Disorders That Disrupt Sleep (Parasomnias) Glossary of Medical Terms

Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
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Absorption: Uptake. In the biomedical sciences, absorption has diverse specific meanings.
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Acute: Of abrupt onset, in reference to a disease. Acute often also connotes an illness that is of short duration, rapidly progressive, and in need of urgent care.
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Addiction: A chronic relapsing condition characterized by compulsive drug-seeking and abuse and by long-lasting chemical changes in the brain . Addiction is the same irrespective of whether the drug is alcohol , amphetamines, cocaine , heroin , marijuana , or nicotine . Every addictive substance induces pleasant states or relieves distress. Continued use of the addictive substance induces adaptive changes in the brain that lead to tolerance, physical dependence, uncontrollable craving and, all too often, relapse . Dependence is at such a point that stopping is very difficult and causes severe physical and mental reactions from withdrawal. The risk of addiction is in part inherited. Genetic factors, for example, account for about 40% of the risk of alcoholism . The genetic factors predisposing to addiction are not yet fully understood.
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Aerobic: Oxygen-requiring. Aerobic bacteria need oxygen to grow. Aerobic exercise requires the heart and lungs to work harder to meet the body's increased oxygen demand.
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Alcohol: An organic chemical in which one or more hydroxyl (OH) groups are attached to carbon (C) atoms in place of hydrogen (H) atoms. Common alcohols include ethyl alcohol or ethanol (found in alcoholic beverages), methyl alcohol or methanol (can cause blindness) and propyl alcohol or propanol (used as a solvent and antiseptic ). Rubbing alcohol is a mixture of acetone , methyl isobutyl ketone, and ethyl alcohol. In everyday talk, alcohol usually refers to ethanol as, for example, in wine, beer, and liquor. It can cause changes in behavior and be addictive.
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Alprazolam: A benzodiazepine sedative that causes dose-related depression of the central nervous system. Alprazolam is useful in treating anxiety, panic attacks, insomnia, and muscle spasms. The brand name is Xanax . A generic version is available.
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Anemia: The condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood. The oxygen-carrying capacity of the blood is, therefore, decreased.
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Ankle: The ankle joint is complex. It is made up of two joints: the true ankle joint and the subtalar joint:
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Anticholinergic: The action of certain medications that inhibit the transmission of parasympathetic nerve impulses and thereby reduce spasms of smooth muscle (such as that, for example, in the bladder).
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Anxiety: A feeling of apprehension and fear characterized by physical symptoms such as palpitations , sweating, and feelings of stress . Anxiety disorders are serious medical illnesses that affect approximately 19 million American adults. These disorders fill people's lives with overwhelming anxiety and fear. Unlike the relatively mild, brief anxiety caused by a stressful event such as a business presentation or a first date, anxiety disorders are chronic, relentless, and can grow progressively worse if not treated.
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Apnea: An apnea is a period of time during which breathing stops or is markedly reduced. There are two types of apneas, the more common obstructive sleep apnea and the less common central sleep apnea.
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Arm: 1. In popular usage, the appendage that extends from the shoulder to the hand. However, the medical definition refers to the upper extremity extending from the shoulder only to the elbow, excluding the forearm, which extends from the elbow to the wrist. The arm contains one bone: the humerus. 2. In a randomized clinical trial, any of the treatment groups. Most randomized trials have two "arms," but some have three "arms," or even more.
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Attenuate: To weaken, dilute, thin, reduce, weaken, diminish.
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Benzodiazepines: A class of drugs that act as tranquilizers and are commonly used in the treatment of anxiety. Benzodiazepines can cause drowsiness.
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Biofeedback: A method of treatment that uses monitors to feed back to patients physiological information of which they are normally unaware. By watching the monitor, patients can learn by trial and error to adjust their thinking and other mental processes in order to control "involuntary" bodily processes such as blood pressure, temperature, gastrointestinal functioning, and brain wave activity.
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Bladder: Any pouch or other flexible enclosure that can hold liquids or gases but usually refers to the hollow organ in the lower abdomen that stores urine -- the urinary bladder. The kidneys filter waste from the blood and produce urine, which enters the bladder through two tubes called ureters. Urine leaves the bladder through another tube, the urethra . In women, the urethra is a short tube that opens just in front of the vagina . In men, it is longer, passing through the prostate gland and then the penis . Infection of the bladder is called cystitis .
