Common Terms A-C

Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat.

In histology, adipose tissue or body fat or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and insulates the body. Obesity or being overweight in humans and most animals does not depend on body weight but on the amount of body fat—to be specific, adipose tissue. Two types of adipose tissue exist: white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose tissue also serves as an important endocrine organ by producing hormones such as leptin, resistin, and the cytokine TNFα. The formation of adipose tissue appears to be controlled by the adipose gene. Adipose tissue was first identified by the Swiss naturalist Conrad Gessner in 1551.

Aerobics is a form of physical exercise that combines rhythmic aerobic exercise with stretching and strength training routines with the goal of improving all elements of fitness (flexibility, muscular strength, and cardio-vascular fitness). It is usually performed to music and may be practiced in a group setting led by an instructor, although it can be done solo and without musical accompaniment. With the goal of preventing illness and promoting physical fitness, practitioners perform various routines comprising a number of different dance-like exercises. Formal aerobics classes are divided into different levels of intensity and complexity. Aerobics classes may allow participants to select their level of participation according to their fitness level. Many gyms offer a wide variety of aerobic classes for participants to take. Each class is designed for a certain level of experience and taught by a certified instructor with a specialty area related to their particular class.

Amino acids are molecules containing an amine group, a carboxylic acid group and a side chain that varies between different amino acids. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent. In an alpha amino acid, the amino and carboxylate groups are attached to the same carbon atom, which is called the α–carbon. The various alpha amino acids differ in which side chain (R group) is attached to their alpha carbon. These side chains can vary in size from just a hydrogen atom in glycine, to a methyl group in alanine, through to a large heterocyclic group in tryptophan.

Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass. Muscles trained using anaerobic exercise develop differently compared to aerobic exercise, leading to greater performance in short duration, high intensity activities, which last from mere seconds up to about 2 minutes. Any activity after about two minutes will have a large aerobic metabolic component.

Anorexia nervosa is an eating disorder characterized by extremely low body weight, distorted body image and an obsessive fear of gaining weight.

The term anorexia nervosa was established in 1873 by Sir William Gull, one of Queen Victoria's personal physicians. The term is of Greek origin: a (α, prefix of negation), n (ν, link between two vowels) and orexis (ορεξις, appetite), thus meaning a lack of desire to eat.

An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols, ascorbic acid or polyphenols.

Although oxidation reactions are crucial for life, they can also be damaging; hence, plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, and vitamin E as well as enzymes such as catalase, superoxide dismutase and various peroxidases. Low levels of antioxidants, or inhibition of the antioxidant enzymes, cause oxidative stress and may damage or kill cells.

As oxidative stress might be an important part of many human diseases, the use of antioxidants in pharmacology is intensively studied, particularly as treatments for stroke and neurodegenerative diseases. However, it is unknown whether oxidative stress is the cause or the consequence of disease.

Antioxidants are widely used as ingredients in dietary supplements in the hope of maintaining health and preventing diseases such as cancer and coronary heart disease. Although initial studies suggested that antioxidant supplements might promote health, later large clinical trials did not detect any benefit and suggested instead that excess supplementation may be harmful. In addition to these uses of natural antioxidants in medicine, these compounds have many industrial uses, such as preservatives in food and cosmetics and preventing the degradation of rubber and gasoline.

Asan  is a body position, typically associated with the practice of Yoga, intended primarily to restore and maintain a practitioner's well-being, improve the body's flexibility and vitality, and promote the ability to remain in seated meditation for extended periods. These are widely known as Yoga postures or Yoga positions, which is currently practiced for exercise and as alternate medicine.

Ascorbic acid is a sugar acid with antioxidant properties. Its appearance is white to light-yellow crystals or powder, and it is water-soluble. One form of ascorbic acid is commonly known as vitamin C. The name is derived from a- (meaning "no") and scorbutus (scurvy), the disease caused by a deficiency of vitamin C. In 1937 the Nobel Prize for chemistry was awarded to Walter Haworth for his work in determining the structure of ascorbic acid (shared with Paul Karrer, who received his award for work on vitamins), and the prize for Physiology or Medicine that year went to Albert Szent-Györgyi for his studies of the biological functions of L-ascorbic acid. At the time of its discovery in the 1920s, it was called hexuronic acid by some researchers.

