macrophages: see immune system

mammogram. X-ray of the breasts.

mastectomy. Surgical removal of the breast, usually done for breast cancer.

mastoid. The bony prominence just behind the ear.

Mantoux test. A skin test for tuberculosis. (Diagnosis of tuberculosis)

melena. Stools that have turned black due to the presence of blood. For blood to turn stools black the origin of the bleeding should be in the first part of the gastrointestinal tract, i.e. esophagus, stomach or duodenum. The black color arises from the presence of acid hematin, which is formed when acid of the stomach acts on hemoglobin.

meninges. The layers covering the brain and the spinal cord. There are three such layers, the duramater (outermost), the arachnoid (middle layer) and the piamater (innermost).

menopause. Cessation of menstruation. cf climacteric.

menstruation. The periodic bleeding that occurs in a woman of the reproductive age group.

metastasis. The phenomenon of movement from one site to another. In biological terms, tumours metastasize from their site of origin, such as breast, to other, distant sites. Cancers advance in two ways. They can spread to immediately adjacent tissue: this is called spread by infiltration. They can also spread by the blood stream or by the lymph stream to distant sites. This is called metastasizing. Benign tumours do not metastasize. In general the first site of metastasis of malignant tumours is to the nearby lymph nodes. After the lymph nodes, tumours of the gastrointestinal tract usually first metastasize to the liver, while tumours of other organs usually first metastasize to the lungs. Apart from the lungs and liver, common sites of metastasis are the bones, the brain and (for abdominal cancers) the peritoneal cavity. See breast cancer, colorectal cancer.

mucosa, mucous membrane. The inner lining of all hollow organs is made of a layer of specialized tissue. This lining is called the mucosa or the mucous membrane. In many organs the mucous membrane produced a gelatinous substance called mucous. The mucosa of one organ differs from that of another. See also epithelium.

mycobacterium tuberculosis. see tuberculosis

myocardium. Muscle of the heart. Myocardial infarct = damage to the heart muscle caused by a reduced blood flow, as in coronary thrombosis. Myocardial ischemia= decreased blood supply to the heart muscle. This may result in a myocardial infarct.


nitrous oxide. A gas used as an anesthetic agent. Also called laughing gas.


obstruction. In the body, any block in the flow of fluid. Intestinal obstruction = a condition in which the passage of food and intestinal contents is hampered by a narrowing of the bowel; urinary obstruction ("obstructive uropathy")=obstruction to the flow of urine.

oral submucous fibrosis. A marked thickening of the mucosa of the mouth, in which the patient is unable to open the mouth (trismus) properly. Patients with OSMF have a higher chance of developing oral cancer.

osteoporososis. A disease of the bones, in which the bones lose calcium and become porous, weaker and susceptible to fractures.

otitis. Inflammation of the ear. Otitis externa, media and interna refer to inflammation of the external, middle and inner ear respectively.

oxytocin. A hormone, secreted by the pituitary, it causes contraction of the uterus and production of milk. It may have a role to play in parturition (the process of childbirth).


pandemic. <Gr pas=all, demos=people>Disease that occurs with a high incidence over a large area, such as a country, continent or world. A widespread epidemic.

Pare, Ambrose 1510-1590. French surgeon. See biographical dictionary.

parturition. (L parere=to give birth) The process of giving birth to a child.

Pasteur, Louis. 1822-95. French chemist. See biographical dictionary.

pathogen: Anything that causes disease. This may be a toxin, a chemical, a drug or a micro-organism. The majority of micro-organisms are in fact not pathogenic to man. In immune deficiency microbes that are normally not pathogenic may become pathogenic.

pelvis. The set of bones attached to the lower end of the spine, that also provides an articulation for the hip bones. The Ashape differs in men and women. The pelvic cavity is the area enclosed by the bony pelvis, and contains the urinary bladder, the rectum and the reproductive organs in the female. The pelvic cavity is continuous above with the abdominal cavity, and in a sense forms part of it.

peptic ulcer. A peptic ulcer is a break in the mucosa of the stomach or duodenum, and is caused by acid. The shape of the ulcer may be linear, circular, oval or irregular. Most ulcers are less than 1 cm in size.

peritoneum. The thin layer of tissue that surrounds the abdominal organs. Peritonitis: inflammation of the peritoneum.

pharmacology. The science of drugs. Pharmacodynamics of a drug refers to the effects of the drug on the body, while the pharmacokinetics of the drug is the manner in which the body handles, and gets rid of the drug.

pharynx. The first part of the esophagus (foodpipe). At the pharynx the windpipe (trachea) and the foodpipe open together.

phenol. A disinfectant

pilonidal sinus. See sinus.

pituitary gland. A tiny hormone-secreting organ, about the size of a pea, located at the base of the brain.

portal vein. The vein that drains blood from the digestive tract and takes it to the liver. Portal hypertension: elevated pressure in the portal vein.

posterior. Situated towards the back, or rear of an organ or the body.

povidone iodine (betadine). An antiseptic. Releases iodine in solution, and has extremely broad spectrum antimicrobial effects. It is bactericidal to all viruses, bacteria and fungi.

pregnancy. A female's state of being with child, due to give birth. Calculate the expected date of birth!

primary intention. The manner in which a wound heals quickly from apposed, healthy margins.

proximal. Closer to the heart. e.g., in the lower limb, the proximal part is the thigh, the distal part is the toe.

pus. A fluid containing bacteria, dead cells and toxins, that arises out of infection. Pus is usually dirty white in colour, and foul smelling.

pyrazinamide. A drug for tuberculosis.(Diagnosis of tuberculosis)