By P. Thorald. Randolph-Macon College.

Radial artery Z Follow a drop of blood from the stomach to the inferior vena cava cheap januvia 100 mg online. Inferior vena cava 1 Follow a drop of blood from the aortic semilunar valve of the heart to the forearm and back to the heart purchase januvia 100mg visa. Right ventricle 3 Follow a drop of blood from the anterior tibial vein to the lungs generic 100mg januvia with amex. Lung capillaries Chapter 11 Keeping Up Your Defenses: The Lymphatic System In This Chapter Delving into lymphatic ducts Noodling around with nodes Exploring the lymphatic organs ou see it every rainy day — water buy discount januvia 100mg on line, water everywhere order januvia 100mg amex, rushing along gutters and down Ystorm drains into a complex underground system that most would rather not give a second thought. Well, it’s time to give hidden drainage systems a second thought: Your body has one. Interstitial or extracellular fluid moves in and around the body’s tissues and cells constantly. It leaks out of blood capillaries at the rate of nearly 51 pints a day, carrying various substances to and away from the smallest nooks and crannies. But the one or two liters of extra fluid that remain around the tissues become a substance called lymph that needs to be managed to maintain fluid balance in the internal environment. That’s where the lymphatic system steps in, forming an alternative route for the return of tissue fluid to the bloodstream. It’s a body-wide filter that traps and destroys invading microorganisms as part of the body’s immune response network. It can remove impurities from the body, help absorb and digest excess fats, and maintain a stable blood volume despite varying environmental stresses. We bet that you won’t take your little lymph nodes for granted anymore after you’re done with this chapter. Duct, Duct, Lymph The story of the lymphatic system (shown in Figure 11-1) begins deep within the body’s tis- sues at the farthest reaches of blood capillaries, where nutrients, plasma, and plasma pro- teins move out into cells, while waste products like carbon dioxide and the fluid carrying those molecules move back in through a process known as diffusion. Roughly 10 percent of the fluid that leaves the capillaries remains deep within the tissues as part of the interstitial (meaning “between the tissues”) fluid. But in order for the body to maintain sufficient volume of water within in the circulatory system, eventually this plasma and its protein must get back into the blood. So the lymphatic vessels act as a recycling system to gather, trans- port, cleanse, and return this fluid to the bloodstream. To collect the fluid, minute vessels called lymph capillaries are woven throughout the body, with a few caveats and exceptions. There are no lymph capillaries in the central nervous system, teeth, outermost layer of the skin, certain types of cartilage, any other avascular tissue, and bones. And because bone marrow makes lymphocytes, which we explain in the next section, it’s considered part of the lymphatic system. Plus, lacteals (lymphatic capillaries found in the villi of the intes- tines) absorb fats to mix with lymph, forming a milky fluid called chyle. Made up of loosely overlapping endothelial cells anchored by fine filaments, lymph capillaries behave as if their walls are made of cellular one-way valves. When the pressure outside the capillary is Chapter 11: Keeping Up Your Defenses: The Lymphatic System 183 greater than it is inside, the filaments anchoring the cells allow them to open, permit- ting interstitial fluid to seep in. Rising differential pressure across the capillary walls eventually forces the cell junctions to close. Once in the capillaries, the trapped fluid is known as lymph, and it moves into larger, vein-like lymphatic vessels. The lymph moves slowly and without any kind of central pump through a combination of peristalsis, the action of semilunar valves, and the squeezing influence of surrounding skeletal mus- cles, much like occurs in veins. In the skin, lymph vessels form networks around veins, but in the trunk of the body and around internal organs, they form networks around arteries. Lymph vessels have thin- ner walls than veins, are wider, have more valves, and — most important — regularly bulge with bean-shaped sacs called lymph nodes (more on those in the later section “Poking at the Nodes”). Just as small tree branches merge into larger ones and then into the trunk, lymphatics eventually merge into the nine largest lymphatic vessels called lymphatic trunks. The biggest of these at nearly 1 ⁄12 feet in length is the thoracic duct; nearly all the body’s lymph vessels empty into it. Only those vessels in the right half of the head, neck, and thorax empty into its smaller mate, the right lymphatic duct.

