General Health Terms and Definitions

Glossary: A
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the addition of an acetyl group (-COCH3) group to a molecule.
having a pH of less than 7.
having a short and relatively severe course.
assisting in the prevention, amelioration, or cure of a disease.
Adrenal glands
a pair of small glands, located above the kidneys, consisting of an outer cortex and inner medulla. The adrenal cortex secretes cortisone-related hormones and the adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).
adequate intake. A recommended intake value based on observed or experimentally determined approximations or estimates of nutrient intake by a group of healthy people that are assumed to be adequate, The AI is used when the RDA cannot be determined.
acquired immune deficiency syndrome. AIDS is caused by the HIV (Human Immunodeficiency Virus) virus, which attacks the immune system, leaving the infected individual vulnerable to opportunistic infection.
basic; having a pH of more than 7.
One of a set of alternative forms of a gene. Diploid cells possess two homologous chromosomes (one derived from each parent) and therefore two copies of each gene. In a diploid cell, a gene will have two alleles, each occupying the same position on homologous chromosomes.
Alzheimer’s disease
a neurological condition characterized by the degeneration of brain cells. Symptoms include memory loss, confusion, and physical decline.  Alzheimer’s disease usually occurs later in life and worsens over time.
Amino acids
organic (carbon-containing) molecules that serve as the building blocks of proteins.
refers to the absence of oxygen or the absence of a need for oxygen.
a chemical compound that is structurally similar to another but differs slightly in composition (e.g., the replacement of one functional group by another).
a rapidly developing and severe systemic allergic reaction. Symptoms may include swelling of the tongue, throat, and trachea, which can result in difficulty breathing, shock, and loss of consciousness. If not treated rapidly, anaphylaxis can be fatal.
the condition of having less than the normal number of red blood cells or hemoglobin in the blood, resulting in diminished oxygen transport. Anemia has many cause, including: iron, vitamin B-12, or folate deficiency, bleeding, abnormal hemoglobin formation (e.g., sickle cell anemia), rupture of red blood cells (hemolytic anemia), and bone marrow diseases.
a birth defect, known as a neural tube defect, resulting from failure of the upper end of the neural tube to close during embryonic development. Anencephaly is a devastating and sometimes fatal birth defect resulting in the absence of most or all of the cerebral hemispheres of the brain.
Angina pectoris
pain generally experienced in the chest, but sometimes radiating to the arms or jaw, due to a lack of oxygen supply to the heart muscle.
Angiography (coronary)
a diagnostic test used to identify the exact location and severity of coronary artery disease.  During angiography a small tube or catheter is inserted into an artery and guided with the assistance of a fluoroscope (x-ray) to the opening of the coronary arteries which supply blood to the heart.  A dye, visible on x-rays, is then injected into each coronary artery to reveal the extent and severity of blockages.  Images produced by angiography are known as angiograms.
a negatively charged ion.
a substance that counteracts the cellular effects of a natural compound, for example, a nutrient or a hormone.
also known as immunoglobulins (Ig), antibodies are specialized proteins produced by white blood cells that circulate in the blood recognizing and binding to foreign proteins, microorganisms or toxins in order to neutralize them. They are a critical part of the immune response.
a class of compounds that inhibit the formation of blood clots.
a class of medication used to prevent seizures, commonly used in individuals with seizure disorders or epilepsy.
a substance that is capable of causing an immune response.
a chemical that blocks the affect of histamine in a susceptible tissues.  Histamine is released by immune cells during an allergic reaction and also during infection with viruses which cause the common cold.  The interaction of histamine with the mucus membranes of the eyes and nose results in “watery eyes” and the “runny nose” often accompanying allergies and colds.  Antihistamines can alleviate such symptoms.
any substance that prevents or reduces damage caused by reactive oxygen species (ROS) or reactive nitrogen species (RNS). ROS and RNS are highly reactive chemicals that attack other molecules and modify their chemical structure. Antioxidants are commonly added to foods to prevent or delay their deterioration due to exposure to air.
Antiresorptive agents
medications or hormones that inhibit bone resorption.
gene-directed cell death or programmed cell death that occurs when age, condition, or state of cell health dictates. Cells that die by apoptosis do not usually elicit the inflammatory responses that are associated withnecrosis. Cancer cells are not able to undergo apoptosis.
an abnormal heart rhythm. The heart rhythm may be too fast (tachycardia), too slow (bradycardia) or irregular. Some arrhythmias, such as ventricular fibrillation, may lead to cardiac arrest if not treated promptly.
a respiratory condition characterized by difficulty breathing and reversible narrowing of the airways, known as bronchospasm.
a lack of coordination or unsteadiness usually related to a disturbance in the cerebellum, a part of the brain that regulates coordination and equilibrium.
also known as arteriosclerosis, atherosclerosis results from the accumulation of cholesterol-laden plaque in artery walls.  Plaque accumulation causes a narrowing and a loss of elasticity of the arteries, sometimes referred to as hardening of the arteries.
adenosine triphosphate. An important compound for the storage of energy in cells, as well as the synthesis (formation) of nucleic acids.
Atrophic gastritis
a chronic inflammation of the lining of the stomach, which ultimately results in the loss of glands in the stomach (atrophy) and decreased stomach acid production.
decrease in size or wasting away of a body part or tissue.
Autoimmune disease
Autoimmune diseases occur when the body tissues are mistakenly attacked by its own immune system. The immune system is a complex organization of cells and antibodies designed normally to destroy pathogens, particularly viruses and bacteria that cause infections. Individuals with autoimmune diseases have antibodies in their blood which target their own body tissues.

Glossary B:
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single-celled organisms that can exist independently, symbiotically (in cooperation with another organism) or parasitically (dependent upon another organism, sometimes to the detriment of the other organism). Examples of bacteria include acidophilus (found in yogurt), streptococcus the cause of strep throat, and E. coli (a normal intestinal bacteria, as well as a disease-causing agent).
Balance study
a nutritional balance study involves the measurement of the intake of a specific nutrient as well as the elimination of that nutrient in urine, feces, sweat, etc. If intake is greater than loss of a particular nutrient the individual is said to be in “positive balance.” If intake is less than loss, an individual is said to be in “negative balance” for the nutrient of interest.
a yellow, green fluid made in the liver and stored in the gallbladder. Bile may then pass through the common bile duct into the small intestine where some of its components aid in the digestion of fat.
Bile acids
components of bile, formed by the metabolism of cholesterol. Bile acid deficiency may lead to the formation of cholesterol gallstones, because bile salts (formed from bile acids) are required to dissolve cholesterol in bile so that it may be eliminated via the intestines.
the portion of a nutrient (or other chemical) that can be absorbed, transported, and utilized physiologically.
a physical, functional, or biochemical indicator (e.g., the presence of a particular metabolite) of a physiological or disease process.
Bone mineral density (BMD)
a term used in quantifying the mineralization of bone. The mineral component of bone consists largely of calcium and phosphorus. BMD is possitively associated with bone strength and resistance to fracture.  BMD can be determined through a low radiation X-ray technique known as DEXA.
Bone remodeling
the continuous turnover process of bone that includes bone resorptionand bone formation. An imbalance in the regulation of bone remodeling’s two contrasting events, bone resorption and bone formation, increases the fragility of bone and may lead to osteoporosis.
a chemical used to maintain the pH of a system by absorbing hydrogen ions (which would make it more acidic) or absorbing hydroxyl ions (which would make it more alkaline).

