Glossary
- Page ID
- 84753
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| Words (or words that have the same definition) | The definition is case sensitive | (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] | (Optional) Caption for Image | (Optional) External or Internal Link | (Optional) Source for Definition |
|---|---|---|---|---|---|
| (Eg. "Genetic, Hereditary, DNA ...") | (Eg. "Relating to genes or heredity") |  |
The infamous double helix | https://bio.libretexts.org/ | CC-BY-SA; Delmar Larsen |
| Word(s) | Definition | Image | Caption | Link | Source |
|---|---|---|---|---|---|
| FR | free radical | ||||
| LP | lipid peroxide | ||||
| NO | nitric oxide | ||||
| O2 | super oxide free radical | ||||
| OH | hydroxyl free radical | ||||
| VO2 max | the amount of oxygen used per kilogram of body weight per minute while engaging in exercise at the fastest rate attainable by the person performing the exercise; aerobic capacity | ||||
| β-A, beta-amyloid | a protein of unknown function that is abundant in senile plaques | ||||
| Absorption | the passage of materials contained within the GI tract into the circulatory system | ||||
| Accommodation | the process of adjusting the curvature of the lens to focus light from – objects located at different distances from the eye | ||||
| Acetylcholine | a neurotransmitter used in numerous activities (e.g., memory; controlling skeletal muscle, cardiac muscle, smooth muscle, and certain glands) | ||||
| Acquired active immunity | the ability to produce a secondary immune response that is strong enough to prevent significant adverse effects from any subsequent encounter with the antigen | ||||
| Action potential | the process by which an impulse travels along a neuron or a muscle cell | ||||
| Acute gastritis | an abnormal condition consisting of short term inflammation of the stomach | ||||
| AD | Alzheimer’s disease | ||||
| Ad libitum, AL | with reference to diet, being able to eat as much as desired at any time | ||||
| ADH | antidiuretic hormone | ||||
| Advanced glycation end-product, AGE | a protein chain containing glucose cross-links | ||||
| Afterimage | a lingering perception that an image is present after the actual image in the eye has changed or disappeared | ||||
| AGE | advanced glycation end product | ||||
| Age changes | developmental changes that occur in the later years of life | ||||
| Age-related macular degeneration, AMD | a disease of the eye that reduces vision by causing degeneration of the cones in the macular region of the retina | ||||
| AL (ad libitum) | with reference to diet, being able to eat as much as desired at any time | ||||
| Allergic response | an excessive undesirable immune response against a foreign antigen | ||||
| Alveolus (pl., alveoli) | a small cup-shaped outpocketing in the lung where gas exchange occurs | ||||
| Alzheimer's disease , AD | a form of dementia characterized by memory loss and by the presence of excessive senile plaques and neurofibrillar tangles in the brain | ||||
| Amino acid | a molecular unit that makes up protein molecules | ||||
| Amyloid | a specific type of protein found within or between cells | ||||
| Amyloid precursor protein, APP | a protein in cell membranes whose breakdown yields beta-amyloid and other products | ||||
| Anemia | an abnormal condition consisting of a low concentration of red blood cells in the blood | ||||
| Aneurysm | an abnormal outpocketing of either a blood vessel or the wall of the heart | ||||
| Antagonistic pleiotropy | having several effects that oppose one another | ||||
| Antibody | a protein molecule that is produced by immune system plasma cells and that adheres to antigens and assists in combating antigens | ||||
| Antigen | a substance that causes an immune response | ||||
| Antigen-specific receptor | a type of surface receptor on a T-cell that allows that T-cell to bind to one and only one substance capable of initiating an immune response | ||||
| Antioxidant, AOX | a substance that converts free radicals into substances that are not free radicals by donating one or more electrons to other molecules | ||||
| AOX (Antioxidant) | a substance that converts free radicals into substances that are not free radicals by donating one or more electrons to other molecules | ||||
| APO | apolipoprotein | ||||
| APOE | apolipoprotein E | ||||
| Apolipoprotein E , APOE | a lipoprotein that helps move cholesterol and other lipoproteins from cell to cell and through cell membranes, and also seems to help in neuron development and repair | ||||
| Apoptosis | programmed cell death | ||||
| APP | amyloid precursor protein | ||||
| Appendicitis | an abnormal condition involving inflammation of the appendix | ||||
| Aqueous humor | the liquid that fills the region in the eye behind the cornea and in front of the lens | ||||
| Arthritis | an abnormal condition that involves inflammation of joints between bones | ||||
| Ascites | the presence of extra fluid in the abdominal cavity | ||||
| Atherosclerosis | a disease involving the formation and enlargement of a weak scar-like material in the walls of arteries | ||||
| ATP, adenosine triphosphate | a nucleotide used for transferring energy within a cell | ||||
| Atrophic gastritis | an abnormal condition resulting in excessive thinning of the lining of the stomach | ||||
| Auerbach's plexus | a network of nerve cells in the wall of the GI tract that helps to control functions of the GI tract | ||||
| Auto-antibody | an antibody that can act against a native body material | ||||
| Autoimmune reaction | an immune response against a normal body part | ||||
| Autonomic motor neuron | a motor neuron involved in controlling either cardiac muscle, smooth muscle, or a gland | ||||
| Axon | a neuron projection that conducts impulses away from the nerve cell body of that neuron | ||||
| Basement membrane | a non-cellular layer between a layer of cells and the material under the layer of cells | ||||
| Basilar membrane | a flexible membrane within the cochlea of the ear that supports the organ of corti | ||||
| B-cell | a type of specialized lymphocyte that can produce antibody-secreting cells as part of an immune response; B-lymphocyte | ||||
| Bed sore | a patch of skin that has died because it received insufficient blood flow; a decubitus ulcer | ||||
| Benign neoplasm | a neoplasm that does not spread to other areas | ||||
| Benign prostatic hypertrophy, BPH | an abnormal non-cancerous condition in which the prostate gland grows and becomes excessively enlarged | ||||
