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obesity
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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.
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object of addiction
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The psychoactive drug or rewarding behavior with which a person with
addiction has a pathological relationship.
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obstructive sleep apnea
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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.
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occipital lobe
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The region in the back of the brain responsible for visual processing.
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occlusion
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The closing or blocking of a hollow organ or body part.
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occult
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Something not visible to the naked eye but seen under a microscope or through lab tests.
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omega-3 fatty acids
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omega-6 fatty acids
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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.
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oncogene
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A
gene that, under certain conditions, can cause
cancer.
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oncologist
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A physician who deals with the diagnosis and treatment of cancer. There are three types?medical oncologists, radiation oncologists, and surgical oncologists.
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Ondine's curse
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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).
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onychomycosis
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open prostatectomy
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A surgical procedure in which an enlarged
prostate is removed through an
incision in the abdomen.
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ophthalmologist
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A physician who specializes in treating the eye and eye disease.
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ophthalmoscope
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An instrument with a light and mirrors for examining the deep interior of the eye.
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opiate
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Any painkilling drug such as morphine or codeine derived from the opium poppy.
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opioid
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Any narcotic, natural or synthetic, that behaves in the body like an opium-derived drug.
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optic disk
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The front surface of the
optic nerve, where all the retinal nerve
fibers come together to carry an image to the brain.
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optic nerve
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A cable of specialized nerve
fibers that transmit visual impulses from the eye to the brain.
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optician
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A technician who helps select and fit eyeglasses or contact lenses for people with vision problems.
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optimism
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A characteristic frame of mind that leads a person to expect positive outcomes and to view the world as a positive place.
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optometrist
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A health care professional licensed to examine the eye, and diagnose and treat some eye diseases.
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oral glucose tolerance test
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A test to check for
diabetes. It involves fasting overnight and having blood sugar levels checked before and after drinking a sugary solution.
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oral mucosa
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The layer of soft pinkish tissue that lines the interior of the mouth.
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orbit
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The bony socket that holds the eyeball.
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orbital irradiation
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orchiectomy
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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.
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organic matrix
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organonitrile
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A chemical found in cruciferous vegetables that may have anti-
cancer properties.
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orgasm
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The series of pleasurable, rhythmic muscle contractions that mark the peak of sexual arousal and the release of muscle tension.
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orthopedist
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A medical doctor who specializes in correcting disorders of the bones, joints, muscles, and
tendons.
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orthosis
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A custom shoe insert that helps cushion or realign the foot.
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orthostatic hypotension
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A sudden drop in
blood pressure upon standing or getting out of bed, causing dizziness.
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osseointegration
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A process in which bone heals around an implant to create a stable anchor.
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ossicles
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Three bones in the
middle ear that move in response to sound vibrations.
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ossification
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The process by which bone is formed.
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osteoarthritis
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osteoblasts
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osteoclasts
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Cells that remove bone
tissue.
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osteocytes
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A cell that is embedded in fully formed bone.
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osteomalacia
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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.
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osteomyelitis
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osteons
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The building blocks of compact bone, the hard, tightly-packed
tissue that forms the outer shell of bones.
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osteopath
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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.
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osteopenia
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Mild thinning and weakening of the bones; bone density is lower than normal but not low enough to be classified as
osteoporosis.
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osteophyte
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An outgrowth of bone on a joint or spinal
disk; commonly called a bone spur.
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osteoporosis
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Significant thinning and weakening of bones over time, making them vulnerable to breaks.
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osteotomy
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An operation in which bone is cut to change its alignment or shorten or lengthen it.
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otic capsule
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otitis externa
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