What role do cilia play in the respiratory system?

Cilia play a major role throughout the body, especially in the respiratory system. They can be described as hair-like structures that are found on the outside of cells lining the bronchus within the respiratory system. The cilia of the respiratory system move together in a wave-like motion that is critical to their function. This wave-like motion occurs in tandem with other nearby cilia, and works together with mucus producing goblet cells to trap and remove...

Cilia play a major role throughout the body, especially in the respiratory system. They can be described as hair-like structures that are found on the outside of cells lining the bronchus within the respiratory system. The cilia of the respiratory system move together in a wave-like motion that is critical to their function. This wave-like motion occurs in tandem with other nearby cilia, and works together with mucus producing goblet cells to trap and remove toxins, microorganisms, and other debris that enter the respiratory system. This helps to protect the lungs by capturing the various invaders first in the mucus. The cilia then function together using their wave-like motion to move the mucus up and away from the lungs and back into the throat. This function of the cilia protects the vital respiratory system, helping to fight against infection and damage to the lungs.

What is sneezing? |

Causes and Symptoms

During the breathing process, the lung part of the chest cavity is expanded and air is allowed to flow in. When impulses that cause excitation reach a threshold level in the nasal lining, a message is transferred to the sneeze reflex center of the brain via the sensory nerves. At that point, the stimulus provides the chest muscles with the signal to convulse and therefore squeeze the lungs. The contracted muscles in the pharynx block the exit of the air from the mouth and instead detour it through the nasal cavity and out into the atmosphere. The phenomenon of genuine sneezing cannot be performed voluntarily and, at the same time, cannot be easily suppressed. In fact, suppression may create an increase in pressure in the acoustic part of the body, with occasional serious results.

During inhalation, air is inserted through the nostrils, heated to the body temperature, humidified, and finally filtered of foreign contaminants (such as bacteria and dust particles) before it enters the lungs. When the air contains a large quantity of particles, such as dust or pollen during windy conditions, or is drier or colder than expected, sneezing takes place. The main reason for this reaction is irritation of the nerve endings, which is temporarily relieved by the explosive blowing of air during sneezing. The process is intensified in both children and adults by several nasal disorders, such as congestion attributed to bacterial infection, cold, allergy created by foreign particles, pressure, or a growth inside the nostril. In addition, up to one-third of the population tends to sneeze when exposed to a sudden bright light, a reaction termed photic sneeze reflex (also known as photoptarmosis) that may be genetic.

Treatment and Therapy

In a way similar to coughing, in which air is expelled through the mouth, sneezing has a protective role in breathing. The hairs inside the nostrils, known as cilia, serve as the filtering device and, when they cannot trap the contaminants, as the instigators for the irritation of the nerve endings. Their presence is therefore instrumental in protecting the windpipe from the solid particles that are suspended in air. Parents may have a young child blow his or her nose in order to remove the trapped particles in the nasal mucus. This action should be performed with the minimum damage of the capillaries, which may collapse and lead to a nosebleed, possibly followed by an infection.

Perspective and Prospects

Sneezing is very important because it serves as the first weapon of the respiratory system’s defense against invading foreign particles. The search goes on for inhalers and other medications to relieve the effects of sneezing, as well as for various means to release the pressure created by the common cold and rhinoviruses. The traditional methods of soothing nerve endings with steam and other vaporizers are still dependable and help in avoiding the subsequent spread of the more serious viral infections such as pneumonia and bronchiolitis.

Bibliography

Adler, Tina. “The Radical Theory of Sneezing.” Environmental Health Perspectives 113, no. 11 (November 1, 2005): A736.

Can, Ilknur, et al. "Sneezing and Runny Nose: Should Allergy Testing be Routinely Performed." Indian Journal of Otalaryngology and Head and Neck Surgery 65 (August, 2013): 267–270.

Fowler, Michael A., and Nancy McKemie. "What's the Reason for All That Sneezing and Wheezing?" Tuscon: Fireship Press, 2012.

Karpa, Kelly Dowhower. “The Assault on Allergies: From Diagnostics to Treatments.” Drug Topics (June, 2000): 12S–16S.

Knight, Allan. Asthma and Hay Fever: How to Relieve Wheezing and Sneezing. New York: Arco, 1981.

McCarthy, Robert. “New Approaches to Allergic Rhinitis and Asthma.” Patient Care 34, no. 19 (October 15, 2000): 108–118.

Miller, Kathryn E., and Ian M. Mackay. "From Sneeze to Wheeze: What We Know About Rhinovirus Cs." Journal of Clinical Virology 57, no 4 (August, 2013): 291–299.

Ross-Flanigan, Nancy. “Nothing to Sneeze At.” Health 14, no. 3 (April, 2000): 102–104.

Voelker, Rebecca. “Allergies: More than Just Sniffles and Sneezes.” Business and Health 18, no. 4 (April, 2000): 19–25.

In The Boy in the Striped Pajamas, how does Gretel feel about the new house?

Gretel hates their new home at "Out-With." In Chapter 3, Bruno mentions that he hates it here and says that it's horrible. Gretel agrees with her brother and says, "I know what you mean...it's not very nice, is it?" (Boyne 24). Whenever Bruno mentions that he misses his friends, Gretel tells him that she misses her friends too. After Bruno shows Gretel the view of the concentration camp from the window in his...

Gretel hates their new home at "Out-With." In Chapter 3, Bruno mentions that he hates it here and says that it's horrible. Gretel agrees with her brother and says, "I know what you mean...it's not very nice, is it?" (Boyne 24). Whenever Bruno mentions that he misses his friends, Gretel tells him that she misses her friends too. After Bruno shows Gretel the view of the concentration camp from the window in his room, Gretel is perplexed, and comments, "Who would build such a nasty-looking place?" (Boyne 32). Gretel notices the size and symmetry of each of the houses in the concentration camp and thinks deeply about their new environment. Bruno mentions that he was right when he told Gretel that there were children nearby. However, Gretel comments that they aren't the type of children she would be interested in playing with. She also says, "Those children look like they've never had a bath in their lives" (Boyne 37). As the novel progresses, Gretel develops a crush on Lieutenant Kotler and seems to occupy her time with fantasizing about him and studying. Overall, Gretel is not happy in their new home at "Out-With" and wishes to go back to Germany. 

What are stress-related diseases? |

Introduction

The term “stress,” as it is used in the field of psychology, may be defined as the physical or psychological disturbance an individual experiences as a result of what that individual perceives to be an adverse or challenging circumstance. Four observations concerning this definition of stress should be made. First, stress is what the individual experiences, not the circumstance causing the stress (the stressor). Second, individuals differ in what they perceive to be stressful. What may be very stressful for one individual may not be at all stressful for another. Hans Selye, the researcher who did more than anyone else to make the medical community and the general population aware of the concept and consequences of stress, once noted that, for him, spending the day on the beach doing nothing would be extremely stressful. This difference in people’s perceptions is behind the familiar concept that events do not cause stress. Instead, stress comes from a person’s perception or interpretation of events.

Third, stress occurs in response to circumstances that are seen as negative, but stress may also arise from challenging circumstances, even positive ones. The well-known Social Readjustment Rating Scale developed by Thomas Holmes and Richard Rahe includes both positive and negative life events. A negative event, such as the death of a spouse, is clearly stressful; however, marriage, generally viewed as a positive life event, can also be stressful. Fourth, stressors can lead to stress-related disturbances that are psychological, physiological, or both. The psychological response is rather unpredictable. A given stressor may result in one individual responding with anger, another with depression, and another with a new determination to succeed.

General Adaptation Syndrome

The physiological response is more predictable. Beginning in the 1930s, Selye began studying the human response to stressors. Eventually he identified what he termed the general adaptation syndrome
to describe the typical pattern of physical responses. Selye divided the general adaptation syndrome into three stages: alarm, resistance, and exhaustion.

The first stage begins when an individual becomes frightened, anxious, or even merely concerned. The body immediately undergoes numerous physical changes to cope with the stressor. Metabolism speeds up. Heart and respiration rates increase. The hormones epinephrine, norepinephrine, and cortisol are secreted. Sugar is released from the liver. The muscles tense. Blood shifts from the internal organs to the skeletal musculature. These and a host of other changes are aimed at helping the body cope, but the price paid for this heightened state of arousal typically includes symptoms such as headache, upset stomach, sleeplessness, fatigue, diarrhea, and loss of appetite. The body’s increase in alertness and energy is accompanied by a lowered state of resistance to illness.

Obviously, people cannot remain in the alarm stage for long. If the stressor is not removed, the body enters the resistance stage—a stage that may last from minutes to days or longer. During this stage, the body seeks to adapt to the stressor. The physical changes that occurred during the alarm stage subside. Resistance to illness is actually increased to above-normal levels. Because the body is still experiencing stress, however, remaining in this stage for a long period will eventually lead to physical and psychological exhaustion—the exhaustion stage.