| Bile | a liquid secreted by the liver and stored in the gall bladder and that contains bilirubin, cholesterol and other waste materials | ||||
| Bilirubin | a substance consisting of remnants of hemoglobin molecules from red blood cells | ||||
| Biological aging | aging in the physical structures and functioning of the body that affects either the body’s ability to survive or its appearance | ||||
| Biorhythm | a cyclic fluctuation or oscillation of a biological process | ||||
| BMR, basal metabolic rate | the rate of energy use needed to sustain body functions when a person is awake and in a state of complete rest | ||||
| Bone marrow | the specialized tissue that is housed within bones and that produces blood platelets and some types of blood cells | ||||
| Bone marrow | the specialized tissue that is housed within bones and that produces blood platelets and some types of blood cells | ||||
| Bone matrix | the material between bone cells in bone tissue | ||||
| BPH, benign prostatic hypertrophy | an abnormal non-cancerous condition in which the prostate gland grows and becomes excessively enlarged | ||||
| Bruch's membrane | a non-cellular membrane that lies between the pigmented epithelium of the retina and the choroid layer | ||||
| Caloric restriction, CR | receiving a diet that is limited in the number of calories it contains | ||||
| Cancer | a disease consisting of the uncontrolled reproduction and spreading of cells; a neoplasm that spreads to other areas; a malignant neoplasm | ||||
| Carbohydrate | a molecule consisting of one or more simple sugar molecules | ||||
| Cardiac muscle | the type of muscle that is found only in the heart | ||||
| Cardiac output, CO | the amount of blood pumped by each ventricle of the heart in one minute | ||||
| Cataracts | the condition of having so many opacities close to the center of the lens of the eye that vision is greatly impaired | ||||
| Cavity | a spot of decay on a tooth | ||||
| CCK, cholecystokinin | a hormone from the small intestine that stimulates emptying of the gall bladder | ||||
| Cells | the living structural and functional units of the body | ||||
| Central nervous system , CNS | the combination of the brain and the spinal cord | ||||
| Cerumen | a semi-solid waxy material that is secreted into the ear canal by ceruminous glands; ear wax | ||||
| Cervix | the narrow lower portion of the uterus | ||||
| Chain reaction | with free radicals, a sequence of chemical reactions where free radicals react with substances that are not free radicals and form new free radicals | ||||
| Chronological aging | the passage of time since birth | ||||
| Cilia | microscopic hair-like structures that project from cells and that swing back and forth | ||||
| Circadian rhythm | a cyclic fluctuation or oscillation that repeats itself approximately every 24 hours | ||||
| Cirrhosis | an abnormal condition characterized by the presence of much scar tissue within the liver because of chronic liver damage | ||||
| Clonal selection | the process of destroying lymphocytes capable of binding to native body materials and initiating an immune response against native body materials | ||||
| CNS | central nervous system | ||||
| Collagen | a tough non-elastic fibrous structural protein that is found outside of cells | ||||
| Colorectal cancer | cancer of the large intestine | ||||
| Compact bone | the type of bone tissue that is dense and that forms the outer layer of bone; cortical bone | ||||
| Compliance | the ability to increase or decrease in volume as a result of a change in pressure | ||||
| Conduction | the process by which an impulse travels along a neuron | ||||
| Cones | photoreceptors in the eye that have different responses to different colors of light | ||||
| Coronary artery | a blood vessel that transports blood to capillaries within heart muscle | ||||
| Cortical bone | the type of bone tissue that is dense and that forms the outer layer of bone; compact bone | ||||
| Cosmetic aging | changes in outward appearance with advancing age | ||||
| Cough reflex | a reflex that causes bursts of air to be expired rapidly to force materials out of airways located below the pharynx | ||||
| CR | caloric restriction | ||||
| Creatinine | a waste material from muscle cells | ||||
| Cross-link | a chemical connection between molecules | ||||
| Cross-sectional study | a study that places individuals with similar ages into groups and evaluates them one time | ||||
| Cross-sequential study | a study method that combines the cross-sectional method and the longitudinal method. Cross-sectional studies on age categories are repeated on the same population as time passes. | ||||
| Crush fracture | a type of fracture caused by compression forces acting on a bone that result in collapse of the bone | ||||
| Crystallized intelligence | using cognitive skills with familiar learned activities | ||||
| cT-cells | cytotoxic T-cell | ||||
| Cytoskeleton | a network of microfilaments and microtubules that provides support within a cell | ||||
| Dead space | the volume of air in the lower airways that does not reach the alveoli during ventilation but that remains in the lower airways during ventilation | ||||
| Declarative memory | remembering specific facts that a person tried to learn so they could be | ||||
| Defecation | the elimination of feces through the anus; a bowel movement | ||||
| Dementia | an abnormal condition that involves a serious decline in memory functioning accompanied by a major decline in at least one other mental function | ||||
| Dementia with Lewy bodies | a type of age-related dementia characterized by the presence of excess round masses of clumped microfilaments in neurons | ||||
| Dendrite | a neuron projection that conducts impulses toward the nerve cell body of that neuron | ||||
| Dentin | a firm layer located internal to the enamel of a tooth | ||||
| Depth perception | the perception of the distance from the eyes to an object being viewed; binocular vision | ||||
| Dermis | the layer of the skin underlying the epidermis | ||||
| Development | developmental changes that occur before birth or during childhood | ||||
| Developmental changes | irreversible normal changes in a living organism that occur as time passes | ||||
| DHEA | dehydroepiandrosterone; a steroid hormone of unknown function | ||||
| DHT | a principal sex hormone in men, much of which is produced by the testes and the prostate gland; 5-alpha-dihydrotestosterone | ||||
