Acute—Describes a condition or illness that begins suddenly and is short-lasting.

Affective disorder—A mental disorder involving abnormal moods and emotions; affective disorders primarily consist of depression for the data reported here.

Anemia—A condition in which the blood does not contain enough hemoglobin, the compound that carries oxygen from the lungs to other parts of the body.

Aneurysm—An abnormal swelling of the wall of an artery, caused by a weakening in the vessel wall.

Anomaly—Deviation from the normal standard, especially as a result of congenital defects.

Arrhythmias—Abnormal heart rhythms.

Artery—A large blood vessel that carries oxygen in the blood from the heart to tissues and organs in the body.

Asphyxia—Suffocation, which can be caused by choking on an object, by lack of oxygen in the air, or by chemicals such as carbon monoxide, which reduce the amount of oxygen in the blood.

Asthma—A disorder characterized by inflamed airways and difficulty breathing.

Atherosclerosis—The progressive narrowing and hardening of the arteries over time, known to occur to some degree with aging; but other risk factors (such as high cholesterol, high blood pressure, smoking, diabetes and family history for atherosclerotic disease) that accelerate this process have been identified.

Biliary tract—The system of organs and ducts through which bile is made and transported from the liver. Bile is a liquid produced in the liver whose function is to remove waste from the liver and break down fats as food is digested.

Cancer—A group of diseases in which cells grow unrestrained in an organ or tissue in the body. It can spread to tissues around it and destroy them or be transported through blood or lymph pathways to other parts of the body.

Cardiac arrest—The sudden cessation of the heart's pumping action, possibly due to a heart attack, respiratory arrest, electrical shock, extreme cold, blood loss, drug overdose, or a severe allergic reaction.

Central nervous system—The brain and spinal cord.

Cerebrovascular disease—A disease affecting any artery supplying blood to the brain; may cause blockage or rupture of a blood vessel, leading to a stroke. An artery is a large blood vessel that carries oxygen in the blood from the heart to tissues and organs in the body. Stroke is damage to part of the brain because of a lack of blood supply (due to a blockage in an artery or the rupturing of a blood vessel). Stroke can lead to complete or partial loss of function in the area of the body that is controlled by the damaged part of the brain.

Chest pain—There are many causes of chest pain, principally angina (which results from inadequate oxygen supply to the heart muscle, also caused by coronary artery disease or spasm of the coronary arteries) and heart attack (coronary occlusion). A diagnosis of chest pain upon discharge from the hospital can indicate that the underlying cause of the pain was not discovered during the hospital stay.

Chronic obstructive lung (pulmonary) disease (COPD)—A combination of lung diseases including emphysema and bronchitis. Emphysema is a chronic disease in which the small air sacs in the lungs (the alveoli) become damaged, resulting in difficulty breathing. Bronchitis is an inflammation of the bronchial tubes (which connect the trachea to the lungs), characterized by blockage of airflow in and out of the lungs.

Circulatory system—Cardiovascular system consisting of the heart, blood vessels, and lymphatics. Common diseases of the circulatory system include coronary atherosclerosis, congestive heart failure, heart attack, and cardiac dysrhythmia.

Coagulopathy—Coagulation is a process that plays a large role in the hardening and thickening of blood to form a clot; coagulopathy is a disorder of this clotting mechanism.

Congenital—Present or existing at the time of birth.

Congestive heart failure—Inability of the heart to efficiently pump blood through the body, causing buildup of blood in the veins and of other body fluids in tissue.

Coronary—Structures that encircle another structure (such as the coronary arteries, which encircle the heart); commonly used to refer to a coronary thrombosis or a heart attack.

Coronary thrombosis—The blockage of a coronary artery by a blood clot.

Diabetes—General term usually referring to diabetes mellitus, a state of inadequate insulin production.

Electrolyte—Substance that dissociates into ions when fused or in solution and thus becomes capable of conducting electricity, an ionic solute. Fluid and electrolyte disorders have many causes including water deficit, gastrointestinal losses (such as diarrhea), and excessive diuretic therapy (treaments to decrease urine secretion).

Epilepsy—A disorder of the nervous system in which abnormal electrical activity in the brain causes seizures (sudden uncontrolled waves of electrical activity in the brain, causing involuntary movement or loss of consciousness).

Fetal distress—Physical distress experienced by a fetus because of lack of oxygen.

Gestation—The period of time between fertilization of an egg by a sperm and birth of a baby.

Heart valve—The structure at each exit of the four chambers of the heart that allows blood to exit but not to flow back in.

Hodgkin's disease—A cancer of lymphoid tissue (found in lymph nodes and the spleen) that causes the lymph nodes to enlarge and function improperly; may cause illness, fever, loss of appetite, and weight loss.

Human immunodeficiency virus (HIV)—A retrovirus that attacks helper T cells of the immune system and causes acquired immunodeficiency syndrome (AIDS); transmitted through sexual intercourse or contact with infected blood.

