5.4: Exercise, Nutrition, Hormones, and Bone Tissue
All of the organ systems of your body are interdependent, and the skeletal system is no exception. The food you take in via your digestive system and the hormones secreted by your endocrine system affect your bones.
Exercise and Bone Tissue
During long space missions, astronauts can lose approximately 1 to 2 percent of their bone mass per month. This loss of bone mass is thought to be caused by the lack of mechanical stress on astronauts’ bones due to the low gravitational forces in space. Lack of mechanical stress causes bones to lose mineral salts and collagen fibers, and thus strength. Similarly, mechanical stress stimulates the deposition of mineral salts and collagen fibers. The internal and external structure of a bone will change as stress increases or decreases so that the bone is an ideal size and weight for the amount of activity it endures. That is why people who exercise regularly have thicker bones than people who are more sedentary. It is also why a broken bone in a cast atrophies while its contralateral mate maintains its concentration of mineral salts and collagen fibers. The bones undergo remodeling as a result of forces (or lack of forces) placed on them.
Numerous, controlled studies have demonstrated that people who exercise regularly have greater bone density than those who are more sedentary. Any type of exercise will stimulate the deposition of more bone tissue, but resistance training has a greater effect than cardiovascular activities. Resistance training is especially important to slow down the eventual bone loss due to aging and for preventing osteoporosis.
Nutrition and Bone Tissue
The vitamins and minerals contained in all of the food we consume are important for all of our organ systems. However, there are certain nutrients that affect bone health.
Calcium and Vitamin D
You already know that calcium is a critical component of bone, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet. However, calcium cannot be absorbed from the small intestine without vitamin D. Therefore, intake of vitamin D is also critical to bone health. In addition to vitamin D’s role in calcium absorption, it also plays a role, though not as clearly understood, in bone remodeling.
Milk and other dairy foods are not the only sources of calcium. This important nutrient is also found in green leafy vegetables, broccoli, and intact salmon and canned sardines with their soft bones. Nuts, beans, seeds, and shellfish provide calcium in smaller quantities.
Except for fatty fish like salmon and tuna, or fortified milk or cereal, vitamin D is not found naturally in many foods. The action of sunlight on the skin triggers the body to produce its own vitamin D (Figure 5.22), but many people, especially those of darker complexion and those living in northern latitudes where the sun’s rays are not as strong, are deficient in vitamin D. In cases of deficiency, a doctor can prescribe a vitamin D supplement.
Other Nutrients
Vitamin K also supports bone mineralization and may have a synergistic role with vitamin D in the regulation of bone growth. Green leafy vegetables are a good source of vitamin K.
The minerals magnesium and fluoride may also play a role in supporting bone health. While magnesium is only found in trace amounts in the human body, more than 60 percent of it is in the skeleton, suggesting it plays a role in the structure of bone. Fluoride can displace the hydroxyl group in bone’s hydroxyapatite crystals and form fluorapatite. Similar to its effect on dental enamel, fluorapatite helps stabilize and strengthen bone mineral. Fluoride can also enter spaces within hydroxyapatite crystals, thus increasing their density.
Omega-3 fatty acids have long been known to reduce inflammation in various parts of the body. Inflammation can interfere with the function of osteoblasts, so consuming omega-3 fatty acids, in the diet or in supplements, may also help enhance production of new osseous tissue. Table 5.5 summarizes the role of nutrients in bone health.
| Nutrients and Bone Health | |
|---|---|
| Nutrient | Role in bone health |
| Calcium | Needed to make calcium phosphate and calcium carbonate, which form the hydroxyapatite crystals that give bone its hardness |
| Vitamin D | Needed for calcium absorption |
| Vitamin K | Supports bone mineralization; may have synergistic effect with vitamin D |
| Magnesium | Structural component of bone |
| Fluoride | Structural component of bone |
| Omega-3 fatty acids | Reduces inflammation that may interfere with osteoblast function |
Hormones and Bone Tissue
The endocrine system produces and secretes hormones, many of which interact with the skeletal system. These hormones are involved in controlling bone growth, maintaining bone once it is formed, and remodeling it.
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth in several ways. It triggers chondrocyte proliferation in epiphyseal plates, resulting in the increasing length of long bones. GH also increases calcium retention, which enhances mineralization, and stimulates osteoblastic activity, which improves bone density.
GH is not alone in stimulating bone growth and maintaining osseous tissue. Thyroxine, a hormone secreted by the thyroid gland promotes osteoblastic activity and the synthesis of bone matrix. During puberty, the sex hormones (estrogen in girls, testosterone in boys) also come into play. They too promote osteoblastic activity and production of bone matrix, and in addition, are responsible for the growth spurt that often occurs during adolescence. They also promote the conversion of the epiphyseal plate to the epiphyseal line (i.e., cartilage to its bony remnant), thus bringing an end to the longitudinal growth of bones. Additionally, calcitriol, the active form of vitamin D, is produced by the kidneys and stimulates the absorption of calcium and phosphate from the digestive tract.
Aging and the Skeletal System
Osteoporosis is a disease characterized by a decrease in bone mass that occurs when the rate of bone resorption exceeds the rate of bone formation, a common occurrence as the body ages. Notice how this is different from Paget’s disease. In Paget’s disease, new bone is formed in an attempt to keep up with the resorption by the overactive osteoclasts, but that new bone is produced haphazardly. In fact, when a physician is evaluating a patient with thinning bone, he or she will test for osteoporosis and Paget’s disease (as well as other diseases). Osteoporosis does not have the elevated blood levels of alkaline phosphatase found in Paget’s disease.
While osteoporosis can involve any bone, it most commonly affects the proximal ends of the femur, vertebrae, and wrist. As a result of the loss of bone density, the osseous tissue may not provide adequate support for everyday functions, and something as simple as a sneeze can cause a vertebral fracture. When an elderly person falls and breaks a hip (really, the femur), it is very likely the femur that broke first, which resulted in the fall. Histologically, osteoporosis is characterized by a reduction in the thickness of compact bone and the number and size of trabeculae in cancellous bone.
Figure 5.23 shows that women lose bone mass more quickly than men starting at about 50 years of age. This occurs because 50 is the approximate age at which women go through menopause. Not only do their menstrual periods lessen and eventually cease, but their ovaries reduce in size and then cease the production of estrogen, a hormone that promotes osteoblastic activity and production of bone matrix. Thus, osteoporosis is more common in women than in men, but men can develop it, too. Anyone with a family history of osteoporosis has a greater risk of developing the disease, so the best treatment is prevention, which should start with a childhood diet that includes adequate intake of calcium and vitamin D and a lifestyle that includes weight-bearing exercise. These actions, as discussed above, are important in building bone mass. Promoting proper nutrition and weight-bearing exercise early in life can maximize bone mass before the age of 30, thus reducing the risk of osteoporosis.
For many elderly people, a hip fracture can be life threatening. The fracture itself may not be serious, but the immobility that comes during the healing process can lead to the formation of blood clots that can lodge in the capillaries of the lungs, resulting in respiratory failure; pneumonia due to the lack of poor air exchange that accompanies immobility; pressure sores (bed sores) that allow pathogens to enter the body and cause infections; and urinary tract infections from catheterization.
Current treatments for managing osteoporosis include bisphosphonates (the same medications often used in Paget’s disease), calcitonin, and estrogen (for women only). Minimizing the risk of falls, for example, by removing tripping hazards, is also an important step in managing the potential outcomes from the disease.
Hormones That Influence Osteoclasts
Bone modeling and remodeling require osteoclasts to resorb unneeded, damaged, or old bone, and osteoblasts to lay down new bone. Two hormones that affect the osteoclasts are parathyroid hormone (PTH) and calcitonin.
PTH stimulates osteoclast proliferation and activity. As a result, calcium is released from the bones into the circulation, thus increasing the calcium ion concentration in the blood. PTH also promotes the reabsorption of calcium by the kidney tubules, which can affect calcium homeostasis (see below).
The small intestine is also affected by PTH, albeit indirectly. Because another function of PTH is to stimulate the synthesis of vitamin D, and because vitamin D promotes intestinal absorption of calcium, PTH indirectly increases calcium uptake by the small intestine. Calcitonin, a hormone secreted by the thyroid gland, has some effects that counteract those of PTH. Calcitonin inhibits osteoclast activity and stimulates calcium uptake by the bones, thus reducing the concentration of calcium ions in the blood. As evidenced by their opposing functions in maintaining calcium homeostasis, PTH and calcitonin are generally not secreted at the same time. Table 5.6 summarizes the hormones that influence the skeletal system.
| Hormones That Affect the Skeletal System | |
|---|---|
| Hormone | Role |
| Growth hormone | Increases length of long bones, enhances mineralization, and improves bone density |
| Thyroxine | Stimulates bone growth and promotes synthesis of bone matrix |
| Sex hormones | Promote osteoblastic activity and production of bone matrix; responsible for adolescent growth spurt; promote conversion of epiphyseal plate to epiphyseal line |
| Calcitriol | Stimulates absorption of calcium and phosphate from digestive tract |
| Parathyroid hormone | Stimulates osteoclast proliferation and resorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine |
| Calcitonin | Inhibits osteoclast activity and stimulates calcium uptake by bones |
Contributors and Attributions
- Chapter 6. Authored by : OpenStax College. Provided by : Rice University. Located at : http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22<EMAIL_ADDRESS>. Project : Anatomy & Physiology. License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/content/col11496/latest/ .


