Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «P»:
Presentation, vertex: In a vertex presentation, the top of the
baby's head comes first at delivery. The vertex here refers specifically to the top
of the head The word "vertex" in Latin means a "whirlpool, whirlwind, top
of the mountain, or the top of the head." Why "top of ...
Presenteeism: The problem of workers being on the job but, because of medical conditions, not fully functioning. The health problems that result in presenteeism include such chronic or episodic ailments as seasonal include: depression, back pain, arthritis, heart disease, high blood pressure, and ga...
Pressor: Causing a rise in blood pressure.
A pressor base is a substance (chemically
classified as a base) capable of raising the blood pressure.
A pressor nerve is a nerve that, when stimulated, increases the
A pressor reflex is a nerve reflex that constricts arterioles
Pressor substance: A substance that elevates the arterial blood pressure. For example, prostacyclin (prostaglandin PGI2) is a potent pressor substance. In medicine, pressor refers to raising the blood pressure. The word comes from the French verb "presser" meaning "to exert pressure" or "to squeeze...
Pressure hives: See Pressure urticaria....
Pressure neuropathy: "Pinching" a nerve by putting
too much pressure on it. For example, the sciatic
nerve may be painfully compressed by a ruptured disc in the
lower spine, causing sciatica. Pressure neuropathy is also called nerve compression.
In pressure neuropathy there is excessive...
Pressure sore: A sore area of skin that develops when the blood supply to it is cut off for more than two to three hours due to pressure on it and lack of movement. As the skin dies, the pressure sore first appears as a red painful area, which in time turns purple. Left untreated, the skin can break...
Pressure urticaria: A common type of hives (urticaria) that occurs after the skin has been under pressure, often the feet after standing or the buttocks after sitting for a long time or areas where clothing is tight. The hives are typically deep and invisible to the eye. The hives may begin hours af...
Pressure wound: See: Pressure sore....
Pressure, intraocular: The pressure created by the
continual renewal of fluids within the eye. The intraocular pressure
is increased in glaucoma.
angle-closure glaucoma, the intraocular pressure rises because the
canal into which the
fluid in the front part of the eye normally drains is...
Pressure, low blood
Pressure, low blood: Any blood pressure that is below the normal expected for an individual in a given environment. Low blood pressure is also referred to as hypotension.
Low blood pressure is a relative term because the blood pressure normally varies greatly with activity, age, medications, and u...
Prevalence: The proportion of individuals in a population having a disease. Prevalence is a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time....
Preventive medicine: Medicine designed to avert and avoid
disease. Screening for
hypertension and treating it before it causes disease is good
preventive medicine. Preventive medicine is a proactive approach....
Priapism: Abnormally persistent erection of the penis in the
absence of sexual desire. Priapism can occur in persons with sickle cell anemia. Named after Priapus, the Greek and Roman god of procreation, whose nude
statues were placed in fields as scarecrows (where their attributes became well known)...
Primary: First or foremost in time or development. The primary teeth (the baby teeth) are those that come first. Primary may also refer to symptoms or a disease to which others are secondary.
A primary tumor is one that is at the original site at which it arose. For example, a primary brain tumor is...