\cos(ω_0t+φ)\cos(νt+ψ)\).
Verify that the sum equals this latter signal.


11.23: Digestive System Answers
1. Add the labels to the diagram of a mammal’s gut below.
2. Match the region of the digestive system in the list below with the correct function.
| Region/organ | Function |
|---|---|
| B. Pancreas |
Produces the enzymes to digest proteins, fats and carbohydrates in the small intestine. Also produces the hormone insulin |
| H. Tongue | Organ that mixes food in the mouth and makes swallowing happen |
| N. Rumen | Micro-organisms digest cellulose in this modified part of the stomach |
| L. Salivary glands | Produce saliva containing salivary amylase |
| K. Oesophagus | Carries the food from the mouth to the stomach |
| F. Gall bladder | Stores bile |
| M. Pyloric sphincter | This muscle controls the passage of food out of the stomach |
| D. Pharynx | Both food and air pass along this |
| A. Rectum | Indigestible matter held here before defecation |
| I. Liver | Produces bile |
| E. Stomach |
A bag made of muscle where food is held. Gastric juice and hydrochloric acid are added here. |
| J. Small intestine |
Where food is mixed with bile and digestion of proteins, fats and carbohydrates takes place |
| G. Colon | Water and salt are absorbed here |
|
C. Functional caecu m ? |
Where micro-organisms digest fibre in rabbits and horses |
3. True or False?
 T
- b) These are all herbivores: cows, horses, goats, giraffes, rabbits and guinea pigs. T
- c) Plant material has high food value and animals need to eat only a little to get all the nutrients they need.
-
- F. Plants have a low food value and animals need to eat a large volume to obtain sufficient nutrients.
- d) Herbivores have well developed teeth for crushing and grinding plant cell walls. T
- e) Herbivores have glands that produce enzymes to digest plant material.
-
- F. No mammals produce their own enzymes to digest the cellulose cell walls of plants. Herbivores rely on microorganisms that can digest cellulose to do this for them.
- f) The rumen holds micro-organisms that digest cellulose. T
- g) Animals with a rumen also have a functional caecum to help digest cellulose.
-
- F. Herbivores either have a rumen or a functional caecum, not both.
- h) Carnivores need to eat most of the day to get enough nutrients.
-
- F. Meat has a high food value and is easily digested so carnivores can eat a quick meal and spend the rest of the day (and even the next) resting.
- i) Carnassial teeth are modified canines for shearing flesh and bone.
-
- F. Carnassials are modified combined premolars and molars.
- j) Open rooted teeth are found in rats and rabbits and grow throughout the animal’s life. T
- k) The numbers in a dental formula indicate the numbers of different kinds of teeth in one side only of the mouth of an animal. T
- l) Dentine is the hardest substance in a tooth.
-
- F. No, enamel found on the outside of the tooth is the hardest substance in the body.
4. Match the terms in the list below with the descriptions in the table
| Term | Description |
|---|---|
| Enamel | Hardest substance in the body; covers the tooth |
| Dentine | Found under the enamel of the tooth |
| Incisors | Chisel-shaped teeth at the front of the mouth |
| Dental formula |
The way in which the number of the different kinds of teeth of mammals can be expressed |
| Diastema |
A space in the mouth of rodents and herbivores where the canines would normally be. |
| Open rooted | These teeth keep growing through the life of the animal. (E.g. in rodents). |
| Premolars and molars | These teeth are used for grinding food. |
| Premolars and molars | These teeth are also used for grinding food. |
| Canines |
Long cone shaped teeth, well developed in carnivores, form tusks in male pigs (boars). |
| Carnassial teeth |
These teeth are found in carnivores. They are formed from premolars and molars and are used for shearing flesh |
5. Circle the odd one out.
- a) Rabbit, guinea pig, horse, goat , rat, zebra.
-
- All are herbivores with a functional caecum except the goat which has a rumen
- b) Sheep, cow, goat, antelope, giraffe, pig , camel.
-
- All have rumens except for the pig which has an unmodified stomach with a single compartment - monogastric.
- c) Incisors, canines, carnassials , molars, premolars.
-
- All are teeth types as given in the dental formula. Carnassials are modified premolars and molars.
- d) Stomach, oesophagus, liver, small intestine, rectum, caecum.
-
- All are parts of the digestive tube or tract except for the liver which is a gland supplying secretions to the gut (among many other functions).