Selye has noted that over the course of life, most people go through the first two stages many, many times. Such is necessary to adapt to the demands and challenges of life. The real danger is found in not eliminating the stressor. During the exhaustion stage, the body is very vulnerable to disease and in extreme cases may suffer collapse and death. Although later research has found subtle differences in the stress response, depending on the stressor involved, the basic findings of Selye have continued to be supported. In addition to the direct physiological effects of stress on the body, indirect effects may also lead to illness. For example, stress may cause or exacerbate behavioral risk factors such as smoking, alcohol use, and overeating.

Heart Disease and Immune Effects

Specific illnesses can also be caused or promoted by stress. For many years Americans have been aware of the relationship between stress and heart disease. The biochemical changes associated with stress lead to higher blood pressure, an increased heart rate, and a release of fat into the bloodstream. If the fat is completely consumed by the muscles through physical activity (for example, defending oneself from an attacker), no serious health consequences follow. If, however, a person experiences stress without engaging in physical activity (a more common scenario in Western culture), the fat is simply deposited on the walls of the blood vessels. As these fatty deposits accumulate, life is threatened.

The work of two cardiologists, Meyer Friedman and Ray Rosenman, is of particular importance to a discussion of heart disease and stress. Friedman and Rosenman demonstrated, based originally on personal observation and subsequently on clinical research, that there is a personality type that is particularly prone to heart disease. The personality type that is at the greatest risk was found to be one which is highly stressed—impatient, hostile, hard-driving, and competitive. They termed this a Type A personality. The low-risk person, the Type B personality, is more patient, easygoing, and relaxed.

Numerous studies have examined health based on the Type A-Type B concept. Virtually all have supported Friedman and Rosenman’s conclusions. One major report, however, did not; subsequent analysis of that report and other research generally has indicated that the aspects of the Type A personality that are threatening to one’s health are primarily the hostility, cynicism, and impatience, not the desire to achieve.

A newer area of research that is even more fundamental to understanding how stress is related to disease involves the immune system. As the physiological changes associated with stress occur, the immune system is suppressed. The immune system has two primary functions: to identify and destroy hazardous foreign materials called antigens (these include bacteria, viruses, parasites, and fungi) and to identify and destroy the body’s own cells that have undergone changes associated with malignancy. Thus, if the immune system is suppressed, the body is less able to detect and defend against a host of diseases. An example of this effect again involves research with laboratory rats. One such investigation involved placing tumor cells in the bodies of rats. Some of the rats were then exposed to an abundance of stress. Those that were given this treatment were less resistant to the cancer. Their tumors were larger, and they developed sooner than those found in the “low-stress” rats.

The recent growth of the field of psychoneuroimmunology focuses specifically on the chemical bases of communication between mind and body. Research in this area provides evidence that the body’s immune system can be influenced by psychological factors that produce stress. One study, for example, showed that during students’ examination periods, the levels of students’ antibodies that fight infections were lowest. Thus they were most vulnerable to illness at that most stressful time. Health centers confirm that students tend to report more illness during examination times.

As research continues, the number of specific diseases that can be linked to stress grows. A partial listing of stress-related diseases and disorders for which recent research is available would include acne, asthma, cancers (many types), colds, coronary thrombosis, diabetes mellitus, gastric ulcers, herpes simplex (types 1 and 2), human immunodeficiency virus (HIV) infection, hyperlipidemia, hypertension, infertility, irritable bowel syndrome (IBS), migraine headache, mononucleosis syndrome, rheumatoid arthritis, streptococcal infection, stroke, systemic lupus erythematosus, and tuberculosis.

Research has shown that stress may also play a role in depression, sleep disturbances, ovulation, and brain atrophy associated with Alzheimer’s disease. Stress as a cause of stomach ulcers has been essentially negated, with the discovery that these ulcers are generally caused by the bacterium Helicobacter pylori, which can be treated with antibiotics. However, stress may still play a role in decreasing the mucous lining of the stomach, which makes it more vulnerable to ulcer formation. Some experts feel that there is no illness that is not in some way influenced by stress.

Few, if any, of these physical problems are caused solely by stress. Many other factors influence risk, including genetic composition, gender, race, environmental conditions, and nutritional state. Nevertheless, stress is frequently an important factor in determining initial resistance as well as the subsequent course of a given disease.

Stress Reduction and Coping

Some individuals appear to live with many stressors yet generally avoid physical and psychological illness. Understanding why is important, because it can provide insight as to what the average person can and should do to lower stress levels. Dispositional factors (optimistic versus pessimistic, easygoing versus hard-driving, friendly versus hostile) are probably most important in determining a person’s stress level. The Type A-Type B research is an example of research demonstrating the influence of dispositional factors.

Research with twins has found that temperament is largely inborn; however, any individual can choose to be more optimistic, generous, and patient. Norman Cousins
is often cited as an example of a person who decided to change his outlook and mental state to preserve his life. He had read Selye’s The Stress of Life (1956), which describes how negative emotions can cause physical stress and subsequent disease. Cousins, who had a rare and painful illness from which he was told he would most likely never recover, decided that if negative emotions could harm one’s health, then positive emotions could possibly return one’s health.

As Cousins describes his experience in Anatomy of an Illness as Perceived by the Patient (1979), he left his hospital room for a more pleasant environment, began trading massive doses of drugs for massive doses of vitamin C and a steady diet of television comedies and laughter, and decided to stop worrying. To the surprise of his medical team, his recovery began at once. Though this now-classic example is only anecdotal, the research on disposition and stress would support the assumption that Cousins’s decision to change his mental state and stop worrying—not his avoidance of traditional medical care—was a truly important influence.

A related area of research has investigated how psychological hardiness helps people resist stress. Studies by Suzanne Kobasa and her colleagues examined business executives who all had an obvious abundance of stressors in their lives. In comparing those hardy individuals who handled the stressors well with the nonhardy individuals, the researchers found that the two groups differed in three important but basic ways.

The first was commitment. Stress-resistant executives typically possessed a clear sense of values. They had clear goals and a commitment to those goals. Less hardy executives were more likely to feel alienation. The second was challenge. The hardy executives welcomed challenges and viewed change rather than stability as the norm in life. Their less healthy counterparts viewed change with alarm. The third factor was control. The hardy executives felt more in control of their lives. This aspect of Kobasa’s research overlaps with research conducted since the 1960s involving a concept known as the locus of control. People with an internal locus of control are those individuals who believe they are influential rather than powerless in controlling the direction of their lives. This area of research has also found that such a belief lowers stress.

Many studies have been conducted to examine the relationship between physical fitness and mental health. What has emerged from this heavily researched area is a clear conclusion: Exercise can lower stress levels. Though regular, sustained aerobic exercise is generally advocated, research has found that even something as simple as a daily ten-minute walk can have measurable beneficial effects. During exercise, there is a release of chemical substances, including neurotransmitters called endorphins. Endorphins act to decrease pain and produce feelings of well-being, somewhat like an opiate. Exposure to stress has been shown to increase the level of endorphins in the body. For example, studies were conducted with runners, one group using naloxone, a substance that blocks the effects of opiates, and the other group a placebo that had no effect on the body. After strenuous runs, those taking the placebo reported feelings of euphoria, sometimes known as runners’ high. Those taking naloxone reported no such feelings. During exercise, the body releases other chemicals, including dopamine, which is thought to act as an antidepressant. Thus there is abundant evidence of the stress-reducing benefits of exercise.

Another approach to reducing stress involves learning to evoke a physical relaxation response, a term coined by Harvard Medical School cardiologist Herbert Benson. Benson became intrigued by the ability of some people who practice meditation to lower their blood pressure, heart rate, and oxygen consumption voluntarily. He discovered that the process is not at all mystical and can be easily taught. The process involves getting comfortable, closing the eyes, breathing deeply, relaxing muscles, and relaxing the mind by focusing on a simple word or phrase.

Others are helped by using an electronic device that closely monitors subtle physiological changes. By observing these changes (typically on a monitor), a person can, for example, learn to slow down a heart rate. This is known as biofeedback training. Many other techniques and suggestions arising from research as well as common sense can lower stress. A strong social support system has been found to be very important; disciplining oneself not to violate one’s own value system is essential. Even having a pet that needs love and attention has been found to lower stress.

Research and the Future

A general recognition that a relationship exists between mind and body is at least as old as the biblical Old Testament writings. Proverbs 17:22 reads, “A cheerful heart is good medicine,/ but a crushed spirit dries up the bones.” Hippocrates, generally considered the father of medicine, sought to understand how the body could heal itself and what factors could slow or prevent this process. He clearly perceived a relationship between physical health and what is now termed stress, though his understanding was shallow.

Several physiologists of the nineteenth century made contributions; however, it was not until the twentieth century that the classic studies of American physiologist Walter Bradford Cannon proved the link scientifically. Cannon and his student Philip Bard began their analysis of stress and physiological arousal to disprove the idea espoused by others, that emotion follows physiological arousal.