Glossary: C
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the process of deposition of calcium salts. In the formation of bone this is a normal condition. In other organs, this could be an abnormal condition. Calcification of the aortic valve causes narrowing of the passage (aortic stenosis).
also known as malignancy, cancer refers to abnormal cells, which have a tendency to grow uncontrollably and metastasize or spread to other areas of the body. Cancer can involve any tissue of the body and can have many different forms in one tissue. Cancer is a group of more than one hundred different diseases.
considered a macronutrient because carbohydrates provide a significant source of calories (energy) in the diet. Chemically, carbohydrates are neutral compounds composed of carbon, hydrogen and oxygen. Carbohydrates come in simple forms known as sugars and such as starches and fiber.
the introduction of a carboxyl group (-COOH) or carbon dioxide into a compound.
a cancer-causing agent; adjective: carcinogenic.
the formation of cancer cells from normal cells.
Carcinoid syndrome
the pattern of symptoms exhibited by individuals with carcinoid tumors.  Carcinoid tumors secrete excessive amounts of the neurotransmitter,serotonin. Seratonin causes blood vessels to dilate (widen). Symptoms include flushing, diarrhea, and sometimes wheezing.
literally, disease of the heart muscle that often leads to abnormal function.
referring to the heart and blood vessels.
Cardiovascular diseases
literally, diseases affecting the heart and blood vessels. The term has come to encompass a number of conditions that result from atherosclerosis, including myocardial infarction (heart attack), congestive heart failure, and stroke.
a compound that is required to transport long chain fatty acids across the inner membrane of the mitochondria, in the form of acyl-carnitine, where they can be metabolized for energy.
a soft, elastic tissue that composes most of the skeleton of vertebrate embryos and except for a small number of structures is replaced by bone during ossification in the higher vertebrates. Cartilage cushions joints, connects muscles with bones, and makes up other parts of the body such as the larynx (voice box) and the outside portion of the ears.
Case-control study
a study in which the risk factors of people who have been diagnosed with a disease are compared with those without the disease. Because the risk factor (e.g., nutrient intake) is generally measured at the time of diagnosis, it is difficult to determine whether the risk factor was present prior to the development of the disease. Another potential draw back is the difficulty in obtaining well-matched control subjects.
Case reports
individual observations based on small numbers of subjects. This type of research cannot indicate causality but may indicate areas for further research.
increase the speed of a chemical reaction without being changed in the overall reaction process. See enzyme.
substances with a specific chemical structure (a benzene ring with two adjacent hydroxyl groups and a side chain of ethylamine) that function as hormones or neurotransmitters. Examples include epinephrine, norepinephrine, and dopamine.
clouding of the lens of the eye. As cataracts progress they can impair vision and may result in blindness.
a positively charged ion.
Celiac disease
also known as celiac sprue, celiac disease is an inherited disease in which the intestinal lining is inflamed in response to the ingestion of a protein known as gluten. Treatment of celiac disease involves the avoidance of gluten, which is present in many grains, including rye, oats, and barley. Inflammation and atrophy of the lining of the small intestine leads to impaired nutrient absorption.
Cell membrane
also called the plasma membrane. The external limiting membrane of a cell. It is composed of  lipids (fat molecules) that have a hydrophobic (insoluble in water) end and a hydrophilic (water-soluble) end.  Cell membranes are made of lipid bilayers in which the lipids line up in two layers with the hydrophobic ends facing each other and the hydrophilic ends facing the outside and the inside of the cell.
Cell signaling
communication among individual cells so as to coordinate their behavior to benefit the organism as a whole. Cell-signaling systems elucidated in animal cells include cell-surface and intracellular receptor proteins, protein kinases and protein phosphatases (enzymes that phosphorylateand dephosphorylate proteins), and GTP-binding proteins.
Central nervous system (CNS)
the brain, spinal cord, and spinal nerves.
Cerebrospinal fluid
the fluid that bathes the brain and spinal chord.
Cerebrovascular disease
disease involving the blood vessels supplying the brain, including cerebrovascular accident (CVA), also known as a stroke.
the combination of a metal with an organic molecule to form a ring-like structure known as a chelate. Chelation of a metal may inhibit or enhance its bioavailability.
Literally, treatment with drugs. Commonly used to describe the systemic use of drugs to kill cancer cells, as a form of cancer treatment.
a lipid used in the construction of cell membranes and as a precursor in the synthesis of steroid hormones. Dietary cholesterol is obtained from animal sources, but cholesterol is also synthesized by the liver. Cholesterol is carried in the blood by lipoproteins (e.g., LDL and HDL). In atherosclerosis, cholesterol accumulates in plaques on the walls of some arteries.
Cholestatic liver disease
liver disease resulting in the cessation of bile excretion. Cholestasis may occur in the liver, gall bladder or bile duct (duct connecting the gall bladder to the small intestine).
resembling acetylcholine in action, a cholinergic drug for example. Cholinergic nerve fibers liberate or are activated by theneurotransmitter, acetylcholine.
Chorionic villus sampling (CVS)
a procedure for obtaining a small sample of  tissue from the placenta (chorionic villi) for the purpose of prenatal diagnosis of genetic disorders. CVS can be performed between 9 to 12 weeks of pregnancy.
a structures composed of a long DNA molecule and associated proteins that carries part of the hereditary information of an organism.
Chronic disease
an illness lasting a long time. By definition of the U.S. Center for Health Statistics, a chronic disease is a disease lasting 3 months or more.
a condition characterized by irreversible scarring of the liver, leading to abnormal liver function. Cirrhosis has a number of different causes, including chronic alcohol use and viral hepatitis B and C.
Clinical trial
a research study, generally used to evaluate the effectiveness of a new treatment in human participants. Clinical trials are designed to answer specific scientific questions and to determine the efficacy of new treatments for specific diseases or health conditions.
an exact copy of a DNA segment; produced by recombinant DNA technology.
the process of involved in forming a blood clot
a molecule that binds to an enzyme and is essential for its activity, but is not permanently altered by the reaction. Many coenzymes are derived from vitamins.
a compound that is essential for the activity of an enzyme.
an adjective referring to the processes of  thinking, learning, perception, awareness, and judgment.
Cohort study
a study that follows a large group of people over a long period of time, often 10 years or more. In cohort studies, dietary information is gathered before disease occurs, rather than relying on recall after disease develops.
a fibrous protein that is the basis for the structure of skin, tendon, bone, cartilage and all other connective tissue.
Collagenous matrix (of bone)
The organic (nonmineral) structural element of bone. Collagen is a fibrous protein that provides the organic matrix upon which bone mineralize crystallizes.
sometimes called the large bowel or intestine, the colon is a long, coiled, tubelike organ that removes water from digested food after it has passed through the small intestine. The remaining material, solid waste called stool, moves through the colon to the rectum and leaves the body through the anus.
Colorectal adenoma
a tumor of the colon or rectum that arises in glandular tissue.  Although not cancer, colorectal adenomas may develop into colorectal cancer over time.
Colorectal cancer
cancer of the colon (large intestine) or rectum.
Congenital hypothyroidism
also known as cretinism, congenital hypothyroidism occurs in two forms, although there is considerable overlap. The neurologic form is characterized by mental and physical retardation and deafness. It is the result of maternal iodine deficiency that affects the fetus before its own thyroid is functional. The myxedematous or hypothyroid form is characterized by short stature and mental retardation. In addition to iodine deficiency, the hypothyroid form has been associated with selenium deficiency and the presence of goitrogens in the diet that interfere with thyroid hormone production.
Congestive heart failure (CHF)
a disorder of the heart, resulting in the loss of the ability to pump blood efficiently enough to meet the demands of the body. Symptoms may include swelling, shortness of breath, weakness, and exercise intolerance.
the transparent covering of the front of the eye that transmits and focuses light into the eye.
Coronary artery
the vessels that supply oxygenated blood to the heart muscle itself, so named because they encircle the heart in the form of a crown.
Coronary artery bypass graft (CABG)
a surgical procedure used in individuals with significant narrowings and blockages of coronary arteries to create new routes around narrowed and blocked arteries, permitting increased blood flow to the heart muscle. The bypass graft for a CABG can be a vein from the leg or an inner chest wall artery.
Coronary heart disease (CHD)
also known as coronary artery disease and coronary disease, coronary heart disease is the result of atherosclerosis of the coronary arteries. Atherosclerosis may result in narrowing or blockage of the coronary arteries and is the underlying cause of myocardial infarction (heart attack).
any of the steroid hormones made by the cortex (outer layer) of theadrenal gland. Cortisol is a corticosteroid. A number of medications areanalogs of natural corticosteroid hormones.
Creatine phosphate
a high-energy compound found in muscle cells which is used to convert ADP into ATP by donating phosphate molecules to the ADP. ATP is the molecule which is converted into ADP with a release of energy that the body then uses.
Crohn’s disease
an inflammatory disease of the gastrointestinal tract, often affecting thesmall intestine and colon.
Cross-sectional study
a study of a group of people at one point in time to determine whether a risk factor or a level of a risk factor is associated with the occurrence of a disease.  Because the disease outcome and the risk factor (e.g., nutrient intake) are measured at the same time, a cross-sectional study provides a “snapshot” view of their relationship. Cross-sectional studies cannot provide information about causality.
Cystic fibrosis (CF)
a genetic (inherited) disease characterized by the production of abnormal secretions, leading to the accumulation of mucus in the lungs, pancreas, and intestine.  This build-up of mucus causes difficulty breathing and recurrent lung infections, as well as problems with nutrient absorption due to problems in the pancreas and intestines. Without treatment, CF results in death for 95 percent of affected children before age five; however, the longest-lived CF patient survived into his late 30s.
Cytochrome P-450
an enzyme that plays an important role in the metabolism of drugs and toxins in the liver. It also plays a role in the synthesis (formation) ofsteroid hormones in the adrenal cortex.
a protein made by cells that affects the behavior of other cells. Cytokines act on specific cytokine receptors in the cells they affect.