47.2: The Importance of Biodiversity to Human Life
Skills to Develop
- Identify chemical diversity benefits to humans
- Identify biodiversity components that support human agriculture
- Describe ecosystem services
It may not be clear why biologists are concerned about biodiversity loss. When biodiversity loss is thought of as the extinction of the passenger pigeon, the dodo bird, and even the woolly mammoth, the loss may appear to be an emotional one. But is the loss practically important for the welfare of the human species? From the perspective of evolution and ecology, the loss of a particular individual species is unimportant (however, the loss of a keystone species can lead to ecological disaster). Extinction is a normal part of macroevolution. But the accelerated extinction rate means the loss of tens of thousands of species within our lifetimes, and it is likely to have dramatic effects on human welfare through the collapse of ecosystems and in added costs to maintain food production, clean air and water, and human health.
Agriculture began after early hunter-gatherer societies first settled in one place and heavily modified their immediate environment. This cultural transition has made it difficult for humans to recognize their dependence on undomesticated living things on the planet. Biologists recognize the human species is embedded in ecosystems and is dependent on them, just as every other species on the planet is dependent. Technology smoothes out the extremes of existence, but ultimately the human species cannot exist without its ecosystem.
Human Health
Contemporary societies that live close to the land often have a broad knowledge of the medicinal uses of plants growing in their area. Most plants produce secondary plant compounds , which are toxins used to protect the plant from insects and other animals that eat them, but some of which also work as medication. For centuries in Europe, older knowledge about the medical uses of plants was compiled in herbals—books that identified plants and their uses. Humans are not the only species to use plants for medicinal reasons: the great apes, orangutans, chimpanzees, bonobos, and gorillas have all been observed self-medicating with plants.
Modern pharmaceutical science also recognizes the importance of these plant compounds. Examples of significant medicines derived from plant compounds include aspirin, codeine, digoxin, atropine, and vincristine (Figure \(\PageIndex{1}\)). Many medicines were once derived from plant extracts but are now synthesized. It is estimated that, at one time, 25 percent of modern drugs contained at least one plant extract. That number has probably decreased to about 10 percent as natural plant ingredients are replaced by synthetic versions. Antibiotics, which are responsible for extraordinary improvements in health and lifespans in developed countries, are compounds largely derived from fungi and bacteria.
In recent years, animal venoms and poisons have excited intense research for their medicinal potential. By 2007, the FDA had approved five drugs based on animal toxins to treat diseases such as hypertension, chronic pain, and diabetes. Another five drugs are undergoing clinical trials, and at least six drugs are being used in other countries. Other toxins under investigation come from mammals, snakes, lizards, various amphibians, fish, snails, octopuses, and scorpions.
Aside from representing billions of dollars in profits, these medicines improve people’s lives. Pharmaceutical companies are actively looking for new compounds synthesized by living organisms that can function as medicine. It is estimated that 1/3 of pharmaceutical research and development is spent on natural compounds and that about 35 percent of new drugs brought to market between 1981 and 2002 were from natural compounds. The opportunities for new medications will be reduced in direct proportion to the disappearance of species.
Agricultural Diversity
Since the beginning of human agriculture more than 10,000 years ago, human groups have been breeding and selecting crop varieties. This crop diversity matched the cultural diversity of highly subdivided populations of humans. For example, potatoes were domesticated beginning around 7,000 years ago in the central Andes of Peru and Bolivia. The potatoes grown in that region belong to seven species and the number of varieties likely is in the thousands. Each variety has been bred to thrive at particular elevations and soil and climate conditions. The diversity is driven by the diverse demands of the topography, the limited movement of people, and the demands created by crop rotation for different varieties that will do well in different fields.
Potatoes are only one example of human-generated diversity. Every plant, animal, and fungus that has been cultivated by humans has been bred from original wild ancestor species into diverse varieties arising from the demands for food value, adaptation to growing conditions, and resistance to pests. The potato demonstrates a well-known example of the risks of low crop diversity: the tragic Irish potato famine when the single variety grown in Ireland became susceptible to a potato blight, wiping out the crop. The loss of the crop led to famine, death, and mass emigration. Resistance to disease is a chief benefit to maintaining crop biodiversity, and lack of diversity in contemporary crop species carries similar risks. Seed companies, which are the source of most crop varieties in developed countries, must continually breed new varieties to keep up with evolving pest organisms. These same seed companies, however, have participated in the decline of the number of varieties available as they focus on selling fewer varieties in more areas of the world.
The ability to create new crop varieties relies on the diversity of varieties available and the accessibility of wild forms related to the crop plant. These wild forms are often the source of new gene variants that can be bred with existing varieties to create varieties with new attributes. Loss of wild species related to a crop will mean the loss of potential in crop improvement. Maintaining the genetic diversity of wild species related to domesticated species ensures our continued food supply.
Since the 1920s, government agriculture departments have maintained seed banks of crop varieties as a way to maintain crop diversity. This system has flaws because, over time, seed banks are lost through accidents, and there is no way to replace them. In 2008, the Svalbard Global Seed Vault (Figure \(\PageIndex{2}\)) began storing seeds from around the world as a backup system to the regional seed banks. If a regional seed bank stores varieties in Svalbard, losses can be replaced from Svalbard. The seed vault is located deep into the rock of an arctic island. Conditions within the vault are maintained at ideal temperature and humidity for seed survival, but the deep underground location of the vault in the arctic means that failure of the vault’s systems will not compromise the climatic conditions inside the vault.
Art Connection
The Svalbard Global Seed Vault is located on Spitsbergen island in Norway, which has an arctic climate. Why might an arctic climate be good for seed storage?
Crop success is largely dependent on the quality of the soil. Although some agricultural soils are rendered sterile using controversial cultivation and chemical treatments, most contain a huge diversity of organisms that maintain nutrient cycles—breaking down organic matter into nutrient compounds that crops need for growth. These organisms also maintain soil texture that affects water and oxygen dynamics in the soil that are necessary for plant growth. If farmers had to maintain arable soil using alternate means, the cost of food would be much higher than it is now. These kinds of processes are called ecosystem services. They occur within ecosystems, such as soil ecosystems, as a result of the diverse metabolic activities of the organisms living there, but they provide benefits to human food production, drinking water availability, and breathable air.
Other key ecosystem services related to food production are plant pollination and crop pest control. Over 150 crops in the United States require pollination to produce. One estimate of the benefit of honeybee pollination within the United States is $1.6 billion per year; other pollinators contribute up to $6.7 billion more.
Many honeybee populations are managed by apiarists who rent out their hives’ services to farmers. Honeybee populations in North America have been suffering large losses caused by a syndrome known as colony collapse disorder, whose cause is unclear. Other pollinators include a diverse array of other bee species and various insects and birds. Loss of these species would make growing crops requiring pollination impossible, increasing dependence on other crops.
Finally, humans compete for their food with crop pests, most of which are insects. Pesticides control these competitors; however, pesticides are costly and lose their effectiveness over time as pest populations adapt. They also lead to collateral damage by killing non-pest species and risking the health of consumers and agricultural workers. Ecologists believe that the bulk of the work in removing pests is actually done by predators and parasites of those pests, but the impact has not been well studied. A review found that in 74 percent of studies that looked for an effect of landscape complexity on natural enemies of pests, the greater the complexity, the greater the effect of pest-suppressing organisms. An experimental study found that introducing multiple enemies of pea aphids (an important alfalfa pest) increased the yield of alfalfa significantly. This study shows the importance of landscape diversity via the question of whether a diversity of pests is more effective at control than one single pest; the results showed this to be the case. Loss of diversity in pest enemies will inevitably make it more difficult and costly to grow food.
Wild Food Sources
In addition to growing crops and raising animals for food, humans obtain food resources from wild populations, primarily fish populations. For approximately 1 billion people, aquatic resources provide the main source of animal protein. But since 1990, global fish production has declined. Despite considerable effort, few fisheries on the planet are managed for sustainability.
Fishery extinctions rarely lead to complete extinction of the harvested species, but rather to a radical restructuring of the marine ecosystem in which a dominant species is so over-harvested that it becomes a minor player, ecologically. In addition to humans losing the food source, these alterations affect many other species in ways that are difficult or impossible to predict. The collapse of fisheries has dramatic and long-lasting effects on local populations that work in the fishery. In addition, the loss of an inexpensive protein source to populations that cannot afford to replace it will increase the cost of living and limit societies in other ways. In general, the fish taken from fisheries have shifted to smaller species as larger species are fished to extinction. The ultimate outcome could clearly be the loss of aquatic systems as food sources.