Asthma is a predisposition to chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed. Asthma affects 7% of the population of the United States, 6.5% of British people and a total of 300 million worldwide. During asthma attacks (exacerbations of asthma), the smooth muscle cells in the bronchi constrict, the airways become inflamed and swollen, and breathing becomes difficult. This is often referred to as a tight chest and is a sign to immediately take medication.

Ballistic stretching is a form of passive stretching or dynamic stretching in a bouncing motion. Ballistic stretches force the limb into an extended range of motion when the muscle has not relaxed enough to enter it. It involves fast "bouncing" movements where a double bounce is performed at the end range of movement. Ballistic stretching should only be used by athletes who know their own limitations and with supervision by their trainer.

Ballistic stretching has been found to be hazardous towards the body. It can injure vital muscles and nerves with the sharp jerking movements. It is even possible for tissue to be ripped off the bone.

A barbell is a piece of exercise equipment used in weight training, weightlifting and powerlifting. It consists of a stonehenge a metal bar, one or more sets of weight plates, and a set of collars. Barbells range in length from 4 feet (1.2 m) to 7 feet (2.1 m). The central portion varies in diameter, but is close to one inch (2.54 cm), and is often engraved with a knurled crosshatch pattern to help lifters get a good grip. Disc weights (plates) are slid onto the outer portions of the bar to obtain the desired total weight. These weights are often secured with collars to prevent them from sliding off during the exercise (which can result in injuries) or flinging the unevenly-loaded barbell through the air.

Bariatrics is the branch of medicine that deals with the causes, prevention, and treatment of obesity. The term bariatrics was created around 1965, from the Greek root bar- ("weight," as in barometer), suffix -iatr ("treatment," as in pediatrics), and suffix -ic ("pertaining to"). The field encompasses dieting, exercise and behavioral therapy approaches to weight loss, as well as pharmacotherapy and surgery.

Basal metabolic rate (BMR), and the closely related resting metabolic rate (RMR), is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans). The release of energy in this state is sufficient only for the functioning of the vital organs, such as the heart, lungs, brain and the rest of the nervous system, liver, kidneys, sex organs, muscles and skin. BMR decreases with age and with the loss of lean body mass. Increasing muscle mass increases BMR. Aerobic fitness level, a product of cardiovascular exercise, while previously thought to have effect on BMR, has been shown in the 1990s not to correlate with BMR, when fat-free body mass was adjusted for. New research[citation needed] has however come to light which suggests aerobic exercise does increase resting energy consumption (see "Aerobic vs. anaerobic exercise"). Illness, previously consumed food and beverages, environmental temperature, and stress levels can affect one's overall energy expenditure as well as one's BMR.

Behaviour therapy, or behavior therapy, can be studied scientifically by observing overt behaviour, without discussing internal mental states. Without holding inner states as causal, Skinner's radical behaviourism accepted internal states as part of a causal chain of behaviour, but continued to hold that the only way to improve the internal state was through environmental manipulation.

Behaviorism (or behaviourism), also called the learning perspective (where any physical action is a behavior), is a philosophy of psychology based on the proposition that all things which organisms do — including acting, thinking and feeling — can and should be regarded as behaviors. The school of psychology maintains that behaviors as such can be described scientifically without recourse either to internal physiological events or to hypothetical constructs such as the mind. Behaviorism comprises the position that all theories should have observational correlates but that there are no philosophical differences between publicly observable processes (such as actions) and privately observable processes (such as thinking and feeling).

From early psychology in the 19th century, the behaviorist school of thought ran concurrently and shared commonalities with the psychoanalytic and Gestalt movements in psychology into the 20th century; but also differed from the mental philosophy of the Gestalt psychologists in critical ways.[citation needed] Its main influences were Ivan Pavlov, who investigated classical conditioning, Edward Lee Thorndike, John B. Watson who rejected introspective methods and sought to restrict psychology to experimental methods, and B.F. Skinner who conducted research on operant conditioning.