Cannon found a variety of stressors that led to the release of the hormones adrenaline and noradrenaline (or, properly now, epinephrine and norepinephrine). Heat, cold, oxygen deprivation, and fright all led to hormonal changes as well as a number of additional physiological adaptations. Cannon was excited about this discovery and impressed with the body’s remarkable ability to react to stressors. All these changes were aimed at preparing the body for what Cannon termed the fight-or-flight response. It was Selye’s task to build on Cannon’s work. His description of the reaction subsequently termed the general adaptation syndrome first appeared in a scientific journal in 1936. As knowledge of the stress concept began to spread, interest by the public as well as the research community increased.

Literally tens of thousands of stress research studies conducted throughout the world were completed during the last half of the twentieth century. Of particular importance was the discovery by three American scientists that the brain produces morphinelike antistress substances. The discovery of these substances, named endorphins, won the 1977 Nobel Prize for the scientists involved and opened a whole new area of research.

Research has shown that the brain itself produces neuropeptides, or brain message transmitters, that may also be produced by macrophages—white blood cells that attack viruses and bacteria. Because some forms of stress-reduction such as relaxation also seem to result in production of neuropeptides, if the brain could be caused to produce more of these substances, the immune system could be strengthened. The hope remains that someday an endorphin-type drug could be used to counter some of the unhealthy effects of stress, ensuring better health and longer lives. Better health and longer lives are available even today, however, for all people who are willing to make lifestyle changes based on current knowledge.

Bibliography

Greenberg, Jerrold S. Comprehensive Stress Management. 11th ed. New York: McGraw, 2009. Print.

Kahn, Ada P., ed. The Encyclopedia of Stress and Stress-Related Diseases. 2d ed. New York: Facts On File, 2005. Print.

Kendall-Tackett, Kathleen, ed. The Psychoneuroimmunology of Chronic Disease: Exploring the Links Between Inflammation, Stress, and Illness. Washington, DC: Amer. Psychological Assn., 2010. Print.

Khazan, Inna Z. The Clinical Handbook of Biofeedback: A Step by Step Guide for Training and Practice with Mindfulness. Chichester: Wiley, 2013. Print.

Marks, David, Michael Murray, Brian Evans, and Emee Vida Estacio. Health Psychology: Theory Research, and Practice. 3rd ed. London: Sage, 2011. Print.

Romas, John A., and Manoj Sharma. Practical Stress Management: A Comprehensive Workbook for Managing Change and Promoting Health. 5th ed. San Francisco: Pearson, 2010. Print.

Seaward, Brian L. Managing Stress: Principles and Strategies for Health and Well-being. 7th ed. Sudbury: Jones, 2012. Print.

Sapolsky, Robert M. Why Zebras Don’t Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping. Rev. ed. New York: Holt, 2004. Print.

Selye, Hans. The Stress of Life. Rev. ed. New York: McGraw, 1978. Print.

What is drive theory? |

Introduction

One goal of science is to understand, predict, or manipulate natural events. A scientist may start by observing an event of interest and measuring it as precisely as possible to detect any changes. In experimental research, scientists systematically manipulate various other events to see whether the event of interest also changes. In survey research, different events are measured to see whether they vary with the event of interest. Understanding is achieved when the relationship between the event of interest (the dependent variable) and other events (independent variables) is established. One can then predict or manipulate the event of interest. A theory provides a guideline to organize the variables into a system based on common properties. To a psychologist, the dependent variable is the behavior of all animals and humans, and the independent variables (also called determinants) may be any other variable related to behaviors. Psychological research aims to discover the determinants of a certain behavior, some of which are motivational variables. The field of motivation
examines why a particular behavior occurs, why it is so strong, and why it is so persistent.

A drive is a process related to the source of behavioral energy originating from within the body that is created by disturbances in homeostasis (a state of systemic equilibrium). A homeostatic imbalance creates a state of need for certain stimuli from the environment that can restore the balance. For example, abnormal body temperature and hyperosmolality of the body fluid (electrolyte concentration outside cells that is higher than that of the intracellular fluid, resulting in cell dehydration) are disturbances in homeostasis. The homeostatic balance can be restored through two means: physiological and behavioral. Physiological means such as vasodilation, sweating, and panting serve to reduce body temperature, while concentration of electrolytes in the urine by the kidneys reduces hyperosmolality. Behavioral means such as taking off clothes, turning on an air conditioner, and drinking cold liquid lower body temperature; drinking water would also result in reduction of hyperosmolality. One may examine a case of homeostatic imbalance in detail to illustrate how the two means function to restore the balance.

When the body fluid volume is reduced (hypovolemia) because of loss of blood or of body fluid due to intense sweating, the body responds immediately by vasoconstriction, reducing urine volume (through vasopressin release), and conserving sodium (through aldosterone release). Those are physiological means that will restore the blood pressure and prevent circulatory failure. Eventually, however, the body must get back the lost fluid from the environment via behavior (seeking water and drinking) to achieve long-lasting homeostasis. The physiological means are immediate and effective, but they are only stopgap measures. Behavior is the means by which the animal interacts with its environment to get back the lost resource.

Drive, Reinforcement, and Learning

The concept of drives is very important to the theories of Clark L. Hull, a neo-behaviorist. According to Hull, a drive has at least two distinct functions as far as behavioral activation is concerned: without drives there could be no reinforcement and thus no learning, because drive reduction is the reinforcement; and without drives there could be no response, for a drive activates behavioral potentials into performance. Drive theory maintains that a state named “drive,” or D, is a necessary condition for behavior to occur, but D is not the same as the bodily need. D determines how strongly and persistently a behavior will occur; it connects the need with the behavior. This distinction between need and drive is necessary because while the state of need serves as the source of behavior, the intensity of behavior is not always related to the intensity of need. Need can be defined as a state of an organism attributable to deprivation of a biological or psychological requirement, related to a disturbance in the homeostatic state.

There are cases in which the need increases but behavior does not, or in which the need remains but behavior is no longer manifested. Prolonged deprivation, for example, may not result in a linear or proportional increase in behavior. A water-deprived animal may stop drinking even before cellular dehydration is restored to the normal state; the behavior is changing independent of homeostatic imbalance. Cessation of behavior is seen as being attributable to drive reduction.

Hull uses D to symbolize drive and sHr (H is commonly used to denote this, for convenience) to symbolize a
habit that consists of an acquired relationship between stimulus (S) and response (R). It represents a memory of experience in which certain environmental stimuli and responses were followed by a reward. An effective reward establishes an S-R relationship; the effect is termed reinforcement. One example of an H would be an experience of maze stimuli and running that led to food. H is a behavioral potential, not a behavior. Food deprivation induces a need state that can be physiologically defined; then D will energize H into behavior. The need increases monotonically with hours of deprivation, but D increases only up to three days without food. A simplified version of the Hullian formula for a behavior would be “behavior = HD,” or “performance = behavioral potential energizer.” The formula indicates that learning, via establishing behavioral potential, and D, via energizing the potential, are both necessary for performance to occur. This is a multiplicative relationship; that is, when either H or D is zero, a specific performance cannot occur.

Role of Freud’s “Id”

In his psychoanalytical approach to behavioral energy, Sigmund Freud
proposed that psychic energy is the source of human behaviors. The id
is the reservoir of instinctual energy presumed to derive directly from the somatic processes. This energy is unorganized, illogical, and timeless, knowing “no values, no good or evil, no morality,” according to Freud in 1933. The id operates according to the pleasure principle, using the primary process to discharge its energy as soon as possible, with no regard for reality. When the discharge is hindered by reality, however, the ego handles the situation according to the reality principle, using a secondary process to pursue realistic gratification. The ego mediates between the id on one hand and reality on the other.

Freud thus conceptualized the id to be the energy source and the ego to manage behavior in terms of reality. Learning is manifested in the way the ego manages behavior for gratification under the restriction of the environment and the superego. In this model, the drive is seen as the energizer of behavior. The similarity between the Freudian and Hullian concepts of drive is obvious. Food deprivation would generate homeostatic imbalance, which is the somatic process, and the need, which is similar to the energy of the id. The organism cannot obtain immediate gratification because of environmental constraints on acquiring food, so behavior is generated to negotiate with the environment. Drive is much like the ego, since it energizes the behavioral potentials into behaviors to seek reality gratification, which is equivalent to drive reduction. The concept of pleasure and behavioral changes commonly appears in various theories that incorporate a subtle influence of Freudian thought.

Deprivation and Incentive Motives

In one classic experiment, Carl J. Warden studied the persistence of behavior as a function of various sources, including the strength of a drive, using an apparatus called a Columbia obstruction box. He demonstrated that a rat without food would cross an electrified grid to reach a goal box that held food. When the rat was immediately brought back from the goal box to the start box, it would cross the grid again and again. The number of grid crossings was positively related to the number of days without food for up to three days. From the fourth day without food, however, the number of crossings slowly decreased. When baby rats were placed in the goal box, a mother rat would cross the grid repeatedly. When a male or female rat was placed in the goal box, a rat of the opposite sex would cross repeatedly. The number of crossings by the male rat was positively related to the duration it spent without a female companion.