Psychological and Moral Value
Finally, it has been argued that humans benefit psychologically from living in a biodiverse world. A chief proponent of this idea is entomologist E. O. Wilson. He argues that human evolutionary history has adapted us to live in a natural environment and that built environments generate stressors that affect human health and well-being. There is considerable research into the psychological regenerative benefits of natural landscapes that suggests the hypothesis may hold some truth. In addition, there is a moral argument that humans have a responsibility to inflict as little harm as possible on other species.
Summary
Humans use many compounds that were first discovered or derived from living organisms as medicines: secondary plant compounds, animal toxins, and antibiotics produced by bacteria and fungi. More medicines are expected to be discovered in nature. Loss of biodiversity will impact the number of pharmaceuticals available to humans.
Crop diversity is a requirement for food security, and it is being lost. The loss of wild relatives to crops also threatens breeders’ abilities to create new varieties. Ecosystems provide ecosystem services that support human agriculture: pollination, nutrient cycling, pest control, and soil development and maintenance. Loss of biodiversity threatens these ecosystem services and risks making food production more expensive or impossible. Wild food sources are mainly aquatic, but few are being managed for sustainability. Fisheries’ ability to provide protein to human populations is threatened when extinction occurs.
Biodiversity may provide important psychological benefits to humans. Additionally, there are moral arguments for the maintenance of biodiversity.
Art Connections
Figure \(\PageIndex{2}\): The Svalbard Global Seed Vault is located on Spitsbergen island in Norway, which has an arctic climate. Why might an arctic climate be good for seed storage?
- Answer
-
The ground is permanently frozen so the seeds will keep even if the electricity fails.
Glossary
- secondary plant compound
- compound produced as byproducts of plant metabolic processes that is usually toxic, but is sequestered by the plant to defend against herbivores


18: Management of Technology and Innovation
After reading this chapter, you should be able to answer these questions:
- What do we mean by the management of technology and innovation (MTI), and why is it crucial?
- How do organizations develop technology and innovation?
- What are external sources of technology and innovation development, and when are they best used?
- What are internal sources of technology and innovation development, and when are they best used?
- How and why do entrepreneurs develop MTI skills?
- No matter what method is used, what skills do you need to successfully manage technology and innovation?
- How do you look into the future to keep pace?
Acer Group—Becoming a Hardware + Software + Services Global Competitor
Do you think that you would be interested in a career in the technology space? Here is an overview of the history of Acer Corporation that will provide a glimpse into this industry. Acer Group was established in 1976. The Acer Group’s family of brands includes Acer, Gateway, Packard Bell, and eMachines. The multibrand strategy of Acer allows each brand to target different customer needs in the worldwide personal computer market. Acer was the third-largest maker of personal computers (second largest in notebooks) in 2008 and had revenues exceeding $16 billion. In 2017, Acer is sixth in the personal computer industry with revenues exceeding $70 billion. This Taiwanese firm has established itself as a global player in the PC market and has expanded into gaming and other related businesses. How it got there is through innovative use of alliances and acquisitions as well as forward-looking development within the firm.
The Firm’s History
Acer was founded in 1976 as Multitech. The focus of Multitech was on trade and product design (internal innovation). Just three years later, Multitech designed Taiwan’s first mass-produced computer product. The focus from the start was on a product for export—Taiwan is such a small market the firm knew it needed to make a global footprint in the computer market. Multitech, which became Acer in 1987, developed a long-term mission to allow anyone to use and benefit from technology. They have built their reputation on the development and manufacturing of sophisticated, intuitive, easy-to-use products.
Early Innovations
When Multitech first started, the PC market was young and the founders saw many opportunities. Acer holds more patents than any other Taiwanese-based corporation, and Taiwan accounts for 70 percent of global computer hardware manufacturing. When Acer beat IBM to the market with 32-bit PCs in 1986, it signaled the beginning of the end for IBM’s PC business. Until 1990, Acer was more internally innovative than it was externally oriented for alliances and acquisitions.
External Technology Development
In 1990, Altos Peripherals was acquired. This marked the beginning of two decades of multiple alliances and acquisitions by Acer. Because of Acer’s success in developing innovations, other companies were willing and eager to develop different types of alliances. Some of the early alliances allowed Acer to partner with some of the biggest players in the computer technology industry. For example:
- 1996—Acer signed a reciprocal patent licensing agreement with IBM, Intel, and Texas Instruments allowing the use of one other’s patented technology.
- 1999—Acer Group and IBM formed a seven-year procurement and technology alliance.
This strategy has continued:
- 2010—Acer and Founder Technology signed a memorandum of mutual understanding to strengthen their long-term PC business cooperation.
- 2016—Acer’s board of directors approved the establishment of a joint venture with Starbreeze AB to design, manufacture, promote, market, and serve StarVR Virtual Reality Head-Mounted Displays.
As Acer grew in strength in the marketplace, it began to make acquisitions. These acquisitions were aimed at multibranding as well as obtaining technological innovations. For example:
- 1998—Acer acquired Texas Instruments’ TI-Acer interest and renamed the company Acer Semiconductor Manufacturing Inc.
- 2007—Acer merged with Gateway Inc.
- 2008—Acer merged with Packard Bell Inc.
- 2008—Acer acquired E-TEN .
- 2015—Acer acquired GPS cycling computer brand Xplova.
- 2016—Acer acquired wireless pet camera maker Pawbo.
To illustrate the usefulness of this strategy, in 2011 Acer Inc. bought iGware Inc. for $320 million to try to enter the potentially lucrative cloud market. Then in 2012, Acer created cloud software and infrastructure tools for devices.
Acer also developed equity-based partnerships. Examples of this strategy include:
- 2009—Acer acquired 29.9% of Olidata.
- 2015—Acer invested in robotics start-up company Jibo .
- 2016—Acer made an equity investment in grandPad, a provider of technology solutions specifically designed for senior citizens.
- 2017—Acer became the largest corporate shareholder of AOPEN Inc.
Becoming a Global Competitor
While Acer was changing its business model from internal innovations as well as evolving from a manufacturing company to a development and marketing firm, it continued to spread its global footprint. It did this through various partnerships and by developing innovative products with its partners and within its own R&D areas. For example, in 2003 Acer launched the Empowering Technology Platform to meld hardware, software, and service to provide end-to-end technologies to customers. In 2008, the Aspire One was launched as the company’s first mobile Internet device. In addition, Acer made a strong move into the high-end gaming market with the Aspire Predator series.
These steps were designed to enhance and strengthen Acer’s global position. Acer’s product range includes PC notebooks and netbooks, desktop computers, storage systems, peripheral devices, LCD televisions, and e-business solutions. The firm is number one in a number of markets with various products. The Europe, Middle East, and Africa (EMEA) market is a stronghold for Acer’s mobile computing solutions. Acer is the largest supplier of LCD televisions in Western Europe. Acer is first in the notebook market in Italy, Spain, Austria, Holland, Switzerland, Russia, Belgium, Denmark, Hungary, Poland, and the Slovakian Republic.
In the United States and Canada, Acer is making its mark through its Channel Business Model (CBM). It developed this model as it expanded beyond Taiwan and continued to improve it as it divested its manufacturing facilities. This model allows Acer to be flexible in adapting to global IT market trends. CBM involves collaboration with partners and suppliers to develop and market top-tier products and services. In 2003, they used this model to co-brand a notebook computer with Ferrari, the Italian carmaker.
In 2009, Acer unveiled the Acer F900 and M900 smartphones at the Mobile World Congress. They began by shipping to channel partners in EMEA and Asia. These products have a relatively large 3.8-inch-wide VGA display and a 3.75G HSPA connectivity for high-speed data transfer, and they are the introductory products with Acer’s new widget-based user interface that provides easy navigation with vivid 3D animation. The acquisition of Packard Bell was key to Acer’s entrance into this market with this advanced product.
From 2008 to 2013, Acer’s strategy was to enhance worldwide presence with a new multi-brand strategy. With the successful completion of the mergers of Gateway and Packard Bell, Acer then heavily emphasized its goal to further strengthen its global footprint with a multi-brand strategy and solid partnerships. Since 2014, the Acer Group has been transforming into a hardware + software + services company.
To accomplish this shift, Acer needed to spin off or divest certain units. This accomplished two things: 1) it made cash available for acquisitions and other new business development, and 2) it refocused the strategy of Acer.
Examples of the spin-offs and divestments included:
- 2000—Acer spun off its manufacturing operation to focus on developing technologically advanced, user-friendly solutions.
- 2000—Acer split off its OEM (Original Equipment Manufacturing) business unit to create Wistron Corp., an independent design and IT manufacturing company.
