12.9D: Functions of the Cerebellum in Integrating Movements
The cerebellum uses feedforward processing and modularity to process information.
- Describe the functions of the cerebellum in integrating movments
Key Points
- The function of the cerebellum can be described by the principles of feedforward processing and modularity.
- Feedforward processing means signals move in one direction through the cerebellum, from input to output.
- Modularity describes the modular nature of the cerebellar system, where modules with similar structures function relatively independently. Modules consist of clusters of neurons with common inputs but distinct outputs.
Key Terms
- purkinje : Purkinje cells are a class of GABAergic neurons located in the cerebellar cortex. They are some of the largest neurons in the human brain, with an intricately elaborate dendritic arbor characterized by a large number of dendritic spines.
- feedforward processing : A property of some neural circuits where signals move unidirectionally through the system from input to output, with very little recurrent internal transmission.
- microzone : A group of Purkinje cells that all have the same somatotopic receptive field. Microzones contain on the order of 1,000 Purkinje cells each, arranged in a long, narrow strip, and oriented perpendicular to the cortical folds.
Cerebellar Function
Feedforward Processing
The cerebellum differs from most other parts of the brain in that the signal processing is almost entirely feedforward—that is, signals move unidirectionally through the system from input to output, with very little recurrent internal transmission.
The small amount of recurrence that does exist consists of mutual inhibition; there are no mutually excitatory circuits. This feedforward mode of operation means that the cerebellum, in contrast to the cerebral cortex, cannot generate self-sustaining patterns of neural activity.
Signals enter the circuit, are processed by each stage in sequential order, and then leave. As Eccles, Ito, and Szentágothai wrote,”This elimination in the design of all possibility of reverberatory chains of neuronal excitation is undoubtedly a great advantage in the performance of the cerebellum as a computer, because what the rest of the nervous system requires from the cerebellum is presumably not some output expressing the operation of complex reverberatory circuits in the cerebellum, but rather a quick and clear response to the input of any particular set of information.”
Divergence and Convergence
Cells of the Cerebellum : Transverse section of a cerebellar folium, showing its principal cell types and connections.
In the human cerebellum, information from 200 million mossy fiber inputs is expanded to 40 billion granule cells, whose parallel fiber outputs then converge onto 15 million Purkinje cells. Because of the way that they are lined up longitudinally, the 1,000 or so Purkinje cells belonging to a microzone may receive input from as many as 100 million parallel fibers and focus their own output down to a group of less than 50 deep nuclear cells.
Thus, the cerebellar network receives a modest number of inputs, processes them very extensively through its rigorously structured internal network, and sends out the results via a very limited number of output cells.
Modularity
The cerebellar system is functionally divided into more or less independent modules, that probably number in the hundreds to thousands. All modules have a similar internal structure, but different inputs and outputs.
A module (a multizonal microcompartment in the terminology of Apps and Garwicz) consists of a small cluster of neurons in the inferior olivary nucleus, a set of long narrow strips of Purkinje cells in the cerebellar cortex (microzones), and a small cluster of neurons in one of the deep cerebellar nuclei.
Different modules share input from mossy fibers and parallel fibers, but in other respects they appear to function independently. The output of one module does not appear to significantly influence the activity of other modules.
Plasticity
The synapses between parallel fibers and Purkinje cells, and the synapses between mossy fibers and deep nuclear cells, are both susceptible to modification of their strength. In a single cerebellar module, input from as many as a billion parallel fibers converge onto a group of less than 50 deep nuclear cells, and the influence of each parallel fiber on those nuclear cells is adjustable. This arrangement gives tremendous flexibility for fine-tuning the relationships between the cerebellar inputs and outputs.
Zones and microzones in the cerebellum : This schematic illustration of the structure of zones and microzones in the cerebellum shows three levels of magnification. These zones and microzones help explain the modular nature of the cerebellar function. On the left is a simplified illustration of what the cerebellar cortex would look like if all the folds were straightened out—the vertical dimension is the rostro-caudal axis of the cerebellum, the horizontal dimension is the medio-lateral axis. A zone is a longitudinally oriented strip of the cortex, and a microzone is a thin, longitudinally oriented portion of a zone. As the illustration on the right shows, Purkinje cell dendritic trees are flattened in a way that aligns with the microzone length, and parallel fibers cross the microzones at right angles.
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5.9: Promoting yourself as a student researcher
You may think that this discussion about copyright and fair use doesn’t apply to you, since you are only creating papers to share in class. However, you can publish and share your work online, even while you are a student. As you progress in your studies and head toward your first professional job, you’ll want to present yourself in the best possible light. Carefully consider what you want to share and how. Here are some things you can do:
- Join professional social networking communities such as LinkedIn that allow you to manage your professional identity. (The ISU Career Services offices can help you set up your LinkedIn page and give advice about your online presence.)
- There are some journals that publish student research specifically, like Involve for mathematics research or Journal of Critical Thought and Praxis for education research.
- If you participate in scholarly conferences, such as ISU’s Symposium on Undergraduate Research and Creative Expression, consider sharing your research online. One place you can do this is ISU’s Digital Repository .
Whenever you create something or interact with people online you leave behind a digital footprint: clues about yourself that future professors, colleagues, and supervisors will be able to find for years to come.


20.7: Development of Blood Vessels and Fetal Circulation
By the end of this section, you will be able to:
- Describe the development of blood vessels
- Describe the fetal circulation
In a developing embryo,the heart has developed enough by day 21 post-fertilization to begin beating. Circulation patterns are clearly established by the fourth week of embryonic life. It is critical to the survival of the developing human that the circulatory system forms early to supply the growing tissue with nutrients and gases, and to remove waste products. Blood cells and vessel production in structures outside the embryo proper called the yolk sac, chorion, and connecting stalk begin about 15 to 16 days following fertilization. Development of these circulatory elements within the embryo itself begins approximately 2 days later. You will learn more about the formation and function of these early structures when you study the chapter on development. During those first few weeks, blood vessels begin to form from the embryonic mesoderm. The precursor cells are known as hemangioblasts . These in turn differentiate into angioblasts , which give rise to the blood vessels and pluripotent stem cells, which differentiate into the formed elements of blood. (Seek additional content for more detail on fetal development and circulation.) Together, these cells form masses known as blood islands scattered throughout the embryonic disc. Spaces appear on the blood islands that develop into vessel lumens. The endothelial lining of the vessels arise from the angioblasts within these islands. Surrounding mesenchymal cells give rise to the smooth muscle and connective tissue layers of the vessels. While the vessels are developing, the pluripotent stem cells begin to form the blood.
Vascular tubes also develop on the blood islands, and they eventually connect to one another as well as to the developing, tubular heart. Thus, the developmental pattern, rather than beginning from the formation of one central vessel and spreading outward, occurs in many regions simultaneously with vessels later joining together. This angiogenesis —the creation of new blood vessels from existing ones—continues as needed throughout life as we grow and develop.
Blood vessel development often follows the same pattern as nerve development and travels to the same target tissues and organs. This occurs because the many factors directing growth of nerves also stimulate blood vessels to follow a similar pattern. Whether a given vessel develops into an artery or a vein is dependent upon local concentrations of signaling proteins.
As the embryo grows within the mother’s uterus, its requirements for nutrients and gas exchange also grow. The placenta—a circulatory organ unique to pregnancy—develops jointly from the embryo and uterine wall structures to fill this need. Emerging from the placenta is the umbilical vein , which carries oxygen-rich blood from the pregnant person to the fetal inferior vena cava via the ductus venosus to the heart that pumps it into fetal circulation. Two umbilical arteries carry oxygen-depleted fetal blood, including wastes and carbon dioxide, to the placenta. Remnants of the umbilical arteries remain in the adult. (Seek additional content for more information on the role of the placenta in fetal circulation.)