These animals were all manifesting the effect of different drives: hunger, maternal instinct, and sex. It was shown that the maternal drive was associated with the greatest number of crossings (twenty-two times in twenty minutes), followed by thirst (twenty times), hunger (seventeen), female sex drive (fourteen), male sex drive (thirteen), and exploration (six). Warden demonstrated that various internal forces, created by deprivation and hormonal state, and external forces, created by different goal objects, together determine the grid-crossing behavior. The level of deprivation induces drive motivation; the reward in the goal box induces incentive motivation. In this example, the focus is on drive motivation.

If one were to place a well-trained rat into a maze, it might or might not run to the goal box. Whether it would run, how fast it would run, and how well (in terms of errors) it would run would depend on whether the subject were food deprived. With food deprivation, the well-trained rat would run to the goal box with few errors. If it had just been fed, it would not run; it would simply wander, sniff at the corner, and go to sleep. The environmental stimulus (the maze) is the same; the rat’s behavior is different because the internal force—the drive created by food deprivation—is different. A need state produces D, and D triggers behavior. The behavior that will occur is determined jointly by the past experience of learning, which is termed H, and by stimuli, S, from the environment. An inexperienced rat, without the H of maze running, will behave differently from a well-trained rat in a maze. D is an intervening variable: It connects need and behavior, so one must consider both the source (need) and the consequence (behavior) to define D. When D is zero, there will be no maze running, no matter how well trained the rat is. On the other hand, if there is no H (training), the proper maze-running behavior will not occur, no matter how hungry the rat is. An animal must be exposed to a maze when hungry to learn to negotiate the various turns on the way to the goal box containing food. Without food deprivation (and the resultant D), the animal would not perform even if it could; one cannot tell whether an animal has the knowledge to run the maze until one introduces a D variable. H is a potential of behavior, and D makes the potential into the observable reality of performance. Motivation turns a behavior on.

These ideas can be applied to countless real-life examples. If a person is not very good at playing tennis (has a low H), for example, no matter how motivated (high D) he or she is, that person will not be able to beat a friend who is an expert at the game. If a person is very good at tennis (high H) but does not feel like playing (low D), perhaps because of a lack of sleep, he or she will not perform well. The same situation would apply to taking a test, delivering a speech, or running a marathon.

Puzzle-Box Learning

In another experiment involving drive, Edward L. Thorndike
put a cat into a puzzle box. The cat attempted to get out via various behaviors (mewing, scratching, and so on). By chance, it stepped on a plate that resulted in the door opening, allowing the cat to escape. The cat was repeatedly returned to the box, and soon it would escape right away by stepping on the plate; other, useless behaviors were no longer manifested. The source of D in this case was the anxiety induced by confinement in the box, which could be measured by various physiological changes, such as heart rate and hormonal levels. Escaping makes the anxiety disappear, and D is reduced. D reduction results in an increase in the probability that the behavior immediately preceding it (stepping on the plate) will recur. Thorndike describes this puzzle-box learning as trial and error, implying a blind attempt at various means of escape until one happens to work. He states that a “satisfying effect” will create repetition, calling this the law of effect; the essence of the satisfying effect appears to be drive reduction. A five-stage learning cycle, then, consists of need, drive, behavior, drive reduction, and behavior repetition.

Central Motive State

The question of how a habit (H) is formed and how it is stored in the brain is a lively research topic in the psychobiology of learning, memory, and cognition, as well as in neuropsychology, which deals with learning deficit and loss of memory. Drive and reinforcement are important variables that determine whether learning will succeed and whether past learning will be manifested as behaviors. Research on hunger and thirst forms one subfield of psychobiology.

If D is the common energizer of various behaviors, then all sources of D—hunger, thirst, sex, mothering, exploration—should have something in common physiologically. The so-called central motive state is hypothesized to be such a state. It is known that arousal is common to the sources of D. Research involves biological delineation of the sources of D; researchers are studying the mechanisms of hunger, for example. There has been insufficient attention paid to the physiological processes by which hunger may motivate various behaviors and by which drive reduction would serve as a reinforcement in learning. Extreme lack of motivation can be seen in some depressed and psychotic patients, which results in both a lack of new learning and a lack of manifesting what is already known. The neuronal substrates of this “lack of energy” represent one problem under investigation in the area of drive and motivation.

Bibliography

Amsel, Abram. Mechanisms of Adaptive Behavior: Clark Hull’s Theoretical Papers, with Commentary. New York: Columbia UP, 1984. Print.

Bolles, Robert C. Theory of Motivation. 2nd ed. New York: Harper, 1975. Print.

Deckers, Lambert. Motivation: Biological, Psychological, and Environmental. 4th ed. Boston: Pearson, 2014. Print.

Freud, Sigmund. New Introductory Lectures on Psychoanalysis. New York: Norton, 1933. Print.

Hull, Clark L. Principles of Behavior. New York: Appleton, 1943. Print.

Miller, Neal. Learning, Motivation, and Their Physiological Mechanisms. New Brunswick: Aldine, 2007. Print.

Petri, Herbert L., and John M. Govern. Motivation: Theory, Research, and Applications. 6th ed. Belmont: Wadsworth, 2013. Print.

Pfaff, Donald W., ed. The Physiological Mechanisms of Motivation. New York: Springer, 1982. Print.

Reeve, Johnmarshall. Understanding Motivation and Emotion. 5th ed. Hoboken: Wiley, 2009. Print.

Ryan, Richard M., ed. The Oxford Handbook of Human Motivation. New York: Oxford UP, 2012. Print.

Stellar, James R., and Eliot Stellar. The Neurobiology of Motivation and Reward. New York: Springer, 1985. Print.

Warden, Carl John. Animal Motivation: Experimental Studies on the Albino Rat. New York: Columbia UP, 1931. Print.

What are trimethoprim and sulfamethoxazole? How do they interact with other drugs?

Folate

Effect: Supplementation Likely Helpful

Both trimethoprim and sulfamethoxazole interfere with folate: The sulfamethoxazole makes it hard for invading bacteria to manufacture folate, and the trimethoprim makes it hard for bacteria to use the folate. The net effect is to starve the bacteria of this necessary vitamin.

Humans and other mammals are much less affected by these antibiotics than are bacteria, because of the different way humans process folate. However, trimethoprim can still interfere to some extent with the body’s ability to utilize this essential nutrient. Folate supplementation may be helpful if one takes this antibiotic for a long period of time (to prevent urinary tract infections, for example).

PABA (Para-Aminobenzoic Acid)

Effect: Interference with Action of Drug

The supplement PABA may make trimethoprim/sulfamethoxazole less effective. Persons being treated with this drug should not take PABA except on medical advice.

Potassium

Effect: Possible Harmful Interaction

Trimethoprim/sulfamethoxazole might increase levels of potassium in the body. Therefore, persons on long-term treatment with this antibiotic should not take potassium supplements except on the advice of a physician.

White Willow

Effect: Possible Negative Interaction

The herb white willow contains substances very similar to aspirin. On this basis, one should not combine white willow with trimethoprim or sulfamethoxazole.

St. John’s Wort and Other Herbs

Effect: Potential Increased Risk of Photosensitivity

Sulfa drugs can cause increased sensitivity to the sun. Various herbs, including St. John’s wort and dong quai, can also cause this problem. Combined treatment with herb and drug might increase the risk further.

Bibliography

Alappan, R., M. A. Perazella, and G. K. Buller. “Hyperkalemia in Hospitalized Patients Treated with Trimethoprim-Sulfamethoxazole.” Annals of Internal Medicine 124 (1996): 316-320.

Vinnicombe, H. G., and J. P. Derrick. “Dihydropteroate Synthase from Streptococcus pneumoniae: Characterization of Substrate Binding Order and Sulfonamide Inhibition.” Biochemical and Biophysical Research Communications 258 (1999): 752-757.

What is the endocrine system, and how does it affect behavior?

Introduction

People have suspected that substances in the body contribute to behavior for a long time. During the fifth century bce., Hippocrates suggested in his humoral theory, that personality was determined by four body fluids: phlegm, black bile, yellow bile, and blood. The dominance of one of the fluids was associated with a specific behavior pattern, and a proportionate distribution of the fluids resulted in a balanced personality. This theory has contributed terms such as “phlegmatic,” “bilious,” and “good-humored” to describe personality types and states of mind.

Aristotle is reported to have performed castration experiments on both fowl and men to alter behavior. He believed that something produced by the testes caused typically male behavior. Several nineteenth century researchers continued the study of the connection between the testes and male reproductive behavior. In 1849, Arnold Adolphe Berthold implanted testes into the abdomens of castrated cockerels. Successful transplantation restored typical “male” behaviors such as crowing and combativeness.