Acer continues to lead in notebook technology while extending its product lines to enhance people’s lives through technology. In notebook technology, Acer was the leader in branding notebooks (Ferrari 4000 carbon-fiber notebook—2005), green notebooks (2010), and lightest notebook with the longest battery life (Aspire line—2012), as well as the Chromebook launch in 2015 with a 15.6-inch screen. However, its product lines have multiplied into cloud technology, gaming, and other technologies that “add value to customers’ lives” (Acer annual report).
Acer has used a variety of strategic moves to continue to be competitive in the changing world of computer-related technology. Early on, they used internal innovation as a primary growth strategy to build a reputation and establish a footprint in the industry. Then they used external methods of acquiring technology and markets—mergers, acquisitions, alliances, joint ventures, equity positions, etc. Acer continues to nurture its strengths in research and development while continuing to look for new opportunities for acquisition and alliances.
Sources: Anonymous. 2009. Acer website , “ Showcases Multi-brand Products at Computex 2009 including Aspire Timeline Notebook, Aspire One Netbook, Aspire All-In-One PC.” JCN Newswire- Japan Corporate News Network . Tokyo, June 3, 2018; www.acer-group.com; Acer Group 10-K reports.


1.11: Dosage Calculations II
- Calculate drug dosages using metric prefixes and conversion factors.
Effects are dose-dependent
For humans, most doses of micronutrients and medications are measured in milligrams (mg), but some are measured in micrograms because of their potency. Nonmedicinal poisons span the measurement scale; some poisons are so dangerous that a single microgram of it could be deadly, whereas other substances take much more. For example, even water is toxic when consumed in large enough quantities.
Dosage (the size of each dose) determines the strength and duration of the health benefits of nutrients, and also of the therapeutic effects of medical treatments. Dosage also determines the severity of adverse effects of treatments and toxins.
Duration of exposure, that is, the period of time over which the dose was received (all at once or gradually) also determines its effects (the body may build tolerance to gradual exposure to a drug, while a large immediate dose could be deadly).
The route by which a dose is exposed to may affect the outcome. Some medications have different effects depending on whether they are inhaled, ingested, taken transdermally, injected, or inserted.
The dosage, route, concentration, and division over time may all be critical considerations in the administering of drugs, or in responding to exposure to a toxin. In nutrition, the route is usually implied, as nutrients are generally eaten; while dosage and the frequency of ingestion of nutrients are very important variables in preventing disease and promoting overall health.
Drug dosage calculation is required if the physician’s order is different from what is available. Here we will see examples where the medications are administered as fluids or tablets.
Neomycin is an antibiotic. A patient needs 2.5 grams of Neomycin sulfate. 500 mg tablets are available. How many tablets will you give to the patient?
Solution
It is important to set up a concept map, so as to plan the steps involved:
We will set up a series of conversion factors so that each conversion factor produces the next unit in the sequence.
In each step, the previous unit is cancelled and the next unit in the sequence is produced, each successive unit canceling out until only the unit needed in the answer is left.
The patient requires 5 tablets of neomycin.
Epinephrine is used to treat peanut allergies. A 5 year old patient needs an immediate treatment of 120 mcg of epinephrine. The solution is available in concentration of 0.50 mg/mL. Calculate the volume (mL) required for the patient?
Solution
It is important to set up a concept map, so as to plan the steps involved:
We will set up a series of conversion factors so that each conversion factor produces the next unit in the sequence.
In each step, the previous unit is cancelled and the next unit in the sequence is produced, each successive unit canceling out until only the unit needed in the answer is left.
The 5 year old patient requires 0.24 ml of epinephrine.
The doctor’s order is 1.2 g of Folic Acid. Folic Acid is available as 800 mg per tablet. How many tablets should be taken?
Solution
We start with the given, 1.2 g and we want to change grams to number of tablets . First, we convert 1.2 g to mg and then convert mg to tablets . We need a
conversion factor for each step.
Hence, 1.5 tablets should be taken.
The doctor’s order is 1 g of Calcium. What is on hand is Calcium as 500 mg per tablet. How many tablets should be taken?
Solution
Start with 1 g (1000 mg) of Calcium. For the conversion factor, we know that 500 mg Calcium = 1 tablet
\[1000 \cancel{\mathrm{mg}} \times \dfrac{1 \text { tablet }}{500 ~ \cancel{\mathrm{mg}}}=2 ~ tablets \nonumber\]
Hence, 2 tablets should be taken.
Drug Dosage Calculation based on Body Weight.
Many drugs (especially in children) are dosed according to body weight (mg/kg). These calculations are carried in 3-step conversions. The first step is to convert the body weight from pounds (lbs) to kg . The second step is to convert kg of body weight to mg of dose (the total mg dose calculated based on body weight). Finally, the mg dose is converted to the number of tablets.
Demerol is ordered 1.5mg/kg for a patient that is 220 lbs. Demerol is available as 50 mg per tablet. How many tablets should the nurse administer?
Solution
We start with the given, 220 lbs . We want to change the unit from lbs to kg, and then, from kg to total dose (mg) and then the mg dose to tablets . The first conversion factor will cancel out the original unit, lbs , and introduce the unit we are converting to, which is kg . The second conversion factor will cancel out kg , and introduce the unit of the dose (usually mg ) and then mg to tablet .
Hence, the nurse administers 3 tablets.
A doctor prescribes amoxicillin 30mg/kg to a child weighing 73.5 lbs. Amoxicillin is available as 500 mg tablets. How many tablets should the nurse administer?
Solution
Start with the given, 73.5 lbs . We want to change the unit from lbs to kg , and then, from kg to total dose ( mg ) and then mg to tablets . The first conversion factor will cancel out the original unit, lbs, and convert to kg . The second conversion factor will cancel out kg , and convert to the total mg dose and the final conversion will cancel mg to introduce the final unit, tablet .
Hence, the nurse administers 2 tablets.
Career Focus: Pharmacist
A pharmacist dispenses drugs that have been prescribed by a doctor. Although that may sound straightforward, pharmacists in the United States must hold a doctorate in pharmacy and be licensed by the state in which they work. Most pharmacy programs require four years of education in a specialty pharmacy school. Pharmacists must know a lot of chemistry and biology so they can understand the effects that drugs (which are chemicals, after all) have on the body. Pharmacists can advise physicians on the selection, dosage, interactions, and side effects of drugs. They can also advise patients on the proper use of their medications, including when and how to take specific drugs properly. Pharmacists can be found in drugstores, hospitals, and other medical facilities. Curiously, an outdated name for pharmacist is chemist , which was used when pharmacists formerly did a lot of drug preparation, or compounding . In modern times, pharmacists rarely compound their own drugs, but their knowledge of the sciences, including chemistry, helps them provide valuable services in support of everyone’s health.


10.2: Defining Groups and Teams
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To understand group and team communication, we must first understand the definition of a group. Many people think that a group is simply a collection of people, but that is only part of it. If you walk out your front door and pull together the first ten people you see, do you have a group? No! According to Wilson and Hanna, groups are defined as, “a collection of three or more individuals who interact about some common problem or interdependent goal and can exert mutual influence over one another” (14). They goes on to say that the three key components of groups are, “size, goal orientation, and mutual influence” (14). Interpersonal communication is often thought about in terms of dyads, or pairs. Organizational communication might be thought of as a group that is larger than 12 people. While there are exceptions, for the most part, group size is often thought of in terms of 3-12 people.
Case In Point
Astronaut Jim Lovell’s words during the Apollo 13 lunar mission, “Houston, we have a problem,” launched a remarkable tale of effective teamwork and creative problem solving by NASA engineers working to try to save the lives of the jeopardized crew when two oxygen tanks exploded en route to the moon. Details of the dramatic and successful resolution to the problem became widely known in the motion picture Apollo 13, but it’s not just during dramatic moments when the importance of good teamwork is needed or recognized. In fact, some form of team-oriented work is encouraged in most, if not all, organizations today (Hughes, Jones). So if you feel this is unimportant to know, remember that group communication and teamwork skills are critical for your success later in life.
For example, Joseph Bonito, a communication professor at University of Arizona, allows no more than five people in a group to ensure that everyone’s opinions are reflected equally in a discussion. (Baughman and Everett-Haynes). According to Bonito, if there are too many people in a group it’s possible that some individuals will remain silent without anyone noticing. He suggests using smaller groups when equal participation is desirable. So, if the ten people you gathered outside of your front door were all neighbors working together as part of a “neighborhood watch” to create safety in the community, then you would indeed have a group.
For those of you who have participated on athletic teams you’ll notice that these definitions also apply to a team. While all of the qualities of groups hold true for teams, teams have additional qualities not necessarily present for all groups. We like to define a team as a specialized group with a strong sense of belonging and commitment to each other that shapes an overall collective identity. Members of a team each have their own part, or role, to fulfill in order to achieve the team’s greater goals. One member’s strengths can be other member’s weaknesses, so working in a team is beneficial when balancing individual input. While all members of an athletic team share some athletic ability and special appreciation for a particular sport, for example, members of a football team, for example, have highly specialized skills as indicated in the various positions on the team—quarterback, receiver, and running back. In addition to athletic teams, work and professional teams also share these qualities. Now that you know how to define groups and teams, let’s look at characteristics of groups and teams, as well as the different types of groups and teams.