| Diabetes mellitus | a disease that involves inadequate insulin production or inadequate sensitivity of cells to insulin and that results in inhibition of the regulation of blood glucose levels | ||||
| Diabetic retinopathy (DR) | a disease of the eye that is associated with diabetes mellitus and that reduces vision because of sorbitol accumulation in the retina | ||||
| Diarrhea | the condition of having more than three relatively liquid and voluminous bowel movements in one day | ||||
| Diastolic pressure | the lowest blood pressure attained between contractions of the ventricles of the heart | ||||
| Dietary Reference Intakes, DRIs | a comprehensive method for establishing and evaluating recommended dietary intake recommendation | ||||
| Dietary restriction, DR | receiving a diet that is limited in the amount of food | ||||
| Diffusion | the movement of materials from an area where they are in high concentration to an area where they are in lower concentration | ||||
| Diglyceride | a lipid molecule composed of one glycerol and two fatty acid molecules | ||||
| Disaccharide | a molecule consisting of two simple sugar molecules | ||||
| Diurnal rhythm | a repetitive cycle of events that occurs once in each 2-hour period; circadian rhythm | ||||
| Diverticula | deep outpocketings in the wall of the large intestine | ||||
| Diverticulitis | the abnormal condition of having inflamed diverticula | ||||
| Diverticulosis | a disease condition consisting of the presence of deep outpocketings in the wall of the large intestine | ||||
| Dizziness | the sensation that the body is unstable | ||||
| DM | diabetes mellitus | ||||
| DNA, deoxyribonucleic acid | the nucleic acid that makes up genes | ||||
| DR | dietary restriction | ||||
| dT-cells | delayed hypersensitivity T-cell | ||||
| Duodenal peptic ulcer | a peptic ulcer in the duodenum | ||||
| Early onset AD | a form of Alzheimer's disease with onset before age 65, usually during the sixth decade of life | ||||
| Economic aging | age changes in financial status | ||||
| Edema | the presence of extra fluid between cells | ||||
| Ejaculation | the expulsion of semen from the penis caused by reflexive rhythmic peristaltic contractions of the urethra, other male reproductive ducts, and muscles at the base of the penis | ||||
| Elastase | an enzyme that breaks down elastic fibers into elastin peptides | ||||
| Elastin | a resilient structural protein that is found outside of cells | ||||
| Elastin peptides | short pieces of the protein chain that composed elastin | ||||
| Electron | small negatively charged particle that moves about at a distance from the nucleus of an atom | ||||
| Electron transport | a series of steps where electrons lose energy | ||||
| Embolus, emboli | a mass (usually a blood clot) that is transported within a blood vessel | ||||
| Enamel | a hard substance that covers the exposed surface a tooth | ||||
| Endocrine gland | a structure that has hormone secretion as its primary function | ||||
| Endolymph | the fluid that fills the membranous chambers of the inner ear | ||||
| Endometrium | the innermost layer of the uterus | ||||
| Endothelium | the innermost layer of a blood vessel | ||||
| Endurance | the length of time that vigorous activities can be performed without stopping | ||||
| Energy | the power that makes things happen; the ability to do work | ||||
| Energy balance | the condition of having the amount of energy taken in over a period of time equal the amount of energy used during the same period | ||||
| Enzyme | a protein substance that increases the rate of chemical reactions in a regulated manner | ||||
| Epidermis | the outer layer of the skin | ||||
| Episodic memory | remembering the times and places at which events happened | ||||
| Erectile tissue | the spongy tissue in the penis and the clitoris that fills with blood and becomes firm during sexual arousal | ||||
| Erection | the swelling, elongating, and stiffening of the penis due to engorgement of the erectile tissue with blood | ||||
| ERT, estrogen replacement therapy | the administration of estrogen-like substances to bolster the effects of estrogen in the body when levels of endogenous estrogen become low | ||||
| Estrogen | a principal sex hormone, most of which is produced by the ovaries | ||||
| Evolutionary theory | a theory that attempts to explain how aging developed in concert with natural selection | ||||
| Expiration | the movement of air out of the respiratory system; exhalation | ||||
| Expiratory reserve volume, ERV | the amount of air that can be forcefully expired after expiring the tidal volume | ||||
| Explicit memory | remembering specific facts that a person tried to learn so they could be remembered | ||||
| External ear | the region of the ear external to the eardrum | ||||
| Familial AD, FAD | a form of Alzheimer's disease with onset before age 65, usually during the sixth decade of life | ||||
| Fat | lipid molecules composed of one glycerol and three fatty acid molecules; triglycerides | ||||
| Fecal incontinence | the abnormal condition of eliminating feces at inappropriate times at least once per month | ||||
| Feces | a mixture consisting largely of undigested materials, waste products, and bacteria that is located in the large intestine | ||||
| Fiber | dietary polysaccharides that cannot be broken down by digestive enzymes | ||||
| Fibroblast | a cell that can produce and secrete proteins that form collagen and elastin fibers | ||||
| Fibrocartilage | the type of cartilage that consists of a smooth, slippery, and resilient substance that contains many thick collagen fibers and that has the consistency of hard rubber | ||||
| Filtration | the separation of small substances from large ones when fluid pressure forces the small substances through the pores in a membrane | ||||
| Fluid intelligence | using cognitive skills in new situations to learning novel problem-solving, motor activities, or reasoning | ||||
| Foam cell | a fat-filled macrophage in a vessel wall | ||||
| Follicle | in the ovary, a cluster of cells that surrounds a developing egg cell | ||||
| Fovea centralis | the central region of the macula lutea that contains the highest concentration of cones | ||||
| Free radical, FR | an atom or molecule with an unpaired electron (* = unpaired electron) | ||||
| FSH | follicle stimulating hormone | ||||