- e) Saliva, bile, pancreatic juice, chyme , gastric juice.
- All are secretions into the gut except chyme which is the name given for the liquid "food" as it passes down the gut.
- f) Pancreas, salivary glands, liver; gall bladder ; intestinal glands.
- All are glands that produce secretions into the gut except the gall bladder that stores the bile produced by the liver.
- g) Pepsin, amylase, lipase, bile , protease.
- All are digestive enzymes that break down large food molecules into smaller ones except for bile that breaks down the large "globs" of fat into smaller ones so the digestive enzymes can be effective.
- h) Reticulum, functional caecum , omassum, abomassum, rumen.
- All are parts of the rumen except for functional caecum.
6. The dental formula below is of a rabbit.
-
-
- 2 0 3 3
- 1 0 2 3
-
This formula indicates that the rabbit:
- b) has a diastema
7. Peristalsis is: :a) the rhythmic contraction of the smooth muscle in the gut wall to push food along
8. Colour in (and label) the diagram of a villus in the small intestine using the colours suggested below.
- Outer layer of columnar epithelium - Yellow :Artery - Red
- Vein - Blue :Lymphatic vessel - Green
- Capillaries - Red turning to blue
- Label the lacteal; lumen of the gut; artery; vein; lymphatic vessel
9. Arrange the following parts of the digestive system in the order in which food passes through on the way from the mouth to the anus.
| mouth | A. pharynx | H. oesophagus | D. stomach | B. pyloric sphincter | F. small intestine | E. caecum | G. colon | C. rectum | anus |
|---|
10. The digestive enzymes in the gut break down the large food molecules into smaller ones that can be absorbed through the walls of the villi.
Complete the table below showing the large food molecules, the enzymes that digest them and the product of that breakdown.
| Large molecule | Digestive enzyme | Small molecule after digestion |
|---|---|---|
| Carbohydrates e.g. Starch | Amylase | Glucose |
| Fats or lipids | Lipase | Fatty acids and glycerol |
| Proteins | Pepsin, protease | Amino acids |
11. Some of these are functions of the liver: (Circle seven)
-
- Making bile
- Producing heat
- Storing vitamin A
- Storing glycogen
- Storing iron
- Removing toxic molecules like alcohol from the blood
- Making blood proteins
12. Just for fun!
There are a number of errors in the description of digestion below. Correct as many as you can find.
-
Food
egestedingested by the animal is bitten off by thecanine teethincisors and chewed by theincisorspremolars and molars . Saliva, anacidalkaline solution secreted by thetonsilsalivary glands, contains the enzymepepsinsalivary amylase which begins the digestion offatsstarch/carbohydrates.
-
In the stomach
pyloricgastric juice is secreted which contains enzymes to digeststarchprotein . Inallsome herbivore animals thesmall intestinestomach is modified into atwofour chambered organ called thegizzardrumen . Here the grass etc. is mixed with micro-organisms that break down theproteincellulose plant walls.
-
A ring of muscle called a
rictussphincter controls the passage of food from the stomach into thecaecumsmall intestine , wheregallbile and pancreatic juice are secreted.Hydrochloric acidsodium bicarbonate is also secreted here to make thechylechymeacidicalkaline .
-
In the small intestine
villasvilli increase the surface area for absorption of the digested material. Food then passes into thecoloncaecum on its way to thecaecumcolon .
-
In horses and sheep the
facultative colonfunctional caecum holds micro-organisms which break downanimalplant cell walls. In thereticulumcolon gas isabsorbedproduced and the waste material passes out of the digestive system via theurethrarectum/anus .
Total possible corrections to find 27


9.20: Putting It Together- Academic Argument
Now that you have learned the keys to a successful argument, apply them in your own writing. As you compose an argument, remember to do the following:
- Construct a thesis that is focused, debatable, assertive, reasonable, and able to be supported with evidence;
- Avoid logical fallacies, such as post hoc, straw man, false dichotomy, bandwagon, ad hominem, hasty generalization, slippery slope, and begging the question;
- Build common ground with readers, paying attention to tone, language, and rhetorical appeals;
- Incorporate rebuttal and refutation, fairly acknowledging counterargument while still arguing the strengths of your claim.
Remember that academic argument, as well as effective persuasion in the professional and personal arenas, is guided by careful research and reasoned discourse.
Contributors and Attributions
CC licensed content, Shared previously
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