Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «P»:
Parthenogenesis: Development of a germ cell without
fertilization. This is what happens in the formation of ovarian teratomas (dermoid cysts). All of the chromosomes in these benign tumors of the ovary come from the mother. The counterpart of the ovarian teratoma is the hydatidiform mole, a tumor th...
Partial hysterectomy: In a partial hysterectomy, the
uterus is surgically removed but the cervix is left in place. Also called a subtotal
Partial laryngectomy: A surgical procedure on the voice box designed to preserve the voice. The surgeon removes part of the
voice box -- one vocal cord, part of a cord, or the epiglottis -- and leaves the rest, The stoma opening into the trachea is temporary. After a brief recovery period, the trac...
Partial seizure: A seizure that affects only one
part of the brain. Symptoms depend on which part is
affected. One part of the body, or multiple body parts
confined to one side of the body, may start to twitch
uncontrollably. Partial seizures may involve head turning,
eye movements, lip smackin...
Partial syndactyly: A condition in which
fingers or toes are partially joined together. Syndactyly can involve
the bones or just the skin. With partial syndactyly, the connection
extends from the base only part way up the involved digits. Partial
syndactyly is the opposite of complete syndactyl...
Participant: 1. In a clinical trial, someone who takes part in it. A participant may or may not have a disease. The term participant in this regard is synonymous with the term subject.
2. In health care benefits, a person who is eligible to receive health benefits under a health benefits plan. The ...
Particle, alpha: A tiny mass of material composed of two protons and two neutrons.
Alpha particles do not travel very far from their radioactive source. They cannot pass through a piece of paper, clothes or even the layer of dead cells which normally protects the skin. Because alpha particles cann...
Parturition: Childbirth, the process of delivering
the baby and placenta from the uterus to the vagina to the outside
world. Also called labor and delivery.
Parturition comes from the Latin parturire, "to be ready to bear young" and is related to partus, the past participle of parere, "to produce...
Parumbilical: Near the umbilicus (the "belly button").
The parumbilical veins are small veins in the front wall of the abdomen near the umbilicus....
Parvovirus B19: See: Fifth disease...
Infection with one of a family of small single-stranded DNA viruses. (Parvovirus
means small virus, from the Latin parvus, small.) One type, parvovirus B19, infects only humans. There are also animal parvoviruses, but they do not infect humans. A person cannot catch parvoviru...
PAS: 1. Physician-assisted suicide.
2. Personal alert system (an alarm system for an elderly or infirm person).
3. Periodic acid-Schiff (a stain used to detect carbohydrates in tissue).
Passage, nasal: The walls of the nasal passages are coated with respiratory mucous membranes which contain innumerable tiny hair-like cells that act to move waves of mucus toward the throat. Dust, bacteria, and other particles inhaled from the air are trapped by the mucus in the nose, carried back, ...
Passive exercise: Movement of the body, usually of the limbs, without effort by the patient. The patient is passive....
Passive immunity: Immunity produced by the transfer to one person of antibodies that were produced by another person. Protection from passive immunity diminishes in a relatively short time, usually a few weeks or months. For example, antibodies passed from the mother to the baby before birth confer ...