There are three major shunts—alternate paths for blood flow—found in the circulatory system of the fetus. Two of these shunts divert blood from the pulmonary to the systemic circuit, whereas the third connects the umbilical vein to the inferior vena cava. The first two shunts are critical during fetal life, when the lungs are compressed, filled with amniotic fluid, and nonfunctional, and gas exchange is provided by the placenta. These shunts close shortly after birth, however, when the newborn begins to breathe. The third shunt persists a bit longer but becomes nonfunctional once the umbilical cord is severed. The three shunts are as follows (Figure \(\PageIndex{1}\)):
- The foramen ovale is an opening in the interatrial septum that allows blood to flow from the right atrium to the left atrium. A valve associated with this opening prevents backflow of blood during the fetal period. As the newborn begins to breathe and blood pressure in the atria increases, this shunt closes. The fossa ovalis remains in the interatrial septum after birth, marking the location of the former foramen ovale.
- The ductus arteriosus is a short, muscular vessel that connects the pulmonary trunk to the aorta. Most of the blood pumped from the right ventricle into the pulmonary trunk is thereby diverted into the aorta. Only enough blood reaches the fetal lungs to maintain the developing lung tissue. When the newborn takes the first breath, pressure within the lungs drops dramatically, and both the lungs and the pulmonary vessels expand. As the amount of oxygen increases, the smooth muscles in the wall of the ductus arteriosus constrict, sealing off the passage. Eventually, the muscular and endothelial components of the ductus arteriosus degenerate, leaving only the connective tissue component of the ligamentum arteriosum.
- The ductus venosus is a temporary blood vessel that branches from the umbilical vein, allowing much of the freshly oxygenated blood from the placenta—the organ of gas exchange between the pregnant person and fetus—to bypass the fetal liver and go directly to the fetal heart. The ductus venosus closes slowly during the first weeks of infancy and degenerates to become the ligamentum venosum.


Section 07: Proof-theoretic concepts
We will use the symbol ‘⊢’ to indicate that a proof is possible. This symbol is called the turnstile . Sometimes it is called a single turnstile, to underscore the fact that this is not the double turnstile symbol (⊨) that we used to represent semantic entailment in ch. 5.
When we write {\(\mathcal{A}\) 1 ,\(\mathcal{A}\) 2 ,...}⊢\(\mathcal{B}\), this means that it is possible to give a proof of \(\mathcal{B}\) with \(\mathcal{A}\) 1 ,\(\mathcal{A}\) 2 ,... as premises. With just one premise, we leave out the curly braces, so \(\mathcal{A}\) ⊢ \(\mathcal{B}\) means that there is a proof of \(\mathcal{B}\) with \(\mathcal{A}\) as a premise. Naturally, `\(\mathcal{C}\) means that there is a proof of \(\mathcal{C}\) that has no premises.
Often, logical proofs are called derivations. So \(\mathcal{A}\) ⊢ \(\mathcal{B}\) can be read as ‘\(\mathcal{B}\) is derivable from \(\mathcal{A}\).’
A theorem is a sentence that is derivable without any premises; i.e., \(\mathcal{T}\) is a theorem if and only if ⊢\(\mathcal{T}\).
It is not too hard to show that something is a theorem— you just have to give a proof of it. How could you show that something is not a theorem? If its negation is a theorem, then you could provide a proof. For example, it is easy to prove¬(\(Pa\)&¬\(Pa\)), which shows that (\(Pa\)&¬\(Pa\)) cannot be a theorem. For a sentence that is neither a theorem nor the negation of a theorem, however, there is no easy way to show this. You would have to demonstrate not just that certain proof strategies fail, but that no proof is possible. Even if you fail in trying to prove a sentence in a thousand different ways, perhaps the proof is just too long and complex for you to make out.
Two sentences \(\mathcal{A}\) and \(\mathcal{B}\) are provably equivalent if and only if each can be derived from the other; i.e., \(\mathcal{A}\)⊢\(\mathcal{B}\) and \(\mathcal{B}\)⊢\(\mathcal{A}\)
It is relatively easy to show that two sentences are provably equivalent— it just requires a pair of proofs. Showing that sentences are not provably equivalent would be much harder. It would be just as hard as showing that a sentence is not a theorem. (In fact, these problems are interchangeable. Can you think of a sentence that would be a theorem if and only if \(\mathcal{A}\) and \(\mathcal{B}\) were provably equivalent?)
The set of sentences {\(\mathcal{A}\) 1 ,\(\mathcal{A}\) 2 ,...} is provably inconsistent if and only if a contradiction is derivable from it; i.e., for some sentence \(\mathcal{B}\), {\(\mathcal{A}\) 1 ,\(\mathcal{A}\) 2 ,...} ⊢ \(\mathcal{B}\) and {\(\mathcal{A}\) 1 ,\(\mathcal{A}\) 2 ,...}⊢¬\(\mathcal{B}\).
It is easy to show that a set is provably inconsistent: You just need to assume the sentences in the set and prove a contradiction. Showing that a set is not provably inconsistent will be much harder. It would require more than just providing a proof or two; it would require showing that proofs of a certain kind are impossible .


5.14: Decisions and Strategy
- Explain how a retail strategy guides the decisions of an organization
As you read earlier, strategic planning is a formal process that evaluates the market and the factors that influence it, the needs of the consumer, the relative position of the competition, the firm’s own capabilities, the financial implications, given required trade-offs. The output of this process is a strategic plan, a shared document that serves as the “road map” for how the firm will pursue its strategic objectives.
And, because strategic planning is both internally and externally oriented, it crystallizes the opportunities present for a firm and how best to capitalize upon them.
In particular, situational and customer analysis captures those factors that will support and those that will challenge organizational success. In this way, the resulting strategic plan will influence and guide the decision-making of the firm. Specifically, strategic planning helps retailers make decisions around growth opportunities, consumer targeting, and performance. Growth marketing is when firms capitalize upon new initiatives and their sources, whether that is new items, categories, locations, or markets. Consumer targeting is when they differentiate themselves in-market–allocating resources to optimize locations, layouts, assortment, and overall positioning to attract specific targets. This also includes decisions round whether to open new, remodel existing or to close underperforming locations. Performance is when they assess overall returns through the marketing mix and retail operations like inventory, cost, and capital management.
Any of these could require evolution of the current business model, adoption of new value propositions or operational tactics. Thus, these strategic considerations create decision-points for a retailer.
Contributors and Attributions
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There are several ways to assess the condition of the newborn. The most widely used tool is the Neonatal Behavioral Assessment Scale (NBAS) developed by T. Berry Brazelton. This tool has been used around the world to help parents get to know their infants and to make comparisons of infants in different cultures (Brazelton & Nugent, 1995). The baby’s motor development, muscle tone, and stress response are assessed.
The Apgar test is conducted one minute and five minutes after birth. This is a very quick way to assess the newborn’s overall condition. Five measures are assessed: the heart rate, respiration, muscle tone (quickly assessed by a skilled nurse when the baby is handed to them or by touching the baby’s palm), reflex response (the Babinski reflex is tested), and color. A score of 0 to 2 is given on each feature examined. An Apgar of 5 or less is cause for concern. The second Apgar should indicate improvement with a higher score.
Watch it
Watch this video that explains how to calculate the Apgar score for a newborn.
A link to an interactive elements can be found at the bottom of this page.
We have been discussing a number of teratogens associated with a low birth weight such as cocaine, tobacco, etc. A child is considered to have a low birth weight if they weigh less than 5.8 pounds (2500 grams). About 8.17 percent of babies born in the United States are of low birth weight and 1.4 percent are born very low birth weight.
[1]
A low birth weight baby has difficulty maintaining adequate body temperature because it lacks the fat that would otherwise provide insulation. Such a baby is also at more risk of infection. And 67 percent of these babies are also preterm which can make them more at risk for a respiratory infection. Very low birth weight babies (2 pounds or less) have an increased risk of developing cerebral palsy. Many causes of low birth weight are preventable with proper prenatal care.
Premature Birth
A child might also have a low birth weight if it is born at less than 37 weeks gestation (which qualifies it as a preterm baby). In 2016, 9.85 percent of babies born in the U.S. were preterm.
[2]
Early birth can be triggered by anything that disrupts the mother’s system. For instance, vaginal infections or gum disease can actually lead to premature birth because such infection causes the mother to release anti-inflammatory chemicals which, in turn, can trigger contractions. Smoking and the use of other teratogens can also lead to preterm birth.