Glossary: D
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De novo synthesis
the formation of an essential molecule from simple precursor molecules.
a chemical reaction involving the removal of a carboxyl (-COOH) group from a compound.
Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning. Criteria for the diagnosis of dementia include impairment of attention, orientation, memory, judgment, language, motor and spatial skills. By definition, dementia is not due to major depression or psychosis. Alzheimer’s disease is the most common cause of dementia. Other causes include but are not limited to: AIDS, alcoholism (the dementia is due to thiamine deficiency), insufficient blood flow to the brain (vascular dementia), brain injury, brain tumors, drug toxicity, multiple sclerosis, and infections of the central nervous system.
Dental caries
cavities or holes in the outer two layers of a tooth–the enamel and the dentin. Dental caries are caused by bacteria which metabolizecarbohydrates (sugars) to form organic acids which dissolve tooth enamel. If allowed to progress, dental caries may result in tooth decay, infection, and loss of teeth.
Depletion-repletion study
a nutritional study designed to determine the requirement for a specific nutrient. Generally, subjects are placed on a diet designed to deplete them of a specific nutrient over time. Once depletion is achieved, gradually increasing amounts of the nutrient under study are added to the diet until the individual shows evidence of sufficiency or repletion.
inflammation of the skin. This term is often used to describe a skin rash.
dual energy X-ray absorptiometry. A precise instrument that uses the energy from very small doses of X-rays to determine bone mineral density (BMD) and to diagnose and follow the treatment ofosteoporosis.
Diabetes (diabetes mellitus)
a chronic condition associated with abnormally high levels of glucose (sugar) in the blood. The two types of diabetes are referred to as insulin-dependent (type I) and non-insulin dependent (type II). Type I diabetes results from a lack of adequate insulin secretion by the pancreas.  Type II diabetes (also known as adult-onset diabetes) is characterized by an insensitivity of the tissues of the body to insulin secreted by the pancreas (insulin resistance).
Diabetic ketoacidosis
a potentially life-threatening condition characterized by ketosis (elevated levels of ketone bodies in the blood) and acidosis (increased acidity of the blood). Ketoacidosis occurs when diabetes is not adequately controlled.
Diastolic blood pressure
the lowest arterial blood pressure during the heart beat cycle. The diastolic blood pressure is measured while the heart muscle is filling with blood.
changes in a cell resulting in its specialization for specific functions, such as those of a nerve cell. In general, differentiation of cells leads to a decrease in proliferation.
a process, which does not require energy expenditure, by which particles in solution move from a region of higher concentration to one of lower concentration.
a complex of two protein molecules.  Heterodimers are complexes of two different proteins, while homodimers are complexes of two of the same protein.
an agent that increases the formation of urine by the kidneys, resulting in water loss from the individual using the diuretic.
deoxyribonucleic acid.  A long thread-like molecule made up of large numbers of nucleotides. Nucleotides in DNA are composed of a nitrogen containing base, a 5-carbon sugar (deoxyribose), and phosphate groups. The sequence of bases in DNA serves as the carrier of genetic (hereditary) information.
Double blind
refers to a study in which neither the investigators administering the treatment nor the participants know which participants are receiving the experimental treatment and which are receiving the placebo.
dietary reference intake. Refers to a set of at least four nutrient-based reference values (RDA, AI, UL, EAR), each with a specific use in defining recommended dietary intake levels for individual nutrients in the U.S. The DRIs are determined by expert panels appointed by the Food and Nutrition Board of the Institute of Medicine.
daily value. Refers to the dietary reference values required as the basis for declaring nutrient content on all products regulated by the U.S. Food and Drug Administration (FDA), including nutritional supplements. The DVs for vitamins and minerals reflect the National Academy of Sciences’ 1968 RDAs, and do not reflect the most up to date Dietary Reference Intakes.

Glossary: E
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estimated average requirement; a nutrient intake value that is estimated to meet the requirement of  half of the healthy individuals in a particular life stage and gender group.
a diagnostic test that uses ultrasound to make images of the heart. It can be used to assess the health of the valves and chambers of the heart, as well as to measure cardiac output.
Electroencephalogram (EEG)
a recording of the electrical activity of the brain, used to diagnose neurological conditions such as seizure disorders (epilepsy).
ionized (dissociated into positive and negative ions) salts in the body fluids. Major electrolytes in the body include sodium, potassium, magnesium, calcium, chloride, bicarbonate, phosphate.
a stable atomic particle with a negative charge.
Electron transport chain
a group of electron carriers in mitochondria that transport electrons to and from each other in a sequence, in order to generate ATP.
One of the 103 chemical substances that cannot be divided into simpler substances by chemical means. For example, hydrogen, magnesium, lead, and uranium are all chemical elements. Trace elements are chemical elements that are required in very small (trace) amounts in the diet to maintain health. For example, copper, selenium, and iodine are considered trace elements.
the hard, white, outermost layer of a tooth.
Endocrine system
the glands and parts of glands that secrete hormones that integrate and control the body’s metabolic activity. Endocrine glands include the pituitary, thyroid, parathyroids, adrenals, pancreas, ovaries, and testes.
a biological catalyst. That is, a substance that increases the speed of a chemical reaction without being changed in the overall process. Enzymes are vitally important to the regulation of the chemistry of cells and organisms.
Epidemiologic study
a study examining disease occurrence in a human population.
also known as seizure disorder. Individuals with epilepsy experience seizures, which are the result of uncontrolled electrical activity in the brain. A seizure may cause a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms.
a soft muscular tube that connects the throat to the stomach. When a person swallows, the muscular walls of the esophagus contract to push food down into the stomach.
the causes or origin of a disease.
the elimination of wastes from blood or tissues.
Extracellular fluid (ECF)
the volume of body fluid excluding that in cells. ECF includes the fluid in blood vessels (plasma) and fluid between cells (interstitial fluid).