Characteristics of Groups
- Interdependence . Groups cannot be defined simply as three or more people talking to each other or meeting together. Instead, a primary characteristic of groups is that members of a group are dependent on the others for the group to maintain its existence and achieve its goals. In essence, interdependence is the recognition by those in a group of their need for the others in the group (Lewin; Cragon, Wright& Kasch; Sherblom). Imagine playing in a basketball game as an individual against the five members of another team. Even if you’re considered the best basketball player in the world, it’s highly unlikely you could win a game against five other people. You must rely on four other teammates to make it a successful game.
- Interaction . It probably seems obvious to you that there must be interaction for groups to exist. However, what kind of interaction must exist? Since we all communicate every day, there must be something that distinguishes the interaction in groups from other forms of communication. Cragon, Wright and Kasch state that the primary defining characteristic of group interaction is that it is purposeful. They go on to break down purposeful interaction into four types: problem solving, role playing, team building, and trust building (7). Without purposeful interaction a true group does not exist. Roles, norms, and relationships between members are created through interaction. If you’re put into a group for a class assignment, for example, your first interaction probably centers around exchanging contact information, settings times to meet, and starting to focus on the task at hand. It’s purposeful interaction in order to achieve a goal.
Group Communication Then
The first study that was published on group communication in the New School era of communication study was credited to Edwin Black in 1955. He studied the breakdowns in group interactions by looking at communication sequences in groups. However, it wasn’t until the 1960s and 70s that a large number of studies in group communication began to appear. Between 1970 and 1978 114 articles were published on group communication and 89 more were published by 1990 (Stacks & Salwen 360). Study in group communication is still important over a decade later as more and more organizations focus on group work for achieving their goals.
- Synergy . One advantage of working in groups and teams is that they allow us to accomplish things we wouldn’t be able to accomplish on our own. Remember back to our discussion of Systems Theory in Chapter 5. Systems Theory suggests that “The whole is greater than the sum of its parts.” This is the very idea of synergy (Sherblom). In an orchestra or band, each person is there to perform in order to help the larger unit make music in a way that cannot be accomplished without each member working together.
- Common Goals . Having interaction and synergy would be relatively pointless in groups without a common goal. People who comprise groups are brought together for a reason or a purpose. While most members of a group have individual goals, a group is largely defined by the common goals of the group. Think of the example at the beginning of the chapter: Your common goal in a class group is to learn, complete an assignment, and earn a grade. While there may be differences regarding individual goals in the group (what final grade is acceptable for example), or how to achieve the common goals, the group is largely defined by the common goals it shares.
- Shared Norms . Because people come together for a specific purpose, they develop shared norms to help them achieve their goals. Even with a goal in place, random interaction does not define a group. Group interaction is generally guided by norms a group has established for acceptable behavior. Norms are essentially expectations of the group members, established by the group and can be conscious and formal, or unconscious and informal. A couple of examples of group norms include the expectation that all members show up at group meeting times, the expectation that all group members focus on the group instead of personal matters (for example, turning cell phones and other distractions off), and the expectation that group members finish their part of the work by the established due date. When members of the group violate group norms, other members of the group get frustrated and the group’s overall goal may be affected.
- Cohesiveness . One way that members understand of the idea of communicating in groups and teams is when they experience a sense of cohesiveness with other members of the group. When we feel like we are part of something larger, we experience a sense of cohesion or wholeness, and may find a purpose that is bigger than our own individual desires and goals. It is the sense of connection and participation that characterizes the interaction in a group as different from the defined interaction among loosely connected individuals. If you’ve ever participated in a group that achieved its goal successfully, you are probably able to reflect back on your feelings of connections with the other members of that group.
You may be asking yourself, what about teams? We have focused primarily on groups, but it’s critical to remember the importance of team communication characteristics as well as group communication characteristics. Check out this article that breaks down team characteristics and skills that ensure team success (we bet you’ll find similarities to the group characteristics that we have just explained).
Types of Groups
Not all groups are the same or brought together for the same reasons. Brilhart and Galanes categorize groups “on the basis of the reason they were formed and the human needs they serve” (9). Let’s take a look!
- Primary Groups . Primary groups are ones we form to help us realize our human needs like inclusion and affection. They are not generally formed to accomplish a task, but rather, to help us meet our fundamental needs as relational beings like acceptance, love, and affection. These groups are generally longer term than other groups and include family, roommates, and other relationships that meet as groups on a regular basis (Brilhart & Galanes). These special people in your life constituate primary groups because they offer love and support for the long run, and given this, primary groups are typically more meaningful than secondary groups.
- Secondary Groups . Unlike primary groups, we form secondary groups to accomplish work, perform a task, solve problems, and make decisions (Brilhart & Galanes; Sherblom; Cragan, Wright & Kasch). Larson and LaFasto state that secondary groups have “a specific performance objective or recognizable goal to be attained; and coordination of activity among the members of the team is required for attainment of the team goal or objective” (19).
- Activity Groups . Activity Groups are ones we form for the purpose of participating in activities. I’m sure your campus has many clubs that are organized for the sole purpose of doing activities. On our campus, for example, a popular club on our campus is the Surf Club, in which members meet for the purpose of scheduling surfing times, arranging rides, and choosing where to surf.
- Personal Growth Groups . We form Personal Growth Groups to obtain support and feedback from others, as well as to grow as a person. Personal Growth Groups may be thought of as therapy groups. An example that is probably familiar to you is Alcoholics Anonymous, where alcoholics can share their stories and struggles and get support from others affected by alcohol. There are many personal growth groups available for helping us develop as people through group interaction with others, such as book clubs, weight watchers, and spiritual groups.
- Learning Groups . Learning Groups focus mainly on obtaining new information and gaining knowledge. If you have ever been assigned to a group in a college class, it most likely was a learning group with the purpose of interacting in ways that can help those in the group learn new things about the course content.
- Problem-Solving Groups . These groups are created for the express purpose of solving a specific problem. The very nature of organizing people into this type of group is to get them to collectively figure out effective solutions to the problem they have before them. Committees are an excellent example of people who are brought together to solve problems.
After looking at the various types of groups, it’s probably easy for you to recognize just how much of your daily interaction occurs within the contexts of groups. The reality is, we spend a great deal of time in groups, and understanding the types of groups you’re in, as well as their purpose, goes a long way toward helping you function as a productive member.
Contributions and Affiliations
- Survey of Communication Study. Authored by : Scott T Paynton and Linda K Hahn. Provided by : Humboldt State University. Located at : en.wikibooks.org/wiki/Survey_of_Communication_Study. License : CC BY-SA: Attribution-ShareAlike
- Image of band. Authored by : _mattxb. Located at : https://commons.wikimedia.org/wiki/File:Brittensinfonia_concert.jpg . License : CC BY: Attribution
- Image of surfers. Authored by : Stan Shebs. Located at : commons.wikimedia.org/wiki/File:Oahu_North_Shore_surfing_catching_wave.jpg. License : CC BY-SA: Attribution-ShareAlike


10.5: Lymphatic System Answers
1. a. Add labels or colour in the diagram of a capillary bed and associated lymphatic vessels.
2. How is tissue fluid formed? Tissue fluid is the fluid that leaves the capillaries to surround the cells of the tissues. Water leaves the capillaries by osmosis and substances like salts, amino acids and glucose generally move by diffusion.
3. Add the following labels to the diagram showing the formation of lymph below.
- Blood capillary; blood entering capillary at high pressure; blood leaving capillary at low pressure
- tissue fluid; lymph; lymphatic vessel; cells of tissue
4. Compare plasma, serum, tissue fluid and lymph by filling in the cells in the table below.
| Blood plasma | Serum | Tissue fluid | Lymph | |
|---|---|---|---|---|
| Definition/where found |
Clear fluid part of blood |
Fluid left when blood clots |
Fluid surrounding cells. Formed from plasma |
Fluid in lymphatic vessels |
5. When lymph has entered the lymphatics, how does it make its way back to the blood stream? Lymph flows along the lymphatic vessels pushed along by the contraction of the muscles surrounding them. Valves prevent it flowing backwards. It flows through at least one lymph node before rejoining the blood circulation via a vessel cranial to the heart.
6. This is a function of lymph nodes:
- b) Filtering bacteria and debris from lymph
7. Mark the positions of the following lymph nodes on the picture of the dog below.
- Popliteal; superficial inguinal; submandibular prescapular; parotid
8. Name three organs of the lymphatic system (other than lymph nodes).
- i. Spleen
- ii. Thymus
- iii Lymph nodules e.g Peyer's patches
- iv Bone marrow
9. List three functions of the lymphatic system
- i. Filtering debris, bacteria etc. from the lymph.
