iatrogenic.<Gr iatros=healer>A disease or complication caused by the medical treatment.
icterus. Yellow discolouration of the skin or eyes. cf jaundice, which is yellow discolouration caused by increased bilirubin in the blood.
immunodeficiency is a defect in the function of the
protective immune system. This immune system fights bacteria and
viruses, and even destroys cancer cells that may develop in the
body. The body becomes
susceptible to many infections, which may even cause death. Immunodeficiency present since birth is called congenital. Immunodeficiency more often develops later in life, and is termed acquired.
Immunodeficiency can be acquired from drugs, cancers, and other diseases, one of which is AIDS.
immune system is the group of cells that fights against bacteria,
viruses and any other cells that are foreign to the body and
therefore potentially pathogenic. It consists of leukocytes (the
white blood cells), the lymphocytes, and the macrophages. These
cells are present in the blood. They are also present in the
liver, spleen and bone marrow. The lymphocytes in addition are
present in large quantities in the lymph nodes.
The leukocytes are best at engulfing bacteria, viruses, fungal cells, and even cancer cells. Neutrophils, also called polymorphonuclear leukocytes (PMN's or polys) are the most abundant of the leukocytes. Once the invading cells are engulfed, they are killed in special compartments called phagosomes. The phagosomes contain several toxic molecules, including some oxidants, which kill the pathogens.
Macrophages are large cells, also capable of engulfing pathogenic micro-organisms. Their importance lies in the fact that they are normally the initiators of the immune response.
The lymphocytes are best at producing immunoglobulins. Lymphocytes are of two main types: T lymphocytes and B lymphocytes.
The immune response starts with exposure to a pathogen, such as a virus. The macrophages recognize the virus as foreign, and send signals that cause the leukocytes to come quickly to the virus, and cause the lymphocytes to multiply and produce immunoglobulins.
immunoglobulins. Immunoglobulins are large protein molecules that can attach to bacteria and viruses and destroy them. Immunoglobulins are of different types, mainly G, M and A. The different immunoglobulins vary in their properties, but overall have similar functions. Immunoglobulins are produced by lymphocytes.
immunosuppression. Medically induced suppression of the immune response, to prevent rejection and to allow a transplanted organ to survive.
incision. A cut, usually the cut in the skin made by a surgeon.
inflammation. A tissue condition characterized by swelling, pain, redness, and decreased function.
intestine. The part of the alimentary tract between the stomach and the anus.
intravenous. In the vein. A term used for the administration of fluids and drugs by injecting into a vein.
ischemia. Lack of blood supply that causes deleterious effects.
isoniazid. A drug for tuberculosis. (Diagnosis of tuberculosis)
jaundice.(ME jaundis=yellow) An illness caused by increased bilirubin in the blood, and characterized by yellow discolouration, usually first seen in the eyes. Jaundice is a result of the presence of bilirubin in excessive quantities in the blood. There are several causes of jaundice, the commonest being hepatitis. Icterus is yellow discolouration, and is nearly synonymous with jaundice.
jaw. Either of the two bones of the head, involved in chewing: the upper jaw (maxilla) or the lower jaw (mandible)
jejunum. One of the three parts of the small intestine. Follows the duodenum, and leads on to the ileum. Absorbs proteins, carbohydrates and fat, as well as some vitamins such as folic acid (one of the vitamins B).
joint. The place of union of two bones. An articulation. Not all joints allow movement.
jugular. (L jugulum=throat) pertaining to the neck Jugular vein=one of the major neck veins: the right or left internal jugular, or the right or left external jugular vein.
Kaposi's sarcoma. An otherwise rare skin cancer, often seen in AIDS patients. (Article on AIDS)
Kala azar. (Hindi kala=black, Persian azar=illness) A disease caused by Leishmania donovani, and characterized by fever, enlargement of the spleen, and hyperpigmentation. Also called leishmaniasis.
kidney. One of a pair of organs in the abdomen, located adjacent to the spine, and responsible for removing urea and other wastes from the blood. Urine is produced by the kidneys.
keloid. A scar on the skin, that invades the adjacent skin tissue, with small infiltrative projections that somewhat resemble a crab. Keloids are commoner in dark-skinned races, and tend to occur after trauma or surgery over bony prominences such as the sternum (breastbone). It can continue to grow for years. (cf hypertrophic scar)
laceration. A rough tear, split or cut in the skin.
larynx. The voice box, the first part of the windpipe that is modified to produce sound. It is located in the neck and corresponds externally to the Adam's apple in males.
leishmaniasis. One of a group of parasitic diseases caused by protozoa of the genus Leishmania, eg. Kala azar.
lens. The transparent structure in the eye, located just behind the pupil, responsible for focussing the light rays. Opacity of the lens is called cataract. Intraocular lens. An artificial lens that is placed in the eye after removal of the natural lens, which may have become diseased, as in cataract.
leukocytes: see immune system
leukocytosis. An increased number of white cells in the blood, usually signifying inflammation.
leukoplakia. Whitish, plaque-like lesions on mucosa, particluarly the mucosa of the mouth. Leukoplakia may turn into cancer in a few patients.
ligament. Cord-like tissue that binds bone to bone. Ligaments are present only at joints.
lingual.(L lingua= tongue) Pertaining to the tongue.
liver. The largest solid organ in the body, it is located in the right abdomen and participates in digestion as well as several other metabolic processes.
lumbar. <latin lumbaris, the loin> Usually used to denote the lower back, or that part of the back that is in relation to the abdomen. The lumbar vertebrae are the bones of the spine in the lower back.
lumen. The hollow space within a tubular organ. The lumen is surrounded by the walls of the organ.
lumpectomy. Removal of a lump. Usually used for surgical excision of a lump in the breast, as a form of breast-conserving surgery.
lymph. Lymph is a colorless fluid that oozes out of the capillaries that carry blood. After circulating through the tissues the lymph enters the lymph vessels, or lymphatics, and finds its way back into the blood through a communication at the neck. The lymph carries immune cells to cells all over the body, and carries away infections, cancer cells and debris. The lymph first goes into a local group of lymph nodes, then to larger groups of nodes and finally into a large duct called the thoracic duct. The thoracic ducts enter the blood.
lymph nodes. Lymph nodes are nodules of tissue that contain lymphocytes. They are spherical or roughly ovoid in shape, and normally measure 1-10 mm in size. Most lymph nodes are distributed along major arteries, and tend to be present in groups of 10-50. Lymph produced anywhere in the body always goes to the nearest lymph node, where the bacteria and other foreign particles are filtered out. The cleansed lymph passes on to the next level of nodes, or to the blood stream. The lymph nodes enlarge in disease. The commonest disease of lymph nodes is lymphadenitis, or inflammation of the nodes, where the nodes become large and painful.
lymphocytes: see immune system