| Gag reflex | a reflex that causes closure of the openings into the larynx and the esophagus when irritating materials enter the pharynx | ||||
| Gall stone | a solid mass formed from materials in bile | ||||
| Gas exchange | the movement of gases between the atmosphere and the blood | ||||
| Gastric peptic ulcer | a peptic ulcer in the stomach | ||||
| Gastric refluxing | the movement of stomach contents upward and into the esophagus | ||||
| Gene | a length of DNA used to direct the formation of an amino acid chain | ||||
| Genitalia | external reproductive structures | ||||
| Gerontology | the study of aging | ||||
| GFR, glomerular filtration rate | the rate of filtration through the glomeruli | ||||
| GH | growth hormone | ||||
| GI tract, gastrointestinal tract | the portion of the digestive system that consists of a tube extending from the mouth to the anus | ||||
| Glare | seeing bright areas in the wrong places in the field of view because of scattered light striking the retina in the wrong places and in a disorganized way | ||||
| Glaucoma | a disease of the eye that reduces vision by causing an increase in pressure within the eye due to an accumulation of aqueous humor | ||||
| Glomerulus | a tuft of capillaries in each nephron in the kidney | ||||
| Glucagon | a hormone from the pancreas that tends to increase blood sugar levels | ||||
| Glucose | a simple sugar that is found in abundance in the body and that provides major source of energy for cells | ||||
| Glycation | using glucose to form cross-links between protein chains | ||||
| Glycoprotein | a molecule consisting of a combination of carbohydrate and protein | ||||
| Glycosylation | using glucose to form cross-links between protein chains | ||||
| Glycoxydation | using glucose to form cross-links between protein chains | ||||
| Gonads | the primary reproductive organs (i.e., testes in males, ovaries in females), which produce hormones and sperm cells or egg cells | ||||
| H2O2 | hydrogen peroxide | ||||
| Hair cells | neurons in the inner ear that respond to bending caused by different stimuli (e.g., vibrations, gravity, rotation of the head) | ||||
| Hayflick limit | the maximum number of divisions a cell can undergo | ||||
| HCl | an acid secreted by the stomach; hydrochloric acid | ||||
| HDL | high density lipoprotein | ||||
| Hearing | the conscious perception of sound vibrations | ||||
| Heart rate (HR) | the number of times the heart beats in one minute | ||||
| Heat shock proteins | proteins produced by cells when they are stressed. Heat shock proteins have a protective effect. | ||||
| Hemorrhoid | a varicose vein in the rectum or the anal canal | ||||
| Heterochromatin | masses of tightly wound DNA and protein | ||||
| Histamine | a substance from cells that initiates inflammation | ||||
| HLA protein | a type of protein molecule on a cell surface that serves to identify that cell as belonging to a specific person | ||||
| HLA receptor | a surface receptor molecule on a T-cell that is able to bind to specific identification molecules (i.e., HLA protein) found on other body cells | ||||
| Homeostasis | the state of having proper and fairly steady conditions | ||||
| Hormone | a substance that result from manufacturing processes in cells, that is secreted into the blood, and that alters the activities of cells in other parts of the body | ||||
| hT-cell | helper T-cell | ||||
| Hyaline cartilage | the type of cartilage that consists of a smooth, slippery, white substance having the consistency of hard rubber | ||||
| Hydrogen peroxide (H2O2) | a reactive oxygen species containing two hydrogen atoms and two oxygen atoms | ||||
| Hydroxyl radical, OH | a free radical containing hydrogen atom and one oxygen atom and having 17 electrons | ||||
| IDDM, insulin-dependent diabetes mellitus | the type of diabetes mellitus wherein death ensues unless insulin therapy is provided | ||||
| IL-2, interleukin-2 | a substance secreted by hT-cells that enhances an immune response by stimulating macrophages to phagocytize more antigen, stimulating the production of more of the hT-cells and cT-cells, and stimulating the proliferation and activity of B cells | ||||
| IL-1, interleukin-1 | a secretion that stimulates T-cells to produce more identical T-cells during an immune response | ||||
| IL-6, interleukin-6 | an interleukin that stimulates inflammation, macrophages, osteoclasts, and other activities | ||||
| Immune response | the activities of the immune system whereby the system combats an antigen | ||||
| Implicit memory | remembering specific facts that a person did not try intentionally to learn so they could be remembered | ||||
| Impotence | the inability of a man to engage in sexual intercourse because the penis is not sufficiently erect to be inserted into the vagina | ||||
| Incidental memory | remembering information or skills that were self-taught | ||||
| Inhibin | a sex hormone from gonads that helps regulate sex hormone production by the | ||||
| Initiation | with free radicals, a chemical that converts a molecule to a free-radical | ||||
| Inner ear | the region of the ear internal to the oval window | ||||
| Inspiration | the movement of air into the respiratory system; inhalation | ||||
| Inspiratory reserve volume, IRV | the amount of air that can be forcefully inspired after inspiring the tidal volume | ||||
| Insulin | a hormone from the pancreas that tends to decrease blood sugar levels | ||||
| Insulin-like growth factor, IGF | signaling substances from cells that stimulate growth and regulate other cell activities | ||||
| Intercellular material | substances located between cells | ||||
| Interleukin, IL | a signaling substance that helps regulate immune responses and other body functions | ||||
| Interneuron | a neuron that carries impulses from one neuron to another neuron | ||||
| Interstitial cells of Leydig | the cells among the seminiferous tubules in the testes that produce sex hormones | ||||
| Intervertebral disc | a pad of fibrocartilage located between the vertebrae in the spinal column | ||||
| Intrinsic factor | a substance secreted by the stomach that promotes the absorption of vitamin B12 by the small intestine | ||||
| Ion | an atom that has lost or gained one or more electrons | ||||
| Ischemia | the condition of having inadequate blood flow | ||||
| Jaundice | the condition wherein parts of the body have a yellow or brown color because of the accumulation of bilirubin | ||||
| Joint capsule | the thick layer of fibrous material that encases a synovial membrane and that helps to bind bones together | ||||