- ii. Producing lymphocytes .
- iii. Returning fluid to the circulatory system.
10. True or false?
- i. A major function of lymph nodes is to filter foreign substances from the lymph. T
- ii. Lymphatic vessels are identical in structure to veins. F The walls of lymphatics are much thinner (1 cell thick) than those of veins (many cells thick).
- iii. The heart beat helps push lymph along lymphatic vessels. F The heart beat has no effect on lymph flow. The contraction of the muscles surrounding the lymphatic vessels is the main mechanism that pushes lymph along.
- iv. The cisterna chyli and thoracic duct are parts of the lymphatic system. T
- v. The spleen is the largest lymphatic organ. T
- vi. The spleen is an important store of white blood cells. F The spleen stores red blood cells .
- vii. The thymus gland is located cranially to the heart T
- viii. A major function of the thymus is to produce monocytes. F The thymus produces and modifies lymphocytes.
- ix. Peyers patches are located in the wall of the stomach. F Peyer's patches are small lymph nodes located in the wall of the small intestine.
- x. The lymphatic system sometimes transports cancer cells around the body. T


41.14: Hormonal Control of Osmoregulatory Functions - Other Hormonal Controls for Osmoregulation
- Describe hormonal control by the renin-angiotensin-aldosterone system
Renin-Angiotensin-Aldosterone
The renin-angiotensin-aldosterone system (RAAS) is a hormone system that regulates blood pressure and water (fluid) balance. This system proceeds through several steps to produce angiotensin II, which acts to stabilize blood pressure and volume. Renin is secreted by a part of the juxtaglomerular complex and produced by the granular cells of the afferent and efferent arterioles. Renin is a circulating enzyme that acts on angiotensinogen, which is made in the liver, converting it to angiotensin I. Defective renin production can cause a continued decrease in blood pressure and cardiac output. After renin facilitates the production of angiotensis I, angiotensin converting enzyme (ACE) then converts angiotensin I to angiotensin II. Angiotensin II raises blood pressure by constricting blood vessels and also triggers the release of the mineralocorticoid aldosterone from the adrenal cortex. This, in turn, stimulates the renal tubules to reabsorb more sodium. Angiotensin II also triggers the release of anti-diuretic hormone (ADH) from the hypothalamus, leading to water retention in the kidneys. It acts directly on the nephrons, decreasing glomerular filtration rate. Thus, via the RAAS, the kidneys control blood pressure and volume directly. Medically, blood pressure can be controlled by drugs that inhibit ACE (called ACE inhibitors).
Mineralocorticoids
Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance. One type of mineralocorticoid, known as aldosterone, regulates sodium levels in the blood. Almost all of the sodium in the blood is reclaimed by the renal tubules under the influence of aldosterone. As sodium is always reabsorbed by active transport and water follows sodium to maintain osmotic balance, aldosterone manages not only sodium levels, but also the water levels in body fluids. Aldosterone also stimulates potassium secretion concurrently with sodium reabsorption. By contrast, absence of aldosterone means that no sodium is reabsorbed in the renal tubules; all of it is excreted in the urine. In addition, the daily dietary potassium load is not secreted; retention of potassium ions (K+) can cause a dangerous increase in plasma K+ concentration. Patients who have Addison’s disease have a failing adrenal cortex and cannot produce aldosterone. They constantly lose sodium in their urine; if the supply is not replenished, the consequences can be fatal.
Antidiurectic Hormone
Antidiuretic hormone or ADH (also called vasopressin) helps the body conserve water when body fluid volume, especially that of blood, is low. It is formed by the hypothalamus, but is stored and released from the posterior pituitary gland. It acts by inserting aquaporins in the collecting ducts, promoting reabsorption of water. ADH also acts as a vasoconstrictor (constricting blood vessels) and increases blood pressure during hemorrhaging.
Atrial Natriuretic Peptide Hormone
The atrial natriuretic peptide (ANP) hormone lowers blood pressure by acting as a vasodilator (dilating or widening blood vessels). It is released by cells in the atrium of the heart in response to high blood pressure and in patients with sleep apnea. ANP affects salt release; because water passively follows salt to maintain osmotic balance, it also has a diuretic effect. ANP also prevents sodium reabsorption by the renal tubules, decreasing water reabsorption (thus acting as a diuretic) and lowering blood pressure. Its actions suppress the actions of aldosterone, ADH, and renin.
Contributions and Attributions
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44828/latest...ol11448/latest . License : CC BY: Attribution
- Epinephrine. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Epineph...nism_of_action . License : CC BY-SA: Attribution-ShareAlike
- Norepinephrine. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Norepin...ne%23Mechanism . License : CC BY-SA: Attribution-ShareAlike
- epinephrine. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/epinephrine . License : CC BY-SA: Attribution-ShareAlike
- norepinephrine. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/norepinephrine . License : CC BY-SA: Attribution-ShareAlike
- adrenergic. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/adrenergic . License : CC BY-SA: Attribution-ShareAlike
- catecholamine. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/catecholamine . License : CC BY-SA: Attribution-ShareAlike
- Gray1185. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gray1185.png . License : Public Domain: No Known Copyright
- OpenStax College, Biology. October 23, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44828/latest...ol11448/latest . License : CC BY: Attribution
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44828/latest/?collection=col11448/latest . License : CC BY: Attribution
- aquaporin. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/aquaporin . License : CC BY-SA: Attribution-ShareAlike
- renin. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/renin . License : CC BY-SA: Attribution-ShareAlike
- angiotensin. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/angiotensin . License : CC BY-SA: Attribution-ShareAlike
- Gray1185. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gray1185.png . License : Public Domain: No Known Copyright
- OpenStax College, Hormonal Control of Osmoregulatory Functions. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44828/latest/Figure_41_05_01.jpg . License : CC BY: Attribution


6.5: General Strategy for Factoring Polynomial Expressions
By the end of this section, you will be able to:
- Recognize and use the appropriate method to factor a polynomial completely
Recognize and Use the Appropriate Method to Factor a Polynomial Completely
You have now become acquainted with all the methods of factoring that you will need in this course. The following chart summarizes all the factoring methods we have covered, and outlines a strategy you should use when factoring polynomials.
-
Is there a greatest common factor?
Factor it out. -
Is the polynomial a binomial, trinomial, or are there more than three terms?
If it is a binomial:-
Is it a sum?
Of squares? Sums of squares do not factor.
Of cubes? Use the sum of cubes pattern. -
Is it a difference?
Of squares? Factor as the product of conjugates.
Of cubes? Use the difference of cubes pattern.
- Is it of the form \(x^2+bx+c\)? Undo FOIL.
-
Is it of the form \(ax^2+bx+c\)?
If a and c are squares, check if it fits the trinomial square pattern.
Use the trial and error or “\(ac\)” method.
- Use the grouping method.
-
Is it a sum?
-
Check.
Is it factored completely?
Do the factors multiply back to the original polynomial?
Remember, a polynomial is completely factored if, other than monomials, its factors are prime !
Factor completely: \(7x^3−21x^2−70x\).
Solution
\(\begin{array} {ll} {7x^3−21x^2−70x} & \\ \text{Is there a GCF? Yes, }7x. & \\ \text{Factor out the GCF.} &7x(x^2−3x−10) \\ \text{In the parentheses, is it a binomial, trinomial,} & \\ \text{or are there more terms?} & \\ \text{Trinomial with leading coefficient 1.} & \\ \text{“Undo” FOIL.} &7x(x\hspace{8mm})(x\hspace{8mm}) \\ &7x(x+2)(x−5) \\ \text{Is the expression factored completely? Yes.} & \\ \text{Neither binomial can be factored.} & \\ \text{Check your answer.} & \\ \text{Multiply.} & \\ & \\ & \\ \hspace{15mm}7x(x+2)(x−5) & \\ \hspace{10mm}7x(x^2−5x+2x−10) & \\ \hspace{15mm}7x(x^2−3x−10) & \\ \hspace{13mm}7x^3−21x^2−70x\checkmark & \end{array} \)
Factor completely: \(8y^3+16y^2−24y\).
- Answer
-
\(8y(y−1)(y+3)\)
Factor completely: \(5y^3−15y^2−270y\).
- Answer
-
\(5y(y−9)(y+6)\)
Be careful when you are asked to factor a binomial as there are several options!
