Copy of `MediChecks - Medical glossary`

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MediChecks - Medical glossary Category: Health and Medicine Date & country: 06/01/2008, UK Words: 1901

Osteogenesis imperfecta
a genetic disorder in which bones are abnormally fragile, leading to multiple breaks and deformity

Osteochondroma
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

Osteochondritis dissecans
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

Osteoblast
a cell that forms bone

Osteitis
inflammation of bone

Osteitis deformans
another name for Paget's disease

Osteoarthritis
see Degenerative arthritis

Ossification
the formation and maintenance of bone

Osmosis
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

Osgood-Schlatter disease
painful enlargement and inflammation of the area of the shinbone just below the knee, usually occurring in adolescent boys

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

Orphan drugs
drugs used to treat rare diseases; not normally produced because potential sales are small

Orgasm
involuntary contraction of genital muscles experienced at the peak of sexual excitement

Organ donation
an agreement to allow one or more organs to be removed and transplanted into someone else

Organism
any single, functioning form of life

Orchidopexy
an operation to correct an undescended testicle

Orchitis
inflammation of a testicle, which can be caused by infection with the mumps virus

Orbit
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

Oral contraceptives
drugs taken in pill form to prevent pregnancy; contain synthetic progesterone and oestrogen hormones

Optician
a person who specialises in the making and adjustment of eyeglasses and contact lenses

Optic neuritis
inflammation of the optic nerve, often causing a partial loss of vision

Optic
pertaining to the eyes

Optic nerves
the pair of nerves that carry visual information from the retina to the brain

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)

Ophthalmoplegia
partial or total loss of the ability to move the eyes

Ophthalmoscopy
examination of the inside of the eye using a lighted viewing instrument

Ophthalmia
severe inflammation of the eyes

Ophthalmologist
a doctor who specialises in care of the eyes; treats eye diseases and disorders

Open heart surgery
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

Oocyte
an egg cell that has not developed completely

Oophorectomy
the surgical removal of one or both ovaries; used to treat the growth of ovarian cysts or tumours

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

Oligohydramnios
an unusually small amount of amniotic fluid surrounding the foetus in the uterus, which can lead to complications with the pregnancy

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

Oestrogen replacement therapy
treatment with synthetic estrogens drugs to relieve symptoms of menopause and to help protect women against osteoporosis and heart disease

Oesophagus
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

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

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

Ocular
describes something related to the eyes

Oculomotor nerves
nerves that stimulate movement of the eyeball

Occupational therapy
treatment to relearn physical skills lost as a result of an illness or accident

Occult blood
blood in the faeces that can be detected only by chemical tests

Occupational disease
a disease that occurs as a result of factors in the workplace

Occlusion
the blocking of an opening or passageway in the body

Obsessive-compulsive disorder
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

Oat cell carcinoma
another term for small-cell carcinoma

Obesity
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

Nystagmus
persistent, rapid, involuntary movement of the eyes

Numbness
the lack of sensation in a part of the body because of interruption of nerve impulses

Nurse-midwife
a registered nurse who specialises in the care of a mother and child during pregnancy, labour, and delivery

Nutrient
any substance that the body can use to maintain its health

Nucleus
the centre or most important point of an object

Nucleotide bases
molecules that form nucleic acids

Nucleic acids
substances found in every living organism that provide the instructions for development; includes DNA and RNA

Nosocomial infection
an infection acquired in a hospital

NSAID
see Nonsteroidal anti-inflammatory drug

Norwalk virus
a virus that causes acute gastro-enteritis

Norepinephrine
a hormone that regulates blood pressure by causing blood vessels to narrow and the heart to beat faster when blood pressure drops

Nonnarcotic analgesic
a drug that relieves pain by blocking the production of chemicals that stimulate pain-sensing nerves

Noninvasive
a term that is used to describe medical procedures that do not enter or penetrate the body; also refers to noncancerous tumours that do not spread to other sections of the body

Nondisjunction
an error that occurs during the division of sex chromosomes, causing either too much or too little genetic information to be placed in an egg or sperm when it is formed

Non-insulin-dependent diabetes
a type of diabetes mellitus that occurs mainly in those over 40 who are overweight; it is usually treated with diet changes and drugs that increase production of insulin by the pancreas (also known as type II diabetes mellitus)

Non-Hodgkin's lymphoma
any cancer in lymphoid tissue (found mostly in the spleen and lymph glands) that is not Hodgkin's disease

Node
a small, rounded tissue mass

Nodule
a small lump of tissue that is usually abnormal; can form under the skin or protrude

Nocturia
urination or a sleep-disturbing need to urinate during the night

Nocturnal emission
ejaculation of semen during sleep, which is normal in adolescent males; commonly called a wet dream

Night terrors
a form of nightmare causing abrupt awakening in terror; occurs mostly in children

Nitrates
a group of drugs that widen blood vessels; used to treat insufficient blood supply to the heart (angina pectoris) and reduced pumping efficiency of the heart (heart failure)

Niacin
a vitamin important in many chemical processes in the body; also known as vitamin B3

Neutrophil
a type of white blood cell

Nevus
a marking on the skin; can be present at birth (birthmark) or develop later (such as a mole)

Neurotransmitters
chemicals that transfer messages from one nerve cell to another or from a nerve cell to a muscle cell

Neurotoxins
chemicals that attack and damage nerve cells

Neurosis
relatively mild emotional disorders (such as mild depression and phobias)

Neuropathy
disease, inflammation, or damage to the nerves connecting the brain and spinal cord to the rest of the body

Neuroleptic
an antipsychotic drug

Neuroma
a noncancerous tumour occurring in nerve tissue

Neurone
another term for a nerve cell

Neurofibromatosis
a condition in which connective tissue tumours occur on nerves in the skin

Neurofibrillary tangles
abnormal spiral filaments on nerve cells in the brain; characteristic of Alzheimer disease

Neuritis
inflammation of a nerve, often characterised by pain, numbness, or tingling; also used to describe nerve damage and disease from causes other than inflammation

Neural tube defects
problems in the development of the spinal cord and brain in an embryo, such as the failure of the spine to enclose the spinal cord (spina bifida) and the failure of the brain to develop (anaencephaly)

Neuralgia
pain along the course of a nerve caused by irritation or damage to the nerve

Neural tube
the tube located along the back of an embryo that later develops into the spinal cord and brain

Nerve cell
the basic unit of the nervous system; transmits chemical messages throughout the body

Nerve compression
pressure on a nerve, which can cause nerve damage and muscle weakness

Nerve block
the dulling of sensation in an area of the body by injecting a painkiller into or around a nerve leading to that section of the body

Nerve
a bundle of fibres that transmit electrical messages between the brain and areas of the body; these messages convey sensory or motor function information

Nephrosclerosis
the replacement of normal kidney structures with scar tissue

Nephrostomy
the surgical placement of a tube into the kidney to drain urine