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Blood: The familiar red fluid in the body that contains white and red blood cells , platelets , proteins , and other elements. The blood is transported throughout the body by the circulatory system . Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.
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Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
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Brain stem: The stemlike part of the brain that is connected to the spinal cord. Or conversely, the extension of the spinal cord up into the brain. The brain stem is small but important. It manages messages going between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate , and blood pressure. The brain stem also controls consciousness and determines whether one is awake or sleepy.
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Breathing: The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction, and then exhaled due to muscle relaxation.
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Caffeine: A stimulant found naturally in coffee beans, tea leaves, cocoa beans (chocolate) and kola nuts (cola) and added to soft drinks, foods, and medicines. A cup of coffee has 100-250 milligrams of caffeine. Black tea brewed for 4 minutes has 40-100 milligrams. Green tea has one-third as much caffeine as black tea.
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Cerebrovascular: Pertaining to the blood vessels and, especially, the arteries that supply the brain. As in cerebrovascular accident or cerebrovascular disease.
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Cerebrovascular disease: Disease of the blood vessels and, especially, the arteries that supply the brain. Cerebrovascular disease is usually caused by atherosclerosis and can lead to a stroke. See also atherosclerosis, stroke.
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Childhood: (1) The time for a boy or girl from birth until he or she is an adult. (2) The more circumscribed period of time from infancy to the onset of puberty .
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Chloral hydrate: A prescription sedative/hypnotic drug developed in the 19th century. The drug acts rapidly and induces sleep within 60 minutes, and is used for the short–term treatment of insomnia . Chloral hydrate can be taken orally in syrup or capsule form and is also available in the form of rectal suppositories. The medical use of chloral hydrate has declined over the years due to the development of the barbiturates and benzodiazepines .
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Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time.
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Chronic renal failure: Slow progressive loss of kidney function over the span of years, resulting in permanent kidney failure. Chronic kidney disease is common and may go undiagnosed until the process is far advanced and renal failure is on the horizon. People with permanent kidney failure need dialysis or a transplanted kidney to do the work of their failed kidneys.
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Condition: The term "condition" has a number of biomedical meanings including the following:

1. An unhealthy state, such as in "this is a progressive condition."
2. A state of fitness, such as "getting into condition."
3. Something that is essential to the occurrence of something else; essentially a "precondition."
4. As a verb: to cause a change in something so that a response that was previously associated with a certain stimulus becomes associated with another stimulus; to condition a person, as in behavioral conditioning.

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Critical care: Intensive care. The specialized care of patients whose conditions are life-threatening and who require comprehensive care and constant monitoring, usually in intensive care units.
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Dementia : Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning.
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Depression : An illness that involves the body, mood, and thoughts, that affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood. It is not a sign of personal weakness or a condition that can be wished away. People with a depressive disease cannot merely "pull themselves together" and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people with depression.
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Dialysis: The process of cleansing the blood by passing it through a special machine. Dialysis is necessary when the kidneys are not able to filter the blood. Dialysis allows patients with kidney failure a chance to live productive lives. There are two types of dialysis: hemodialysis and peritoneal dialysis. Each type of dialysis has advantages and disadvantages. Patients can often choose the type of long term dialysis that best matches their needs.
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Dopamine: An important neurotransmitter (messenger) in the brain.
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Dreams: Thoughts, visions, and other sensations that occupy the mind in sleep .
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Dysfunction: Difficult function or abnormal function.
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Dyskinesia: Difficulty or distortion in performing voluntary movements, as in tic, chorea, spasm, or myoclonus. The term dyskinesia may be used in relation to Parkinson's disease and other extrapyramidal disorders. Dyskinesia can occur as a side effect of certain medications such as L-dopa and the antipsychotics.
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Electrocardiogram : A recording of the electrical activity of the heart. An electrocardiogram is a simple, non-invasive procedure. Electrodes are placed on the skin of the chest and connected in a specific order to a machine that, when turned on, measures electrical activity all overaround the heart. Output is usually in the form of a long scroll of paper displaying a printed graph of activity. Newer models output the data directly to a computer and screen, although a print-out may still be made.
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Electroencephalogram: A study of electrical current within the brain. Electrodes are attached to the scalp. Wires attach these electrodes to a machine which records the electrical impulses. The results are either printed out or displayed on a computer screen. Electroencephalogram is abbreviated EEG.