In the second half of the twentieth century, behaviorism was largely eclipsed as a result of the cognitive revolution. Though these two schools of psychological thought may not agree theoretically, they have complemented each other in practical therapeutic applications. One notable legacy of behaviorist investigations is Cognitive-Behavioral Therapy, a popular treatment that uses cognitive models alongside behaviorist techniques such as 'systematic desensitization' and 'contingency management' that have demonstrable utility in helping people with certain pathologies, such as simple phobias, PTSD, and addiction.

Binge eating is a pattern of disordered eating which consists of episodes of uncontrollable eating. It is sometimes as a symptom of binge eating disorder. During such binges, a person rapidly consumes an excessive amount of food. Most people who have eating binges try to hide this behaviour from others, and often feel ashamed about being fat or depressed about their overeating. Eating binges can be followed by so-called compensatory behaviour, acts by which the person tries to compensate for the effects of overeating. Examples of such acts are purging (induced vomiting or laxative abuse), fasting, and heavy exercising.

Although people who do not have any eating disorder may occasionally experience episodes of overeating, frequent binge eating is often a symptom of an eating disorder. Binge eating is a central feature of bulimia nervosa and binge eating disorder. It is also practiced by some people with an eating disorder not otherwise specified or anorexia nervosa.

Bioelectrical impedance analysis (BIA) is a commonly used method for estimating body composition. Since the advent of the first commercially available devices in the mid-1980s the method has become popular owing to its ease of use, portability of the equipment and its relatively low cost compared to some of the other methods of body composition analysis. It is familiar in the consumer market as a simple instrument for estimating body fat. BIA actually determines the electrical impedance, or opposition to the flow of an electric current through body tissues which can then be used to calculate an estimate of total body water (TBW). TBW can be used to estimate fat-free body mass and, by difference with body weight, body fat.

Many of the early research studies showed that BIA was quite variable and it was not regarded by many as providing an accurate measure of body composition. In recent years technological improvements have made BIA a more reliable and therefore more acceptable way of measuring body composition. Nevertheless it is not a "gold standard" or reference method. Like all assessment tools, the result is only as good as the test done. Although the instruments are straightforward to use, careful attention to the method of use (as described by the manufacturer) should be given.

Simple devices to estimate body fat, often using BIA, are available to consumers as body fat meters. These instruments are generally regarded as being less accurate than those used clinically or in nutritional and medical practice. They tend to under-read body fat percentage.

In recent years, more accurate methods of Bioelectrical Impedance Analysis have been developed.

Blood pressure (BP) is a force exerted by circulating blood on the walls of blood vessels, and is one of the principal vital signs. During each heartbeat, BP varies between a maximum (systolic) and a minimum (diastolic) pressure. The mean BP, due to pumping by the heart and resistance in blood vessels, decreases as the circulating blood moves away from the heart through arteries. It has its greatest decrease in the small arteries and arterioles, and continues to decrease as the blood moves through the capillaries and back to the heart through veins. Gravity, valves in veins, and pumping from contraction of skeletal muscles, are some other influences on BP at various places in the body.

The term blood pressure usually refers to the pressure measured at a person's upper arm. It is measured on the inside of an elbow at the brachial artery, which is the upper arm's major blood vessel that carries blood away from the heart. A person's BP is usually expressed in terms of the systolic pressure and diastolic pressure, for example 120/80.

Bulimia nervosa is an eating disorder characterized by recurrent binge eating, followed by compensatory behaviors. The most common form is defensive vomiting, sometimes called purging; fasting, the use of laxatives, enemas, diuretics, and over exercising are also common. The word bulimia derives from the Latin (būlīmia), which originally comes from the Greek βουλιμία (boulīmia; ravenous hunger), a compound of βους (bous), ox + λιμός (līmos), hunger.

Bulimia nervosa was named and first described by the British psychiatrist Gerald Russell in 1979.

Caffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee, which in English became caffeine.

Caffeine is found in varying quantities in the beans, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba mate, guarana berries, and the Yaupon Holly.

In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, enjoy great popularity. Caffeine is the world's most widely consumed psychoactive substance, but, unlike many other psychoactive substances, it is legal and unregulated in nearly all jurisdictions. In North America, 90% of adults consume caffeine daily. The U.S. Food and Drug Administration lists caffeine as a "multiple purpose generally recognized as safe food substance".