Glossary: F
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Familial adenomatous polyposis
a hereditary syndrome characterized by the formation of many polyps in the colon and rectum, some of which ultimately develop into colorectal cancer.
Fatty acid
an organic acid molecule consisting of a chain of carbon molecules and a carboxylic acid (COOH) group. Fatty acids are found in fats, oils, and as components of a number of essential lipids, such as phospholipids andtriglycerides. Fatty acids can be burned by the body for energy
Femoral neck
a portion of the thighbone (femur). The femoral neck is found near the hip, at the base of the head of femur, which makes up the ball of the hip joint. Fractures of the femoral neck sometimes occur in individuals with osteoporosis.
Fibrocystic breast condition (FCC)
a benign (noncancerous) condition of the breasts, characterized by lumpiness and discomfort in one one or both breasts.
the addition of nutrients to foods to prevent or correct a nutritional deficiency, to balance the total nutrient profile of food, or to restore nutrients lost in processing.
a break in a bone or cartilage, often but not always the result of trauma.
Free radical
a very reactive atom or molecule typically possessing a single unpaired electron.
a very sweet 6-carbon sugar abundant in plants. Fructose is increasingly common in sweeteners such as high-fructose corn syrup.

Glossary: G
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a small pear shaped sac adjacent to the liver. The gallbladder stores bile which is secreted by the liver and releases bile into the small intestine through the common bile duct.
�pebbles� formed by the precipitation (crystallization) of cholesterol (most common in the U.S. and Europe) or bilirubin (most common in Asia) in the gallbladder. Gallstones may be asymptomatic (without symptoms) or they may result in inflammation and infection of the gallbladder.
Gastroesophageal reflux disease (GERD)
a condition in which stomach contents, including acid, back up (reflux) into the esophagus, causing inflammation and damage to the esophagus. GERD can lead to scarring of the esophagus, and may increase the risk of cancer of the esophagus in some patients.
referring to or affecting the stomach and intestines (small and large bowel).
a region of DNA that controls a specific hereditary characteristic, usually corresponding to a single protein.
Gene expression
the full use of the information in a gene through transcription andtranslation leading to production of a protein.
all of the genetic information (encoded in DNA) possessed by an organism.
the production of glucose from non-carbohydrate precursors, such as amino acids (the building blocks of proteins).
a 6-carbon sugar which plays a major role in the generation of energy for living organisms.
a large polymer (repeating units) of glucose molecules, used to store energy in cells, especially muscle and liver cells.
enlargement of the thyroid gland. Goiter is one of the earliest and most visible signs of iodine deficiency. The thyroid enlarges in response to persistent stimulation by TSH (see Function). In mild iodine deficiency, this adaptation response may be enough to provide the body with sufficient thyroid hormone. However, more severe cases of iodine deficiency result in hypothyroidism. Thyroid enlargement may also be caused by factors other than iodine deficiency, especially in iodine sufficient countries, such as the U.S.
a substance that induces goiter formation by interfering with thyroid hormone production or utilization.
a condition characterized by abnormally high blood levels of uric acid (urate). Urate crystals may form in joints, resulting in inflammation and pain. Urate crystals may also form in the kidney and urinary tract, resulting in kidney stones. The tendency to develop elevated blood uric acid levels and gout is often inherited.
guanosine triposphate. A high energy molecule, required for a number of biochemical reactions, including nucleic acid and protein synthesis (formation).

Glossary: H
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Hartnup’s disease
a genetic disorder resulting in defective absorption of the amino acid, tryptophan.
high density lipoproteins. HDL transport cholesterol from the tissues to the liver where it can be eliminated in bile. HDL-cholesterol is considered good cholesterol, because higher blood levels of HDL-cholesterol are associated with lower risk of heart disease.
compounds of iron complexed in a characteristic ring structure known as a porphyrin ring.
a medical procedure that uses a specialized machine to filter waste products from the blood, while restoring its normal constituents. Hemodialysis is needed to perform the work of the kidneys if they can no longer function effectively.
the oxygen-carrying pigment in red blood cells.
rupture of red blood cells.
Hemolytic anemia
Anemia resulting from hemolysis (the rupture of red blood cells).
excessive or uncontrolled bleeding.
literally, inflammation of the liver. Hepatitis caused by a virus is known as viral hepatitis. Other causes of hepatitis include toxic chemicals and alcohol abuse.
Hereditary spherocytosis
a hereditary form of anemia characterized by abnormally shaped red blood cells which are spherical and abnormally fragile. The increased fragility of these red blood cells leads to hemolytic anemia (anemia caused by the rupture of red blood cells).
a dimer or complex of two different molecules, usually proteins.
possessing two different forms (alleles) of a specific gene.
human immunodeficiency virus. The virus that causes AIDS.
a sulfur-containing amino acid, which is an intermediate in the metabolism of another sulfur-containing amino acid, methionine.  Elevated homocysteine levels in the blood have been associated with increased risk of cardiovascular disease.
a dimer or complex of two of the same molecule, usually a protein.
having the same relative position, value, or structure.
possessing two identical forms (alleles) of a specific gene.
a chemical, released by a gland or a tissue, which affects or regulates the activity of specific cells or organs.  Complex bodily functions, such as growth and sexual development, are regulated by hormones.
a calcium phosphate salt. Hydroxyapatite is the main mineral component of bone of bone and teeth, and is what gives them their rigidity.
a chemical reaction involving the addition of a hydroxyl (-OH) group to a compound.
excess secretion of parathyroid hormone by the parathyroid glands resulting in the disturbance of calcium metabolism. Symptoms may include increased blood levels of calcium (hypercalcemia), decreased blood levels of phosphorus, loss of calcium from bone, and kidney stone formation.
high blood pressure, defined as a systolic blood pressure greater than 140 mm Hg and/or diastolic blood pressure greater than 90 mm Hg.
an excess of thyroid hormone which may result from an overactive thyroid gland or nodule, or from taking too much thyroid hormone.
a deficiency of parathyroid hormone, which may be characterized by low blood calcium levels (hypocalcemia).
An area at the base of the brain that regulatesbodily functions, such as body temperature, hunger, and thirst.
an educated guess or proposition that is advanced as a basis for further investigation. A hypothesis must be subjected to an experimental test to determine its validity.
a deficiency of thyroid hormone which is normally made by the thyroid gland, located in the front of the neck.

Glossary: I
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of unknown cause.
Impaired glucose tolerance
a metabolic state between normal glucose regulation and overt diabetes. Generally, blood glucose levels are higher than normal, but lower than those accepted as diagnostic for diabetes.
not dissolvable. With respect to bioavailability, certain substances form insoluble complexes that cannot be dissolved in digestive secretions, and therefore cannot be absorbed by the digestive tract.
a peptide hormone secreted by the b-cells of the pancreas required for normal glucose metabolism.
Insulin resistance
diminished responsiveness to insulin.
Intracellular fluid (ICF)
the volume of fluid inside cells.
In vitro
literally “in glass” referring to a test or research done in the test tube, outside a living organism.
In vivo
“inside a living organism”. An in vivo assay evaluates a biological process occurring inside the body.
an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons.
Ion channel
a protein, embedded in a cell membrane that serves as a crossing point for the regulated transfer of an ion or a group of ions across the membrane.
compounds that have the same numbers and kinds of atoms but that differ in the way the atoms are arranged.