Anoxia and Hypoxia
One of leading causes of infant brain damage is lack of oxygen shortly after birth. Hypoxia occurs when the infant is deprived of the adequate amount of oxygen, leading to mild to moderate brain damage. Apoxia occurs when the infant undergoes a total lack of oxygen, which can lead to severe brain damage. This lack of oxygen is typically caused by umbilical cord problems, birth canal problems, blocked airways, and placenta abruption. Both hypoxia and anoxia can lead to cerebral palsy and a host of other medical disorders.
[3]
Modification, adaptation, and original content.
Authored by
: Julie Lazzara for Lumen Learning.
Provided by
: Lumen Learning.
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1.35: Pharmacists and Medicare Part D- helping patients navigate their prescription benefits
At the end of this case, students will be able to:
- Describe Medicare Part D and the role of the pharmacist in assisting beneficiaries
- Identify medications and immunizations covered by Medicare Part D
- Recall factors that may contribute to Medicare beneficiaries selecting non-optimal plans
- Identify resources and tools that pharmacists can utilize to help patients with plan selection
Introduction
Originally, individuals enrolled in Medicare did not have access to outpatient prescription coverage through the program. Seeing the need for coverage, Congress passed legislation for the inclusion of a drug benefit within the Medicare program, known as the Medicare Prescription Drug Improvement and Modernization Act of 2003. 1 As a result of this, outpatient prescription coverage, known as Medicare Part D, became available to beneficiaries in 2006.
Enrolling in Medicare Part D is voluntary and beneficiaries, who most often pay a monthly premium, can obtain their coverage through either stand-alone prescription or Medicare Advantage plans. Both options are provided by private companies that contract with the Centers for Medicare and Medicaid Services (CMS). The Medicare Part D plan must provide a minimum benefit based upon a standard benefit design, which has four distinct phases where beneficiaries pay different costs for their medications. In 2021, this standard benefit had a $445 deductible, an initial coverage phase, a coverage gap (which begins when the full cost of the medication reaches $4,130), and catastrophic coverage (starting when a beneficiary’s out-of-pocket expenses for medications reach $6,550). 2 Many enhanced plans exist in addition to the standard plans, and in 2021 beneficiaries had, on average, 60 different plans to choose from. 3 Additionally, medications placed on different tiers on the plan’s formulary may have different associated costs than others. Specific medications may be full cost or require a copayment or coinsurance depending on the plan structure, deductibles, and phase of coverage. This variation in cost can be confusing to beneficiaries and result in poor medication adherence. For example, patients may think their medication will always be expensive if they are currently in a deductible phase, not realizing that they may be liable for a lower cost once they enter the initial coverage phase.
Insurance plans contain costs and provide safety stops by utilizing coverage restrictions. These restrictions include quantity limits, step therapy, and prior authorizations. All Medicare Part D plans must cover at least two chemically distinct drugs in each drug category to ensure that people can obtain the drugs that they are prescribed, but plans can choose which specific drugs they will offer. However, CMS has identified six categories of drugs, commonly referred to as the “six protected classes” and requires Medicare Part D plans to cover “all or substantially all” of the drugs in those classes. 4 In addition, there are several classes of drugs that Medicare Part D plans do not cover. 5 Finally, in addition to drugs, Medicare Part D plans also cover all commercially available vaccines that are not covered under Part B. 6
The variation among plans, the number of plans, and the changing medication costs across the phases of the benefit lead many beneficiaries to select sub-optimal plans. In a review of plan choices, it was found that beneficiaries spent more than they needed for coverage. 7 Additionally, many do not switch plans despite changes to their benefits that could affect the coverage and cost of their medications. 8 This may be a result of the complexity of the benefit and the tool designed to assist beneficiaries with finding the best coverage. 9 Pharmacists are well-positioned to help with this complex process and provide guidance to beneficiaries.

CC: “I’m having a hard time breathing and I don’t have an inhaler at home to use.”
Patient: JP is a 68-year-old male (72 in, 98.1 kg) who is a regular patient at your clinic for his COPD and diabetes care.
HPI: JP was diagnosed with COPD three years ago. He had a cold two weeks ago and his pulmonary symptoms have gradually worsened over that time. Today he is coughing and wheezing as he sits in the waiting room. His symptoms include shortness of breath, chest tightness and wheezing, and a persistent productive cough.
PMH: COPD (x 3 years); T2DM (x 6 years); HTN (x 10 years); major depressive disorder; osteoarthritis of the hands; shingles (single episode two years ago; has not received Shingrix ® )
FH:
- Mother: deceased (breast cancer)
- Father: deceased (stroke)
- Brother: alive (72 years); HTN, COPD
SH:
- Drinks socially (3-4 beers on the weekends)
- Denies smoking and illicit substance use
Medications:
- Spiriva ® Handihaler ® one capsule daily
- Ventolin ® HFA two puffs four times daily PRN
- Lisinopril/HCTZ 20/12.5 mg one tablet daily
- Sertraline 50 mg one tablet daily
- Lantus Solostar ® 100 u/mL 30 units subcutaneously daily at bedtime
- Viagra ® 50 mg one tablet one hour prior to sexual activity
Labs/vitals:
- BP 148/82 mmHg
- HgbA1c 8.4%
SDH: JP has been married for 35 years and is a retired electrician. He has traditional Medicare and a Medicare Part D plan that his son helped him to choose two years ago. His retirement income is limited; he states he can only afford generic medications and can often only pay for his inhalers and his insulin every other month. He has tried different inhalers that are often too expensive for him. His doctor prescribed the Spiriva ® Handihaler ® about six months ago, but he admits that he struggles to use the capsules in the device due to his arthritis.
Case Questions
- What factors should be considered when finding a plan for this patient?
- Through what type of Medicare plans are beneficiaries able to access Medicare Part D benefits?
- What information and strategies could you discuss with JP to help him better afford his medications like his insulin and inhalers? Are any of JP’s drugs NOT covered by his Medicare Part D plan?
- The Medicare website is a helpful resource to help individuals find the most cost-effective coverage. JP needs help with finding a new plan. He fills his medications at the retail pharmacy CVS, has a zip code of 01608, and does not qualify for any assistance with the cost of his medications. Utilizing the Medicare Plan Finder to compare the available options, what stand-alone Medicare Part D plan has the lowest annual cost including the plan premium and medication costs?
- How does JP benefit from the identification of Medicare’s six protected classes?
- Would JP’s Shingrix ® vaccine be covered under his Medicare Part D plan or his Medicare Part B? Would JP have to pay out of pocket costs to receive this vaccine?
Author Commentary
Patients who cannot access medications due to cost or the inherent complexity of their Medicare Part D plan may be at risk for health complications and serial hospitalizations due to non-adherence. 4 There are safeguards built into the Medicare Part D plans to ensure medication accessibility and equity for Medicare beneficiaries, including tiered costs, special insulin tiers, and protected medication classes. However, many patients are unaware of these benefits or struggle with health literacy challenges that prevent them from maximizing the benefits of these plans. 9
Pharmacists, with their broad knowledge of drug classes and insurance complexities, are key health care advocates who can assist Medicare patients with these challenges. While helping patients to navigate the Medicare plan choices and understand the structure and benefits of the plans, pharmacists can help to improve medication access, reduce overall medication costs, and improve health outcomes for their patients. 4 Pharmacists may also incorporate other assistance programs to help improve access and reduce medication costs even for those who have chosen an appropriate Medicare plan; for example, if a patient is eligible for a state pharmacy assistance program (SPAP), the costs associated with Medicare Part D may be lower. Pharmacists should become familiar with general eligibility requirements for state insurance assistance, Extra Help through Social Security, manufacturer assistance programs, discount programs like GoodRx, and Medicaid dual eligibility.