| Kcal, kilocalorie | the unit of energy most often used in measuring the energy content in food | ||||
| Keratin | a structural protein found in the outermost layer of the epidermis, in air, and in the nails of the fingers and toes | ||||
| Keratinocyte | a cell that can make keratin | ||||
| Ketoacid | a small molecule resulting from the breakdown of a fatty acid or an amino acid; ketone | ||||
| Ketoacidosis | the abnormal condition of having excess ketoacids in the body | ||||
| Ketone | a small molecule resulting from the breakdown of a fatty acid or an amino acid; ketoacid | ||||
| Lacrimal fluid | a liquid secreted by the lacrimal glands that bathes the front surface of the eye | ||||
| Lactase | an enzyme that assists in the breakdown of lactose | ||||
| Lactic acid | a substance produced by the partial breakdown of glucose in cells that have a low amount of oxygen | ||||
| Lactose | a type of sugar that consists of one glucose molecule joined to one galactose molecule; milk sugar | ||||
| Lactose intolerance | the condition of producing an insufficient quantity of lactase to properly digest dietary lactose | ||||
| Langerhans cell | a cell in the epidermis of the skin that carries out phagocytosis and assists in initiating an immune response | ||||
| Late onset AD | a form of Alzheimer's disease with onset usually after age 60 | ||||
| LDL | low density lipoprotein | ||||
| Lewy body | a round mass of clumped microfilaments in neurons found in excess numbers in types of dementia including Parkinson's disease | ||||
| LH | luteinizing hormone | ||||
| Life expectancy of a population | the average age at which death occurs for the members of a population | ||||
| Ligament | a cable-like structure composed largely of collagen fibers that binds one bone to another bone | ||||
| Lipid peroxide, LP | a lipid molecule that is a free radical | ||||
| Lipofuscin | a mixture of certain chemical waste products from normal cell activities | ||||
| Lipoprotein | a molecule consisting of a combination of lipid and protein | ||||
| Localization of sound | the perception of the direction from which a sound originates | ||||
| Longitudinal study | a study that evaluates individuals over a period of time | ||||
| Lower airways | air passages within the lungs that conduct air to and from alveoli | ||||
| Lymphocyte | a type of white blood cell that functions as part of the immune system | ||||
| Lymphokines | a group of substances from lymphocytes that augments the defensive effects of an immune response in several ways including by activating macrophages and certain lymphocytes, by causing inflammation, and by protecting normal body cells from viruses | ||||
| Macrophage | a cell outside of the blood that performs phagocytosis and that assists in immune responses | ||||
| Macula lutea | the region of the retina that is in line with the center of the cornea and the lens and that has a high concentration of cones | ||||
| Maillard reaction | a reaction that forms glucose cross-links between protein chains | ||||
| Malignant neoplasm | a neoplasm that spreads to other areas, cancer | ||||
| Malnutrition | the condition of lacking nutritional homeostasis | ||||
| Maltose | a molecule that consists of two glucose molecules linked together | ||||
| Maturation | developmental changes that result in the transformation of a child into an adult | ||||
| Maximum longevity (XL) | the greatest age ever achieved by any member of a species | ||||
| mB-cell | memory B-cell | ||||
| Mean longevity (ML) | the average age at which death occurs for the members of a population | ||||
| Melanin | a brown pigment found in the epidermis, in hair, and in other places | ||||
| Melanocyte | a cell that can make melanin | ||||
| Memory | with regard to the immune system, the ability of the system to respond to an antigen more quickly and more intensely when the antigen is encountered a second or subsequent time | ||||
| Menopause | the time when age changes in the ovaries cause menstrual cycles to cease for at least one year | ||||
| Menstrual cycle | a sequence of events in the uterus that repeats itself and that involves thickening, deterioration, and shedding of the endometrium; uterine cycle | ||||
| Menstruation | the shedding and passage of the endometrium and blood through the vagina | ||||
| Metastasis | the spreading of cancer from one location to another | ||||
| Metastatic cancer | cancer that is transported to other parts of the body through blood, lymph, or other body fluids | ||||
| Middle ear | the region of the ear between the eardrum and the oval window | ||||
| Minute volume | the volume of air that is inspired or expired per minute | ||||
| Mitochondria | organelles that release useful energy for cells | ||||
| Mitochondrial DNA, mtDNA | DNA in mitochondria | ||||
| ML | mean longevity | ||||
| Molecule | a group of atoms or ions bound together in a specific ratio | ||||
| Monoglyceride | a lipid molecule composed of one glycerol and one fatty acid molecule | ||||
| Monosaccharide | a single simple sugar molecule | ||||
| Motor end plate | the modified area of a muscle cell membrane that contains receptor molecules to receive and respond to neurotransmitter molecules from a motor neuron | ||||
| Motor neuron | a nerve cell that conducts impulses that control the actions of a muscle or a gland | ||||
| Motor unit | the combination of one motor neuron and all the muscle cell it controls | ||||
| mRNA (messenger RNA) | a nucleic acid that carries information to determine the sequence of amino acids in a protein molecule | ||||
| mT-cell | memory T-cell | ||||
| mtDNA | mitochondrial DNA | ||||
| Myelin | a substance that coats axons and dendrites and that allows impulses to travel faster along these structures | ||||
| Myocardium | the layer of muscle in the heart, which is the middle layer of the heart | ||||
| Myofilament | a protein filament in a muscle cell that is involved in producing contraction of the cell | ||||
| Myoglobin | a type of protein in muscle cells that attracts oxygen from the blood into muscle cells and stores oxygen | ||||
| Myometrium | the muscular middle layer of the uterus | ||||
| Near point (of accommodation) | the smallest distance from the eye that an object can be located and still be seen clearly | ||||
| Negative energy imbalance | the condition wherein the amount of energy taken in over a period of time is less than the amount of energy used during the same period | ||||
