A to Z Medical and Healthy Living Glossary
Here is an online glossary of medical and healthy living terms for non-medical people. This page is for medical and healthy living terms beginning with the letter 'A'.
- Abdomen - The space inside the body below the diaphragm, above the pelvis and in front of the spine, containing the stomach, intestines, liver and other vital organs. For medical purposes the abdomen is divided into nine regions: at the top, the right and left hypochondriac regions with the epigastrium between them; in the centre, the right and left lumbar regions with the umbilical between them; and at the bottom, the right and left iliac regions with the hypogastrium between them.
- Abdominal Wall - Muscular tissue which surrounds the abdomen.
- ABO System - The system used for classifying blood groups.
- Abscess - A painful swollen area where pus forms. Usually it is triggered by an infection. The formation of an abscess is often accompanied by a high temperature. An acute abscess can be dealt with by opening and draining when it has reached the stage where sufficient pus has been formed. A chronic abscess usually needs to be treated using drugs.
- Absorption - The process of taking into the body substances such as proteins or fats which have been digested from food and enter the bloodstream from the stomach and intestines.
- Acanthosis - A disease of the prickle cell layer of the skin, where warts appear on the skin or inside the mouth.
- Acapnia - The condition of not having enough carbon dioxide in the blood and tissues.
- Accommodative Squint - A squint when the eye is trying to focus on an object which is very close.
- Accessory Nerve - The eleventh cranial nerve which supplies the muscles in the neck and shoulders.
- ACE - An enzyme that increases blood pressure.
- Acetabulum or Cotyloid cavity - The part of the pelvic bone, shaped like a cup, into which the head of the femur fits to form the hip joint.
- Acetaminophen - The same as paracetamol.
- Acetylcholine - A substance released from nerve endings, which allows nerve impulses to move from one nerve to another or from a nerve to the organ it controls. Acetylcholine receptors are of two types, muscarinic, found in parasympathetic post-ganglionic nerve junctions, and nicotinic, found at neuromuscular junctions and in autonomic ganglia. Acetylcholine acts on both types of receptors, but other drugs act on one or the other.
- Acid - A chemical compound containing hydrogen, which reacts with an alkali to form a salt and water.
- Acidaemia - A state in which the blood has too much acid in it. It is a feature of untreated severe diabetes.
- Active ingredient - Substance in a product that performs the main function of that product.
- Acute - The term which is used to describe a disease that appears quickly, produces severe symptoms and rapidly reaches its crisis. An example is acute appendicitis.
- Acute Toxicity - A toxic reaction that occurs shortly after exposure to a toxin (usually within a few hours or days).
- Adrenaline - The hormone that prepares the body for action - the 'fight or flight' response - during emergencies or at times of strong personal emotion. It raises the heart and breathing rates, increases the blood sugar level and delays the onset of tiredness in the muscles. Adrenaline is secreted by the adrenal glands, which are located above each kidney.
- Adulterant - Contaminant to a product added either intentionally to thin the product or unintentionally. In the USA, the federal government prohibits adulterants in food.
- Aerobic - Process that requires oxygen.
- Aerobic bacteria - Bacteria that multiply in oxygenated environments.
- Aflstoxin - A virulent poison produced by the fungus Aspergillus flavus that can contaminate peanuts and cereals if they are stored in warm, humid conditions. It is not destroyed by cooking and can inpair the bodies' immune system and cause cancer.
- Agrochemicals - Chemical compounds, such as fertilizers and pesticides, used in intensive farming. In most cases, agrochemicals are present in food only in tiny quantities that are further reduced by washing or peeling fruit and vegetables. Some experts have claimed that the widespread use of agrochemicals has caused the rise in a number medical complaints such as asthma, allergies even infertility. Although there is circumstantial evidence, there is little scientific proof to support these claims.
- Alkaloids - Nitrogen containing compounds, produced mainly by plants. Some, including codeine, morphine and quinine, are used for medical purposes. However, some alkaloids can be poisonous. Solanine (found in potatoes which have turned green after prolonged exposure to light) and nicotine. In small amounts nicotine has a stimulating effect, but large doses are toxic.