During the late nineteenth and early twentieth centuries, knowledge of behavior and its causes increased. The science of ethology, which focuses on animal behavior, came into existence. In the early 1900s, John B. Watson founded a branch of psychology that became known as behavior science. This area of psychology concentrated on human behavioral studies. Eventually, ethology and behavior science contributed to biopsychology, also known as psychobiology, or biological psychology, a branch of psychology that analyzes data from neurosciences, genetics, endocrinology, and physiology in the quest for biological explanations of behavior, thoughts, and feelings. Biopsychology embraces several subdivisions. Physiological psychology focuses on nervous system and endocrine system research. Psychopharmacology specializes in the effects of drugs on the nervous system and, ultimately, on behavior. The development of therapeutic drugs is a goal of this discipline. The neuropsychologist studies the effects of brain damage on behavior. Psychophysiology differs from physiological psychology in that the psychophysiologist uses only human subjects while the physiological psychologist experiments on laboratory animals. Early research in physiological psychology focused on the nervous system, but it soon became evident that the endocrine system also influenced behavior and that the two systems were integrated and had coordinated effects on behavior. The classic endocrine system consists of ductless glands that produce chemical substances called hormones. The hormones elicit physiological responses, either locally or at some distant target site. When acting at a distance, the hormones travel to the site by way of the circulatory system.

Hans Selye, a Canadian scientist, proposed a direct connection between the endocrine system and behavior. In 1946, he described physiological events that were triggered by stress. This set of bodily changes became known as the general adaptation syndrome. The syndrome involved the mobilization of the autonomic nervous system, the adrenal glands, and the anterior lobe of the pituitary.

As research continued, data on the role of the endocrine system in determining behavior began to accumulate. Researchers continue to look to the endocrine system to provide clues about the causes of psychiatric diseases and the efficacy of hormone therapy in treating the diseases, as well as in altering behavior patterns.

Invertebrates

Among most invertebrates (animals without backbones), endocrine glands are not in evidence. There is, however, an invertebrate endocrine system. Specialized cells known as neurosecretory cells serve as endocrine tissue. The cells, which resemble neurons (the functional cells of the nervous system) are hormone producers. In invertebrate animals such as the hydra and planaria, the secretions (hormones) of the neurosecretory cells seem to influence growth and may be the underlying cause of the tremendous powers of regeneration possessed by the animals. There are indications that the development of sexuality, the laying of eggs, and the release of sperm may be under hormonal control in these animals. Attempts to establish the link between hormones and invertebrate behavior when the hormones are produced by neurosecretory cells have inherent problems. A historic method of studying hormone influence involves removal of the secreting organ, which causes a hormone deficit. Changes in physiology, behavior, or both are observed. Utilization of this method was complicated by the difficulty in removing all the functioning neurosecretory cells. Modern gene deletion or knockout technologies, which can remove a hormone or its receptor from a single tissue as well the whole animal, allow a more thorough assessment of the effects of hormone deficit.

Hormone effects are observable and measurable in the more developed invertebrates such as the Arthropoda. Studies carried out on insects and crustaceans indicate the presence of both neurosecretory cells and endocrine glands. Among the behaviors and activities controlled by the hormones released from either the cells or the glands are molting, sexual differentiation, sexual behavior, water balance, and diapause. Because arthropods are encased in an outer skeletal structure, it is necessary for the animals to shed their outer structure to grow. During the growth years, the animals go through cycles of shedding the outer skeleton (molting), growing, and reforming an outer coat. There is evidence that insects are under hormonal control when they enter a state of diapause, or arrested behavior in adverse times.

Vertebrates

All vertebrates (animals with backbones) have a well-developed and highly organized endocrine system. The classic endocrine system consists of the pituitary, the pineal, the thyroid, the thymus, the pancreas, a pair of adrenals (each adrenal acts as two glands—the adrenal cortex produces unique hormones and functions independently of the adrenal medulla), a pair of parathyroids, and a pair of ovaries or testes. Most tissues in the body produce hormones that help the central nervous system integrate needs and function of the organism. Adipose tissue hormones signal the level of stored energy to the brain, which determines the satiety or hunger necessary to maintain energy stores. Endocrine tissue in the gastrointestinal tract readies the system for the digestive process. During a pregnancy, the placental tissue assumes an endocrine function. Although the kidneys do not produce a hormone directly, they release an enzyme that converts a blood protein into a hormone that stimulates red blood cell production.

All vertebrates have a pituitary. The pituitary is a small, round organ found at the base of the brain. This major endocrine gland interacts with the hypothalamus of the nervous system. Together they modulate many behaviors. The hypothalamus monitors physiological status by receiving neural input and hormone signals from many peripheral tissues. In turn, the hypothalamus signals the pituitary by either neural impulse or chemical messengers called neurotransmitters. The pituitary responds by releasing into the peripheral blood circulation, or stopping release, of pituitary hormones that will have an effect on peripheral physiology to alter the physiological event and influence behavior. The endocrine system exerts its effects by binding to cellular receptors that in turn regulate intracellular biochemistry such as metabolism and gene expression. The human endocrine system is typical of vertebrate endocrine systems and their effect on behavior, although more complex, as reflected by a more complex human system. For example, melanocyte-stimulating hormones, which are generated by the anterior lobe of the pituitary, greatly increase skin pigmentation in amphibians. This creates a protective coloration. In humans, certain types of melanocyte-stimulating hormones may darken the skin, especially in certain hormonal conditions as those found in pregnancy. However, the melanocyte-stimulating hormones are not the cause for racial skin tone variation. Other melanocyte-stimulating hormones affect appetite and sexual arousal. There are enough similarities among human and animal endocrine functions and effects, however, to warrant the use of data from both ethology and human behavioral studies in determining the biological bases for behavior.

Influence on Reproductive Behavior

The influence of the endocrine system on behavior has been studied on many levels. Much of the work has been done on animals. There is, however, a growing body of information on hormonal effects on a variety of human behaviors, including reproductive and developmental behavior, reaction to stress, learning, and memory. Studies carried out in reproductive and developmental biology on both animal and human subjects have substantiated the belief that hormones influence mating behavior, developmental events including sexual differentiation, and female and male sexuality.

Castration experiments have linked the testes with a male mating behavior pattern in animals. The sexually active adult male aggressively seeks and attempts to mount the female whether she is receptive or not. The castrated male retains the ability to mount a female but loses the aggressiveness and persistence of the normal male’s pursuit. The castrated animal may assume more submissive female behavior and even engage in homosexual encounters. Normally, the release of reproductive hormones in the male is noncyclic, whereas in the female it is cyclic. Castrated animals begin to exhibit the female, cyclic pattern of hormone release. The hormonal influence is confirmed by administering androgens (male hormones) to the castrated animals. Male mating behavior and the noncyclic release of hormones returns.

The presence of male hormones has an effect on the female cycle and sexual receptivity. Pheromones are substances secreted on the body of one individual that influence the behavior of another. These chemical messengers function during mate attraction, territoriality, and episodes of fear. Their existence and functions are well documented throughout the animal kingdom, especially among insects and mammals. In experiments using rats, it was shown that the pheromones act in conjunction with male hormones in bringing the female rat to a state of receptivity. The urine of noncastrated males contains androgens. When a male is introduced into a cage of sexually inactive females, the male sends off chemical signals by way of pheromones and the androgen-containing urine. The result is the accelerated onset of estrus, or sexual receptivity, on the part of the females. Castrated males produce pheromones but do not have androgens in their urine. When castrated males are introduced into a cage of inactive females, the estrous cycle is not affected.

Female mammals, with the exception of monkeys, apes, and humans, also experience estrus. Under hormonal control, the female is receptive to the male once or twice a year, when her eggs are available for fertilization. This period of receptivity is known as the estrous phase, or heat. Research shows that the particular female hormone that induces estrus is progesterone.

Hormonal Influences

The work done by researchers in developing contraceptives clarified the role of hormones in the functioning of the human female reproductive system. The system operates in a monthly cycle, during which ovarian and uterine changes occur under hormonal control. These hormones do not affect the woman’s receptivity, which is not limited to fertile periods. Progesterone has effects on the nervous system and may be responsible for changes in mood or behavior.

Testosterone derivatives known as anabolic steroids are illegally used by some athletes in an attempt to increase muscularity, strength, and performance. Although both sexes do experience the desired effects, long-term, high-dosage usage has undesirable consequences. This is particularly true in women, who begin to exhibit a deepening of the voice, a male body shape, and increased body and facial hair. Both men and women can become sterile. Psychotic behaviors and states such as depression and anger have been recorded.

Developmental biologists indicate that hormones exert their influence as early as six or seven weeks into embryonic development. At this point, undifferentiated tissue with the potential of developing into either a female or a male reproductive system will develop into a male system in the presence of testosterone and into a female system in its absence. There is some evidence that the embryonic hormones have an effect on the developing brain, producing either a male or female brain. Functionally, this may account for the cyclic activity of female reproductive hormones and the noncyclic activity of male hormones. A few anatomical differences between male and female brains have been observed in both rats and humans. In the hypothalamus of the brain, there are cell bodies called nuclei. In rats and in humans, these nuclei are larger in males than in females.

