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Glossary - O

Displaying glossary terms beginning with the letter O: 1 - 50 of 64 in total
obesity
A body weight that is much higher than is healthy. Defined as having a body mass index of 30 or more. Obesity puts a person at greater risk of developing numerous chronic diseases.
object of addiction
The psychoactive drug or rewarding behavior with which a person with addiction has a pathological relationship.
obstructive sleep apnea
A disorder marked by heavy snoring and interrupted breathing during sleep. It increases the risk of developing high blood pressure and having a stroke and is more common in people who are obese.
occipital lobe
The region in the back of the brain responsible for visual processing.
occlusion
The closing or blocking of a hollow organ or body part.
occult
Something not visible to the naked eye but seen under a microscope or through lab tests.
omega-3 fatty acids
Beneficial fats, also known as n-3 fatty acids. These are polyunsaturated fat found in fatty fish, such as salmon.
omega-6 fatty acids
Fatty acids found in certain foods that the body needs for good health but can't make on its own. Also known as n-6 fatty acids.
oncogene
A gene that, under certain conditions, can cause cancer.
oncologist
A physician who deals with the diagnosis and treatment of cancer. There are three types?medical oncologists, radiation oncologists, and surgical oncologists.
Ondine's curse
A rare and potentially fatal breathing disorder in which a person doesn't take enough breaths per minute, particularly at night when there are episodes where breathing ceases (sleep apnea).
Related health topics: Uterine Cancer
onychomycosis
Toenail fungus.
open prostatectomy
A surgical procedure in which an enlarged prostate is removed through an incision in the abdomen.
ophthalmologist
A physician who specializes in treating the eye and eye disease.
ophthalmoscope
An instrument with a light and mirrors for examining the deep interior of the eye.
opiate
Any painkilling drug such as morphine or codeine derived from the opium poppy.
Related health topics: Retinopathy, Type 2 Diabetes Mellitus
opioid
Any narcotic, natural or synthetic, that behaves in the body like an opium-derived drug.
optic disk
The front surface of the optic nerve, where all the retinal nerve fibers come together to carry an image to the brain.
optic nerve
A cable of specialized nerve fibers that transmit visual impulses from the eye to the brain.
optician
A technician who helps select and fit eyeglasses or contact lenses for people with vision problems.
Related health topics: Retinopathy
optimism
A characteristic frame of mind that leads a person to expect positive outcomes and to view the world as a positive place.
optometrist
A health care professional licensed to examine the eye, and diagnose and treat some eye diseases.
oral glucose tolerance test
A test to check for diabetes. It involves fasting overnight and having blood sugar levels checked before and after drinking a sugary solution.
oral mucosa
The layer of soft pinkish tissue that lines the interior of the mouth.
orbit
The bony socket that holds the eyeball.
orbital irradiation
X-ray treatment to the eye; sometimes used in more serious cases of Graves' eye disease.
orchiectomy
Surgery to remove the testicles. Usually done to remove a cancerous testicle or to lower testosterone levels and slow or halt the growth of prostate cancer.
organic matrix
The protein framework of bone tissue.
organonitrile
A chemical found in cruciferous vegetables that may have anti-cancer properties.
orgasm
The series of pleasurable, rhythmic muscle contractions that mark the peak of sexual arousal and the release of muscle tension.
orthopedist
A medical doctor who specializes in correcting disorders of the bones, joints, muscles, and tendons.
orthosis
A custom shoe insert that helps cushion or realign the foot.
orthostatic hypotension
A sudden drop in blood pressure upon standing or getting out of bed, causing dizziness.
osseointegration
A process in which bone heals around an implant to create a stable anchor.
ossicles
Three bones in the middle ear that move in response to sound vibrations.
ossification
The process by which bone is formed.
osteoarthritis
A joint disease in which the cartilage that lines the joints slowly deteriorates. Also called degenerative joint disease.
osteoblasts
Cells that build bone tissue.
Related health topics: Obesity
osteoclasts
Cells that remove bone tissue.
osteocytes
A cell that is embedded in fully formed bone.
osteomalacia
A condition in which bones are soft and weak, usually due to a lack of vitamin D or an inability of the body to use vitamin D properly.
osteomyelitis
A bone infection caused by bacteria or fungi.
osteons
The building blocks of compact bone, the hard, tightly-packed tissue that forms the outer shell of bones.
osteopath
A doctor licensed to practice medicine, perform surgery, and prescribe drugs. The training is similar to that of a regular M.D., but more emphasis is placed on the importance of the musculoskeletal system and the body's ability to heal itself.
osteopenia
Mild thinning and weakening of the bones; bone density is lower than normal but not low enough to be classified as osteoporosis.
osteophyte
An outgrowth of bone on a joint or spinal disk; commonly called a bone spur.
osteoporosis
Significant thinning and weakening of bones over time, making them vulnerable to breaks.
osteotomy
An operation in which bone is cut to change its alignment or shorten or lengthen it.
otic capsule
The bony shell that surrounds the inner ear.
otitis externa
An infection of the skin lining the ear canal of the outer ear. Also called swimmer's ear.