| Negative feedback | a process that prevents or reverses changes | ||||
| Neoplasm | a group of cells that continue cell reproduction in an uncontrolled fashion | ||||
| Nephron | a unit of structure and function in the kidney consisting of a glomerulus, Bowman's capsule, and a renal tubule | ||||
| Neurofibrillar tangle (NTs) | a network of fibers composed of one or two protein fibers in a neuron twisted into a helix | ||||
| Neuromuscular junction | the site of transmission of an impulse from a neuron to a muscle cell | ||||
| Neuron | a nerve cell | ||||
| Neurotransmitter | a substance that transmits an impulse from a neuron to another structure | ||||
| NIDDM (non-insulin dependent diabetes mellitus) | the type of diabetes mellitus wherein survival is not dependent upon the administration of insulin therapy | ||||
| Nitric oxide (*NO) | a free radical that serves as a signaling substance in the body | ||||
| NK cell (natural killer cell) | a non-specific lymphocyte that destroys cancer cells | ||||
| Non-enzymatic glycation | reactions forming glucose cross-links between protein chains without the use of enzymes | ||||
| Norepinephrine | a substance that is used as a neurotransmitter and as a hormone and the causes effects of the sympathetic nervous system other than those in the skin | ||||
| NT | neurofibrillar tangle | ||||
| Obesity | having a body weight that is greater than 20 percent more than the desirable body weight and a percent body fat that exceeds 25 percent (men)or 30 percent (women), or having a body mass index of more than 30 | ||||
| Opacities | opaque spots in the lens of the eye | ||||
| Optic disc | the region of the retina to which the optic nerve is attached | ||||
| Oral mucosa | the lining of the oral cavity | ||||
| Organ | an organized group of different tissues that performs certain functions | ||||
| Organ of Corti | the rows of neurons on the basilar membrane of the inner ear that respond to vibrations | ||||
| Organelle | a structural component of a cell that is composed of several or many molecules | ||||
| Osmotic pressure | a measure of the total concentration of dissolved materials in a liquid | ||||
| Osteoarthritis | a type of arthritis that is characterized by the deterioration of cartilage and the formation of extra bone | ||||
| Osteoblast | the type of cell in bone tissue that produces bone matrix | ||||
| Osteoclast | the type of bone cell that removes bone matrix from a bone | ||||
| Osteocyte | the type of bone cell that remains quiescent unless some severe condition develops in the bone | ||||
| Osteon | a long thick tube of bone matrix which, when fused with other osteons, composes compact bone tissue | ||||
| Osteoporosis | a disease of the skeletal system that causes substantial reductions in the quantity and strength of bone matrix | ||||
| Otolith | a heavy crystal that is embedded in the gel attached to the ends of the protruding hair cells in the utricle and the saccule of the inner ear | ||||
| Ovarian cycle | a sequence of events in the ovaries that repeats itself and that results in the production of hormones and ova | ||||
| Overweight | having a body weight that is 10=20 percent greater than the desirable body weight | ||||
| Ovulation | the release of an ovum from an ovary | ||||
| Oxidation | removing one or more electrons from an atom or molecule | ||||
| Oxidative phosphorylation | chemical reactions where phosphate groups and the energy from electrons are transferred to molecules (e.g., ATP) | ||||
| Pancreatitis | inflammation of the pancreas | ||||
| Pentosidine | glucose cross-links between certain specific amino acids in protein chains | ||||
| Peptic ulcer | an abnormal condition consisting of a pit created by the death and pealing away of cells because of the presence of secretions from the stomach | ||||
| Perfusion | the passage of blood through the vessels in a body part | ||||
| Perilymph | the fluid that fills the bony chambers of the inner ear | ||||
| Periodontal disease | a disease at the base of teeth | ||||
| Peripheral nervous system (PNS) | all parts of the nervous system outside of the brain and the spinal cord, all nerves | ||||
| Peristalsis | a wave of contraction that travels along a tube-shaped structure and that causes material contained within the tube to move along progressively | ||||
| Peroxyl radical (*ROO) | a free radical containing an organic molecule joined to two oxygen atoms | ||||
| Peroxynitrite anion (ONOO-) | a reactive oxygen species that is toxic to cells | ||||
| Phagocytosis | the process by which a cell engulfs a particle and takes it into the cell | ||||
| Photoreceptor | a neuron in the sensory retina that responds to light by starting impulses in the form of action potentials | ||||
| Physiological theory | a theory that attempts to explain how aging occurs in a living animal | ||||
| Pigmented epithelium | the outer layer of the retina | ||||
| Plasma | the liquid portion of blood | ||||
| Plasma cells | a B-cell that produces antibodies | ||||
| PMN | polymorphonuclear leukocyte (a type of white blood cell) | ||||
| PNS | peripheral nervous system | ||||
| Polysaccharide | a molecule consisting of many simple sugar molecules | ||||
| Polyunsaturated fatty acid, PUFA | a fatty acid molecule with more than one double bond in the carbon chain | ||||
| Positive energy imbalance | the condition wherein the amount of energy taken in over a period of time is greater than the amount of energy used during the same period | ||||
| Post-menopausal osteoporosis | the type of osteoporosis that occurs most commonly in women during the years following menopause; Type I osteoporosis | ||||
| Presbycusis | the ear disorder consisting of a significant decrease in the ability to hear due to aging | ||||
| Presbyopia | farsightedness caused by age-related stiffening of the lens | ||||
| Presenilin | a protein which when mutated is correlated with increased risk of Alzheimer’s disease | ||||
| Primary immune response | the immune response initiated by the first encounter with an antigen | ||||
| Procedural memory | remembering how to perform a process or series of steps | ||||
| Progeroid syndrome | a series of manifestations of aging that occur prematurely | ||||
| Progesterone | a principal sex hormone, most of which is produced by the ovaries | ||||
| Programmed theory | a theory based on the premise that aging occurs in a directed manner | ||||