Learning and memory can be experimentally affected by hormones. Experiments reveal that chemicals that resemble adrenocorticotropic hormone (ACTH) can extend the memory time of rats. Rats, stimulated by electric shock and provided with an avoidance possibility such as moving into another chamber of a cage or climbing a pole in the center of the cage, were administered ACTH-like molecules. The treated rats were able to remember the appropriate reaction to the stimulus for a longer period of time. In other experiments, rats in a maze were administered vasopressin, a posterior pituitary hormone, which increased their frequency in selecting the correct pathway through the maze.

The effect of vasopressin on human memory is not as clearly defined. There have been positive results with schizophrenic patients and patients with alcohol-induced amnesia. In these cases, memory has been enhanced to a limited degree. There is no evidence that learning and memory in humans will be greatly improved by the administration of vasopressin.

Hormones can also effect changes in eating and sleeping behavior. As the prevalence of obesity continues to grow, the physiological psychologist will be challenged to address integrated approaches. Sleeping disorders are also increasing in prevalence and can affect mood, behavior, and quality of life. As more traditional approaches to illness fail to achieve optimal health, understanding neuroendocrinology will become an important foundation to build effective interventions.

Bibliography

Brennan, James F. History and Systems of Psychology. 6th ed. Upper Saddle River, N.J.: Prentice Hall, 2003. Print.

Carlson, Neil R. Physiology of Behavior. 11th ed. Upper Saddle River: Pearson Education, 2013. Print.

Drickamer, Lee C., Stephen H. Vessey, and Elizabeth Jakob. Animal Behavior. 5th ed. New York: McGraw-Hill, 2002. Print.

Goodman, H. Maurice. Basic Medical Endocrinology. 3d ed. San Diego, Calif.: American Elsevier, 2004. Print.

Kostyo, Jack L., and H. Maurice Goodman. “The Endocrine System.” In Handbook of Physiology. New York: Oxford University Press, 1999. Print.

Lovallo, William R. "Do Low Levels of Stress Reactivity Signal Poor States of Health?" Biological Psychology 86.2 (2011): 121–28. Print.

Norris, David O. Vertebrate Endocrinology. 4th ed. Boston: Elsevier Academic Press, 2007. Print.

Pinel, John P. J. Biopsychology. 7th ed. Boston: Allyn & Bacon, 2008. Print.

Wadhwa, Pathik D. "The Contribution of Maternal Stress to Preterm Birth: Issues and Considerations." Clinics in Perinatology 38.3 (2011): 351–84. Print.

Who is Virginia Satir? |

Life

Virginia (Pagenkopf) Satir was the oldest of five children born to Alfred and Minnie Pagenkopf. She developed a keen interest in reading at a very young age. By the age of five, she had decided that she would eventually pursue a career that would involve helping families face and solve problems.

During her teenage years, Satir’s family moved to Milwaukee, Wisconsin, so that she could attend high school. In 1936, she earned a BA in education from Milwaukee State Teachers College (now a part of the University of Wisconsin). In 1948, Satir received an MA in social work from the University of Chicago. After her first marriage ended in divorce, she married Norman Satir in 1951. They divorced in 1957.

During much of the 1950s, Satir worked with families at the Dallas Child Guidance Center and at the Illinois State Psychiatric Institute. In 1959, Satir, Don Jackson, Jules Ruskin, and Gregory Bateson started the Mental Research Institute (MRI) in Palo Alto, California, and created the first formal program in family therapy in the United States. Recognized for her insights into human communication and her understanding of interpersonal relationships and development of self-esteem, Satir became known as the Columbus of family therapy and the mother of family system therapy. She strongly believed that if families could be healed and united, then the problems of the world would be solved, and world peace would eventually be established.

In her efforts to teach people how to cope with their problems, Satir presented hundreds of workshops and training seminars throughout the world. Her change-process model focused on personal growth, health, and the worth of each individual. She authored or coauthored twelve books, including Conjoint Family Therapy (1964), Peoplemaking (1972), and The New Peoplemaking (1988), all three of which achieved international success.

In 1976, Satir was awarded the Gold Medal for “outstanding and consistent service to mankind” by the University of Chicago. The following year, she organized the Avanta Network to implement the Satir model to help people develop coping skills that would change their lives and help them handle problems in their relationships. In 1982, the West German government recognized Satir as one of the twelve most influential leaders in the world at that time. When Satir died in 1988, she had become internationally acclaimed as a therapist, educator, and author.

Bibliography

"About Virginia Satir." Virginia Satir Global Network. Satir Global, n.d. Web. 12 June 2014.

Andreas, Steven. Virginia Satir: The Patterns of Her Magic. Palo Alto.: Science and Behavior, 1991. Print.

Friedlander, Myrna L. Therapeutic Alliances in Couple and Family Therapy: An Empirically Informed Guide to Practice. Washington, DC: Amer. Psychological Assn., 2006. Print.

Jones-Smith, Elsie. Theories of Counseling and Psychotherapy: An Integrative Approach. London: Sage, 2012. Print.

Rambo, Anne Hearon. Family Therapy Review: Contrasting Contemporary Models. New York: Routledge, 2013. Print.

Wilcoxon, S. Allen. Ethical, Legal, and Professional Issues in the Practice of Marriage and Family Therapy. Upper Saddle River: Pearson, 2007. Print.

What are computed tomography (CT) scans? How can they help detect cancer?

Cancers diagnosed: Most

Why performed: CT is a valuable tool for screening for cancer, locating tumors, performing guided biopsy, identifying cancer that has spread, staging cancer, planning and monitoring cancer treatment, and checking for cancer recurrence. CT can identify blood vessels that support a tumor, as well as the tumor’s shape, size, location, and volume. CT scans are used with procedures to diagnose cancer, such as needle-guided biopsies. They are used in cancer treatments, such as radiofrequency ablation and interstitial therapy.

CT images are archived in computers or printed form. Images are printed on film or with laser imaging. They can be sent and viewed online within a facility and can be compared for changes over time.

Conventional CT was developed in the early 1970s. CT uses controlled amounts of thin, high-energy radiation beams. Images are taken from a variety of angles. A computer calculates information about the images and produces a slice image of a specific area of the body. CT can be taken of the entire body or a specific section. Dye is used to enhance images to show more detail and contrast. The contrast dye can be swallowed, received intravenously, or administered in an enema.

CT has evolved to become faster and to use lower doses of radiation. Spiral or helical CT allows images to be collected quickly. The rapid process helps compensate for movements or breathing that otherwise can blur images. Additionally, spiral CT produces thinner slices of images that show even greater detail. A computer stacks the images to create three-dimensional, rotational pictures of a tumor. Spiral CT is especially useful for imaging liver, lung, and pancreatic cancer.

Recent technology allows doctors to use CT with endoscopy to create virtual endoscopy, virtual bronchoscopy, and virtual colonoscopy or CT colonography. The process uses a computer to create and manipulate three-dimensional images to create a “fly-through” view of an organ, as seen on endoscopy.

CT is used to guide surgeons precisely during procedures. CT is used with needle aspiration
biopsy for tumors, such as for breast cancer biopsies. The CT guidance eliminates the need for invasive exploratory surgery.

CT is used to guide certain radiation treatments. For example, interstitial therapy uses CT guidance to insert radioactive material into a tumor. CT is also used to create a three-dimensional image of a tumor to allow external beam radiation to precisely target the tissue and spare as much healthy tissue as possible.

Patient preparation: CT scans may not be appropriate for some people. Patients should let their doctor know if they have diabetes or kidney disease or if they are pregnant. Some facilities conduct a pregnancy test on all women prior to scanning because the radiation can be dangerous to a developing fetus. Children, patients with movement disorders, or patients that are claustrophobic may receive a mild sedative prior to the test. In extreme situations, people may be sedated if they are not able to remain still while the images are taken. Some CT machines may not be used for people that weigh more than three hundred pounds because of size parameters of the machinery. A small percentage of patients are allergic to contrast dye. Patients should let their doctor know if they are allergic or sensitive to contrast dye, iodine, or shellfish.

CT scans are outpatient procedures performed at a hospital radiology department or freestanding radiology center. Patients will receive instructions prior to their procedure, which vary depending on which procedure is conducted. Patients may be instructed not to eat or drink for several hours before the CT. Some patients need to use an enema or laxatives. Patients may need to drink a liquid contrast agent before arriving at the clinic or upon arriving at the clinic.

Patients wear an examination gown or robe for the procedure. They must remove metal objects that can interfere with the imaging process, such as jewelry, hearing aids, hair clips, glasses, or dentures.

Steps of the procedure: Patients are led into the imaging room. A radiology technologist conducts the CT. Patients lie on a narrow table. The technologist may use positioning devices to help patients maintain specific postures for the test. Head-stabilizing devices may be used for brain scans. Patients may be instructed to change positions throughout the procedure.

During the CT scan, the radiologist technician steps into a room that is separated by a glass partition. The radiologist is in constant contact with the patient via a microphone and intercom system. The radiologist technician operates the CT machine.

To take a CT, the table slides into the doughnut-shaped hole of the scanner. Patients must remain motionless while the images are taken. Patients are instructed to take a deep breath and hold it until they are told to exhale. The CT scanner has an X-ray component that emits beams at specific angles. The beams pass through the body and are detected by equipment on the opposite side. The equipment makes buzzing or clicking noises while the scanner is employed.