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Electromyogram: A test used to record the electrical activity of muscles. When muscles are active, they produce an electrical current that is usually proportional to the level of muscle activity. An electromyogram (EMG) is also called a myogram.
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Essential: 1. Something that cannot be done without.
2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid.
3. Idiopathic. As in essential hypertension. "Essential" is a hallowed term meaning "We don't know the cause."
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Event: A set of outcomes. Cardiovascular events might include a heart attack and gastrointestinal events a GI bleed. The use of the term "event" in medicine comes from probability theory.
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Excessive daytime sleepiness: A neurological disorder in which there is a sudden recurrent uncontrollable compulsion to sleep. Excessive daytime sleepiness is also known as narcolepsy.
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Family history: The family structure and relationships within the family, including information about diseases in family members.
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Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness and tiredness. Fatigue can be acute and come on suddenly or chronic and persist.
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Ferritin: The major iron storage protein . The blood level of ferritin serves as an indicator of the amount of iron stored in the body.
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Fever : Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.).
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Flexion: The process of bending or the state of being bent. Flexion of the fingers results in a clenched fist.
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Gastroesophageal: Pertaining to both the stomach and the esophagus , as in the gastroesophageal junction, the place where the esophagus connects to the stomach.
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Gastroesophageal reflux: The return of stomach contents back up into the esophagus This frequently causes heartburn because of irritation of the esophagus by stomach acid.
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Gastrointestinal: Adjective referring collectively to the stomach and small and large intestines.
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Growing pains:Mysterious pains in growing children, usually in the legs. These pains are similar to what the weekend gardener suffers from on Monday-an overuse type of problem. If in playing, children exceed their regular threshold, they will be sore, just like an adult. Growing pains are typically somewhat diffuse (vs. focal) and are not associated with physical changes of the area (such as swelling, redness, etc.).
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Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
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Heart rate: The number of heart beats per unit time, usually per minute. The heart rate is based on the number of contractions of the ventricles (the lower chambers of the heart). The heart rate may be too fast ( tachycardia ) or too slow ( bradycardia ). The pulse is bulge of an artery from the wave of blood coursing through the blood vessel as a result of the heart beat. The pulse is often taken at the wrist to estimate the heart rate.
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Hemoglobin: The oxygen-carrying pigment and predominant protein in the red blood cells . Hemoglobin forms an unstable, reversible bond with oxygen. In its oxygenated state it is called oxyhemoglobin and is bright red. In the reduced state it is called deoxyhemoglobin and is purple-blue.
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Hemorrhage: Bleeding or the abnormal flow of blood.
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Hospital: It may seem unnecessary to define a "hospital" since everyone knows the nature of a hospital. A hospital began as a charitable institution for the needy, aged, infirm, or young.
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Hygiene: The science of preventive medicine and the preservation of health. From the name of Hygeia, the daughter of Asklepios, the Greek god of medicine (whose staff with entwined snake is the symbol of medicine). Asklepios (known to the Romans as Aesculapius) had a number of children including not only Hygeia but also Panaceia, the patroness of clinical medicine. Hygeia also followed her father into medicine. As the patroness of health, Hygeia was charged with providing a healthy environment to prevent illness. In Greek, "hygieia" means health.
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Hyperactivity: A higher than normal level of activity. An organ can be described as hyperactive if it is more active than usual. Behavior can also be hyperactive.
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Hypnosis: A part of healing from ancient times. The induction of trance states and the use of therapeutic suggestion were a central feature of the early Greek healing temples, and variations of these techniques were practiced throughout the ancient world.
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Incidence: The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain date.
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Injure: To harm, hurt, or wound. The word injure may be in physical or emotional sense. Treadmill machines may injure anyone who gets on one. Sexual molestation injures children. From the Latin injuria meaning injury.
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Injury: Harm or hurt. The term "injury" may be applied in medicine to damage inflicted upon oneself as in a hamstring injury or by an external agent on as in a cold injury . The injury may be accidental or deliberate, as with a needlestick injury . The term "injury" may be synonymous (depending on the context) with a wound or with trauma .
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Insomnia: The perception or complaint of inadequate or poor-quality sleep because of one or more of the following: difficulty falling asleep; waking up frequently during the night with difficulty returning to sleep; waking up too early in the morning; or unrefreshing sleep. Insomnia is not defined by the number of hours of sleep a person gets or how long it takes to fall asleep. Individuals vary normally in their need for, and their satisfaction with, sleep. Insomnia may cause problems during the day, such as tiredness, a lack of energy, difficulty concentrating, and irritability.