Glossary: J, K
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a yellowish staining of the skin and whites of the eyes due to increased bilirubin (a bile pigment) levels in the blood. Jaundice can be an indicator of red blood cells rupturing (hemolysis), or disease of the liver or gallbladder.
Ketone bodies
any of three acidic chemicals (acetate, acetoacetate, and beta-hydroxybutyrate). Ketone bodies may accumulate in the blood (ketosis) when the body has inadequate glucose to use for energy, and must increase the use of fat for fuel. Ketone bodies are acidic, and very high levels in the blood are toxic and may result in ketoacidosis.
Kidney stones
also known as renal calculi, kidney stones are the result of crystallization of certain substances found in urine, including calcium, phosphate, oxalic acid, and uric acid. Stones may form in the urine collecting area (pelvis) of the kidney, as well as the ureters (narrow tubes connecting the kidney to the urinary bladder).

Glossary: L
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low density lipoprotein. Lipoproteins (particles composed of lipids andprotein) are the form in which fats are transported throughout the body, in the bloodstream.  LDL transport cholesterol from the liver to the tissues of the body.  A high proportion of cholesterol carried in LDL (LDL-cholesterol) is associated with an increased likelihood of developing cardiovascular diseases (heart disease and stroke). Oxidized LDL appear to play an important role in the development ofatherosclerosis.
Left ventricular hypertrophy (LVH)
abnormal thickening of the wall of the left ventricle (lower chamber) of the heart muscle. The ventricles have muscular walls in order to pump blood from the heart through the arteries, but LVH occurs when the ventricle must pump against abnormally high volume or pressure loads. LVH may accompany congestive heart failure (CHF).
members of the large family of plants known as leguminosae. In this context the term refers to the fruits or seeds of leguminous plants (e.g., peas and beans) that are used for food.
the transparent structure inside the eye that focuses light rays onto the retina (the nerve cells at the back of the eye).
an acute or chronic form of cancer that involves the blood-forming organs. Leukemia is characterized by an abnormal increase in the number of white blood cells in the tissues of the body with or without a corresponding increase of those in the circulating blood, and is classified according to the type of white blood cell most prominently involved.
different types of fat molecules. For example, phospholipids, cholesterol, triglycerides.
Lipoic acid
a coenzyme, essential for the oxidation of alpha-keto acids, such as pyruvate, in metabolism.
particles composed of lipids and protein, that allows for transport of fat and cholesterol through the blood. A lipoprotein particle is composed of an outer shell of phospholipid, which renders the particle soluble in water; a core of fats called lipid, including cholesterol and a surface apoprotein molecule that allows tissues to recognize and take up the particle.
Lp(a) lipoprotein
A lipoprotein particle in which the protein (apolipoproteinB-100) is chemically linked to another protein apolipoprotein(a). Increased blood levels of Lp(a) are associated with an increased risk of cardiovascular diseases.
Lumbar spine
the portion of the spine, commonly referred to as the small of the back. The lumbar portion of the spine is located between the thorax (chest) and the pelvis.
also known as systemic lupus erythematosus (SLE). Lupus is a chronic inflammatory condition caused by an autoimmune disease. An autoimmune disease occurs when the body’s tissues are attacked by its own immune system. Individuals with lupus have unusual antibodies in their blood that are targeted against their own body tissues.
a white blood cell that creates an immune response when activated by a foreign molecule (antigen). T lymphocytes or T-cells develop in an organ called the thymus and are responsible for cell-mediated immunity, while B-lymphocytes develop in the bone marrow and are responsible for the production of antibodies (immunoglobulins).

Glossary: M
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Macrocytic anemia
low red blood cell count, characterized by the presence in the blood of larger than normal red blood cells.
a small area of the retina where vision is the keenest. The macula is located in the center of the retina and provides central vision. Activities that require central vision include driving, reading and other activities that require sharp, straight-ahead vision.
Magnetic Resonance Imaging (MRI)
a special imaging technique that uses a powerful magnet and a computer to provide clear images of soft tissues. Tissues that are well-visualized using MRI include the brain and spinal cord, abdomen, and joints.
Malabsorption syndrome
a disease or condition that results in poor absorption of nutrients from food.
an infectious disease caused by parasitic microorganisms called plasmodia. Malaria can be spread among humans through the sting of certain types of mosquitos (Anopheles) or by a contaminated needle or transfusion. Malaria is a major health problem in the tropics and subtropics, affecting over 200 million people world wide.
Megaloblastic anemia
low red blood cell count, characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. Red blood cells, when mature, have no nucleus.
a dark brown pigment found in the skin.
Membrane potential
the electrical potential difference across a membrane. The membrane potential is a result of the concentration differences between potassium and sodium across cell membranes which are maintained by ion pumps. A large proportion of the body’s resting energy expenditure is devoted to maintaining the membrane potential, which is critical for nerve impulse transmission, muscle contraction, heart function, and the transport of nutrients and metabolites in and out of cells.
the cyclic loss of blood by a woman, from her uterus (womb) when she is not pregnant. Menstruation generally occurs every 4 weeks after a woman has reached sexual maturity and prior to menopause.
a mathematical or statistical analysis, used to pool the results of all studies investigating a particular effect (e.g., the effect of folic acid supplementation on homocysteine levels) and provide an overall estimate of that effect.
physical and chemical processes within the body involving energy production and utilization.
a compound derived from the metabolism of another compound is said to be a metabolite of that compound.
to spread from one part of the body to another. Cancer is said to metastasize when it spreads from the primary site of origin to a distant anatomical site.
a sulfur containing amino acid, required for protein synthesis and other vital metabolic processes. It can be obtained through the diet in protein or synthesized from homocysteine.
a biochemical reaction resulting in the addition of a methyl group (-CH3) to another molecule.
Migraine headache
a type of headache thought to be related to abnormal sensitivity of blood vessels (arteries) in the brain to various triggers resulting in rapid changes in the artery size due to spasm (constriction). Other arteries in the brain and scalp then open (dilate), and throbbing pain is perceived in the head. The tendency toward migraine appears to involve serotonin, aneurotransmitter that can trigger the release of vasoactive substances in the blood vessels.
nutritionally significant elements. Elements are composed of only one kind of atom. Minerals are inorganic, i.e., they do not contain carbon as do vitamins and other organic compounds.
energy-producing structures within cells. Mitochondria possess two sets of membranes, a smooth continuous outer membrane, and an inner membrane arranged in folds. Among other critical functions, mitochondria convert nutrients into energy via the electron transport chain.
mm Hg
millimeters of mercury. The unit of measure for blood pressure.
the fundamental unit for measuring chemical compounds (abbreviated mol). One mole equals the molecular weight of a compound in grams. The number of molecules in a mole is equal to 6.02 x 1023 (Avogadro’s number).
refers to a disorder or condition that has a number of different causes.
Multiple sclerosis (MS)
an autoimmune disorder, which results in the demyelinization of nerves. In MS, the myelin shealth that allows for efficient transmission of nerve impulses is damaged, resulting in progressive neurological symptoms such as, numbness, tingling, loss of control of certain bodily functions, and paralysis.
a change in a gene, in other words, a change in the sequence of base pairs in the DNA that makes up a gene. Mutations in a gene may or may not result in an altered gene product.
the fatty substance that covers myelinated nerves. Myelin is a layered tissue surrounding the axons or nerve fibers. This sheath acts as a conduit in an electrical system, allowing rapid and efficient transmission of nerve impulses. Myelination refers to the process in which nerves acquire a myelin sheath.
Myocardial infarction (MI)
commonly known as a “heart attack”, a myocardial infarction refers to changes that occur in the heart muscle due to an interruption in its blood supply. An MI is often the result of a clot that lodges in a coronary artery, resulting in deprivation of oxygen to a portion of the heart muscle (ischemia), and ultimately the death (necrosis) of a portion of the heart muscle, if the oxygen supply is not restored within a few minutes.
an inflammation of the heart muscle.
a heme-containing pigment in muscle cells that binds and stores oxygen.