Patient Approaches and Opportunities
As one of the most accessible healthcare providers, pharmacists can be invaluable resources for their Medicare patients. Even simple recommendations can save Medicare patients significant costs during the year, including reminding patients to review their plans annually to ensure their current medications are on the plan’s formulary, assisting with identifying coverage restrictions, and reminding patients to budget accordingly for renewed deductibles that come every January. 5
Additionally, pharmacists can recommend generic drugs, biosimilars, and appropriate therapeutic alternatives that may be in lower cost tiers to further reduce patients’ costs. Requesting 90-day refills from prescribers can improve adherence and reduce copays. Pharmacists can also use this opportunity to ensure a patient’s chosen pharmacy will accept their preferred plan and potentially reduce copays. This strategy may encourage Medicare patients to use a single pharmacy for their prescriptions which can improve their adherence and overall health outcomes. 4
Medication therapy management (MTM), or comprehensive medication review (CMR), is an additional component of Medicare Part D that can be administered by pharmacists to benefit patients. Each insurance plan has criteria for MTM eligibility and may require the beneficiary to have three specific disease states, eight medications, and drug costs that reach the coverage gap to be eligible for MTM services. 6 If patients do not have the required disease states or have reduced drug costs due to prescription cost assistance programs, they may not meet the criteria, even if they are taking multiple medications to treat multiple conditions. However, MTM services are excellent opportunities to improve adherence, identify therapeutic alternatives, reduce polypharmacy, and lower costs for Medicare patients. 4
Related chapters of interest:
- Communicating health information: hidden barriers and practical approaches
- Equity for all: providing accessible healthcare for patients living with disabilities
- Let your pharmacist be your guide: navigating barriers to pharmaceutical access
External resources:
-
Websites:
- Medicaid. State overviews. https://www.medicaid.gov/state-overviews/index.html
- Medicare. Find health and drug plans. www.medicare.gov
- Medicare. Find out if your state has a state pharmaceutical assistance program. https://www.medicare.gov/pharmaceutical-assistance-program/#state-programs
- Medicare. Assistance with Medicare Part D drug costs (manufacturer prescription assistance programs). https://www.cms.gov/Medicare/Prescription-Drug-Coverage/PrescriptionDrugCovGenIn/PAPData
- Medicare. Six ways to get help with prescription drug costs. https://www.medicare.gov/drug-coverage-part-d/costs-for-medicare-drug-coverage/costs-in-the-coverage-gap/6-ways-to-get-help-with-prescription-costs
- Medicare Rights Center, MedicareInteractive.org. Medicare coverage overview. https://www.medicareinteractive.org/get-answers/medicare-basics/medicare-coverage-overview
- Social Security Administration. Extra help with Medicare prescription drug plan costs. https://www.ssa.gov/benefits/medicare/prescriptionhelp/
- NeedyMeds. Find help with the cost of medicine. https://www.needymeds.org/
- Health Affairs. The Part D senior savings model: reducing out-of-pocket costs for insulin in Medicare Part D. https://www.healthaffairs.org/do/10.1377/hblog20200311.582575/full/
-
Journal articles:
- Huffman KF, Upchurch G. The health of older Americans: a primer on Medicare and a local perspective. J Am Geriatr Soc 2018;66(1):25-32.
References
- Hastert JD. H.R.1 – 108th Congress (2003-2004): Medicare Prescription Drug, Improvement, and Modernization Act of 2003. Published December 8, 2003. https://www.congress.gov/bill/108th-congress/house-bill/1 . Accessed March 11, 2021.
- Center for Medicare and Medicaid Services. Announcement 7 of Calendar Year (CY) 2021 Medicare Advantage (MA) capitation rates and Part C and Part D payment policies. Published April 2020. https://www.cms.gov/files/document/2021-announcement.pdf . Accessed January 5, 2021.
- Cubanski J, Damico D. Medicare Part D: a first look at Medicare prescription drug plans in 2021. Published October 29, 2020. https://www.kff.org/medicare/issue-brief/medicare-part-d-a-first-look-at-medicare-prescription-drug-plans-in-2021/ . Accessed January 5, 2021.
- Zagaria M. Drug costs in Medicare dollars and cost-related nonadherence. US Pharm 2019:44(60):8-11. https://www.uspharmacist.com/article/drug-costs-in-medicare-dollars-and-costrelated-nonadherence . Accessed March 14, 2021.
- Gilchrist A. 4 ways pharmacists can be superheroes for Medicare patients. Pharmacy Times. Published July 26, 2013. https://www.pharmacytimes.com/view/4-ways-pharmacists-can-be-superheroes-for-medicare-patients . Accessed March 14, 2021.
- Center for Medicare and Medicaid Services. 2019 Medicare Part D medication therapy management (MTM) programs fact sheet summary of 2019 MTM programs. Updated September 25, 2019. https://www.cms.gov/Medicare/Prescription-Drug-Coverage/PrescriptionDrugCovContra/Downloads/CY2019-MTM-Fact-Sheet.pdf . Accessed December 30, 2020.
- Zhou C, Zhang Y. The vast majority of Medicare Part D beneficiaries still don’t choose the cheapest plans that meet their medication needs. Health Affairs 2012;31(10):2259-65.
- Jacobson G, Damico A. No itch to switch: few Medicare beneficiaries switch plans during the open enrollment period. Published December 2, 2019. https://www.kff.org/medicare/issue-brief/no-itch-to-switch-few-medicare-beneficiaries-switch-plans-during-the-open-enrollment-period/ . Accessed January 13, 2021.
- Jacobson G, Swoope C, Perry M. How are seniors choosing and changing health insurance plans? Published May 13, 2014. https://www.kff.org/medicare/report/how-are-seniors-choosing-and-changing-health-insurance-plans/ . Accessed January 13, 2021.


8.2: Describing...
Firstly, look on the basic characteristics of every character:
Code \(\PageIndex{1}\) (R):
Since SEX and COLOR are categorical, the output in these columns has no sense, but you may want to convert these columns into “true” categorical data. There are multiple possibilities but the simplest is the conversion into factor :
Code \(\PageIndex{2}\) (R):
(To retain the original data, we copied it first into new object data1 . Please check it now with summary() yourself.)
summary() command is applicable not only to the whole data frame but also to individual characters (or variables, or columns):
Code \(\PageIndex{3}\) (R):
It is possible to calculate characteristics from summary() one by one. Maximum and minimum:
Code \(\PageIndex{4}\) (R):
... median:
Code \(\PageIndex{5}\) (R):
... mean for WEIGHT and for each character:
Code \(\PageIndex{6}\) (R):
and
Code \(\PageIndex{7}\) (R):
... and also round the result to one decimal place:
Code \(\PageIndex{8}\) (R):
(Again, the output of colMeans() has no sense for SEX and COLOR .)
Unfortunately, the commands above (but not summary() ) do not work if the data have missed values ( NA ):
Code \(\PageIndex{9}\) (R):
To calculate mean without noticing missing data, enter
Code \(\PageIndex{10}\) (R):
Another way is to remove rows with NA from the data with:
Code \(\PageIndex{11}\) (R):
Then, data2.o will be free from missing values.
Sometimes, you need to calculate the sum of all character values:
Code \(\PageIndex{12}\) (R):
... or the sum of all values in one row (we will try the second row):
Code \(\PageIndex{13}\) (R):
... or the sum of all values for every row:
Code \(\PageIndex{14}\) (R):
(These summarizing exercises are here for training purposes only.)
For the categorical data, it is sensible to look how many times every value appear in the data file (and that also help to know all values of the character):
Code \(\PageIndex{15}\) (R):
Now transform frequencies into percents (100% is the total number of bugs):
Code \(\PageIndex{16}\) (R):
One of the most important characteristics of data variability is the standard deviation :
Code \(\PageIndex{17}\) (R):
Calculate standard deviation for each numerical column (columns 3 and 4):
Code \(\PageIndex{18}\) (R):
If you want to do the same for data with a missed value, you need something like:
Code \(\PageIndex{19}\) (R):
Calculate also the coefficient of variation (CV):
Code \(\PageIndex{20}\) (R):
We can calculate any characteristic separately for males and females. Means for insect weights:
Code \(\PageIndex{21}\) (R):
How many individuals of each color are among males and females?
Code \(\PageIndex{22}\) (R):
(Rows are colors, columns are males and females.)
