Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «P»:
Phenothiazine: One of a group of tranquilizing drugs with antipsychotic actions thought to act by blocking dopaminergic transmission (messages sent using the substance dopamine) within the brain.
Examples of phenothiazines include: chlorpromazine (brand name: Thorazine), fluphenazine (Duraclon), me...
Phenotype: The appearance of an individual, which
results from the interaction of the person's genetic makeup and his
or her environment. By contrast, the genotype is merely the genetic
constitution (genome) of an individual. For example, if a child's
genotype includes the gene for osteogenesis ...
Phenotype, Klippel-Feil: See: Klippel-Feil sequence....
Phenylalanine: An essential amino acid. (The human body cannot make it so it is essential to the diet.) Phenylalanine that is ingested is largely transformed (hydroxylated) to form the amino acid tyrosine, which is used in protein synthesis. Too little phenylalanine curbs physical and intellectual...
Phenylalanine hydroxylase deficiency
Phenylalanine hydroxylase deficiency: The inherited inability to process the amino acid phenylalanine normally, due to deficiency of the enzyme phenylalanine hydroxylase. This deficiency is caused by mutation in the PAH gene (on chromosome 12 in band 12q23.2). Hundreds of different disease-causing...
Phenylketonuria: The inherited inability to metabolize (process) the essential amino acid phenylalanine due to complete or near-complete deficiency of the enzyme phenylalanine hydroxylase.
Newborns are screened for phenylketonuria (PKU) by a blood test, usually with the Guthrie card bloodspot obtai...
Phenylketonuria, maternal: See Maternal phenylketonuria....
Pheresis: Procedure in which the blood is filtered, separated, and a portion retained, with the remainder being returned to the individual.
There are various types of pheresis. In leukapheresis, the leukocytes (white blood cells) are removed. In plateletpheresis, the thrombocytes (blood platelets) ...
Pheromone: An agent secreted by an individual that produces a change in the sexual or social behavior of another individual of the same species; a volatile hormone that acts as a behavior-altering agent.
The term "pheromone" is usually used for sexual attractants (such as bombesin in the moth Bomb...
Philadelphia chromosome (Ph)
Philadelphia chromosome (Ph): The chromosome abnormality that causes chronic myeloid leukemia (CML). Abbreviated as the Ph chromosome.
The Ph chromosome is an abnormally short chromosome 22 that is one of the two chromosomes involved in a translocation (an exchange of material) with chromosome 9. ...
Philippine hemorrhagic fever
Philippine hemorrhagic fever: A
syndrome due to the dengue virus that tends to affect
children under 10, causing abdominal pain, hemorrhage
(bleeding) and circulatory collapse (shock). Known also as
dengue hemorrhagic fever (DHF), it starts abruptly with
high continuous fever and headache plu...
Philtrum: The area from below the nose to the upper lip. Normally
the philtrum is grooved. In fetal alcohol syndrome, the philtrum is flat. ...
Phimosis: A condition whereby the foreskin of the
penis is too tight.
The penis itself consists of a cylindrical shaft with a rounded
tip which is called the glans. The foreskin, or prepuce, is the fold
of skin that covers the glans.
Phimosis is medically defined as "stenosis (tightness) of the...
Phlebitis: Inflammation of a vein. With phlebitis there is
infiltration of the walls of the vein and, usually, the formation of a clot (thrombus) in
the vein (thrombophlebitis). Phlebitis in a leg, for example, will cause the leg to swell
with edema fluid and feel stiff and painful....
Phlebo- (prefix): Means vein. From the Greek
"phleps", vein, which came from the root "phlein", to gush or
overflow. Appears in phlebitis (inflammation of the veins),
phlebotomist (a person who draws blood from veins), and phlebotomy (a