Oat cell carcinoma
another term for small-cell carcinoma
a condition in which there is an excess of body fat; used to describe those who weigh at least 20 percent more than the maximum amount considered normal for their age, sex, and height
a mental disorder in which a person is obsessed with certain thoughts, leading them to repeatedly perform specific acts; for example, constantly washing the hands out of fear of germs and dirt
Obstructive sleep apnoea
the blockage of the airways during sleep, which causes breathing to stop for very short periods of time, commonly caused by excessive relaxation of muscles at the back of the throat
the blocking of an opening or passageway in the body
blood in the faeces that can be detected only by chemical tests
a disease that occurs as a result of factors in the workplace
treatment to relearn physical skills lost as a result of an illness or accident
describes something related to the eyes
Oculomotor nerves
nerves that stimulate movement of the eyeball
Oedema
abnormal build-up of fluid in the body, which may cause visible swelling
Oesophageal spasm
irregular contractions of the muscles in the oesophagus, which lead to difficulty swallowing
Oesophageal varices
swollen veins in the lower oesophagus and possibly the upper part of the stomach; can cause vomiting of blood and passing of black stool
a tube-shaped canal in the digestive tract, connecting the throat to the stomach
Oestrogen
a group of hormones (produced mainly in the ovaries) that are necessary for female sexual development and reproductive functioning
Oestrogen replacement therapy
treatment with synthetic estrogens drugs to relieve symptoms of menopause and to help protect women against osteoporosis and heart disease
Olfactory nerves
nerves that play a role in the sense of smell
Oligodendroglioma
a rare type of cancerous brain tumour that occurs most commonly in the cerebrum
Oligohydramnios
an unusually small amount of amniotic fluid surrounding the foetus in the uterus, which can lead to complications with the pregnancy
Oligospermia
a low level of sperm in the semen; one of the main causes of infertility in men
Oncogenes
genes that, when altered by environmental factors or viruses, can cause abnormal cell growth
Oocyte
an egg cell that has not developed completely
the surgical removal of one or both ovaries; used to treat the growth of ovarian cysts or tumours
any operation in which the heart is stopped temporarily and a machine is used to take over its function of pumping blood throughout the body
Ophthalmia
severe inflammation of the eyes
a doctor who specialises in care of the eyes; treats eye diseases and disorders
Ophthalmoplegia
partial or total loss of the ability to move the eyes
examination of the inside of the eye using a lighted viewing instrument
Opportunistic infection
infection by organisms that would be harmless to a healthy person, but cause infection in those with a weakened immune system (for example, persons with AIDS or chemotherapy patients)
pertaining to the eyes
Optic nerves
the pair of nerves that carry visual information from the retina to the brain
inflammation of the optic nerve, often causing a partial loss of vision
a person who specialises in the making and adjustment of eyeglasses and contact lenses
drugs taken in pill form to prevent pregnancy; contain synthetic progesterone and oestrogen hormones
the socket in the skull that contains the eyeball, along with its blood vessels, nerves, and muscles
Orchidectomy
the surgical removal of one or both of the testicles
Orchidopexy
an operation to correct an undescended testicle
inflammation of a testicle, which can be caused by infection with the mumps virus
an agreement to allow one or more organs to be removed and transplanted into someone else
any single, functioning form of life
involuntary contraction of genital muscles experienced at the peak of sexual excitement
drugs used to treat rare diseases; not normally produced because potential sales are small
Orthopnoea
breathing difficulty experienced while lying flat; can be a symptom of heart failure or asthma
Orthotic
a device used to correct or control deformed bones, muscles, or joints
painful enlargement and inflammation of the area of the shinbone just below the knee, usually occurring in adolescent boys
the process of passage of the solvent portion of a lesser-concentrated solution through a semipermeable membrane into a higher-concentrated solution until the two solutions are equal in concentration; plays an important role in water distribution in the body
Ossification
the formation and maintenance of bone
Osteitis
inflammation of bone
Osteitis deformans
another name for Paget's disease
see Degenerative arthritis
Osteoblast
a cell that forms bone
bone degeneration inside of a joint, causing small pieces of bone and cartilage to become detached
Osteochondritis juvenilis
inflammation of a growing section of bone in a child or adolescent
a noncancerous tumour made up of bone and cartilage
Osteoclast
a cell that breaks down unwanted bone tissue; also refers to a device for fracturing a bone to correct a deformity
Osteodystrophy
defective bone formation
a genetic disorder in which bones are abnormally fragile, leading to multiple breaks and deformity
the softening and destruction of bone
a noncancerous bone tumour
the loss of minerals and softening of bones because of a lack of vitamin D; called rickets in children
the inflammation of bones and bone marrow because of an infection, usually caused by bacteria
a rare hereditary disorder in which bones become harder and more dense, causing them to break more easily
Osteophyte
an outgrowth of bone near a joint
a condition in which bones become less dense, more brittle, and fracture easily
a cancerous bone tumour
Osteosclerosis
an abnormal increase in density and hardness of bone
Otalgia
the medical term for an earache
OTC remedy
see Over-the-counter remedy
inflammation of the outer ear due to an infection; commonly called swimmer's ear
inflammation of the middle ear (between the eardrum and inner ear) because of the spread of an infection from the nose, sinuses, and throat
Otorrhoea
a discharge from an inflamed ear
progressive deafness caused by bone formation around structures in the middle ear
harmful effect that some drugs have on the organs or nerves in the ears, which can lead to hearing and balance problems
medical attention that does not include an overnight stay at a hospital
two almond-shaped glands located at the opening of the fallopian tubes on both sides of the uterus; produce eggs and the sex hormones oestrogen and progesterone
Over-the-counter remedy
a medication that can be purchased without a physician's prescription
Overactive thyroid
Overactive thyroid is the familiar term for hyperthyroidism which means that the thyroid gland produces excess levels of thyroid hormones resulting in a raised metabolism.
an excessively large dose of a drug, which can lead to coma and death
the development and release of the egg from the ovary, which usually occurs halfway through a woman's menstrual cycle
another term for an egg cell
a chemical reaction involving active sources of oxygen (called oxygen free radicals) that damages cells
Oximetry
determination of the amount of oxygen in the blood by measuring the amount of light transmitted through an area of skin
a gas that is colourless, odourless, and tasteless; essential to almost all forms of life
Oxygen free radicals
active forms of oxygen found in pollution, cigarette smoke, and radiation that can damage cells and are believed to play a role in the ageing process and cancer
a hormone produced in the pituitary gland that causes contraction of the uterus during childbirth and stimulation of milk flow during breast-feeding
a poisonous form of oxygen that is present in the earth's upper atmosphere, where it helps to screen the earth from damaging ultraviolet rays