Patients receiving a contrast material may have a CT scan first, receive the contrast material, and then receive a final CT scan. An intravenous (IV) line is inserted into the hand or forearm to deliver injected contrast material. Contrast material may be swallowed. An enema is also used to insert contrast material for gastrointestinal-related CT scans. The contrast material may make patients feel temporarily warm or flushed.

The actual CT scan is short, but the preparation and positioning time makes the procedure last from about ten to thirty minutes. Spiral CTs are shorter in length. Patients are asked to wait until it is confirmed that the images are clear. Patients are observed for allergic reactions for a short time following the procedure.

After the procedure: There are usually no aftercare procedures following CT. If the patient has received sedating medication, a friend or relative must drive the patient home.

Risks: Patients may experience an allergic reaction to the contrast dye. The symptoms include hives, shortness of breath, nausea, wheezing, itching, or a bitter taste in the mouth. Severe allergic reaction or anaphylactic shock is a rare risk. Radiation from CT is higher than that of standard X rays. CT is not recommended for pregnant women.

Results: CT images are read by a radiologist and conveyed to the ordering doctor. The doctor may view the images as well. CT images depict anatomical structures in black, white, and shades of gray. Air, soft tissue, hard tissue, fluids, and the contrast agent show details that otherwise cannot be seen. Abnormal results show different characteristics from what is expected, such as tumors, cysts, cancer metastasis, tumor density, tumor composition, enlarged lymph nodes, or atypical fluid accumulations. In some cases, CT can help differentiate between types of tumors.

Applegate, Kimberly. “Pregnancy Screening of Adolescents and Women Before Radiologic Testing: Does Radiology Need a National Guideline?” Journal of American College of Radiology 4.8 (2007): 533–36. Print.

"Computed Tomography (CT) Scans and Cancer." National Cancer Institute. Natl. Cancer Inst., 16 July 2013. Web. 10 Sept. 2014.

Ishikawa, Susumu., et al. “Mass Screening of Multiple Abdominal Solid Organs Using Mobile Helical Computed Tomography Scanner: A Preliminary Report.” Asian Journal of Surgery 30.2 (2007): 118–21. Print.

Pearce, Mark S., et al. "Radiation Exposure from CT Scans in Childhood and Subsequent Risk of Leukaemia and Brain Tumours: A Retrospective Cohort Study." Lancet 4 Aug. 2012: 499–505. Print.

Sone, Shusuke., et al. “Long-Term Follow-up Study of a Population-Based 1996–1998 Mass Screening Programme for Lung Cancer Using Mobile Low-Dose Spiral Computed Tomography.” Lung Cancer 58.3 (2007): 329–41. Print.

Storrs, Carina. "How Much Do CT Scans Increase the Risk of Cancer?" Scientific American. Scientific American. 18 June 2013. Web. 10 Sept. 2014.

How do Kate Chopin’s “The Story of an Hour” and “Desiree’s Baby” show women in search of their identity?

Both short stories by Kate Chopin center around women who have an experience that changes how they perceive their own identity. Interestingly, as the stories open, neither woman has been particularly concerned with her identity. Desiree, who was a foundling and adopted by the Valmondes, marries Armand and seems perfectly content with her new role as a mother. She is fascinated by her baby as most new mothers are, even commenting on his little fingernails....

Both short stories by Kate Chopin center around women who have an experience that changes how they perceive their own identity. Interestingly, as the stories open, neither woman has been particularly concerned with her identity. Desiree, who was a foundling and adopted by the Valmondes, marries Armand and seems perfectly content with her new role as a mother. She is fascinated by her baby as most new mothers are, even commenting on his little fingernails. She is pleased that since the birth of the baby, Armand has been kinder to the slaves. Everything seems to be going splendidly. Likewise, before Mrs. Mallard gets the news of her husband's death, she did not rebel against her life as a wife. Both she and her husband controlled each other to some degree just by virtue of being married to one another. Both Desiree and Mrs. Mallard are content in the roles and identities their societies and their situations have put them in.

As each story progresses, each woman must come to terms with a different, unfamiliar identity that is thrust upon her. Desiree notices odd changes going on at the plantation and with Armand's mood, but she does not at first think they have anything to do with her. When she recognizes the African features of her baby for the first time and asks her husband what it means, he forces a new identity on her, namely that she is of mixed race. She denies this new identity vehemently. When she appeals to her mother and her mother invites her to move back home, she asks her husband if that is what he wants her to do. Upon hearing his affirmative answer, she must decide whether she can live the rest of her life as a person of mixed race in the antebellum South or whether she can remain living in the home where her husband has made it clear she is not wanted. She rejects both those identities and walks into the swamp with her baby. Although her reasons for doing so are not stated, one can assume that she is sure in her identity as a white person and refuses to capitulate to the false identity she is being required to assume to protect what she now realizes is her husband's false identity. 

Mrs. Mallard's experience is quite different. When she learns of her husband's death, she takes time to ponder what that means for her identity. She realizes that as a widow, she will have a level of unfettered freedom she has never even considered a possibility. Her heart soars at the prospect. She is excited for all the open years spreading before her when she will be able to live life based on her own desires rather than the desires of her husband. She has accepted and embraced her new identity so fully and so completely that when she finds out her husband is still alive, she dies from the shock. 

While Desiree chooses death rather than live with a false identity that is forced upon her, Mrs. Mallard dies of shock when the new identity she has recently acquired is suddenly withdrawn from her.

What is cancer prevention? |

Cancer in the United States: The National Cancer Institute issued a report in 2005 describing various statistical aspects of cancer in the United States. Overall death rates for the most common cancers, such as breast, lung, colorectal, and prostate, had declined. Survival rates for cancer patients were rising. The incidence of cancer had been stable since the 1990’s. However, the prevalence of cancers such as melanoma of the skin and childhood cancers was increasing. Cancer remained the second leading cause of death in the United States. In 2003 more than half a million Americans had lost their lives to cancer.

Lowering the number of cases of cancer is a multifaceted process of avoiding exposures to known carcinogens, modifying lifestyle habits, and taking active steps to enhance the body’s immune system. Although behaviors that help people avoid developing cancer, such as not smoking and lessening consumption of fat and alcohol, are on the rise in the United States, more needs to be done. Prevention generally falls into the categories of lifestyle, chemoprevention (use of vitamins and medicines), preventive surgery, screening, and environment. Prevention of cancer is an active process in which all Americans need to involve themselves to reduce their lifetime chance of cancer.

Research suggests that as much as two-thirds of all cancer can be prevented with lifestyle changes in daily living. Every day, each person makes choices that could increase or reduce that person’s likelihood of developing cancer. No knowledge or program can prevent cancer on its own: People must make responsible choices and integrate them into their lifestyle.

Nutrition: Nutrition is a key part of cancer prevention. Much has been researched and written about the importance of nutrition. Although the relationship between diet and cancer is complex, numerous studies show that nutrition can make a difference in preventing cancer. The American Cancer Society promotes eating five to seven or more servings of fruits and vegetables each day as the single most important step people can take to prevent cancer. People can achieve this goal by eating vegetables and fruits at each meal and for snacks. Strawberries, raspberries, blueberries, and blackberries have cancer-fighting chemicals, as do citrus fruits such as oranges and grapefruit. Certain phytonutrients in vegetables, such as the indoles found in broccoli and cabbage, can help protect against cancer, especially hormone-related cancers. Generally the more color the vegetable has, the healthier and more protective it is. The likelihood of developing colon cancer and other gastrointestinal cancers may be decreased by eating dark green and yellow vegetables. Fruits and vegetables in their whole or natural form (fresh, frozen, dried, or canned) are more protective than supplements with dried extracts.

The nutritional aspect of prevention includes other foods besides fruits and vegetables. The use of whole-grain breads and cereals adds fiber to the diet. High-fiber diets increase motility of food through the colon and are thought to protect against colon cancer. Eating less meat may be accomplished by choosing beans as a protein source; meat consumption has been associated with colon and prostate cancer. Other foods, such as garlic, onions, soybeans, and ginger, are thought to protect against cancer by some experts. Herbal teas such as red clover or green tea have demonstrated promise in studies on cancer prevention.

How food is cooked can affect the nutrients or introduce carcinogens into the body. For example, meat protein cooked at high temperatures produces toxic substances. Studies have linked colorectal adenomas to red meat cooked at high temperatures. Processed meats and bacon contain carcinogens. Boiling vegetables can release nutrients into the water, so steaming is preferred to preserve the vitamins.

Studies have looked at the possibility of food preservatives and additives being carcinogenic, but the studies have not been conclusive. Foods are treated with chemicals to improve taste, increase shelf life, and allow them to be transported long distances in trucks. More than three thousand preservatives and additives are used in the U.S. food supply system. Some experts say that formaldehyde, a suspected carcinogen, is either contained in or released by some food preservatives and constitutes a hazard to humans; however, this has not been proven. Some people have chosen to minimize their exposure to additives and preservatives by eating more food in the raw state and purchasing organic foods and milk.