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A 3-year-old who could accurately multiply 183 by 39 would certainly be intelligent buy 100mg januvia mastercard, but a 25-year-old who could not do so would be seen as unintelligent januvia 100mg online. Thus understanding intelligence requires that we know the norms or standards in a given population of people at a given age cheap 100mg januvia amex. Thestandardization of a test involves giving it to a large number of people at different ages and computing the average score on the test at each age level cheap 100 mg januvia. It is important that intelligence tests be standardized on a regular basis purchase januvia 100 mg online, because the overall level of intelligence in a population may change over time. The Flynn effect refers to the observation that scores on intelligence tests worldwide have increased substantially over the past [21] decades (Flynn, 1999). There are many explanations for the Flynn effect, including better nutrition, increased access to information, and more familiarity with [22] multiple-choice tests (Neisser, 1998). But whether people are actually getting smarter is [23] debatable (Neisser, 1997). Once the standardization has been accomplished, we have a picture of the average abilities of people at different ages and can calculate a person‘smental age, which is the age at which a person is performing intellectually. Most modern intelligence tests are based the relative position of a person‘s score among people of the same age, rather than on the basis of this formula, but the idea of an intelligence “ratio‖ or “quotient‖ provides a good description of the score‘s meaning. It consists of 15 different tasks, each designed to assess intelligence, including working memory, arithmetic ability, spatial ability, and general knowledge about the world (see Figure 9. It also shows significant correlations with measures of everyday functioning among the mentally retarded. The intelligence tests that you may be most familiar with are aptitude tests, which are designed to measure one‘s ability to perform a given task, for instance, to do well in college or in postgraduate training. These tests are useful for selecting students because they predict success in the programs that they are designed for, particularly in the first year of the [25] program (Kuncel, Hezlett, & Ones, 2010). Intelligence tests are also used by industrial and organizational psychologists in the process of personnel selection. Personnel selection is the use of structured tests to select people who are [27] likely to perform well at given jobs(Schmidt & Hunter, 1998). This is normally accomplished by surveying and/or interviewing current workers and their supervisors. Based on the results of the job analysis, the psychologists choose selection methods that are most likely to be predictive of job performance. The Biology of Intelligence The brain processes underlying intelligence are not completely understood, but current research has focused on four potential factors: brain size, sensory ability, speed and efficience of neural transmission, and working memory capacity. Studies that have measured brain volume using neuroimaging techniques find that larger brain size is correlated [28] with intelligence (McDaniel, 2005), and intelligence has also been found to be correlated with the number of neurons in the brain and with the thickness of the cortex (Haier, 2004; Shaw et al. It is important to remember that these correlational findings do not mean that having more brain volume causes higher intelligence. It is possible that growing up in a stimulating environment that rewards thinking and learning may lead to greater brain growth (Garlick, Attributed to Charles Stangor Saylor. Another possibility is that the brains of more intelligent people operate faster or more efficiently than the brains of the less intelligent. Some evidence supporting this idea comes from data showing that people who are more intelligent frequently show less brain activity (suggesting that they need to use less capacity) than those with lower intelligence when they work on a task [31] (Haier, Siegel, Tang, & Abel, 1992). And the brains of more intelligent people also seem to run faster than the brains of the less intelligent. Research has found that the speed with which people can perform simple tasks—such as determining which of two lines is longer or pressing, as quickly as possible, one of eight buttons that is lighted—is predictive of intelligence (Deary, [32] Der, & Ford, 2001). Although intelligence is not located in a specific part of the brain, it is more prevalent in some [34] brain areas than others. Although different tests created different patterns of activation, as you can see in Figure 9. Intelligence has both genetic and environmental causes, and these have been systematically studied through a large number of twin and adoption studies (Neisser et al. These studies have found that between 40% and 80% of Attributed to Charles Stangor Saylor.