Now the same in percents:
Code \(\PageIndex{23}\) (R):
Finally, calculate mean values of weight separately for every combination of color and sex (i.e., for red males, red females, green males, green females, and so on):
Code \(\PageIndex{24}\) (R):


11.6: Summary and Review
Summary
In this chapter, we shed light on the dark side of communication. We live in a world where the quality of our interpersonal relationships can be directly linked to our personal well-being and happiness. Ironically, these same relationships can be the source of some of our greatest misery. Thus, it is important to study not only aspects of communication that can improve our interpersonal relationships, but also to develop an understanding of types of communication that may harm our well-being.
In this chapter we explored various communication aspects of the dark side of communication in interpersonal relationships, including deception, secret tests, jealousy, gaslighting, verbal abuse, intimate partner violence, and social media. We learned that communication can have both positive and negative effects on our relationships and personal well-being, but that some types of communication clearly fall solely on the dark side.
In addition, we highlighted specific communication techniques you can use to lighten the burden on the dark side. Throughout the chapter, we explored specific communication tools to help respond appropriately and effectively to the dark side of communication. Techniques such as perception checking, assertiveness, and setting boundaries can help you maintain open channels of communication while maintaining healthy boundaries. In addition, in this chapter we discussed several techniques for responding to the dark side of communication on social media, including setting appropriate boundaries for your own posts, as well as developing an effective response plan to negative messaging. Through examining the dark side of communication, we can hopefully learn to understand communication patterns and behaviors that both enhance and harm our relationships, and in turn, we can reveal the light and bright side of our partnerships.
As we develop our skills in interpersonal communication, it is important to be aware of how the light and dark sides of communication interact with one another. The light and dark sides of communication are interwoven, such that some unappealing behaviors (i.e., white lies) can lead to positive outcomes, and some desirable behaviors can lead to negative outcomes (i.e., self-disclosure on social media). It is important to remember to commit to honoring yourself, the other person, and the relationship. In doing so, you may lead to greater personal awareness, understanding of the other person, and relationship growth.
Discussion Questions
- Now that you are familiar with the dark side of communication, what areas of the dark side of communication do you believe to be most harmful to relationships?
- What areas of the dark side do you feel are impacting your current relationships? What communication strategies do you use to manage these challenges?
- Identity three communication strategies you have learned throughout this text that can help you respond to different areas of the dark side of communication.
- What communication behavior from the dark side have you witnessed or experienced on social media platforms? Are there any communication behaviors you have seen or experienced that are not included in the discussion of social media and the dark side that you believe should be included?
- Have you used or been on the receiving end of secret tests? How have you responded to secret tests in the past?
- Cultures have different views and expectations regarding deception. Under what circumstances do you believe it is appropriate to tell a lie?


20.4: Going Global – Guilds in an Era of Internationalization
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- Last updated
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- Miranda Banks & David Hesmondhalgh
- University of California Press
As indicated earlier, an important way a guild might define its work differently than a union is by emphasizing promotion of the profession or craft. This has spatial dimensions that have changed in recent decades. Where once a union would look only for local, regional, or national solidarity, in an era of globalization of the media industries, solidarity for the WGA must be threefold: within their own union, member to member and between East and West; among the WGA, the DGA, SAG-AFTRA, and IATSE; and as we explore in this section, among different countries and communities of professional writers that work for the media industries.
This international dimension is not entirely new. For most of its eighty-year existence as a trade union, the Writers Guild has offered professional support to developing guilds and associations in other countries, guiding media and cultural workers in other countries on how to respond to changes in the industry The Writers Guild of America has often called for solidarity not only among its members, but also from aspirants and fellow professional screenwriters across the globe. But in this increasingly globalized era of media production, this aspect has intensified. This was particularly noticeable during the 2007–2008 strike, when the guild made it clear that it would hold accountable any writer who broke the strike. WGA members spoke with film students, instructing them not to take writing jobs with studios as screenwriters. At stake for any writer, locally or globally, was any chance of joining the union. But the guild did not stop at U.S. borders. The WGA asked screenwriters in countries affiliated with the American guild through the International Affiliation of Writers Guilds not to work for American studios during the strike as an act of global solidarity. Having this kind of control of the market on scripts was critical to a successful strike. By including prospective writers and defining them as allies, they increased the chances of unity during the strike.
There is a contradiction in this behavior, however: this unity only confirmed that pathways for international workers into the industry—especially the American industry—are barely open. In this case, solidarity can reaffirm exclusion. And this type of international cooperation is often about leveraging power more than benevolent mutual support. Kevin Sanson argues that global cities offer opportunities for advanced capitalist countries—most notably American but also British and Australian companies—to use their diverse locales, functional technical resources, and skilled practitioners at budget prices. 29 The price of labor is significantly cheaper in part because international production labor is rarely unionized. The easiest way to keep costs low is to film overseas, outsourcing production and postproduction as much as possible to avoid the high costs of unionized labor. The economic and geographic structures of multiplatform global entertainment conglomerates have made transnational production the norm in what are still considered by most national and international audiences to be “Hollywood” productions. 30
While much of so-called Hollywood production labor is now regularly outsourced across international borders, writing has generally stayed in the United States. There are a few jobs, including screenwriting, that tend to be culturally specific: not all jobs cross borders easily or comfortably. The specificities of language and idiom, trends in narrative structure, and cultural references and social issues make writing for a global audience particularly daunting. Companies might be eager to outsource writing to other Anglophone countries, but the reality is that this still rarely occurs. And yet the WGA seems aware that it is only a matter of time before global competition becomes more fierce. Like many other industries, major media corporations are increasingly prone to outsource work to lower-cost regional media capitals. American visual effects and digital postproduction workers’ recent organizing campaigns serve as a legitimate example of U.S. labor’s anxiety about jobs going overseas. Arguably, these developments can provide opportunities for labor in Prague or Budapest or India to earn pay, build skills, build infrastructure, and achieve professional renown. And those jobs could include writing jobs.
The WGA regularly ventures overseas for conversations with other national writers’ guilds and related organizations. While part of the mission is solidarity, they also have hopes of professionalizing their international counterparts in the hope of limiting outsourcing. This represents a model of modified inclusion, something WGA West vice president Howard Rodman explained as “we can’t give you what we have, but we will help you navigate the waters to get there—in the meantime by helping you secure better wages, we will ensure that our native industry does not see your labor as enticing.” 31
Other writers’ guilds exist around the world, primarily in economically developed countries. South Africa, Israel, and Australia have strong screenwriters’ guilds. In the United Kingdom, the WGGB is part social club and part professional organization. Greece and Italy are establishing their guilds as social clubs first (with the hope that professionalization will follow).
The WGA has built connections with screenwriters’ guilds from around the world and continues to build more, in part through professional organizations like the International Association of Writers Guilds. 32 Granted, the tie with each union, association, or professional organization shifts based on the changing nature of labor relations for each individual country. One example of this is in the case of New Zealand. Though writers in New Zealand have been unionized for over forty years, the Employment Contract Act of 1989 was a terrible blow to creative labor in the country. The act transformed the nature of labor in New Zealand, terminating any chance that media workers would hold rights to residuals. Norelle Scott, a member of the New Zealand Writers Guild, explained how the act decimated the power of creative labor—and it was only writers’ affiliation with the International Association of Writers Guilds that kept its membership focused on whatever rights they still controlled. 33 It was through the strength of international partnerships that the New Zealand Writers Guild began to rebuild after this devastating blow. With their ties to the International Association of Writers Guilds, the New Zealand Writers Guild made steps forward, setting agendas and structures for international coproductions and discussing strategies for developing free trade agreements.
Writers in Greece, Italy, and France have over the years developed clear agendas as well—whether or not they are specifically stated. As U.S. formats and sensibilities are exported and transferred around the world, writers who work elsewhere are eager to import professional rights. Many hope in time not only that increased coproductions and transnational industry shifts will lure production dollars but that preproduction will also come to their countries. And with this importation, there is hope that the rights of professional writers will be redefined. American screenwriters see part of that process as making sure local writers protect themselves from their own native industry, no matter what form that native industry assumes.
