| 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 |
| 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 |