Factor completely: \(24y^2−150\)
Solution
\(\begin{array} {ll} &24y^2−150 \\ \text{Is there a GCF? Yes, }6. & \\ \text{Factor out the GCF.} &6(4y^2−25) \\ \text{In the parentheses, is it a binomial, trinomial} & \\ \text{or are there more than three terms? Binomial.} & \\ \text{Is it a sum? No.} & \\ \text{Is it a difference? Of squares or cubes? Yes, squares.} &6((2y)^2−(5)^2) \\ \text{Write as a product of conjugates.} &6(2y−5)(2y+5) \\ & \\ & \\ \hspace{5mm}\text{Is the expression factored completely?} & \\ \hspace{5mm}\text{Neither binomial can be factored.} & \\ \text{Check:} & \\ & \\ & \\ \hspace{5mm}\text{Multiply.} & \\ & \\ \hspace{15mm}6(2y−5)(2y+5) & \\ & \\ \hspace{18mm}6(4y^2−25) & \\ \hspace{18mm}24y^2−150\checkmark \end{array}\)
Factor completely: \(16x^3−36x\).
- Answer
-
\(4x(2x−3)(2x+3)\)
Factor completely: \(27y^2−48\).
- Answer
-
\(3(3y−4)(3y+4)\)
The next example can be factored using several methods. Recognizing the trinomial squares pattern will make your work easier.
Factor completely: \(4a^2−12ab+9b^2\).
Solution
\(\begin{array} {ll} &4a^2−12ab+9b^2 \\ \text{Is there a GCF? No.} & \\ \text{Is it a binomial, trinomial, or are there more terms?} & \\ \text{Trinomial with }a\neq 1.\text{ But the first term is a perfect square.} \\ \text{Is the last term a perfect square? Yes.} &(2a)^2−12ab+(3b)^2 \\ \text{Does it fit the pattern, }a^2−2ab+b^2?\text{ Yes.} &(2a)^2 −12ab+ (3b)^2 \\ &\hspace{7mm} {\,}^{\searrow}{\,}_{−2(2a)(3b)}{\,}^{\swarrow}\\ \text{Write it as a square.} &(2a−3b)^2 \\ & \\ & \\ \quad\text{Is the expression factored completely? Yes.} & \\ \quad\text{The binomial cannot be factored.} & \\ \text{Check your answer.} \\ & \\ & \\ \quad\text{Multiply.} & \\ \hspace{30mm}(2a−3b)^2 \\ \hspace{20mm} (2a)^2−2·2a·3b+(3b)^2 \\ \hspace{24mm}4a^2−12ab+9b^2\checkmark & \end{array} \)
Factor completely: \(4x^2+20xy+25y^2\).
- Answer
-
\((2x+5y)^2\)
Factor completely: \(9x^2−24xy+16y^2\).
- Answer
-
\((3x−4y)^2\)
Remember, sums of squares do not factor, but sums of cubes do!
Factor completely \(12x^3y^2+75xy^2\).
Solution
\(\begin{array} {ll} &12x^3y^2+75xy^2 \\ \text{Is there a GCF? Yes, }3xy^2. & \\ \text{Factor out the GCF.} &3xy^2(4x^2+25) \\ \text{In the parentheses, is it a binomial, trinomial, or are} & \\ \text{there more than three terms? Binomial.} & \\ & \\ \text{Is it a sum? Of squares? Yes.} &\text{Sums of squares are prime.} \\ & \\ & \\ \quad\text{Is the expression factored completely? Yes.} & \\ \text{Check:} & \\ & \\ & \\ \quad\text{Multiply.} & \\ \hspace{15mm}3xy^2(4x^2+25) & \\ \hspace{14mm}12x^3y^2+75xy^2\checkmark \end{array} \)
Factor completely: \(50x^3y+72xy\).
- Answer
-
\(2xy(25x^2+36)\)
Factor completely: \(27xy^3+48xy\).
- Answer
-
\(3xy(9y^2+16)\)
When using the sum or difference of cubes pattern, being careful with the signs.
Factor completely: \(24x^3+81y^3\).
Solution
| Is there a GCF? Yes, 3. | |
| Factor it out. | |
|
In the parentheses, is it a binomial, trinomial,
of are there more than three terms? Binomial. |
|
| Is it a sum or difference? Sum. | |
| Of squares or cubes? Sum of cubes. | |
| Write it using the sum of cubes pattern. | |
| Is the expression factored completely? Yes. | |
| Check by multiplying. |
Factor completely: \(250m^3+432n^3\).
- Answer
-
\(2(5m+6n)(25m^2−30mn+36n^2)\)
Factor completely: \(2p^3+54q^3\).
- Answer
-
\(2(p+3q)(p^2−3pq+9q^2)\)
Factor completely: \(3x^5y−48xy\).
Solution
\(\begin{array} {ll} &3x^5y−48xy \\ \text{Is there a GCF? Factor out }3xy &3xy(x^4−16) \\ \begin{array} {l} \text{Is the binomial a sum or difference? Of squares or cubes?} \\ \text{Write it as a difference of squares.} \end{array} &3xy\left((x^2)^2−(4)2\right) \\ \text{Factor it as a product of conjugates} &3xy(x^2−4)(x^2+4) \\ \text{The first binomial is again a difference of squares.} &3xy\left((x)^2−(2)^2\right)(x^2+4) \\ \text{Factor it as a product of conjugates.} &3xy(x−2)(x+2)(x^2+4) \\ \text{Is the expression factored completely? Yes.} & \\ \text{Check your answer.} & \\ \text{Multiply.} & \\ 3xy(x−2)(x+2)(x^2+4) & \\ 3xy(x^2−4)(x^2+4) & \\ 3xy(x^4−16) & \\ 3x^5y−48xy\checkmark & \end{array}\)
Factor completely: \(4a^5b−64ab\).
- Answer
-
\(4ab(a^2+4)(a−2)(a+2)\)
Factor completely: \(7xy^5−7xy\).
- Answer
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\(7xy(y^2+1)(y−1)(y+1)\)
Factor completely: \(4x^2+8bx−4ax−8ab\).
Solution
\(\begin{array} {ll} &4x^2+8bx−4ax−8ab \\ \text{Is there a GCF? Factor out the GCF, }4. &4(x^2+2bx−ax−2ab) \\ \text{There are four terms. Use grouping.} &4[x(x+2b)−a(x+2b)]4(x+2b)(x−a) \\ \text{Is the expression factored completely? Yes.} & \\ \text{Check your answer.} & \\ \text{Multiply.} & \\ \hspace{25mm}4(x+2b)(x−a) & \\ \hspace{20mm} 4(x^2−ax+2bx−2ab) & \\ \hspace{20mm}4x^2+8bx−4ax−8ab\checkmark \end{array}\)
Factor completely: \(6x^2−12xc+6bx−12bc\).
- Answer
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\(6(x+b)(x−2c)\)
Factor completely: \(16x^2+24xy−4x−6y\).
- Answer
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\(2(4x−1)(2x+3y)\)
Taking out the complete GCF in the first step will always make your work easier.
Factor completely: \(40x^2y+44xy−24y\).
Solution
\(\begin{array} {ll} &40x^2y+44xy−24y \\ \text{Is there a GCF? Factor out the GCF, }4y. &4y(10x^2+11x−6) \\ \text{Factor the trinomial with }a\neq 1. &4y(10x^2+11x−6) \\ &4y(5x−2)(2x+3) \\ \text{Is the expression factored completely? Yes.} & \\ \text{Check your answer.} & \\ \text{Multiply.} & \\ \hspace{25mm}4y(5x−2)(2x+3) & \\ \hspace{24mm}4y(10x^2+11x−6) & \\ \hspace{22mm}40x^2y+44xy−24y\checkmark \end{array}\)
Factor completely: \(4p^2q−16pq+12q\).
- Answer
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\(4q(p−3)(p−1)\)
Factor completely: \(6pq^2−9pq−6p\).
- Answer
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\(3p(2q+1)(q−2)\)
When we have factored a polynomial with four terms, most often we separated it into two groups of two terms. Remember that we can also separate it into a trinomial and then one term.
Factor completely: \(9x^2−12xy+4y^2−49\).
Solution
\(\begin{array} {ll} &9x^2−12xy+4y^2−49 \\ \text{Is there a GCF? No.} & \\ \begin{array} {l} \text{With more than 3 terms, use grouping. Last 2 terms} \\ \text{have no GCF. Try grouping first 3 terms.} \end{array} &9x^2−12xy+4y^2−49 \\ \begin{array} {l} \text{Factor the trinomial with }a\neq 1. \text{ But the first term is a} \\ \text{perfect square.} \end{array} & \\ \text{Is the last term of the trinomial a perfect square? Yes.} &(3x)^2−12xy+(2y)^2−49 \\ \text{Does the trinomial fit the pattern, }a^2−2ab+b^2? \text{ Yes.} &(3x)^2 −12xy+ (2y)^2−49 \\ &\hspace{7mm} {\,}^{\searrow}{\,}_{−2(3x)(2y))}{\,}^{\swarrow} \\ \text{Write the trinomial as a square.} &(3x−2y)^2−49 \\ \begin{array} {ll} \text{Is this binomial a sum or difference? Of squares or} \\ \text{cubes? Write it as a difference of squares.} \end{array} &(3x−2y)^2−72 \\ \text{Write it as a product of conjugates.} &((3x−2y)−7)((3x−2y)+7) \\ &(3x−2y−7)(3x−2y+7) \\ \text{Is the expression factored completely? Yes.} & \\ \text{Check your answer.} & \\ \text{Multiply.} & \\ \hspace{23mm}(3x−2y−7)(3x−2y+7) & \\ \hspace{10mm}9x^2−6xy−21x−6xy+4y^2+14y+21x−14y−49 \qquad & \\ \hspace{25mm}9x^2−12xy+4y^2−49\checkmark & \end{array}\)
Factor completely: \(4x^2−12xy+9y^2−25\).