The WGA has passed on to professional screenwriters across the world their frustration with media production and with the fact that directors, producers, and actors are nearly always paid better. In addition, writers rarely have much control over the way their scripts are used. Spanish screenwriter Agustín Díaz Yanes said, “The worst comment you can ever hear when you go and see a producer is when they say to you: ‘The screenplay is essential.’ That’s when you know they pay peanuts, if they pay at all!” 34 While it is not the sanctity of the screenplay that matters, Yanes’s comment about the place of the writer on the lower end of the creative hierarchy speaks to a frustration widely shared among writers working in the global media industries.
In a global media production landscape, the unique dynamics of individual careers can obscure the trends of the media industries. It is not only the power of the major conglomerates at work but also the needs of trade organizations that guide debate and discussion, as well as actions that define patterns of inclusion and exclusion and hierarchies of power. As Bridget Conor observes in her study of labor problems surrounding the Lord of the Rings trilogy (filmed in New Zealand), extraordinary displays of “empire in action” demand our attention as we study precarious labor in a global economy. 35 With the expanding frontiers of media production—even within the economy of a single film or film series—there is both a fear of what could happen if unionization is quashed on a global level and hope for what could happen if an alliance across countries were solidified among writers’ guilds.


10.5: Fetal Growth and Development
By the end of this section, you will be able to:
- Explain the relevance of genetics in conception and fetal development
- Differentiate between the stages of fetal development
- Explain the physiology of the placenta
- Explain fetal circulation
- Discuss important milestones of fetal growth and development
- Explain the effects of important influences on fetal growth and development
When providing prenatal care, the nurse should understand the basic laws of genetic inheritance in order to provide preconceptual counseling and basic genetic information. Knowledge of the processes of conception and embryonic and fetal development is important for the nurse to understand why and when the fetus is vulnerable. The nurse also needs to comprehend how lifestyle behaviors and environmental exposures affect the pregnancy and the growth and development of the embryo and fetus. Understanding the laws of inheritance, fetal growth and development, and the multiple influences on fetal growth and development is part of the foundation of prenatal care.
Genetics
The study of heredity and the patterns of inherited traits is called genetics . The basics of genetics include understanding the role of chromosomes and genes. Chromosomes are found in the nucleus of every cell in the human body and contain all the person’s genes. Genes are short strands of deoxyribonucleic acid (DNA) found within the chromosome; they carry the traits of inheritance and direct many functions to maintain the health of the human body. The science of genomics maps and studies the functions of genomes, the gene sequencing forming the DNA chain within any cell in the body. Each gene instructs a specific set of proteins to perform a specific function within a person’s body. Any change in the structure or location of a gene within a DNA molecule results in an abnormality within a specific function of the body, such as lactose intolerance. Advances in genetics and genomics contribute to the growing knowledge of prevention, detection, and diagnosis of disease and provide health care providers the means to develop personalized treatment plans. For a list of disorders caused by genetic mutations, see Table 10.11.
| Disorder | Description |
|---|---|
| Sickle cell disease | Changes the structure of the red blood cell, diminishing the ability of the RBC to transport oxygen; most commonly found genetic disorder in people of African descent (recessive) |
| Cystic fibrosis | Produces thick mucus that blocks the bronchi and fibrous tumors causing pancreatic insufficiency; most commonly found genetic disorder in people of European descent (recessive) |
| Tay-Sachs disease | Degenerative nervous system disease resulting in the death of the infant by 2 years of age; most commonly found genetic disorder in people of Ashkenazi Jewish descent (recessive) |
| Huntington chorea | Progressive neuromuscular disorder affecting motor, memory, and behavior (dominant) |
| Hemophilia | Lack of factor VIII in the clotting cascade; without replacement factor VIII, bleeding cannot be controlled (X-linked) |
Perinatally, genetics and genomics present facts and risks to the expectant parents and their families regarding inherited disorders or anomalies. Some families are faced with decisions before they conceive, such as when both prospective parents know they carry the recessive sickle cell trait. Other families make decisions after conception when informed the fetus has a chromosome or genetic disorder, such as Down syndrome or cystic fibrosis .
Inheritance
Nursing care in the perinatal period requires the nurse to understand and explain basic patterns of inheritance to persons considering pregnancy or who are already pregnant. The patterns of inherited traits are the result of dominant or recessive genes. A dominant gene (brown eye color) will mask the trait of a recessive gene (blue eye color) in a person. Autosomal dominant disorders occur when the mutated gene produces the disorder when present in the heterozygous state. Autosomal recessive disorders occur when the mutated gene produces the disorder only when present in the homozygous state. It takes a pair of recessive genes (one from each parent) for the recessive trait to appear in the offspring.
Inherited conditions are also linked to the X and Y chromosomes. The conditions occur based on whether the gene is located only on the X or Y chromosome and if the gene is dominant or recessive. X-linked dominant disorders happen when the mutated gene is located only on the X chromosome and the disorder presents in the heterozygous state. X-linked recessive disorders happen when the mutated gene is located only on the X chromosome and the disorder presents only in the homozygous state. The mutated gene is located only on the Y chromosome in Y-linked disorders. The Y chromosome is paired with the X chromosome during fertilization to produce XY offspring. All XY offspring will have the disorder or trait. Figure 10.12 illustrates these different patterns of inheritance.
Chromosome Abnormalities
Some genetic disorders are the result of inherited abnormal chromosomes. However, most chromosomal disorders are not inherited. Instead, the abnormality occurs during the formation of the egg or the sperm, immediately after fertilization, or during embryonic development. Abnormalities in the chromosomes of the egg or sperm show up in every cell of the person’s body. When abnormalities in the chromosomes occur immediately after fertilization during mitosis, the abnormality shows as mosaicism, in which the abnormality in the chromosome is not present in every cell. In the United States, 1 out of 150 live-born newborns has chromosomal abnormalities (March of Dimes, 2022), and 50 percent of spontaneous abortions (miscarriages) have chromosome abnormalities (Cleveland Clinic, 2023). Health care providers use a karyotype, an image showing the results of a chromosome analysis, to identify anomalies.
A person may have more or fewer than the normal 46 chromosomes. Trisomy 21, Down syndrome , is the most commonly known trisomy abnormality, in which a third copy of the entire 21st chromosome is added. Trisomy 18 and Trisomy 13 also feature an additional entire chromosome. Turner syndrome occurs when an entire X chromosome is missing (Figure 10.13). In Klinefelter syndrome, an extra X chromosome, XXY, is present.
Chromosome structure can be changed in multiple ways. Deletions occur when part of the chromosome is missing. Duplications occur when the entire chromosome or part of a chromosome is duplicated. Inversions are when a part of the chromosome breaks off and reattaches upside down. Rings are when a part of the chromosome breaks away and reattaches to form a ring. Translocations occur when a part of a chromosome is missing and the missing part has attached itself to a different chromosome altogether. These structural abnormalities can affect several genes with unpredictable effects on the affected person’s body structure and physiology.
What do you know about birth defects? Take this quiz from the University of Rochester Medical Center to test your knowledge.
Genetic Counseling
Genetic counseling is the provision of information about inherited conditions, disorders, or abnormalities affecting an individual or a family. The information is provided by a trained professional. Perinatally, counseling is provided to biological parents prior to conception, after a prenatal screening for or diagnosis of a chromosome or genetic disorder, and after the birth of a newborn with a chromosome or genetic or another congenital anomaly. The purpose of genetic counseling is to determine risk for genetic abnormalities, to answer questions about prognosis and long-term care of these conditions, to discuss legal and ethical issues, and to provide referrals to additional services. Risk factors that may indicate the need for genetic counseling include the following:
- Pregnant person aged 35 years or older at the estimated date of delivery (EDD)
- Other biological parent’s age of 50 years or older
- Known carriers of genetic disorders
- Pregnant person’s history of a minimum of two pregnancy losses
- Biological parent of a child with congenital anomalies (stillbirth or live birth)
- Biological parent of a child with developmental delays or sensory disorders
- Family history of either biological parent that includes a relative with genetic or congenital anomalies, developmental delays, or sensory disorders
- Consanguinity or incest
- Exposure to teratogens during pregnancy (Centers for Disease Control and Prevention [CDC], 2022)
The ideal time for obstetric care providers to offer genetic counseling is before conception. Preconception screening for both medical and genetic disorders opens up a dialog between the prospective biological parents. Genetic counseling, based on a comprehensive family genetic history, provides accurate information on the risks and incidence of genetic disorders as a couple in order for the pregnant person to make the most informed decision. A list of genetic disorders and congenital anomalies to include when obtaining the genetic history is included in Table 10.12.