Hypertension—Abnormally high blood pressure, even when at rest.

Hypothyroidism—Underactivity of the thyroid gland, causing tiredness, cramps, a slowed heart rate, and possibly weight gain.

Hypoxia—A reduced level of oxygen in tissues.

Infection—Disease-causing microorganisms that enter the body, multiply, and damage cells or release toxins (poisonous substances). Microorganisms are tiny, single-celled organisms (such as a bacterium, virus, or fungus).

Intracranial—Within the skull.

Intrauterine—In the uterus (womb).

Leukemia—Bone marrow cancers in which white blood cells divide uncontrollably, affecting the production of normal white blood cells, red blood cells, and platelets.

Malignant—A word used to describe a condition that is characterized by uncontrolled growth and/or that can be fatal, such as a cancerous tumor.

Metastasis—The spreading of a cancerous tumor to another part of the body through the lymph, blood, or across a cavity; also sometimes refers to a tumor that has been produced in this way.

Myeloma—A cancer affecting cells in the bone marrow; sometimes used as an abbreviation for multiple myeloma.

Myocardial infarction—The death of an area of heart muscle as a result of being deprived of its blood supply; characterized by severe pain in the chest; commonly called a heart attack.

Neoplasm—Another term for a tumor (may be benign or malignant).

Obstetrics—Branch of medicine dealing with the care of women during pregnancy, childbirth, and the period during which they recover from childbirth.

Osteoarthritis—A disease that breaks down the cartilage that lines joints, especially weight-bearing or misaligned joints; leads to pain, stiffness, and inflammation (redness, pain, and swelling in an injured or infected tissue produced as a result of the body's healing response).

Paralysis—The inability to use a muscle because of injury to or disease of the nerves leading to the muscle.

Perinatal—Occurring just before or just after birth.

Peripheral—Pertaining to or situated at or near the periphery, situated away from a center or central structure.

Pneumonia—Inflammation of the lungs due to a bacterial or viral infection, which causes fever, shortness of breath, and the coughing up of phlegm (mucus and other material produced by the lining of the respiratory tract; also called sputum).

Pneumonitis—Inflammation of the lung secondary to viral or bacterial infection; common symptoms include a productive cough, fever, chills, and shortness of breath.

Puerperium—The time period after childbirth (about 6 weeks) during which a woman's body returns to its normal physical state.

Rehabilitation—Treatment for an injury or illness aimed at restoring physical abilities.

Renal failure—Decline in kidney function over time; caused by a number of disorders which include longstanding hypertension, diabetes, congestive heart failure, lupus, or sickle cell anemia.

Respiratory distress syndrome—A condition experienced after an illness or injury damages the lungs, causing severe breathing difficulty and resulting in a life-threatening lack of oxygen in the blood. In premature infants, it is caused by immaturity of the lungs.

Respiratory failure—The failure of the body to exchange gases properly, which leads to a buildup of carbon dioxide and a lack of oxygen in the blood.

Schizophrenia—A group of mental disorders characterized by abnormal thoughts, moods, and actions; sufferers have a distorted sense of reality and thoughts that do not logically fit together.

Septicemia—Systemic disease associated with the presence and persistence of pathogenic microorganisms or their toxins in the blood; blood poisoning.

Shock—A reduced flow of blood throughout the body, usually caused by severe bleeding or a weak heart; without treatment, can lead to a collapse, coma, and death.

Spinal cord—A long tube of nerve tissue inside the spinal column running from the brain down the length of the back inside of the spine.

Spinal cord injury—Any injury to the spinal cord via blunt or penetrating trauma. Extreme flexion or extension (particularly in the neck) of the spine can result in traction on the spinal cord with subsequent injury and the development of neurologic symptoms.

Spondylolysis—A disorder in which the lower part of the spine is weakened by an abnormally soft vertebra.

Trauma—Physical injury or emotional shock.

Tuberculosis—An infectious bacterial disease transmitted through the air that mainly affects the lungs.

Tumor—An abnormal mass that occurs when cells in a certain area reproduce unchecked; can be cancerous (malignant) or noncancerous (benign).

Thyroid gland—A gland located in the front of the neck below the voice box that plays an important role in metabolism (the chemical processes in the body) and growth; produces thyroid hormone.

Umbilical cord—The tubal structure (consisting of two arteries and one vein) that connects the fetus to the placenta, supplying the fetus with oxygen and nutrients and removing some waste products.

Urinary tract—The structures in the body that are responsible for the production and release of urine, including the kidneys, ureters, bladder, and urethra.

Vascular—Pertaining to blood vessels.

Ventricular fibrillation—Rapid, irregular contractions of the heart.

Visceral—Pertaining to a viscus (one of the organs, as the brain, heart, or stomach, in the great cavities of the body; especially used in the plural, and applied to the organs contained in the abdomen).