Glossary: O

obesity

overweight by 30 percent of the ideal body weight.

obsessive-compulsive disorder (OCD)

an anxiety disorder in which a person has an unreasonable thought, fear, or worry that he or she tries to manage through ritualized activity to reduce the anxiety. Frequently occurring disturbing thoughts or images are called obsessions, and the rituals performed to try to prevent or dispel them are called compulsions.

Obstetrician/Gynecologist (OB/GYN)

Physicians who specialize in general women's medical care, diagnosis and treatment of disorders of the female reproductive system, and care of pregnant women.

obstruction

blockage that prevents the flow of liquids or solids.

occluded artery

an artery that is narrowed by plaque that impedes blood flow.

occult

disease or symptoms that are not readily detectable by physical examination or laboratory tests.

occult bleeding

blood in stool that is not visible to the naked eye.

ocular hypertension

high (greater than 21 mm Hg) intraocular pressure.

odorant

substance that stimulates the sense of smell.

olfaction

the act of smelling.

olfactometer

device for estimating the intensity of the sense of smell.

oligomenorrhea

infrequent or light menstrual cycles.

oma/"-oma"

a suffix meaning "tumor" or "lump."

on-off effect, on-off phenomena

a change in the patient's condition, with sometimes rapid fluctuations between uncontrolled movements and normal movement, usually occurring after long-term use of levodopa and probably caused by changes in the ability to respond to this drug.

oncogenes

genes that promote normal cell division.

oncologist

physician who specializes in treating cancer.

oophorectomy

surgery to remove one or both ovaries.

oophoritis

inflammation of the ovary.

open heart surgery

surgery that involves opening the chest and heart while a heart-lung machine performs for the heart.

open surgery

cutting the skin and tissues during surgery to expose a full view of the structures and organs involved in the procedure.

ophthalmoscopy

examination of the internal structure of the eye.

optic nerve

a bundle of more than 1 million nerve fibers that connects the retina with the brain. The optic nerve is responsible for interpreting the impulses it receives into images.

optional surgery

an operation the patient chooses to have done, which may not be essential to continuation or quality of life. (See also elective surgery.)

oral and maxillofacial surgeon

orthopaedic facial surgeon who is responsible for treating a wide variety of dental problems - including the removal of impacted teeth and reconstructive facial surgery.

oral cancer

a cancer found in the oral cavity (mouth), on the lip, and the

oral dissolution therapy

method of dissolving cholesterol gallstones.

orchiectomy (Also called castration.)

the surgical removal of the testicles.

orchitis

inflammation of the testicle.

oropharynx

the part of the throat at the back of the mouth.

orthodontics

orthodontics is the dental specialty that focuses on the development, prevention, and correction of irregularities of the teeth, bite, and jaws.

orthokeratology

the use of contact lenses to change the shape of the cornea in order to correct refractive error.

orthopaedic surgeon (Also called an orthopaedist.)

a physician who diagnoses, treats, manages the rehabilitation process, and provides prevention protocols for patients who suffer from injury or disease in any of the components of the musculoskeletal system.

orthopaedic surgery (Also called orthopaedics.)

the medical specialty devoted to the diagnosis, treatment, rehabilitation, and prevention of injuries and diseases of the body's musculoskeletal system.

orthosis

a brace or splint used to strengthen or stabilize part of the body, usually an arm or leg.

orthostatic hypotension

a large decrease in blood pressure upon standing; may result in fainting.

osteitis pubis

an inflammation of the pubic symphysis, the bone to which the two hip bones connect in front of the body.

osteoarthritis

a condition caused by wear and tear that causes inflammation of the joint, causing swelling, pain, and stiffness.

osteoblast

cell found in bone; its function is to form the tissue and minerals that give bone its strength.

osteoclast

very large cell formed in bone marrow; its function is to absorb and remove unwanted tissue.

osteocyte

cell found within the bone; its function is to help maintain bone as living tissue.

osteophyte

outgrowth of bone.

osteoporosis

disorder in which bones thin and become brittle and more prone to fracture; most common in women after menopause due to estrogen deficiency.

ostomy

operation that makes it possible for stool to leave the body through an opening made in the abdomen; necessary when part or all of the intestines are removed. Colostomy and ileostomy are types of ostomy.

otitis externa

inflammation of the outer part of the ear extending to the auditory canal.

otitis media

inflammation of the middle ear caused by infection.

otoacoustic emissions

low-intensity sounds produced by the inner ear that can be quickly measured with a sensitive microphone placed in the ear canal.

otolaryngologist

physician/surgeon who specializes in diseases of the ears, nose, throat, and head and neck.

otologist

physician/surgeon who specializes in diseases of the ear.

otoplasty (Also called ear surgery.)

a type of cosmetic plastic surgery procedure aimed at setting prominent ears closer to the head, or reducing the size of larger ears.

otosclerosis

abnormal growth of bone in the inner ear, which prevents structures within the ear from working properly, resulting in a gradual loss of hearing.

otoscope

a lighted instrument that allows the physician to see inside the ear.

ototoxic drugs

drugs that can damage the hearing and balance organs located in the inner ear.

outer ear

external portion of the ear, consisting of the pinna, or auricle, and the ear canal.

outpatient surgery

surgery which allows the patient to go home the same day.

ovaries

pair of small glands, located on either side of the uterus, in which egg cells develop and are stored and the female sex hormones estrogen and progesterone are produced.

ovary

one of a pair of almond-shaped glands situated on either side of the uterus. Egg cells develop in the ovaries.

overflow incontinence

leakage of urine that occurs when the quantity of urine produced exceeds the bladder's capacity to hold it.

overuse conditions

injuries due to minor trauma involving soft-tissue injuries

ovulation

release of a mature egg from an ovary.

ovum

a mature egg cell released during ovulation from an ovary.

oxytocin

hormone produced by the pituitary gland that stimulates contractions of the uterus during labor and release of milk during breast-feeding.

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