| Genetic Disorders | Congenital Anomalies |
|---|---|
|
Thalassemia
Tay-Sachs disease Sickle cell anemia Cystic fibrosis Hemophilia Muscular dystrophy Spinal muscular atrophy Neurofibromatosis Huntington disease Epilepsy Phenylketonuria (PKU) Chromosome abnormality |
Congenital heart disease
Cleft lip and/or cleft palate Limb defects Deafness Blindness Neural tube defects Developmental delay Unexplained pregnancy loss |
Several factors influence a person’s choice to undergo genetic counseling and testing. These factors include socioeconomic, cultural, and religious considerations. Legal, ethical, and moral considerations surrounding decisions based on genetic risks make the decision making a complex process. Nurses who provide information to parents and families about genetics must have the following competencies: interviewing skills, ensuring confidentiality and informed consent, and provision of ethical, legal, psychosocial, and culturally appropriate care. Knowledge competencies include inheritance patterns, genetic probability, financial aspects of counseling and laboratory testing, and the risks and benefits of genetic testing. It is also important for the nurse to know their limitations and refer patients and families to other individuals, groups, or agencies when necessary.
Nurse:
L.K.
Clinical Setting:
Labor and delivery unit
Geographic Location:
South Carolina
I remember when a patient came into the labor and delivery unit with a known fetal congenital anomaly that was incompatible with life outside the uterus . The anomaly was anencephaly (a serious birth defect in which a baby is born without parts of the brain and skull). I was assigned to the patient, who was in early labor. During the admission process, I asked the patient what her plans were for pain relief. The patient stated an epidural and spontaneously said she did not want her mind clouded with drugs so she would be alert during Angel’s (the name the couple had given to their baby) birth and transition. The patient’s husband volunteered that they both had had genetic counseling , but the most important influence on their decision to continue the pregnancy was their minister. The minister also went to genetic counseling to become more informed about the anomaly and the prognosis for the fetus. While in early labor, the patient and her husband openly discussed how they arrived at the decision of continuing to provide life to the fetus and newborn for however long the newborn survived, inside or outside the uterus.
I did not ask this couple to explain their decision-making process. The information was freely given to me. I was not present for the birth of Angel, but I was able to realize how the information this couple received during the genetic counseling played a role in both continuing the pregnancy and the birth plan.
Fetal Development
Nurses practicing in perinatal care need to understand and be able to explain the processes of conception and embryonic and fetal development . Conception, or fertilization, is when the sperm and ovum unite to form the zygote and typically occurs within the fallopian tube. After the zygote has divided into 16 cells, the zygote becomes the morula . Peristalsis and cilia within the fallopian tube help to move the morula into the uterus. The time from conception to when the morula enters the uterus is about 72 hours. Over the next several days, the cells of the morula divide into specialized cells, blastocyst and trophoblast , that will create the fetal structures. The blastocyst is the group of cells forming the embryo and the amnion. The trophoblast is the group of cells forming the placenta and the chorion. The trophoblast and blastocyst implant in the endometrium within 7 to 10 days after conception. When the trophoblast has successfully attached to the endometrium, implantation occurs. The days from conception to implantation are the pre-embryonic stage of development (Figure 10.14).
Embryonic Stage of Development
The embryonic stage of fetal development begins with the completion of implantation and ends at the start of week 9 of gestation. The weeks of gestation during pregnancy are calculated from the first day of the pregnant person’s last menstrual period rather than from the date of conception. In the final days of the pre-embryonic stage, the blastocyst develops into three germ layers called the ectoderm, mesoderm, and endoderm. The formation and development of the organs of the body, called organogenesis , starts at the beginning of the embryonic stage. The three germ layers develop into the organs, tissues, and structures of the body.
Although the nervous system starts forming first, the embryo’s cardiovascular system begins functioning first. The hemoglobin formed by the embryo has a higher affinity for oxygen than adult hemoglobin because the embryo is dependent on the parent for oxygen. The embryo also requires more oxygen to support its rapid growth. The nervous system works within the first 8 weeks of gestation but is not fully developed at birth. This is evident by a newborn’s lack of neuromuscular coordination, developed senses, or speech. The brain is not fully developed until 5 years of age. In most cases, the gonads differentiate into male or female by 8 weeks. The testes stay in the inguinal canal, fully descending between 34 and 36 weeks of gestation.
Exposure to teratogens during organogenesis leads to an increase in the risk of malformations in all systems of the embryo’s body (Figure 10.15). During organogenesis, the trachea and esophagus are one tube. The separation into esophagus and trachea is not complete until 5 weeks of gestation. If the pregnant person is exposed to a teratogen at this critical point, then a congenital anomaly called a tracheal-esophageal (TE) fistula could result. In this anomaly, the esophagus is attached to the trachea rather than to the stomach . Table 10.13 summarizes the weekly changes in embryo development.
| Week of Gestation | Structure and System Development |
|---|---|
| Week 3 |
Neural tube: brain and spinal cord
Heart and gastrointestinal tract Limb buds form |
| Week 4 |
Brain structures begin to form
Stomach, pancreas, and liver start to form Limb buds enlarge |
| Week 5 |
Cranial nerves start to form
Heartbeat is detectable Neuromuscular connections are establishing Eyes and ears are beginning to form |
| Week 6 |
CNS forms, and brain waves are detectable
Fetal circulation is established RBCs are starting to be formed in the liver Lungs begin forming Skeletal structure is laid out |
| Week 7 |
Arm and leg movements, toes visible
Mouth and lips formed Diaphragm formed Nipples, hair follicles, and genitals form |
| Week 8 |
Heart is developed
Facial features continue to develop Intestinal rotation occurs Bone cells replace cartilage |
Fetal Stage of Development
The fetal stage of development begins at 9 weeks of gestation and ends with birth (Figure 10.16). Organs, tissues, and structures of the fetus continue to develop and begin to function. The fetus has its own circulation, and the umbilical cord connects the fetus to the placenta . The skin on the fetal abdomen closes at around 10 weeks of gestation. Exposure to teratogens at this part of organogenesis can result in abdominal congenital anomalies known as gastroschisis (failure of the upper abdomen to close, allowing the stomach to protrude) or omphalocele (failure of the abdomen to close at the umbilicus, allowing the intestines to protrude).
Skeletal system development reaches an important step when ossification starts at 12 weeks’ gestation. The kidneys are capable of producing urine at 12 weeks. Urine production influences the amount of amniotic fluid that is present. Urine production is also required for fetal lung development. When urine is not excreted into the amniotic fluid, as in the case of Potter syndrome, the lungs remain hypoplastic, incapable of inflating. At 16 weeks, the fetus starts forming stool called meconium. Unless infection is present, the fetal gut remains sterile until after birth. Digestive enzymes are not secreted sufficiently until 36 weeks of gestation. This is why preterm newborns do not tolerate formula or even breast milk well. The lungs are among the last organs to complete anatomic development. Until 24 weeks of gestation, the alveoli are not formed or present in sufficient numbers. Without the surface area in the alveoli for gas exchange in the lungs, the fetus has not reached viability , or the ability to survive outside the uterus. For the alveoli to expand and retract for respiration, the lungs need to produce surfactant , a mixture of fats and proteins produced in the lungs that coats the alveoli. When the newborn exhales, surfactant keeps the alveoli from sticking together, interfering with expansion of the alveoli during the next inhalation. The fetus starts producing surfactant at 24 weeks. Table 10.14 lists the milestones in fetal development by weeks of gestation.
| Week of Gestation | Structure and System Development |
|---|---|
| Week 12 |
Ossification begins at 12 weeks and continues through childhood
Urine is formed Limbs move at the joints Eyelids are fused Palate is completely formed Fetal heart rate can be heard by Doppler |
| Week 16 |
Pinna of ear is formed
Respiratory system is formed Hand and foot ridges are formed Fetus is able to make sucking motions Meconium is forming in the intestines |
| Week 20 |
Pancreas is producing insulin
Sleep and activity pattern is present Lanugo and vernix cover the body Nails are formed Brown fat begins to develop |
| Week 24 |
Now viable because alveoli in the lungs are forming in preparation for breathing, and surfactant is starting to be produced by the alveoli
Eyelids begin to open Capable of hearing |
| Week 28 |
Eyelids open and close
Blood formation now occurs in bone marrow Nervous system takes over more functions Fetus has a sleep-wake cycle Fetus reacts more to the sound of the pregnant person’s voice |
| Week 32 |
Bones are developed
Increase in the number of adipose cells Breathing movements are rhythmic |
| Week 37 |
Enzymes for digestion not secreted efficiently until 36 weeks
Testes do not descend until 34–36 weeks Fetus is considered full term at 37 weeks |
You can watch video footage of fetal development inside the womb to observe the stages of development.