- Answer
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\((2x−3y−5)(2x−3y+5)\)
Factor completely: \(16x^2−24xy+9y^2−64\).
- Answer
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\((4x−3y−8)(4x−3y+8)\)
Key Concepts
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How to use a general strategy for factoring polynomials.
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Is there a greatest common factor?
Factor it out. -
Is the polynomial a binomial, trinomial, or are there more than three terms?
If it is a binomial:
Is it a sum?
Of squares? Sums of squares do not factor.
Of cubes? Use the sum of cubes pattern.
Is it a difference?
Of squares? Factor as the product of conjugates.
Of cubes? Use the difference of cubes pattern.
If it is a trinomial:
Is it of the form \(x^2+bx+c\)? Undo FOIL.
Is it of the form \(ax^2+bx+c\)?
If a and c are squares, check if it fits the trinomial square pattern.
Use the trial and error or “\(ac\)” method.
If it has more than three terms:
Use the grouping method. -
Check.
Is it factored completely?
Do the factors multiply back to the original polynomial?
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Is there a greatest common factor?


8.1.5G: Politics
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The higher one’s social class, the higher their levels of political participation and political influence.
Learning Objectives
- Evaluate how social class impacts political participation and political influence
Key Points
- Political office holders tend to be of high socioeconomic status, furthering the impact of class on American politics.
- Wealthy, well-educated Americans are more likely to vote and to donate money to politicians than lower class individuals are.
- Those who vote as members of a social class can be said to be participating in identity politics.
Key Terms
- Political Influence : The extent to which one’s political participation achieves its desired results, or the amount of power a political actor has to achieve his or her will.
- Political Participation : A measure of whether or not a person votes in elections, donates to campaigns, or attends public forums where decisions are made.
Social class impacts one’s level of political participation and political influence. Political participation refers to whether or not a person votes in elections, donates to campaigns, or attends public forums where decisions are made, such as town meetings or city council meetings, for example. Political influence refers to the extent to which one’s political participation achieves its desired results. For example, if one attends a public forum, is their opinion likely to be heard, or if they donate money, is a politician likely to support their desired policy?
Wealthy, well-educated Americans are more likely to vote and to donate money to politicians than lower class individuals. This trend means that middle and upper class individuals have greater political participation and greater political influence than those in lower positions. Additionally, higher status people are more likely to hold political positions than lower class people. An illustration of this is the presidential election between George W. Bush and John Kerry in 2004. Both had millions of dollars of accumulated wealth, and they had higher degrees from Harvard and Yale, respectively.
Those who vote as members of a social class can be said to be participating in identity politics. Identity politics is a phenomenon that arose first at the radical margins of liberal democratic societies in which human rights are recognized, and the term is not usually used to refer to dissident movements within single-party or authoritarian states. Some groups have combined identity politics and Marxist social class analysis and class consciousness. During the 1980s, the politics of identity became very prominent and was linked with new social movement activism.


25.6: Examples
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Example \(\PageIndex{1}\): Calorimetry
The specific heat of aluminum is 900 J/kg·K, and that of water is 4186 J·K. Suppose you drop a block of aluminum of mass 1 kg at a temperature of 80\(^{\circ}\)C in a liter of water (which also has a mass of 1 kg) at a temperature of 20\(^{\circ}\)C. What is the final temperature of the system, assuming no exchange of heat with the environment takes place? How much energy does the aluminum lose/the water gain?
Solution
Let us call \(T_{Al}\) the initial temperature of the aluminum, \(T_{water}\) the initial temperature of the water, and \(T_f\) their final common temperature. The thermal energy given off by the aluminum equals \(\Delta E_{Al} = C_{Al}(T_f − T_{Al})\) (this follows from the definition ( 13.2.1 ) of heat capacity; we could equally well call this quantity “the heat given off by the aluminum”). In the same way, the thermal energy change of the water (heat absorbed by the water) equals \(\Delta E_{water} = C_{water}(T_f −T_{water})\). If the total system is closed, the sum of these two quantities, each with its appropriate sign, must be zero:
\[ 0=\Delta E_{\mathrm{Al}}+\Delta E_{\mathrm{water}}=C_{\mathrm{Al}}\left(T_{f}-T_{\mathrm{Al}}\right)+C_{\mathrm{water}}\left(T_{f}-T_{\mathrm{water}}\right) \label{eq:13.20} .\]
This equation for \(T_f\) has the solution
\[ T_{f}=\frac{C_{\mathrm{Al}} T_{\mathrm{Al}}+C_{\mathrm{water}} T_{\mathrm{water}}}{C_{\mathrm{Al}}+C_{\mathrm{water}}} \label{eq:13.21} .\]
As you can see, the result is a weighted average of the two starting temperatures, with the corresponding heat capacities as the weighting factors.
The heat capacities \(C\) are equal to the given specific heats multiplied by the respective masses. In this case, the mass of aluminum and the mass of the water are the same, so they will cancel in the final result. Also, we can use the temperatures in degrees Celsius, instead of Kelvin. This is not immediately obvious from the final expression (\ref{eq:13.21}), but if you look at (\ref{eq:13.20}) you’ll see it involves only temperature differences, and those have the same value in the Kelvin and Celsius scales.
Substituting the given values in (\ref{eq:13.21}), then, we get
\[ T_{f}=\frac{900 \times 80+4186 \times 20}{900+4186}=30.6^{\circ} \mathrm{C} \label{eq:13.22} .\]
This is much closer to the initial temperature of the water, as expected, since it has the greater heat capacity. The amount of heat exchanged is
\[ C_{\text {water }}\left(T_{f}-T_{\text {water }}\right)=4186 \times(30.6-20)=44,440 \: \mathrm{J}=44.4 \: \mathrm{kJ} \label{eq:13.23} .\]
So, 1 kg of aluminum gives off 44.4 kJ of thermal energy and its temperature drops almost 50\(^{\circ}\)C, from 80\(^{\circ}\)C to 30.6\(^{\circ}\)C, whereas 1 kg of water takes in the same amount of thermal energy and its temperature only rises about 10.6\(^{\circ}\)C.
Example \(\PageIndex{2}\): Equipartition of energy
Estimate the speed of an oxygen molecule in air at room temperature (about 300 K).
Solution
Recall that in Section 13.2 I mentioned that the average translational kinetic energy of a molecule in a system at a temperature \(T\) is \(\frac{3}{2}k_{B}T\) (Equation ( 13.2.7 ), where \(k_B\), Boltzmann’s constant, is equal to 1.38 × 10 −23 J/K. So, at \(T\) = 300 K, a molecule of oxygen (or of anything else, for that matter) should have, on average, a kinetic energy of
\[ \left\langle K_{\text {trans}}\right\rangle=\frac{3}{2} k_{B} T=\frac{3}{2} \times 1.38 \times 10^{-23} \times 300 \: \mathrm{J}=6.21 \times 10^{-21} \: \mathrm{J} \label{eq:13.24} .\]
Since \(K = \frac{1}{2}mv^2\), we can figure out the average value of \(v^2\) if we know the mass of an oxygen molecule. This is something you can look up, or derive like this: One mole of oxygen atoms has a mass of 16 grams (16 is the atomic mass number of oxygen) and contains Avogadro’s number of atoms, 6.02 × 10 23 . So a single atom has a mass of 0.016 kg/6.02 × 10 23 = 2.66 × 10 −26 kg. A molecule of oxygen contains two atoms, so it has twice the mass, \(m\) = 5.32 × 10 −26 kg. Then,
\[ \left\langle v^{2}\right\rangle=\frac{2\left\langle K_{\text {trans}}\right\rangle}{m}=\frac{2 \times 6.21 \times 10^{-21} \: \mathrm{J}}{5.32 \times 10^{-26} \: \mathrm{kg}}=2.33 \times 10^{5} \: \frac{\mathrm{m}^{2}}{\mathrm{s}^{2}} \label{eq:13.25} .\]
The square root of this will give us what is called the “root mean square” velocity, or \(v_{rms}\):
\[ v_{r m s}=\sqrt{2.33 \times 10^{5} \: \frac{\mathrm{m}^{2}}{\mathrm{s}^{2}}}=483 \: \frac{\mathrm{m}}{\mathrm{s}} \label{eq:13.26} .\]
This is of the same order of magnitude as (but larger than) the speed of sound in air at room temperature (about 340 m/s, as you may recall from Chapter 12).