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Internal medicine: A medical specialty dedicated to the diagnosis and medical treatment of adults. A physician who specializes in internal medicine is referred to as an internist. A minimum of seven years of medical school and postgraduate training are focused on learning the prevention, diagnosis, and treatment of diseases of adults. Subspecialties of internal medicine include allergy and immunology, cardiology (heart), endocrinology (hormone disorders), hematology (blood disorders), infectious diseases, gastroenterology (diseases of the gut), nephrology (kidney diseases), oncology (cancer), pulmonology (lung disorders), and rheumatology ( arthritis and musculoskeletal disorders).
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Iron: An essential mineral. Iron is necessary for the transport of oxygen (via hemoglobin in red blood cells) and for oxidation by cells (via cytochrome). Deficiency of iron is a common cause of anemia . Food sources of iron include meat, poultry, eggs, vegetables and cereals (especially those fortified with iron). According to the National Academy of Sciences, the Recommended Dietary Allowances of iron are 15 milligrams per day for women and 10 milligrams per day for men. Iron overload can damage the heart, liver, gonads and other organs. Iron overload is a particular risk in people who may have certain genetic conditions ( hemochromatosis ) sometimes without knowing it and also in people receiving recurrent blood transfusions. Iron supplements meant for adults (such as pregnant women) are a major cause of poisoning in children.
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Kidney: One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary tract. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.

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Knee: The knee is a joint which has three parts. The thigh bone (the femur) meets the large shin bone (the tibia) to form the main knee joint. This joint has an inner (medial) and an outer (lateral) compartment. The kneecap (the patella) joins the femur to form a third joint, called the patellofemoral joint. The patella protects the front of the knee joint.
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Laboratory: A place for doing tests and research procedures and preparing chemicals, etc. Although "laboratory" looks very like the Latin "laboratorium" (a place to labor, a work place), the word "laboratory" came from the Latin "elaborare" (to work out, as a problem, and with great pains), as evidenced by the Old English spelling "elaboratory" designating "a place where learned effort was applied to the solution of scientific problems."
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Leg: In popular usage, the leg extends from the top of the thigh down to the foot. However, in medical terminology, the leg refers to the portion of the lower extremity from the knee to the ankle.
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Limb: The arm or leg.
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Lithium : Lithium carbonate (brand names: Eskalith; Lithobid), a drug used as a mood stabilizer for the treatment of manic/depressive (bipolar) disorder . It prevents or diminishes the intensity of episodes of mania in bipolar patients. Typical symptoms of mania include pressure of speech, motor hyperactivity, reduced need for sleep , flight of ideas, grandiosity, elation, poor judgment, aggressiveness and possibly hostility.
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Medical history: 1. In clinical medicine, the patient's past and present which may contain clues bearing on their health past, present, and future. The medical history, being an account of all medical events and problems a person has experienced, including psychiatric illness, is especially helpful when a differential diagnosis is needed.
2. The history of medicine.
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Medical school: A school with a curriculum leading to a medical degree. The mission of every medical school includes medical teaching, research, and patient care. All medical schools share the goal of preparing students in the art and science of medicine, and providing them with the background necessary to enter the period of graduate medical education. The years of medical school preceding graduate medical education are typically divided into a preclinical phase and a clinical phase.
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Menopause : The time in a woman's life when menstrual periods permanently stop; it is also called the "change of life." Menopause is the opposite of the menarche.
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Menstruation: The periodic blood that flows as a discharge from the uterus. Also called menorrhea, the time during which menstruation occurs is referred to as menses. The menses occurs at approximately 4 week intervals to compose the menstrual cycle.
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Methadone: A synthetic opiate . The most common medical use for methadone is as a legal substitute for heroin in treatment programs for drug addiction. It is usually administered to participating addicts daily in the form of a green, tasteless liquid at a drug treatment clinic. See also: Methadone treatment program .
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Multiple sclerosis : Abbreviated MS. A disease of the central nervous system (CNS) marked by numbness, weakness, loss of muscle coordination, and problems with vision, speech, and bladder control. MS is an autoimmune disease in which the body's immune system attacks myelin, a key substance that serves as a nerve insulator and helps in the transmission of nerve signals. The progress, severity and specific symptoms in MS are unpredictable. One never knows when attacks will occur, how long they will last, or how severe they will be. Most people with MS are between the ages of 20 and 40 at the time of diagnosis. The term "multiple" refers to the multiple places in the CNS that are affected and to the multiple relapses and remissions characteristic of MS.