Formation and Functions of the Placenta
The placenta is a unique organ because it develops for the sole purpose of providing nutrients and oxygen to the developing embryo and fetus and removing the fetal waste products and carbon dioxide. The placenta has a limited lifespan, ending with its delivery after the birth of the newborn. The formation of the placenta starts at implantation .
Formation of the Placenta
The placenta is formed from a blend of tissue from the embryo and the pregnant person. The chorionic membrane and chorionic villi make up the fetal side of the placenta. The chorionic villi develop into the fetal blood vessels that will merge into the umbilical cord vessels. The fetal blood vessels protrude into the decidua basalis, the pregnant person’s side of the placenta. The decidua basalis is one of the three layers of the endometrium and helps to form the cotyledons, or lobes on the pregnant person’s side of the placenta (Figure 10.17).
The placental membrane separates the fetal side of the placenta from the pregnant person’s side. The placental membrane allows transfer of oxygen and nutrients to the fetus and carbon dioxide and waste products to the pregnant person, without the mixing of fetal and parental blood. The amnionic membrane, formed at the same time as the chorion, is part of the placenta and lies over the chorion. The amniotic membrane forms the sac around the embryo and fills with amniotic fluid as the fetus grows and develops. The formation of the placenta is usually complete by week 12 of gestation.
Functions of the Placenta, Membranes, and Amniotic Fluid
The placenta performs physiologic functions for the developing embryo and fetus. Respiration occurs in the placenta. Oxygen diffuses across the placenta membrane from the pregnant person to the fetus, and carbon dioxide diffuses across the placenta membrane from the fetus to the pregnant person. Nutritional intake is another physiologic function of the placenta. Glucose diffuses from the pregnant person to the fetus to provide energy. Amino acids cross the placenta membrane from the pregnant person to the fetus via active transport to be synthesized by the fetus for growth and development. Fatty acids are transported to the fetus via simple diffusion and are essential to building the brain and nerves. Water and electrolytes are transferred from the pregnant person to the fetus via passive diffusion. Iron, calcium, and vitamins require active transport across the placenta membrane from the pregnant person to the fetus. The placenta also acts as the kidneys for the fetus, transporting metabolic waste like urea, uric acid, and bilirubin to the pregnant person to eliminate.
Another important function of the placenta is the production of hormones to support the pregnancy and fetal growth and development. The placenta produces progesterone , estrogen , human chorionic gonadotropin (hCG), human placental lactogen (hPL) , and relaxin .
- Progesterone serves two major functions: to facilitate implantation and to decrease uterine contractions.
- Estrogen stimulates enlargement of the uterus and breasts.
- Human chorionic gonadotropin supports the production of estrogen and progesterone from the corpus luteum until the placenta can produce these hormones.
- Human placental lactogen promotes fetal growth and parental breast development.
- Relaxin is produced first by the corpus luteum and then by the placenta. Relaxin increases the elasticity of the ligaments in the pregnant person, loosening the joints in the body. Relaxin helps prepare the pelvis to accommodate the fetus during the birth process.
The fetal membranes consist of the chorion and amnion. The functions of the fetal membranes are to contain the amniotic fluid and to help protect the fetus from infections. The functions of the amniotic fluid include protecting the fetus from injury, allowing freedom of movement for normal development of the fetus, and maintaining a consistent intrauterine temperature. The fluid is produced by the amniotic membrane in the first 14 weeks of the pregnancy and by the fetal kidneys during the remainder of the pregnancy.
Fetal Circulation
Fetal circulation allows oxygenated blood from the placenta to travel to the major functioning organs of the fetus, and it allows deoxygenated blood to go back to the placenta. This flow of blood requires a different circulation pattern in the fetus than is present in the newborn. The umbilical cord usually inserts into the center of the placenta and contains two arteries and one vein. Oxygenated blood is transported to the fetus from the placenta via the umbilical vein. The ductus venosus connects the umbilical vein to the inferior vena cava of the fetus. This places the oxygenated blood near the right atrium. The foramen ovale shunts the oxygenated blood from the right to left atrium, allowing some of the blood to bypass the right ventricle. The ductus arteriosus connects with the pulmonary artery to the descending aorta, bypassing the lungs so that more oxygenated blood is circulated throughout the body of the fetus. The deoxygenated blood is carried back to the placenta via the umbilical arteries that branch off the right and left internal iliac arteries (Figure 10.18). Fetal circulation is necessary, since the lungs are filled with fluid and cannot supply oxygen to or remove carbon dioxide from the fetus until after birth. When the newborn takes their first breath and starts crying, the pressure within the lungs causes the foramen ovale to close. Within 24 to 48 hours, the ductus arteriosus closes as well because the blood is now circulating in the pulmonary system. When the umbilical cord is clamped and blood ceases to flow through the ductus venosus, it collapses, closing as well.
Influences on Fetal Development
The nutrition and lifestyle habits of the pregnant person, environmental hazards, teratogens, TORCH and other infections, and maternal preexisting conditions can all affect the growth and development of the embryo and fetus. Embryonic and fetal development are affected by the pregnant person’s nutrition prior to and during pregnancy . A deficiency in folic acid has been linked to neural tube defects ( spina bifida , myelomeningocele , encephalocele , and anencephaly ). Too much vitamin A, as from the acne treatment isotretinoin (Accutane) , is linked to cleft lip and palate. Maternal exposure to environmental hazards can be through the lungs, ingestion, and exposure to an organism. A teratogen is anything known to affect the normal growth and development of the embryo or fetus. Teratogens include chemicals, drugs, and lifestyle habits.
TORCH , a group of infectious diseases that can be passed from the pregnant person to the fetus, is a known teratogen. The diseases included in the group are
- toxoplasmosis,
- other (originally only syphilis),
- rubella,
- cytomegalovirus, and
- herpes.
The causative viruses, bacteria, or organisms are capable being transported through the placenta membrane and affecting multiple fetal organ systems, specifically the brain, heart , eyes, ears, and skin. Table 10.15 lists TORCH infection effects on the fetus. If syphilis goes untreated or is treated in the second or third trimester, the newborn will have congenital syphilis or be stillborn. Hepatitis most commonly causes liver disease in the newborn.
| Infection | Effect on the Fetus |
|---|---|
|
Toxoplasmosis
protozoan |
Spontaneous abortion, low birth weight (LBW), hepatomegaly, neurologic damage |
|
Other: Hepatitis B
virus |
Chronically infected, HBV carrier, liver disease |
|
Other: Syphilis
bacteria |
Neurologic damage, congenital syphilis, stillbirth |
|
Rubella
virus |
Congenital rubella syndrome
Deafness, eye anomalies, neurologic deficits, cardiac anomalies |
|
Cytomegalovirus
herpes group virus |
LBW, hearing impairment, microcephaly, neurologic deficits |
|
Herpes
chronic viral infection |
Neurologic deficits, hepatic encephalopathy |
If a pregnant person is human immunodeficiency virus ( HIV ) positive and their CD4 count does not fall below 400, the infant will usually convert to seronegative within 6 months to 2 years of age if the person takes zidovudine (AZT) during pregnancy and/or during labor and birth. Additional information on teratogens and other influences on the growth and development of the fetus are discussed in Chapter 12 Pregnancy at Risk.