Glossary: N
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cell death due to infection or injury.
Neural Tube Defect (NTD)
a birth defect caused by abnormal development of the neural tube, the structure which gives rise to the central nervous system. Neural tube defects include anencephaly and spina bifida.
or neurological; involving nerves or the nervous system (brain, spinal cord, and all sensory and motor nerves).
malfunction or disease pathology of nerves.  Peripheral neuropathy refers to a disease or degenerative state of peripheral nerves resulting in pain, numbness, and sometimes muscle weakness.
toxic or damaging to nervous tissue (brain and peripheral nerves).
a chemical that is released from a nerve cell, which transmits an impulse from that nerve cell to another nerve cell, or to another organ (a muscle, for example). Neurotransmitters are chemical messengers that transmit neurological information from one cell to another.
also called polymorphonuclear leukocytes because they are white blood cells with a multi-lobed nucleus. Neutrophils combat infection by internalizing and destroying disease causing organisms such as bacteria.
The National Institutes of Health are U.S. health agencies, devoted to medical research. Administered under the Department of Health and Human Services (HHS), the NIH consists of more than 20 separate Institutes and Centers.
Nucleic acids
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Long thread-like molecules made up of large numbers of nucleotides. Nucleotides are composed of a nitrogen containing base, a 5-carbon sugar, and one or more phosphate groups. The sequence of bases in DNA or RNA represents the genetic (hereditary) information of a living cell.
molecules composed of a nitrogen containing base, a 5-carbon sugar, and one or more phosphate groups. Long strands of nucleotides form nucleic acids (see above). The sequence of bases in DNA or RNA represents the genetic (hereditary) information of a living cell.
a membrane-bound cellular organelle, which contains DNA organized into chromosomes.

Glossary: O
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Observational study
a study in which no experimental intervention or treatment is applied. Participants are simply observed over time.
One-carbon unit
a biochemical term for functional groups containing only one carbon in addition to other atoms. One-carbon units transferred by folate coenzymes include methyl (-CH3), methylene (-CH2-), fomyl (-CH=O), formimino (-CH=NH), and methenyl (-CH=).  Many biosynthetic reactions involve the addition of a one-carbon unit to a precursor molecule.
Optimum health
in addition to freedom from disease, the ability of an individual to function physically and mentally at his or her best.
refers to carbon-containing compounds, generally synthesized by living organisms.
a degenerative joint condition that is characterized by the breakdown of articular cartilage (cartilage within the joint). Symptoms of osteoarthritis include pain and stiffness in the affected joint(s), particularly after activity.
cells associated with bone that are responsible for the new formation of bone in the bone remodeling process.
cells associated with bone that are responsible for the breakdown or resorption of bone.  Bone remodeling is a continuous process of resorption and  formation.
a disease of adults that is characterized by softening of the bones due to loss of bone mineral. Osteomalacia is characteristic of vitamin D deficiency in adults, while children with vitamin D deficiency suffer from rickets.
a condition of increased bone fragility and susceptibility to bone fracturedue to a loss of bone mineral density (BMD)
a chemical reaction that removes electrons from an atom or molecule.
Oxidative stress
an organism is said to experience oxidative stress when the effects ofprooxidants (e.g. free radicals, reactive oxygen and reactive nitrogen species) exceed the ability of antioxidant systems to neutralize them.

Glossary: P,Q
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a small organ located behind the stomach. The head of the pancreas is connected to the duodenum (the first section of the small intestine). The pancreas makes enzymes that help digest food in the small intestine and hormones, including insulin, that control the amount of glucose in the blood.
Parathyroid glands
glands located behind the thyroid gland in the neck. The parathyroid glands secrete a hormone called parathormone (PTH) that is critical to calcium and phosphorus metabolism.
Parkinson’s disease
a  disease of the nervous system caused by degeneration of a part of the brain called the basal ganglia, and by low production of theneurotransmitter dopamine. Symptoms include muscle rigidity, tremors, and slow voluntary movement.
disease causing agent, such as a virus or a bacteria.
Peptic ulcer disease
a disease characterized by ulcers or breaks in the inner lining (mucosa) of the stomach or duodenum (region of the small intestine closest to the stomach). The three major causes of peptic ulcer disease are non-steroidal anti-inflammatory drugs (NSAIDS), chronic Heliobacter pylori infection, and states of acid hypersecretion, like Zollinger-Ellison syndrome.
a chain of amino acids. A protein is made up of one or more peptides.
Peptide hormones
hormones that are proteins, as opposed to steroid hormones, which are made from cholesterol. Insulin is an example of a peptide hormone.
Peripheral vascular diseases
diseases of the vessels of the extremities such as atherosclerosis, resulting in diminished circulation, pain (claudication), or a blood clot, for example.
Pernicious anemia
the end stage of an autoimmune inflammation of the stomach, resulting in destruction of stomach cells by one’s own antibodies.  Progressive destruction of the cells that line the stomach cause decreased secretion of acid and enzymes required to release food bound vitamin B-12.  Antibodies to intrinsic factor (IF) bind to IF preventing formation of the IF-B-12 complex, further inhibiting vitamin B-12 absorption.
PET scan
positron emission tomography. A diagnostic imaging technique that uses a sophisticated camera and computer to produce images of how a person’s body is functioning. A PET scans shows the difference between healthy and abnormally functioning tissues.
a measure of acidity or alkalinity.
Pharmacologic dose
the dose or intake level of a nutrient many times the level associated with the prevention of deficiency or the maintenance of health.  A pharmacologic dose is generally associated with the treatment of a disease state and considered to be a dose at least 10 times greater than that needed to prevent deficiency.
Phenylketonuria (PKU)
an inherited disorder resulting in the inability to process the amino acid, phenylananine. If not treated, the disorder may result in mental retardation. Treatment is a diet low in phenylalanine. Newborns are screened for PKU, in order to determine the need for treatment before brain damage occurs.
the removal of blood from a vein. Phlebotomy may be used to obtain blood for diagnostic tests or to treat certain conditions, for example, iron overload in hemochromatosis.
lipids (fat molecules) in which phosphoric acid as well as fatty acids are attached to a glycerol backbone. Phospholipids are found in all living cells and in the bilayers of cell membranes.
the creation of a phosphate derivative of an organic molecule. This is usually achieved by transferring a phosphate group (-PO4) from ATP to another molecule.
Physiologic dose
the dose or intake level of a nutrient associated with the prevention of deficiency or the maintenance of health.  A physiologic dose of a nutrient is not generally greater than that which could be achieved through a conscientious diet, as opposed to the use of supplements.
Pituitary gland
a small oval gland located at the base of the brain that secreteshormones regulating growth and metabolism. The pituitary gland is divided into two separate glands, the anterior and posterior pituitary glands, which each secrete different hormones.
a sugar pill or false treatment that is given to a control group while the experimental group is given the experimental treatment. Placebo-controlled studies are conducted to make sure that significant outcomes of a trial are due to the experimental treatment rather than another factor associated with participating in the study.
a temporary organ joining the mother and unborn child (fetus). The placenta transfers oxygen and nutrients from the mother to the fetus, and permits the release of carbon dioxide and waste products from the fetus.
Placental abruption
premature separation of the placenta from the wall of the uterus. Abruption is a potentially serious problem both for the mother and baby.
the liquid part of blood (as opposed to blood cells) that makes up about half its volume. Plasma differs from serum in that the blood sample has not clotted. A centrifuge is used to separate plasma from cells in the laboratory.
Irregularly shaped cell fragments that assist in blood clotting. During normal blood clotting platelets aggregate (group together) to preventhemorrhage.
a disease of the lungs, characterized by inflammation and accumulation of fluid in the lungs. Pneumonia may be caused by infectious agents (e.g., viruses or bacteria) or by inhalation of certain irritants.
the existence of two (or more) forms of a gene with each form being too common to be due merely to new mutation.
a benign (non-cancerous) mass of tissue that forms on the inside of a hollow organ, such as the colon.
a molecule which is an ingredient, reactant, or intermediate in a synthetic pathway for a particular product.
a condition characterized by a sharp rise in blood pressure during the third trimester of pregnancy. High blood pressure may be accompanied by edema (swelling), and kidney problems, as evidenced by protein in the urine. Although preeclampsia is relatively common, occurring in about 5 percent of all pregnancies and more frequently in first pregnancies, it can be a sign of serious problems. In some cases, untreated preeclampsia can progress to eclampsia, a life-threatening situation for both mother and baby.
the proportion of a population with a specific disease or condition at a given point in time.
predicted outcome based on the course of a disease.
rapid cell division.
an atom or molecule that promotes oxidation of another atom or molecule by accepting electrons. Examples of prooxidants include free radicals, reactive oxygen species (ROS) and reactive nitrogen species (RNS).
prevention, often refers to a treatment used to prevent a disease.
Prospective study
a study in which participants are initially enrolled, examined or tested for risk factors (e.g., nutrient intake), and then followed up at subsequent times to determine their status with respect to the disease or condition of interest.
any of a class of hormone-like, regulatory molecules constructed from polyunsaturated fatty acids such as arachidonate. These molecules participate in a number of functions in the body, such as smooth muscle contraction and relaxation, vasodilation, and kidney regulation.
a gland situated at the beginning of the urethra (passage through which urine leaves the body) in men. It secretes an alkaline fluid which is the major component of semen (ejaculatory fluid).  Prostate cancer is the second leading cause of death in men in the U.S.
a complex organic molecule composed of amino acids in a specific order. The order is determined by the sequence of nucleic acids in agene coding for the protein. Proteins are required for the structure, function, and regulation of the body’s cells, tissues, and organs, and each protein has unique functions.
a large compound comprised of protein and polysaccharide units known as glycosaminoglycans (GAGs). GAGs are polymers of sugars and amino sugars, such as glucosamine or galactosamine. Proteoglycans are integral components of structural tissues such as bone and cartilage.
A chronic skin condition often resulting in a red, scaly rash located over the surfaces of the elbows, knees, scalp, and around or in the ears, navel, genitals or buttocks. Approximately 10-15% of patients with psoriasis develop joint inflammation (psoriatic arthritis). Psoriasis is thought to be an autoimmune condition.
Pyruvate kinase deficiency
a hereditary deficiency of the enzyme pyruvate kinase. Pyruvate kinase deficiency results in hemolytic anemia.
one fourth of a sample or population.
one fifth of a sample or population.