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Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."
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Myelitis: Inflammation of the spinal cord.
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Neurological: Having to do with the nerves or the nervous system.
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Neurology: The medical specialty concerned with the diagnosis and treatment of disorders of the nervous system -- the brain, the spinal cord, and the nerves.
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Neuropathy: Any and all disease or malfunction of the nerves.
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NREM sleep : NREM (non-rapid eye movement) sleep is dreamless sleep. During NREM, the brain waves on the electroencephalographic (EEG) recording are typically slow and of high voltage, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively still. NREM sleep is divided into 4 stages of increasing depth leading to REM sleep.
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Olivopontocerebellar: Pertaining to three particular parts of the brain -- namely, the oliva, the pons , and the cortex of the cerebellum . The oliva (olive) is a rounded prominence on the surface of the medulla oblongata in the brain. The olivopontocerebellar pathway consists of nerve fibers that connect the olivary nucleus to the pons and cerebellum. Olivopontocerebellar atrophy is a disorder of this pathway.
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Onset: In medicine, the first appearance of the signs or symptoms of an illness as, for example, the onset of rheumatoid arthritis . There is always an onset to a disease but never to the return to good health. The default setting is good health.
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Organ: A relatively independent part of the body that carries out one or more special functions. The organs of the human body include the eye , ear , heart , lungs , and liver .
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Osteoarthritis: A type of arthritis caused by inflammation, breakdown, and eventual loss of cartilage in the joints. Also known as degenerative arthritis .
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Oxycodone: Oxycodone is the active ingredient in OxyContin. Oxycodone is an opioid, a close relative of morphine, heroin, codeine , fentanyl, and methadone.
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Panic: A sudden strong feeling of fear that prevents reasonable thought or action.
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Parasomnia: A sleep disorder in which odd or dangerous events occur that intrude on sleep. The parasomnias include sleep talking, sleepwalking (somnambulism), sleep terrors, REM behavior disorder, and nocturnal dissociative disorder.
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Pathology: The study of disease. Pathology has been defined as "that branch of medicine which treats of the essential nature of disease." The word "pathology" comes from the Greek words "pathos" meaning "disease" and "logos" meaning "a treatise" = a treatise of disease. The word "pathology" is sometimes misused to mean disease as, for example, "he didn't find any pathology" (meaning he found no evidence of disease). A medical doctor that specializes in pathology is called a pathologist. Pathologists are experts at interpreting microscopic views of body tissues.
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Peripheral: Situated away from the center, as opposed to centrally located.
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Peripheral neuropathy : A problem with the functioning of the nerves outside the spinal cord. Symptoms may include numbness, weakness, burning pain (especially at night), and loss of reflexes.
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Pharmacy: A location where prescription drugs are sold. A pharmacy is, by law, constantly supervised by a licensed pharmacist.
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Polysomnography: Continuous recording of specific physiologic variables during sleep . Polysomnography typically records brain wave changes (electroencephalogram), eye movements (electrooculogram), muscle tone ( electromyogram ), respiration, electrocardiogram (EKG), and leg movements.
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Pregnancy : The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long.
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Pregnant: The state of carrying a developing fetus within the body.
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Primary: First or foremost in time or development. The primary teeth (the baby teeth) are those that come first. Primary may also refer to symptoms or a disease to which others are secondary.
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Progressive: Increasing in scope or severity. Advancing. Going forward. In medicine, a disease that is progressive is going from bad to worse.
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Psychiatric: Pertaining to or within the purview of psychiatry , the medical specialty concerned with the prevention, diagnosis , and treatment of mental illness.
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Pulmonary: Having to do with the lungs. (The word comes from the Latin pulmo for lung).
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Rebound: Return of the original symptoms when maneuvers or treatment is discontinued.
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Reflux: The term used when liquid backs up into the esophagus from the stomach.
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Relapse: The return of signs and symptoms of a disease after a patient has enjoyed a remission . For example, after treatment a patient with cancer of the colon went into remission with no sign or symptom of the tumor, remained in remission for 4 years, but then suffered a relapse and had to be treated once again for colon cancer.