| Propagation | with free radicals, a sequence of chemical reactions where free radical convert other molecules to a free radicals, leaving the original free radicals in an abnormal shape | ||||
| Prostate gland | a donut-shaped gland in men that surrounds the urethra below its point of connection to the bottom of the urinary bladder | ||||
| Protein | a molecule composed of one or more chains of amino acids | ||||
| Psychological aging | age changes that affect the way a person thinks and behaves | ||||
| PUFA | polyunsaturated fatty acid | ||||
| Pulmonary congestion | an accumulation of blood in pulmonary vessels | ||||
| Pulmonary edema | an accumulation of fluid in the lungs from blood vessels in the lungs | ||||
| Pulmonary embolism | the disease condition of having one or more emboli move into the lungs | ||||
| Pulmonary vessel | a blood vessel involved in perfusion of the lungs (e.g., pulmonary artery, pulmonary capillary, pulmonary vein) | ||||
| Pulp | the nerves, blood vessels, and other soft materials in the innermost region of a tooth | ||||
| RBC | red blood cell | ||||
| RBF, renal blood flow | the amount of blood flow through the kidneys per unit time | ||||
| RDA, Recommended Dietary Allowance | the recommended dietary intake of a nutrient as established by the Food and Nutrition Board of the National Academy of Science | ||||
| Reaction time | the time needed to begin a voluntary motion in response to a stimulus | ||||
| Reactive oxygen species, ROS | highly reactive substances that contain oxygen | ||||
| Reception | the process in a neuron of having an impulse generated in response to environmental conditions or to messages from other neurons | ||||
| Receptor for advanced glycation end product, RAGE | a receptor molecule on a cell that bonds to an advanced glycation end product (AGE) | ||||
| Receptor molecule | a molecule in a cell or on a cell membrane that binds to a substance that is carrying a message to the cell | ||||
| Reflex | an involuntary response to a stimulus | ||||
| Reinitiation | chemical reactions where molecules that were formerly free radical interact and form one or more new free radicals | ||||
| Renin | a substance produced by the kidneys that helps to regulate blood pressure, osmotic pressure, and sodium concentration in the body | ||||
| Replicative senescence, RS | the cessation of cell division by a cell as it ages | ||||
| Residual volume, RV | the amount of air left in the lungs after expiring as much as possible | ||||
| Respiratory rate | the number of breaths per minute | ||||
| Rheumatoid arthritis | a type of arthritis characterized by the destruction of cartilage and bone in a joint | ||||
| RNA, ribonucleic acid | the nucleic acid used to guide the synthesis of protein | ||||
| Rods | photoreceptors in the eye that can respond to dim light but that cannot respond differently to different colors of light | ||||
| ROS | reactive oxygen species | ||||
| Sarcolemma | the cell membrane of a muscle cell | ||||
| Sarcomere | a cluster of myofilaments in a muscle cell | ||||
| Sarcopenia | gradual loss of muscle mass by shrinkage of muscle | ||||
| Sarcoplasmic reticulum | the membranes within a muscle cell that constitutes its endoplasmic reticulum | ||||
| Saturated fat | a molecule of fat having fatty acids containing the maximum number of hydrogen atoms | ||||
| Schwann cells | cells in the peripheral nervous system that form myelin | ||||
| SDAT | Senile dementia of the Alzheimer's type | ||||
| Sebaceous gland | a skin gland that secretes sebum | ||||
| Sebum | an oily substance secreted by sebaceous glands | ||||
| Secondary immune response | an immune response produced by the second or subsequent encounter with an antigen | ||||
| Self-antigen | a native body material that can bind to an antigen-specific receptor and therefore can initiate an immune response against a body component | ||||
| Semen | the mixture of sperm cells and secretions that is released from a man's body during sexual activity | ||||
| Seminiferous tubule | a long and highly coiled tube that produces sperm cells in the testes | ||||
| Senescence | age changes that have detrimental effects | ||||
| Senile dementia of the Alzheimer's type, SDAT | a form of Alzheimer's disease with onset usually after age 60 | ||||
| Senile osteoporosis | the type of osteoporosis that occurs most commonly in people of more advanced age, especially those over age 60; Type II osteoporosis | ||||
| Senile plaque, SPs | a round microscopic masses found near brain synapses and having various mixtures and densities of materials | ||||
| Sensory neuron | a nerve cell that monitors conditions and conducts impulses toward the brain or spinal cord | ||||
| Sensory retina | the layer of the retina that is closest to the vitreous humor and that contains several layers of neurons including rods and cones | ||||
| Skeletal muscle | the type of muscle that is almost always attached to bones of the skeletal system | ||||
| Sleep apnea, SA | a condition consisting of having least five temporary cessation of ventilation per hour or exhibiting at least 10 occasions of depressed ventilation and cessation of ventilation per hour when asleep | ||||
| Sliding hiatal hernia | a structural abnormality wherein a portion of the stomach is situated above the diaphragm and is between the diaphragm and the lower end of the esophagus | ||||
| Smooth muscle | a type of muscle that lacks striations and that is under involuntary control by the nervous system and the endocrine system; visceral muscle | ||||
| Social aging | age changes in the interactions people have with others | ||||
| Somatic motor neuron | a motor neuron that controls skeletal muscle | ||||
| Sorbitol | a type of sugar that is derived from glucose and that tends to accumulate in certain | ||||
| SP | senile plaque | ||||
| Speed of movement | the time from the beginning of a motion to the end of that motion | ||||
| Spongy bone | the type of bone tissue that consists of an open network of trabeculae that are fused together; trabecular bone | ||||
| Sporadic Alzheimer's disease | a form of Alzheimer's disease with onset usually after age | ||||
| Stamina | the ability to perform vigorous activity continuously for more than a few seconds | ||||
| sT-cells | suppressor T-cell | ||||
| Stochastic theory | a theory based on the premise that aging occurs by random chance events that occur with no direction or control | ||||