Caffeine has diuretic properties, at least when administered in sufficient doses to subjects that do not have a tolerance for it. Regular users, however, develop a strong tolerance to this effect, and studies have generally failed to support the common notion that ordinary consumption of caffeinated beverages contributes significantly to dehydration.

The calorie is a pre-SI metric unit of energy. The unit was first defined by Professor Nicolas Clément in 1824 as a unit of heat. This definition entered French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule. However, in many countries it remains in common use as a unit of food energy. The kilocalorie per mole remains in use in computational chemistry and molecular spectroscopy.

Definitions vary but are all based on the specific heat capacity of water. The gram calorie, approximately 4.2 J, is based on one gram of water. The kilogram calorie, equal to one thousand gram calories, is based on one kilogram of water. In the context of nutrition, and especially food labelling, a larger unit is used and referred to interchangeably by the terms calorie (or Calorie) and kilocalorie. 

Cancer /ˈkænsə(r)/ (medical term: malignant neoplasm) is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, and do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.

Catabolism (Greek kata = downward + ballein = to throw) is the set of metabolic pathways that break down molecules into smaller units and release energy. In catabolism, large molecules such as polysaccharides, lipids, nucleic acids and proteins are broken down into smaller units such as monosaccharides, fatty acids, nucleotides, and amino acids, respectively. As molecules such as polysaccharides, proteins and nucleic, acids are made from long chains of these small monomer units (mono = one + mer = part), the large molecules are called polymers (poly = many).

Cellulite describes a common paraphysiological cosmetic condition that is claimed to occur in most women, where the skin of the lower limbs, abdomen, and pelvic region becomes dimpled. Cellulite is a description rather than a physical object. The term was first used in the 1920s and began appearing in English language publications in the late 1960s, the earliest reference in Vogue magazine, "Like a swift migrating fish the word cellulite has suddenly crossed the Atlantic." Its existence as a real disorder has been questioned, and the prevailing medical opinion is that it is merely the "normal condition of many women and some men". One cosmetic company has noted its historical place in industrialised societies as an "inappropriate term used by women to describe curves which they judge to be too plump and not very aesthetic".

Synonyms include: adiposis edematosa, dermopanniculosis deformans, status protrusus cutis, and gynoid lipodystrophy. Descriptive names for cellulite include orange peel syndrome, and cottage cheese skin.

Chronic (medicine), a persistent and lasting disease or medical condition, or one that has developed slowly.

Circuit training is a combination of high-intensity aerobics and resistance training designed to be easy to follow and target fat loss, muscle building and heart fitness. An exercise "circuit" is one completion of all prescribed exercises in the program. When one circuit is complete, one begins the first exercise again for another circuit. Traditionally, the time between exercises in circuit training is short, often with rapid movement to the next exercise.

The term cognition (Latin: cognoscere, "to know" or "to recognize") refers to a faculty for the processing of information, applying knowledge, and changing preferences. Cognition, or cognitive processes, can be natural or artificial, conscious or unconscious. These processes are analyzed from different perspectives within different contexts, notably in the fields of linguistics, anesthesia, neurology, psychology, philosophy, anthropology, systemics and computer science. Within psychology or philosophy, the concept of cognition is closely related to abstract concepts such as mind, reasoning, perception, intelligence, learning, and many others that describe capabilities of the mind and expected properties of an artificial or synthetic “mind”. Cognition is considered an abstract property of advanced living organisms and is studied as a direct property of a brain (or of an abstract mind) on at the factual and symbolic levels.

In medicine, a contraindication (pronounced as contra-indication) is a condition or factor that increases the risks involved in using a particular drug, carrying out a medical procedure, or engaging in a particular activity.

Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action. For example, a baby with a fever should never be given aspirin because of the risk of Reye's syndrome, and a person with an anaphylactic food allergy should never eat the food to which they are allergic. Similarly, a person with Hemochromatosis should not be administered iron preparations.

Cross-training (also known as conditioning) refers to training in different ways to improve overall performance. It takes advantage of the particular effectiveness of each training method, while at the same time attempting to neglect the shortcomings of that method by combining it with other methods that address its weaknesses.

 [Next Page]