Glossary

adrenal glands A pair of small glands, one located on top of each kidney, that produce steroid hormones, adrenaline, and noradrena-line to help control heart rate, blood pressure, and other important body functions. antibody A protein that is manufactured by white blood cells to identify, neutralize, or destroy bacteria, viruses, and other harmful microorganisms. antigen A substance that can trigger an immune response, causing the production of an antibody as part of the body's defense against infection. Many antigens are not found naturally in the body; they include microorganisms, toxins, and tissues from another person used in an organ transplant.

brain stem Composed of midbrain, pons, and medulla; contains reticular activating system and other key centers. calcium A mineral that makes bones and teeth strong, helps muscles work, and aids in proper blood clotting. carbohydrate Sugars and starches that are the most efficient source of food energy. The most basic carbohydrate is a simple sugar (such as glucose or fructose), which serves as a building block for complex carbohydrates (starchy foods like pastas, whole grains, and potatoes). cell The basic structural unit of all life. All living matter is composed of cells. central nervous system (CNS) The brain and spinal cord; one of the two major divisions of the nervous system. The CNS is the control network for the entire body. cerebrospinal fluid (CSF) The fluid that fills the areas surrounding the brain and spinal cord.

chromosome An H-shaped structure inside the cell nucleus made up of tightly coiled strands of genes. Each chromosome is numbered (in humans, from 1 through 46) and contains DNA, sequences of which make up genes. cognitive The process of knowing in the broadest sense, including perception, memory, and judgment.

cognitive abilities Mental abilities such as judgment, memory, learning, comprehension, and reasoning. complete blood count (CBC) The number of red blood cells, white blood cells, and platelets in a sample of blood. corticosteroid A group of drugs based on the structure of cortisone (a hormone produced by the adrenal glands) with anti-inflammatory properties.

DNA One of two nucleic acids (the other is RNA) found in the nuclei of all cells. DNA contains genetic information on cell growth, division, and cell function. echolalia Repetition of words or phrases. endocrine glands Glands that manufacture and secrete hormones into the blood. Endocrine glands include the pituitary, thyroid, parathyroid, and adrenal glands, the ovaries and testes, placenta, and part of the pancreas. enzyme A protein that promotes essential functions involved in cell growth and metabolism. folate Also called folic acid, this B vitamin helps the body make nucleic acids (RNA and DNA), amino acids, and red blood cells. gene The biological unit of heredity. Each gene is located at a specific spot on a particular chromosome and is made up of a string of chemicals arranged in a certain sequence along the DNA molecule. gram-negative bacteria A type of bacteria that resists the chemical stain used in Gram's method of identifying microorganisms for characterization purposes. gram-positive bacteria A type of bacteria that retains the violet color of the stain used in Gram's method of identifying microorganisms for characterization purposes. hemoglobin A protein in red blood cells that carries oxygen from the lungs to the body's tissues.

hormones Chemical messengers secreted by endocrine glands to regulate the activity of target cells that play a role in sexual development, calcium and bone metabolism, growth, and many other activities. hypothalamus A brain structure composed of many nuclei with different functions, including regulation of activities of internal organs, monitoring information from the autonomic nervous system, and controlling the pituitary gland. iron A mineral that is an important part of hemoglobin, the blood's oxygen-carrying molecule. Iron also helps the body resist infection and use energy from food. larynx Also called the "voice box," this is the part of the throat containing the vocal cords. lymph gland Also known as a lymph node, this tissue mass contains lymphocytes that filter the lymphatic fluid. lymphatic system The tissues and organs (including the bone marrow, spleen, thymus, and lymph glands) that produce and store cells that fight infection and the network of channels that carry lymph. lymphocyte A type of white blood cell that helps produce antibodies and other substances that fight infection and diseases.

mast cell A type of white blood cell. meninges The membranes that cover and protect the brain and spinal cord. metabolism The chemical and physiological process by which the body builds and maintains itself, and by which it breaks down food and nutrients to produce energy. peptide Any compound consisting of two or more amino acids, the building blocks of proteins.

pharynx The throat area that starts behind the nose and ends at the top of the trachea (windpipe) and esophagus. platelet A type of blood cell that helps prevent bleeding by causing blood clots to form. protein A major component of all body tissue that helps the body grow and repair itself. Protein is also a necessary component of hormones, enzymes, and hemoglobin. red blood cell A cell (also called an erythrocyte)

that carries oxygen to all parts of the body. strabismus Weakness of eye muscles that allows eyes to cross. tactile The ability to receive and interpret stimuli through contact with the skin. thyroid gland A gland located beneath the larynx that produces thyroid hormone and helps regulate growth and metabolism. ventricles Four natural cavities in the brain that are filled with cerebrospinal fluid. virus The smallest known type of infectious agent, causing diseases that range from mild (such as warts) to extremely serious (rabies, AIDS, and probably some types of cancer). white blood cell A blood cell that does not contain hemoglobin, including lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.

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