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rem: In radiation, Roentgen equivalent for man, a roentgen (an international unit of X- or gamma-radiation) adjusted for the atomic makeup of the human body. In ophthalmology, rapid eye movement.

REM sleep : REM sleep is the portion of sleep when there are rapid eye movements (REMs).
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Renal: Having to do with the kidney. From the Latin renes (the kidneys), which gave the French les reins which mean both the kidneys and the lower back.
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Respiratory: Having to do with respiration, the exchange of oxygen and carbon dioxide. From the Latin re- (again) + spirare (to breathe) = to breathe again.
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Respiratory rate: The number of breaths per minute or, more formally, the number of movements indicative of inspiration and expiration per unit time. In practice, the respiratory rate is usually determined by counting the number of times the chest rises or falls per minute. By whatever means, the aim is to determine if the respirations are normal, abnormally fast ( tachypnea ), abnormally slow (bradypnea), or nonexistent ( apnea ).
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Restless legs: See: Restless leg syndrome .
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Reuptake: The reabsorption of a secreted substance by the cell that originally produced and secreted it. The process of reuptake, for example, affects serotonin.
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Sclerosis: Localized hardening of skin.
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Serotonin: A hormone , also called 5-hydroxytryptamine , in the pineal gland , blood platelets, the digestive tract, and the brain. Serotonin acts both as a chemical messenger that transmits nerve signals between nerve cells and that causes blood vessels to narrow.
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Serum: The clear liquid that can be separated from clotted blood. Serum differs from plasma, the liquid portion of normal unclotted blood containing the red and white cells and platelets. It is the clot that makes the difference between serum and plasma.
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Sleep : The body's rest cycle.
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Sleep apnea: The temporary stoppage of breathing during sleep , often resulting in daytime sleepiness. Apnea is a Greek word that means "want of breath."
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Sleep disorders: Any disorder that affects, disrupts, or involves sleep . The most common sleep disorder is probably snoring, although it is usually not medically significant. Insomnia, sleep apnea , restless leg syndrome , and sleepwalking are also sleep disorders. Most large medical centers have diagnostic and treatment facilities dedicated to sleep disorders.
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Sleepwalking : Purposeful moving, usually but not always including walking, while in a deep stage of sleep . Sleepwalking occurs most frequently in children, particularly boys. Sedatives tend to exacerbate rather than cure sleepwalking. The best measures are preventative: ensure that the sleepwalker is in a safe room for walking, and cannot accidentally fall through an open window or down stairs. Some types of sleepwalking are related to seizure disorders , bipolar disorder , or other neurological conditions, but most cases are transitory and due to unknown causes. Also called somnambulism.
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Slow-wave sleep : Stage 3 and 4 non-rapid eye movement (non-REM) sleep.
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Somnambulism: Sleepwalking. Purposeful moving, usually but not always including walking, while in a deep stage of sleep . Sleepwalking occurs most frequently in children, particularly boys. Sedatives tend to exacerbate rather than cure sleepwalking. The best measures are preventative: ensure that the sleepwalker is in a safe room for walking, and cannot accidentally fall through an open window or down stairs. Some types of sleepwalking are related to seizure disorders, bipolar disorders, or other neurological conditions, but most cases are transitory and due to unknown causes.
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Soothing: Bringing comfort, solace, reassurance, peace, composure, quietude.
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Spinal cord: The major column of nerve tissue that is connected to the brain and lies within the vertebral canal and from which the spinal nerves emerge. Thirty-one pairs of spinal nerves originate in the spinal cord: 8 cervical , 12 thoracic , 5 lumbar, 5 sacral, and 1 coccygeal. The spinal cord and the brain constitute the central nervous system ( CNS ). The spinal cord consists of nerve fibers that transmit impulses to and from the brain. Like the brain, the spinal cord is covered by three connective-tissue envelopes called the meninges . The space between the outer and middle envelopes is filled with cerebrospinal fluid ( CSF ), a clear colorless fluid that cushions the spinal cord against jarring shock. Also known simply as the cord.
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Stage: As regards cancer , the extent of a cancer, especially whether the disease has spread from the original site to other parts of the body. See also: Staging .
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Stomach: 1. The sac-shaped digestive organ that is located in the upper abdomen, under the ribs. The upper part of the stomach connects to the esophagus, and the lower part leads into the small intestine.