Glossary: R
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Radiation therapy
the local use of radiation to destroy cancer cells or stop them from dividing and growing.
Randomized controlled trial (RCT)
A clinical trial that involves at least one test treatment and one control treatment, in which the treatments administered are selected by a random process (e.g., coin flips or a random-numbers table).
Randomized design
an experiment in which participants are chosen for the experimental and control groups at random, in order to reduce bias caused by self-selection into experimental and control groups. This type of study design can provide evidence of causality.
recommended dietary allowance.  Set by the Food and Nutrition Board of the Institute of Medicine, the RDA is the average daily dietary intake level sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in a specific life stage and gender group (e.g., women from 19-50 years of age).  It is intended as a goal for daily intake of specific nutrients by individuals.
Reactive oxygen species (ROS)
highly reactive chemicals, containing oxygen, that react easily with other molecules, resulting in potentially damaging modifications.
Reactive nitrogen species (RNS)
highly reactive chemicals, containing nitrogen, that react easily with other molecules, resulting in potentially damaging modifications.
a protein on or protruding from the cell surface to which select chemicals can bind. Binding of a specific molecule (ligand) may result in a cellular signal, or the internalization of the receptor and the ligand.
Recessive trait
a trait that is expressed only when two copies of the gene responsible for the trait are present.
the last section of the large intestine (colon). It connects the sigmoid colon (above) to the anus (below).
Redox reaction
another term for an oxidation-reduction reaction. A redox reaction is any reaction in which electrons are removed from one molecule or atom and transferred to another molecule or atom. In such a reaction one substance is oxidized (loses electrons) while the other is reduced (gains electrons).
a chemical reaction in which a molecule or atom gains electrons.
refers to the kidneys.
the process of breaking down or assimilating something. With respect to bone, resorption refers to the breakdown of bone by osteoclasts that results in the release of calcium and phosphate (bone mineral) into the blood.
Response element
a sequence of nucleotides in a gene that can be bound by a protein. Proteins that bind to response elements in genes are sometimes called transcription factors or binding proteins. Binding of a transcription factor to a response element regulates the production of specific proteins by inhibiting or enhancing the transcription of genes that encode those proteins.
the sensory membrane that lines most of the back of the eye. The retina is composed of several layers including one containing the rods and cones. It receives the image formed by the lens and converts it into chemical and nervous signals which reach the brain by way of the optic nerve.
Rheumatoid arthritis
An autoimmune disease which causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body. Because it can affect multiple other organs of the body, rheumatoid arthritis is a systemic illness and is sometimes called rheumatoid disease.
a molecule consisting of a 5-carbon sugar (ribose), a nitrogen containing base, and one or more phosphate groups.
often the result of vitamin D deficiency. Rickets affects children while their bones are still growing. It is characterized by soft and deformed bones, and is the result of a impaired incorporation of calcium and phosphate into the skeleton.
ribonuceic acid. a chain of nucleotides, which are composed of a nitrogen containing base, a 5-carbon sugar (ribose), and phosphate groups. RNA functions in the translation of the genetic information in DNA to protein synthesis.
an animal that chews cud. Ruminant animals include cattle, goats, sheep, and deer.

