Medical Terminology
Glossary
obesity - body weight 10-20 % over a desirable standard as a result of excessive fat accumulation; types include hypertrophic (adult-onset) and hyperplastic (lifelong)
obstetrics - the specialized branch of medicine that deals with pregnancy, labor, and the period of time immediately following delivery
obturator - anything that obstructs or closes a cavity or opening
occlusion - the act of closure or state of being closed
occult - concealed or hidden from view, as, for example, occult blood in stools
olfactory - pertaining to smell
oligodendrocyte - a neuroglial cell that supports neurons & produces a phospholipid myelin sheath around neuronal axons in the central nervous system
oligospermia - deficiency of spermatozoa in the semen
oliguria - a daily urinary output usually less than 250 ml
oncogene - a gene that has the ability to transform a normal cell into a cancerous cell
oncology - the study of tumors
oogenesis - formation and development of the ovum
oophorectomy - the surgical removal of the ovaries
ophthalmic - pertaining to the eye
ophthalmologist - physician who specializes in the diagnosis and treatment of eye disorders with drugs, surgery, and corrective lenses
ophthalmology - the study of the structure, function, and diseases of the eye
ophthalmoscopy - examination of the interior fundus of the eyeball to detect retinal changes associated with hypertension, diabetes mellitus, atherosclerosis, and increased intracranial pressure
opsin - the glycoprotein portion of a photopigment
opsonization - action of some antibodies that renders bacteria and other foreign cells more susceptible to phagocytosis; also called immune adherence
optic chiasma - crossing point of the optic (II) nerves, anterior to the pituitary gland
optician - a technician who fits, adjusts, & dispenses corrective lenses on prescription of an optometrist or an ophthalmologist
optometrist - specialist with a doctorate degree in optometry who is licensed to examine & test the eyes and to treat visual defects by prescribing corrective lenses
ora serrata - the irregular margin of the retina, lying internal and slightly posterior to the junction of the choroid and ciliary body
oral cholecystogram - X-ray examination of the gallbladder to evaluate for the presence of gallstones, inflammation, and tumors
orbit - the bony, pyramid-shaped cavity of the skull housing the eyeball
organelle - structure inside a cell having characteristic morphology, specialized to perform a specific function in cellular activities
organic compound - compound that always contains carbon and hydrogen and has the atoms held together by covalent bonds; examples include carbohydrates, lipids, proteins, and nucleic acids (DNA and RNA)
organism - a total living form; one individual
orgasm - sensory and motor events involved in ejaculation for the male and in involuntary contraction of the perineal muscles for the female at the climax of sexual intercourse
orifice - any aperture or opening
origin - the place of attachment of a muscle to the more stationary bone at a joint, or the end opposite the insertion
oropharynx - the second portion of the pharynx, lying posterior to the mouth and extending from the soft palate down to the hyoid bone
orthopedics - a branch of medicine dealing with preservation and restoration of the skeletal system, articulations, and related structures
orthopnea - dyspnea (discomfort in breathing) occuring when in the horizontal position
osmoreceptor - hypothalamic receptor that is sensitive to changes in blood osmotic pressure and that, in response to high osmotic pressure (low water concentration), causes the synthesis and release of antidiuretic hormone
osmosis - the net movement of water molecules through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration until an equilibrium condition is achieved
osseus - bony
ossicle - a small bone, as those in the middle ear (incus, malleus, stapes)
ossification - the formation of bone; also called osteogenesis
osteoblast - cell formed from an osteo-progenitor cell; it participates in bone formation by secreting some organic components and inorganic salts
osteoclast - a large multinuclear cell that develops from a monocyte & destroys or resorbs bone tissue
osteocyte - a mature bone cell that maintains the daily activities of bone tissue
osteogenic layer - the inner layer of the periosteum, containing cells responsible for forming new bone during growth and repair
osteology - the study of bones
osteomalacia - deficiency of vitamin D in adults causing demineralization and softening of the bones
osteomyelitis - inflammation of bone marrow or of both the bone and marrow
osteoporosis - age-related disorder characterized by decreased bone mass and increased susceptibility to fractures; may result from decreased levels of estrogens
osteoprogenitor cell - a stem cell derived from mesenchyme, having mitotic potential and ability to differentiate into an osteoblast
otalgia - pain in the ear; earache
otic - pertaining to the ear
otitis media - acute infection of the middle ear, characterized by pain, malaise, fever, and an inflamed tympanic membrane that is subject to rupture
otolith - a particle of calcium carbonate embedded in the otolithic membrane; it functions in maintaining static equilibrium
otolithic membrane - a thick, gelatinous, glycoprotein layer, located directly over the hair cells of the macula in the saccule and utricle of the inner ear
otorhinolaryngology - the branch of medicine that deals with diagnosis and treatment of diseases of the ears, nose, and throat
ovarian follicle - a general name for oocytes (immature ova), regardless of their stage of development, along with their surrounding epithelial cells
ovary - female gonad; it produces ova and hormones (estrogens, progesterone, and relaxin)
ovulation - the rupture of a vesicular ovarian (Graafian) follicle, with discharge of a secondary oocyte into the pelvic cavity
ovum - the female reproductive or germ cell; an egg cell
oxidation - the removal of electrons and hydrogen ions from (or, less commonly, the addition of oxygen to) a molecule; it results in decreasing the molecule's energy content; glucose oxidation in the body is also called cellular respiration
oxyhemoglobin (HbO2) - hemoglobin combined with oxygen
oxytocin (OT) - hormone secreted by neurosecretory cells in the paraventricular (mainly) & supraoptic nuclei of the hypothalamus; stimulates contraction of both smooth muscle fibers in the uterus & contractile cells around mammary ducts