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Stress: Forces from the outside world impinging on the individual. Stress is a normal part of life that can help us learn and grow. Conversely, stress can cause us significant problems.
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Subarachnoid: Literally, beneath the arachnoid, the middle of three membranes that cover the central nervous system. In practice, subarachnoid usually refers to the space between the arachnoid and the pia mater, the innermost membrane surrounding the central nervous system.
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Subarachnoid hemorrhage: Bleeding within the head into the space between two membranes that surround the brain. The bleeding is beneath the arachnoid membrane and just above the pia mater. (The arachnoid is the middle of three membranes around the brain while the pia mater is the innermost one.)
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Substance: 1. Material with particular features, as a pressor substance .
2. The material that makes up an organ or structure. Also known in medicine as the substantia.
3. A psychoactive drug as, for example, in substance abuse .
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Substance abuse: The excessive use of a substance, especially alcohol or a drug. (There is no universally accepted definition of substance abuse.)
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Suicidal: Pertaining to suicide . the taking of ones own life. As in a suicidal gesture, suicidal thought, or suicidal act. An "online lifeline for suicidal undergrads" may help prevent college students from committing suicide.
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Sweating: The act of secreting fluid from the skin by the sweat (sudoriferous) glands. These are small tubular glands situated within and under the skin (in the subcutaneous tissue). They discharge by tiny openings in the surface of the skin.
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Symptom: Any subjective evidence of disease. Anxiety, lower back pain , and fatigue are all symptoms. They are sensations only the patient can perceive. In contrast, a sign is objective evidence of disease. A bloody nose is a sign. It is evident to the patient, doctor, nurse and other observers.
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Syndrome: A set of signs and symptoms that tend to occur together and which reflect the presence of a particular disease or an increased chance of developing a particular disease.
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Tachycardia: A rapid heart rate, usually defined as greater than 100 beats per minute. The tachycardias include sinus tachycardia, paroxysmal atrial tachycardia (PAT), and ventricular tachycardia.
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Tachypnea: (Pronounced tack-ip-nea.) Abnormally fast breathing. A respiratory rate that is too rapid. The normal rate of respirations (breaths per minute) depends on a number of factors, including the age of the individual and the degree of exertion.
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Tardive dyskinesia: A neurological syndrome characterized by repetitive, involuntary, purposeless movements caused by the long-term use of certain drugs called neuroleptics used for psychiatric, gastrointestinal and neurological disorders such as Parkinson's disease . Features may include grimacing, tongue protrusion, lip smacking, puckering and pursing, and rapid eye blinking. Rapid movements of the arms, legs, and trunk may also occur. Impaired movements of the fingers may appear as though the patient is playing an invisible guitar or piano. The incidence of the syndrome rises with the dose and duration of drug treatment. The treatment of tardive dyskinesis is usually to stop or minimize the use of the offending drug. However, for some patients with a severe underlying condition this may not be a feasible option. Replacing the offending drug with substitute drugs may help. Other drugs such as benzodiazepines, adrenergic antagonists, and dopamine agonists may also be beneficial. In an individual case, the symptoms of tardive dyskinesia may remain long after discontinuation of the offending drug or the symptoms may improve or disappear with time.
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Therapy: The treatment of disease .
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Tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow. For example, a medulloblastoma is a tumor that arises from embryonic cells (a blastoma) in the inner part of the brain (the medulla). Diagnosis depends on the type and location of the tumor. Tumor marker tests and imaging may be used; some tumors can be seen (for example, tumors on the exterior of the skin) or felt (palpated with the hands).
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Urinary: Having to do with the kidneys, ureters, and bladder. The urinary system represents the functional and anatomic aspects of the kidneys, ureters, and bladder.
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Urine: Liquid waste. The urine is a clear, transparent fluid. It normally has an amber color. The average amount of urine excreted in 24 hours is from 40 to 60 ounces (about 1,200 cubic centimeters). Chemically, the urine is mainly an aqueous (watery) solution of salt (sodium chloride) and substances called urea and uric acid. Normally, it contains about 960 parts of water to 40 parts of solid matter. Abnormally, it may contain sugar (in diabetes), albumen (a protein) (as in some forms of kidney disease), bile pigments (as in jaundice ), or abnormal quantities of one or another of its normal components.
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Voluntary: Done in accordance with the conscious will of the individual. The opposite of involuntary.
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Xanax: See: Alprazolam .
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