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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.
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 apnea
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.
occlusion
The blocking of an opening
or passageway in the body.
occult
blood
Blood in the feces that
can be detected only by chemical tests.
occupational disease
A disease that occurs as a
result of factors in the workplace.
occupational therapy
Treatment to relearn
physical skills lost as a result of an illness or accident.
ocular
Describes something
related to the eyes.
oculomotor
nerves
Nerves that stimulate movement of the
eyeball.
olfactory
nerves
Nerves that play a role in the sense of
smell.
oligodendroglioma
A rare type of cancerous
brain tumor that occurs most
commonly in the cerebrum.
oligohydramnios
An unusually small amount
of amniotic fluid
surrounding the fetus 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.
oophorectomy
The surgical removal of
one or both ovaries; used to treat the growth of ovarian cysts or tumors.
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.
ophthalmia
Severe inflammation of the eyes.
ophthalmologist
A doctor who specializes
in care of the eyes; treats eye diseases and disorders.
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.
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).
optic
Pertaining to the eyes.
optician
A person who specializes
in the making and adjustment of eyeglasses and contact lenses.
optic
nerves
The pair of nerves
that carry visual information from the retina
to the brain.
optic
neuritis
Inflammation of the optic
nerve, often causing a partial loss of vision.
oral contraceptives
Drugs taken in pill form
to prevent pregnancy; contain synthetic progesterone and estrogen hormones.
orbit
The socket in the skull
that contains the eyeball, along with its blood vessels, nerves, and
muscles.
orchiectomy
The surgical removal of
one or both of the testicles.
orchiopexy
An operation to correct an
undescended testicle.
orchitis
Inflammation of a testicle, which can be caused by
infection with the mumps virus.
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.
orgasm
Involuntary contraction of
genital muscles experienced at the peak of sexual excitement.
orphan
drugs
Drugs used to treat rare
diseases; not normally produced because potential sales are small.
orthopnea
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 .
Osgood-Schlatter disease
Painful enlargement and
inflammation of the area of the shinbone just below the knee, usually
occurring in adolescent boys.
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.
ossification
The formation and
maintenance of bone.
osteitis
Inflammation of bone.
osteitis deformans
Another name for Paget's disease.
osteoarthritis
See degenerative arthritis.
osteoblast
A cell that forms bone.
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.
osteochondroma
A noncancerous tumor 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.
osteogenesis imperfecta
A genetic disorder in which
bones are abnormally fragile, leading to multiple breaks and deformity.
osteolysis
The softening and
destruction of bone.
osteoma
A noncancerous bone tumor.
osteomalacia
The loss of minerals
and softening of bones because of a lack of vitamin D; called rickets in children.
osteomyelitis
The inflammation of bones and bone marrow because of an infection, usually caused by
bacteria.
osteopetrosis
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.
osteoporosis
A condition in which bones
become less dense, more brittle, and fracture easily.
osteosarcoma
A cancerous bone tumor.
osteosclerosis
An abnormal increase in
density and hardness of bone.
otalgia
The medical term for an
earache.
oTC
remedy
See over-the-counter
remedy.
otitis
externa
Inflammation of the outer ear
due to an infection; commonly
called swimmer's ear.
otitis
media
Inflammation of the middle ear
(between the eardrum and inner ear) because of the spread of an infection from the nose, sinuses,
and throat.
otorrhea
A discharge from an
inflamed ear.
otosclerosis
Progressive deafness
caused by bone formation around structures in the middle ear.
ototoxicity
Harmful effect that some
drugs have on the organs or nerves in the ears, which can lead to
hearing and balance problems.
outpatient treatment
Medical attention that
does not include an overnight stay at a hospital.
ovaries
Two almond-shaped glands
located at the opening of the fallopian tubes on both sides
of the uterus; produce eggs and the
sex hormones estrogen and progesterone.
overdose
An excessively large dose
of a drug, which can lead to coma and
death.
over-the-counter remedy
A medication that can be
purchased without a physician's prescription.
ovulation
The development and
release of the egg from the ovary, which usually occurs halfway through
a woman's menstrual cycle.
ovum
Another term for an egg
cell.
oxidation
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.
oxygen
A gas that is colorless,
odorless, 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 aging
process and cancer.
oxytocin
A hormone
produced in the pituitary gland
that causes contraction of the uterus
during childbirth and stimulation of milk flow during breast-feeding.
ozone
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.
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