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The content of our dreams generally relates to our everyday experiences and concerns purchase 100mg januvia free shipping, and frequently our fears and failures (Cartwright order 100mg januvia visa, Agargun generic januvia 100 mg without a prescription, Kirkby januvia 100 mg for sale, & Friedman discount januvia 100 mg with amex, 2006; Domhoff, Meyer-Gomes, & Schredl, [20] 2005). Many cultures regard dreams as having great significance for the dreamer, either by revealing something important about the dreamer’s present circumstances or predicting his future. The [21] Austrian psychologist Sigmund Freud (1913/1988) analyzed the dreams of his patients to help him understand their unconscious needs and desires, and psychotherapists still make use of this technique today. Freud believed that the primary function of dreams was wish fulfillment, or the idea that dreaming allows us to act out the desires that we must repress during the day. Freud believed that the real meaning of dreams is often suppressed by the unconscious mind in order to protect the individual from thoughts and feelings that are hard to cope with. By uncovering the real meaning of dreams through psychoanalysis, Freud believed that people could better understand their problems and resolve the issues that create difficulties in their lives. Although Freud and others have focused on the meaning of dreams, other theories about the causes of dreams are less concerned with their content. One possibility is that we dream primarily to help with consolidation, or the moving of information into long-term memory [22] (Alvarenga et al. Payne and Nadel (2004) argued that the content of dreams is the result of consolidation—we dream about the things that are being moved into long-term memory. Thus dreaming may be an important part of the learning that we do while sleeping (Hobson, Pace- [25] Schott, and Stickgold, 2000). The activation-synthesis theory of dreaming (Hobson & McCarley, 1977; Hobson, [26] 2004) proposes still another explanation for dreaming—namely, that dreams are our brain’s interpretation of the random firing of neurons in the brain stem. As a result, the cortex strings the messages together into the coherent stories we experience as dreams. Although researchers are still trying to determine the exact causes of dreaming, one thing remains clear—we need to dream. Sleep disorders, including insomnia, sleep apnea, and narcolepsy, may make it hard for us to sleep well. Other theories of dreaming propose that dreaming is related to memory consolidation. If you happen to be home alone one night, try this exercise: At nightfall, leave the lights and any other powered equipment off. Does this influence what time you go to sleep as opposed to your normal sleep time? Consider how each of the theories of dreaming we have discussed would explain your dreams. Stereotypes as judgmental heuristics: Evidence of circadian variations in discrimination. Dream consciousness: Our understanding of the neurobiology of sleep offers insight into abnormalities in the waking brain. Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Healthy older adults’ sleep predicts all-cause mortality at 4 to 19 years of follow-up. Dreams as the expression of conceptions and concerns: A comparison of German and American college students. Paradoxical sleep deprivation impairs acquisition, consolidation and retrieval of a discriminative avoidance task in rats. The brain as a dream state generator: An activation-synthesis hypothesis of the dream process. Summarize the major psychoactive drugs and their influences on consciousness and behavior. A psychoactive drug is a chemical that changes our states of consciousness, and particularly our perceptions and moods. These drugs are commonly found in everyday foods and beverages, including chocolate, coffee, and soft drinks, as well as in alcohol and in over-the-counter drugs, such as aspirin, Tylenol, and cold and cough medication. Psychoactive drugs are also frequently prescribed as sleeping pills, tranquilizers, and antianxiety medications, and they may be taken, illegally, for recreational purposes. Moderate Moderate Moderate Restlessness, irritability, headache and body aches, tremors, Slowing of many nausea, vomiting, body functions, and severe constipation, Morphine abdominal pain High Moderate Moderate The chemical makeup of respiratory and opioids is similar to the cardiac All side effects of endorphins, the depression, and morphine but neurotransmitters that the rapid about twice as serve as the body‘s development of addictive as “ natural pain reducers. For instance, sleeping pills are prescribed to create drowsiness, and benzodiazepines are prescribed to create a state of relaxation. In other cases psychoactive drugs are taken for recreational purposes with the goal of creating states of consciousness that are pleasurable or that help us escape our normal consciousness. The use of psychoactive drugs, and especially those that are used illegally, has the potential to create very negative side effects (Table 5.

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