Glossary: S
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Scavenge (free radicals)
to combine readily with free radicals, preventing them from reacting with other molecules.
a disorder caused by lack of vitamin C. Symptoms include anemia, bleeding gums, tooth loss, joint pain, and fatigue. Scurvy is treated by supplying foods high in vitamin C as well as with vitamin C supplements.
uncontrolled electrical activity in the brain, which may produce a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms.
a hormone also known as 5-hydroxytryptamine. Serotonin functions as both a neurotransmitter and a vasoconstrictor (substance that causes blood vessels to narrow).
the liquid part of blood (as opposed to blood cells) that makes up about half its volume. Serum differs from plasma in that the blood sample has clotted. A centrifuge is used in the laboratory to separate serum from cells after blood has clotted.
Short bowel syndrome
a malabsorption syndrome resulting from the surgical removal of an extensive portion of the small intestine.
Sickle cell anemia
a hereditary disease in which a mutation in the gene for one of the proteins that comprises hemoglobin results in the formation of defective hemoglobin molecules known as hemoglobin S. Individuals who arehomozygous for this mutation (possess two genes for hemoglobin S) have red blood cells that change from the normal discoid shape to a sickle shape when the oxygen supply is low. These sickle-shaped cells are easily trapped in capillaries and damaged, resulting in severeanemia. Individuals who are heterozygous for the mutation (possess one gene for hemoglobin S and one normal hemoglobin gene) have increased resistance to malaria.
Sideroblastic anemia
a group of anemias that are all characterized by the accumulation of iron deposits in the mitochondria of immature red blood cells. These abnormal red blood cells do not mature normally, and many are destroyed in the bone marrow before reaching the circulation. Sideroblastic anemias can be hereditary, idiopathic (unknown cause), or caused by such diverse factors as certain drugs, alcohol, or copper deficiency.
Small intestine
the part of the digestive tract that extends from the stomach to the large intestine. The small intestine includes the duodenum (closest to the stomach), the jejunum, and the ileum (closest to the large intestine).
the polyol (sugar alcohol) corresponding to glucose.
Spina bifida
a birth defect, also known as a neural tube defect, resulting from failure of the lower end of the neural tube to close during embryonic development. Spina bifida, the most common cause of infantile paralysis, is characterized by a lack of protection of the spinal cord by its membranes and vertebral bones.
also known as celiac sprue and celiac disease, it is an inherited disease in which the intestinal lining is inflamed in response to the ingestion of a protein known as gluten. Treatment of celiac disease involves the avoidance of gluten, which is present in many grains, including rye, oats, and barley. Inflammation and atrophy of the lining of the small intestine leads to impaired nutrient absorption.
the state of nutrition of an individual with respect to a specific nutrient. Diminished or low status indicates inadequate supply or stores of a specific nutrient for optimal physiological functioning.
a molecule related to cholesterol. Many important hormones such as estrogen and testosterone are steroids. See hormone.
Steroid hormone receptor
a protein within a cell which binds to a specific steroid hormone. Binding of the steroid hormone changes the shape of the receptor protein and activates it, allowing it to activate gene transcription. In this way, a steroid hormone can activate the synthesis of specific proteins.
Stress fracture
a hairline or microscopic break in a bone, usually due to repetitive stress rather than trauma. Stress fractures are usually painful, and may be undetectable by X-ray. Though they may occur in almost any bone, common sites of stress fractures are the tibia (lower leg) and metatarsals (foot).
the sudden death of some brain cells due to lack of oxygen, when blood flow to the brain is impaired by the blockage (usually due to a blood clot) or rupture of a blood vessel in the brain. A stroke is also called a cerebrovascular accident (CVA).
without clinical signs or symptoms; sometimes used to describe the early stage of a disease or condition, before symptoms are detectable by clinical examination or laboratory tests.
a reactant in an enzyme catalyzed reaction.
a nutrient or phytochemical supplied in addition to that which is obtained in the diet.
a combination of symptoms that occur together and is indicative of a specific condition or disease.
Systolic blood pressure
the highest arterial pressure measured during the heart beat cycle. It occurs when the heart muscle is contracting (pumping).

Glossary: T
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any of a large group of plant-derived compounds. Tannins tend to be bitter tasting and may function in pigment formation and plant protection.
a condition of prolonged and painful spasms of the voluntary muscles, especially the fingers and toes (carpopedal spasm) as well as the facial musculature.
one third of a sample or population.
Thalassemia major
Beta thalassemia is a genetic disorder that results in abnormalities of the globin (protein) portion of hemoglobin. An individual who ishomozygous for the beta thalassemia gene (has two copies of the beta thalassemia gene) is said to have thalassemia major. Infants born with thalassemia major develop severe anemia a few months after birth, accompanied by pallor, fatigue, poor growth, and frequent infections. Blood transfusions are used to treat thalassemia major but cannot cure it.
Thalassemia minor
Individuals who are heterozygous for the beta thalassemia gene (carry one copy of the beta thalassemia gene) are said to have thalassemia minor or thalassemia trait. These individuals are generally healthy but can pass the beta thalassemia gene to their children and are said to be carriers of the beta thalassemia gene.
the point at which a physiological effect begins to be produced, for example, the degree of stimulation of a nerve which produces a response or the level of a chemical in the diet that results in a disease.
a butterfly-shaped gland in the neck that secretes thyroid hormones. Thyroid hormones regulate a number of physiologic processes, including growth, development, metabolism, and reproductive function.
Thyroid follicular cancer
a cancer of the thyroid gland that constitutes about 30% of all thyroid cancers. It has a greater rate of recurrence and metastases (spreading to other organs) than thyroid papillary cancer.
Thyroid papillary cancer
the most common form of thyroid cancer, which most often affects women of childbearing age. Thyroid papillary cancer has a lower rate of recurrence and metastases (spreading to other organs) than thyroid follicular cancer.
Total Parenteral Nutrition (TPN)
intravenous (I.V.) feeding that provides patients with essential nutrients when they are too ill to eat normally.
(DNA or transcription); the process by which one strand of DNA is copied into a complementary sequence of RNA.
Transcription factor
generally a protein that functions to initiate, enhance, or inhibit thetranscription of a gene. Transcription factors can regulate the formation of a specific protein encoded by a gene.
Transient ischemic attack (TIA)
sometimes called a small or mini stroke. TIAs are caused by a temporary disturbance of blood supply to an area of the brain, resulting in a sudden, brief (usually less than 1 hour) disruptions in certain brain functions.
(RNA translation) process by which the sequence of nucleotides in a messenger RNA molecule directs the incorporation of amino acids into a protein.
an injury or wound.
trembling or shaking of all or a part of the body.
a triglyceride consists of three molecules of fatty acid combined with a molecule of the alcohol glycerol. Triglycerides serve as the backbone of many types of lipids (fats). Triglycerides are the major form of fat in our diets and are also produced by the body.
an infection caused by bacteria called mycobacteria tuberculosis. Many people infected with tuberculosis have no symptoms because it is dormant. Once active, tuberculosis may cause damage to the lungs and other organs. Active tuberculosis is also contagious and is spread through inhalation. Treatment of tuberculosis involves taking antibiotics and vitamins for at least 6 months.
an infectious disease, spread by the contamination of food or water supplies with the bacteria called salmonella typhi. Food and water can be contaminated directly by sewage or indirectly by flies or poor hygiene. Though rare in the U.S., it is common in some parts of the world. Symptoms include fever, abdominal pain, diarrhea, and a rash. It is treated with antibiotics and intravenous fluids. Vaccination is recommended to those traveling to areas where typhoid is common.

Glossary: U
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Ulcerative colitis
an inflammatory disease of the colon of an unknown cause. Symptoms include abdominal pain and cramping, diarrhea, and rectal bleeding.
a test in which high-frequency sound waves (ultrasound) are bounced off tissues and the echoes are converted into a picture (sonogram).
tolerable upper intake level.  Set by the Food and Nutrition Board of the Institute of Medicine, the UL is the highest level of daily intake of a specific nutrient likely to pose no risk of adverse health effects in almost all individuals in the specified life stage and gender group.

Glossary: V
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Vascular dementia
dementia resulting from cerebrovascular disease, for example a cerebrovascular accident (stroke).
narrowing of a blood vessel.
relaxation or opening of a blood vessel.
of or pertaining to a vertebra, one of the twenty three bones that comprise the spine.
literally a small bag or pouch. Inside a cell, a vesicle is a small organelle surrounded by its own membrane.
marked by a rapid, severe, or damaging course.
a microorganism smaller than a bacteria, which cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself.
an organic (carbon-containing) compound necessary for normal physiological function that cannot be synthesized in adequate amounts, and must therefore be obtained in the diet.

Glossary: W, X, Y, Z
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Zoellinger Ellison syndrome
a rare disorder caused by a tumor called a gastrinoma, most often occurring in the pancreas. The tumor secretes the hormone gastrin, which causes increased production of gastric acid leading to severe recurrent ulcers of the esophagus, stomach, and the upper portions of the small intestine.

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