Exercise: Physical activity and exercise can help protect against developing certain cancers of the breast, colon, and prostate. The most recent guidelines by the Centers for Disease Control and Prevention (CDC) recommend that adults exercise moderately (for example, walking at a brisk pace) for a minimum of thirty minutes per day, five days per week, or exercise vigorously (for example, racewalking, jogging, or running) for a minimum of twenty minutes per day, three days per week. This recommendation complements the need to decrease the epidemic of obesity in the United States, as obesity is associated with increased risk of developing cancers of the colon and rectum, breast, prostate, kidney, and uterus (endometrium).

Alcohol: Alcohol use is associated with increased risk of mouth, esophagus (throat), larynx (voice box), and liver cancer. The amount of alcohol consumed affects the risk of cancer. Men are advised to have no more than two drinks per day and women no more than one drink per day. (One drink is 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor.) Women who drink are at increased risk for breast cancer. When smoking is combined with excessive alcohol consumption, the risk is compounded. Excessive alcohol consumption can result in liver damage that affects the body’s ability to excrete toxins and can effect cancer treatment. Wine is associated with an increased risk of upper digestive tract cancers in heavy users; however, some studies have shown that moderate consumption of red wine, which contains phytochemicals, may convey some cancer-fighting benefits.

Tobacco: Smoking and use of tobacco products is a choice made by many Americans. Smoking produces known carcinogens that can result in lung cancer as well as cancer of the upper respiratory tract (throat, mouth, and windpipe). Secondhand smoke (smoke in the environment that is inhaled by nonsmokers) can affect people’s health, so many states and cities have banned smoking in restaurants or require them to have nonsmoking sections. Many states and cities also ban smoking in workplaces, bars, public buildings, and public gathering places. Though smoking overall is declining and death rates from lung cancer in men are declining, death rates from lung cancer in women have continued to rise.

Other methods of cancer prevention:
Chemoprevention is a term that describes the use of natural or synthetic substances to avert cancer. Methods include the use of cancer-fighting nutrients (such as phytoestrogens) in food, herbs, and supplements that are believed to help prevent cancer. Medications such as tamoxifen or raloxifene to reduce the incidence of breast cancer, and vaccines such as the human papillomavirus (HPV) vaccine can prevent cervical cancer.

Preventive (prophylactic) surgery is useful in some cases for patients at high risk for cancer. Preventive procedures include removal of the breast (mastectomy), ovaries, and Fallopian tubes.

Cancer screening, a key part of cancer prevention, is covered by many insurance companies, including Medicare. Coverage may include mammograms for breast cancer, colorectal cancer diagnostic tests such as a colonoscopy, prostate-specific antigen (PSA) tests for prostate cancer, and Pap smears for cervical cancer. Early detection and treatment is one reason that cancer survival rates are rising.

Protective clothing and gear can help reduce the cancer risk from environmental hazards. Examples of cancer-causing substances that can be introduced into the workplace include silica from cement, wood dust, lacquers, wood finishes, paints, glues, solvents, asphalt, and pesticides. Wearing an appropriate mask and using proper ventilation can help decrease exposure to these toxins. Using the provided safeguards when taking (or giving) X rays in a hospital or at a dental office can decrease exposure to harmful radiation that can cause cancer. Those working outdoors and exposed to the sun’s ultraviolet (UV) rays can minimize their risk of skin cancer by staying out of the sun in midday, using sunscreen, and wearing protective clothing and hats.

Cancer prevention requires vigilance on the part of each individual as well as businesses and the government. However, prevention is the best way to “treat” cancer and can save many lives.

American Institute for Cancer Research. Stopping Cancer Before It Starts: The American Institute for Cancer Research’s Program for Cancer Prevention. New York: St. Martin’s Griffin, 2000.

Conley, Edward J. The Breast Cancer Prevention Plan. New York: McGraw-Hill, 2006.

National Cancer Institute. Cancer Trends Progress Report 2005. Bethesda, Md.: Author, 2005.

Verona, Verne. Nature’s Cancer Fighting Foods. New York: Prentice Hall, 2001.

What are cadmium and cadmium compounds?

Related cancers:

Lung cancer, possibly prostate and kidney cancer

Exposure routes: Inhalation and ingestion

Where found: Food (particularly grain cereal products, potatoes, and other vegetables), cigarette smoke, zinc and lead ores, electroplating and -coating, alloys, pigments (paint, glass, ceramics, porcelain, textiles, plastics, paper, and fireworks), stabilizers in plastics, nickel-cadmium batteries, smoke detectors, radiation detectors, and various electronics and laboratory equipment

At risk: Workers who refine and smelt zinc and lead ores, workers in industries using thermal processes (iron production or welding cadmium-coated steel), and tobacco smokers

Etiology and symptoms of associated cancers: Cadmium exposure can be acute or chronic. Acute toxicity through ingestion of cadmium may cause only short-term illness, but acute toxicity through inhalation can lead to severe damage to the lungs and even death. Chronic exposure to cadmium can cause damage to the lungs, kidneys, and sometimes bones. Studies have shown that inhalation of cadmium in the workplace is associated with lung cancer. Laboratory studies using cultured cells have shown that cadmium damages the deoxyribonucleic acid (DNA) of the cells and affects the cells’ ability to repair DNA damage. These factors are likely to be the mechanism through which cadmium contributes to the formation of cancer in humans.

Lung cancer can affect one lung or both. Lung cancer detection often occurs when the disease has progressed to late stages because symptoms may take years to appear. When symptoms do appear, they often are mistaken for other less serious conditions. Common signs and symptoms of lung cancer are persistent cough (not related to smoking); persistent pain in the chest, shoulder, or back; coughing up mucus or blood; recurrent respiratory infections; shortness of breath; fatigue; unexplained weight loss; and loss of appetite. Many of these symptoms may be attributed initially to other causes before lung cancer is eventually diagnosed. According to the National Toxicology Program's
Report on Carcinogens
, Twelfth Edition (2011), lung cancer is the only cancer that has been confirmed to be associated with cadmium exposure.

Studies from the 1960s and later have had conflicting results regarding a connection between cadmium and prostate cancer. A number of studies have shown increases in the occurrence of prostate cancer in workers exposed to cadmium in nickel-cadmium battery plants and other industrial sites, but conflicting studies have indicated either no increases or increases that were too small to be statistically significant. Cadmium has also been implicated in kidney cancer, with early studies showing a correlation between exposure and increases in kidney cancer. However, further studies have not confirmed this association.

History: Industrial use of cadmium became widespread in the middle of the twentieth century, and the toxic effects due to occupational exposure began to be recognized by the early 1950s. Studies that examined workers who had been exposed to high levels of cadmium were used to examine the toxic effects, and by the 1960s researchers were investigating cadmium’s potential carcinogenicity. Experimental animal studies also were conducted to research the toxicity and carcinogenicity of cadmium. Regarding the role cadmium played in the development of lung cancer, initial studies were inconclusive or conflicting. Confounding factors, such as workers who were also tobacco smokers or were exposed to additional heavy metals, contributed to the confusing results. Because of its toxic effects, many federal, state, and local agencies, including the Environmental Protection Agency (EPA), began to regulate cadmium in a variety of ways, including stipulation of allowable amounts in air and water. In 1992 the Occupational Safety and Health Administration (OSHA) ruled on permissible exposure limits (PELs) for workers exposed to airborne cadmium in the workplace. By 2000 sufficient studies reported that cadmium contributed to the development of lung cancer for it to be designated as a known human carcinogen by the US Department of Health and Human Services.

Bibliography

Adams, Scott V., Michael N. Passarelli, and Polly A. Newcomb. "Cadmium Exposure and Cancer Mortality in the Third National Health and Nutrition Examination Survey." Occupational and Environmental Medicine 69.2 (2012): 153–156. Digital file.

Amer. Cancer Soc. "Known and Probable Human Carcinogens." Cancer.org. ACS, 17 Oct. 2013. Web. 24 Sept. 2014.

Klaassen, Curtis D., ed. Casarett and Doull’s Toxicology: The Basic Science of Poisons. 8th ed. New York: McGraw, 2013. Print.

Silvera, S. A. N., and T. E. Rohan. “Trace Elements and Cancer Risk: A Review of the Epidemiologic Evidence.” Cancer Causes Control 18 (2007): 7–27. Print.

US Dept. of Health and Human Services, Public Health Service, Natl. Toxicology Program. Report on Carcinogens. 11th ed. Research Triangle Park: USDHHS, PHS, NTP, 2005. Print.

US Dept. of Health and Human Services, Public Health Service, Natl. Toxicology Program. "Cadmium and Cadmium Compounds." Report on Carcinogens. 12th ed. N.p.: USDHHS, PHS, NTP, 2011. 80–83. Digital file.

Waisberg, M., P. Joseph, B. Hale, and D. Beyersmann. “Molecular and Cellular Mechanisms of Cadmium Carcinogenesis.” Toxicology 192 (2003): 95–117. Print.