- Allergen - Any substance that causes an allergy, such as the pollen which triggers hay fever, or peanuts which can cause a severe asthma attack or lead to swelling of the tongue and throat.
- Alveoli - Tiny air sacs in the lungs.
- Amines - Nitrogen compounds present in food. Amines can combine with nitrites in food or in the stomach to form nitrosamines, which may be linked with cancer, although there is no conclusive scientific evidence.
- Amino Acids - The basic building blocks of proteins. There are 20 amino acids which are linked in varying sequences to make all the different proteins. Most amino acids can be synthesised by the body, but eight are termed 'essential' or 'indispensable' because the body cannot manufacture them and so they need to be provided by the diet. After they have been broken down from protein, amino acids are carried in the bloodstream to the liver as well as to the other areas of the body where they are needed. They are then reassembled to make the specific forms of protein required by different cells and tissues.
- Anaerobic - Absence of oxygen.
- Anaerobic Bacteria - Bacteria that multiply in an oxygen-free environment.
- Anaphylactic Shock - An extreme allergic reaction in which huge quantities of histamine are released throughout the body, producing rapid swelling and making breathing difficult. If untreated, it can lead to loss of consciousness, heart failure and even death. In susceptible people, an anaphylactic shock can be triggered by foods such as peanuts or insect stings or certain drugs.
- Anti-carcinogens - Agents found in some foods that are thought to counteract carcinogens and so help to prevent some sorts of cancers from forming. Cruciferous vegetables such as broccoli, Brussels sprouts, cabbage, cauliflower and kale are very good sources of these compounds, which include carotenoids, indoles and isothiocyanates.
- Antibacterial Cleanser - A cleaning product which has been designed to kill bacteria as well as clean.
- Antibiotic - a substance, derived from a micro-organism, that kills or inhibits the multiplication of other micro-organisms, usually bacteria or fungi. The most well known antibiotics are penicillin and streptomycin.
- Antibodies - Proteins, in the blood and other body fluids, that fight against infection. They are capable of destroying bacteria and other potentially harmful substances. Antibodies are manufactured in lymph tissue such as that of the spleen, in response to the presence of a foreign substance in the body, such as an allergen or a virus. Each antibody combats a particular infection; for example, a measles antibody cannot fight chickenpox or a cold virus. Once the body has an effective antibody it becomes immune to that disease. Antibodies are transported around the body in the bloodstream.
- Antioxidants - In molecules and cells, antioxidants deactivate free radicals that are the natural by-products of many cellular processes. Free radicals are also created by exposure to various environmental agents such as tobacco smoke and radiation. They can cause damage to cell components that over time may lead to diseases such as cancer. Antioxidants neutralise the free radicals before damage can be done.
- Antivirals - Drugs that are effective against disease-causing viruses. One exampleof an antiviral drug is acyclovir, used to treat shingles as well as other forms of herpes. Certain foods such as garlic also have various antiviral properties.
- Arteriole - A small artery.
- Artery - A thick-walled vessel that carries blood away from the heart.
- Arthritis - Inflammation of the joints or spine, the symptoms of which are a painful swelling, restriction of movement, redness and warmth of the skin. There are a number of different causes of arthritis, such as osteoarthritis, rheumatoid arthritis, tuberculosis and rheumatic fever.
- Assay - Laboratory test or analysis.
- Atheroma - A degenerative condition of the arteries. The inner and middle coats of the arterial walls become scarred, and fatty deposits (cholesterol) are built up at these sites. The blood circulation is impaired, which can cause such problems as angina pectoris, stroke and heart attack. Atheroma is associated with the modern western lifestyle, i.e. lack of exercise, smoking, obesity and too high an intake of animal fats.
- Atherosclerosis - Similar to atheroma, being a degenerative disease of the arteries associated with fatty deposits on the inner arterial walls causing a reduced blood flow.
- ATP (adenosine triphosphate) - An important molecule that is used as energy to drive all cellular processes. ATP can be synthesized during glycolysis, or it can be broken down to form ADP. This releases energy that will be used to drive a metabolic process, such as active transport across cell membranes or the contraction of muscle cells.
- Atria - The two upper chambers of the heart.
- Axon - Fine filament that carries impulses away from a nerve cell body.
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