| Stricture | a ring of scar tissue that inhibits the movement of materials through a tube-shaped structure by causing a narrowing of the structure | ||||
| Stroke | a disease condition involving an injury to or death of brain cells caused by low blood flow or bleeding in an area of the brain | ||||
| Stroke volume, SV | the amount of blood pumped by one contraction of a ventricle of the heart- | ||||
| Subcutaneous layer | the layer of the integumentary system that underlies the skin | ||||
| Superoxide radical | an oxygen molecule containing two oxygen atoms and having 17 electrons | ||||
| Suprachiasmatic nucleus, SCN | a region in the hypothalamus of the brain that regulates circadian rhythms | ||||
| Surface tension | the force of attraction between substances on a surface | ||||
| Surfactant | a substance that reduces surface tension | ||||
| Survival curve | a graph depicting the percentage of a population that is still alive as time passes from a reference point | ||||
| Suspensory ligaments | fibers within the eye that radiate outward from the lens and attach to the ciliary body | ||||
| Sustentacular cells | cells in the wall of seminiferous tubules that promote sperm production; Sertoli cells | ||||
| SV | the amount of blood pumped by one contraction of a ventricle of the heart | ||||
| Swallowing reflex | a reflex that clears the pharynx by pushing materials down into the esophagus | ||||
| Synapse | the site of transmission of an impulse from one neuron to another neuron | ||||
| Synovial cavity | the space between bones joined by a freely movable joint | ||||
| Synovial fluid | the fluid that lubricates and cushions the ends of the bones joined by freely movable joint | ||||
| Synovial membrane | the membrane that surrounds a synovial cavity and that produces and removes synovial fluid | ||||
| Systemic vessel | a blood vessel other than one involved in perfusion of the lungs (i.e., other than a pulmonary vessel) | ||||
| Systolic pressure | the peak blood pressure attained by contraction of the ventricles of the heart | ||||
| Target | with regard to a hormone, a structure that responds to the hormone | ||||
| Tau protein, τ-protein | a protein that seems to promote microtubule formation and that is abundant in neurofibrillar tangles | ||||
| T-cell | a type of immune system cell formed from an unspecialized lymphocyte because of the influence of the thymus on the lymphocyte; T-lymphocyte | ||||
| Telomerase | an enzyme that repairs and replaces telomeres on chromosomes during DNA replication) | ||||
| Telomere | a strand of DNA on the end of a chromosome | ||||
| Termination | a chemical reaction where a free radical is converted to a substance that is not a free radical without forming another free radical | ||||
| Testosterone | a principal sex hormone, most of which is produced by the testes | ||||
| Thrombus, thrombi | a stationary blood clot inside a vessel | ||||
| Tidal volume, TV | the volume of air that is inspired or expired per breath when a person is at rest and breathing quietly | ||||
| Time-lag study | a study method that uses a cross-sectional study procedure more than one time. The cross-sectional procedure is repeated on different groups that have the same age at different times in the study. | ||||
| Tinnitus | the perception of sound by a person when there is no sound external to the person | ||||
| Tissue | an organized group of similar cells and associated intercellular material that performs certain functions | ||||
| TMJ, temporomandibular joint | the joint that attaches the bone of the lower jaw to the skull | ||||
| Total lung capacity, TLC | the total amount of air that the lungs can hold | ||||
| Trabeculae | small pieces of bone tissue which, when fused together, compose trabecular bone | ||||
| Trabecular bone | the type of bone tissue that consists of an open network of trabeculae that are fused together; spongy bone | ||||
| Transmission | the process by which an impulse is passed from a neuron to another structure | ||||
| Triglyceride | a lipid molecule composed of one glycerol and three fatty acid molecules; a molecule of fat | ||||
| Type I fiber | a muscle cell that contracts slowly and can work longer than other types of muscle cells before becoming fatigued | ||||
| Type IIA fiber | a type of muscle cell that contracts quickly and resists becoming fatigued | ||||
| Type IIB fiber | a type of muscle cell that contracts quickly and becomes fatigued quickly | ||||
| Type IIC fiber | a type of muscle cell that contracts at a moderate speed and that becomes fatigued at a moderate period of contraction | ||||
| Underweight | having a body weight that is below the range for desirable body weight | ||||
| Unsaturated fat | a molecule of fat having one or more fatty acids that can contain additional hydrogen atoms linked to their carbon atoms | ||||
| Upper airways | air passages that conduct air into and out of the lungs | ||||
| Urea | a waste product resulting from the detoxification of ammonia by the liver or from the breakdown of proteins | ||||
| Urinary incontinence | the elimination of urine at inappropriate times | ||||
| Uterine fibroid | an abnormal growth consisting of a spherical mass of smooth muscle within | ||||
| Vaccine | a substance that contains an antigen and that is administered to produce an acquired active immunity to that antigen or to antigens that are very similar to it | ||||
| Varicose vein | a vein that has developed and retains an abnormally large diameter | ||||
| Ventilation | the movement of air into and out of the respiratory system; breathing | ||||
| Vertigo | the sensation that either the body or the surrounding environment is pinning when no spinning is actually occurring | ||||
| Vision | the conscious perception of images formed on the retina of the eye | ||||
| Visual acuity | the amount of detail that can be seen | ||||
| Vital capacity, VC | the maximum volume of air that a person can expire after taking the | ||||
| Vitamin D | a vitamin that assists in the absorption of calcium by the small intestine | ||||
| Vitreous humor | the transparent soft gel that fills the region of the eye behind the lens and in | ||||
| Voiding | releasing urine from the body | ||||
| Work of breathing | the amount of energy used or the amount of oxygen consumed to perform ventilation | ||||
| Working memory | remembering information at or close to the level of consciousness so it can be used in cognitive processing | ||||
| XL | maximum longevity |