578 GlossaryProjection(proh-JEK-shun) The characteristic of sensa-
tions in which the sensation is felt in the area where the
receptors were stimulated (Chapter 9).
Prolactin(proh-LAK-tin) A hormone produced by the
anterior pituitary gland that stimulates milk production
by the mammary glands (Chapter 10).
Pronation(proh-NAY-shun) Turning the palm downward,
or lying face down (Chapter 7).
Prophase(PROH-fayz) The first stage of mitosis, in which
the pairs on chromatids become visible (Chapter 3).
Proprioception(PROH-pree-oh-SEP-shun) The sense of
the body, of its place, position, and movement; includes
muscle sense and equilibrium (from the Latin “one’s
own”) (Chapter 7).
Proprioceptor(PROH-pree-oh-SEP-ter) A sensory recep-
tor in a muscle that detects stretching of the muscle
(Syn.—stretch receptor) (Chapter 7).
Prostaglandins(PRAHS-tah-GLAND-ins) Locally acting
hormone-like substances produced by virtually all cells
from the phospholipids of their cell membranes; the
many types have many varied functions (Chapter 10).
Prostate gland(PRAHS-tayt) A muscular gland that sur-
rounds the first inch of the male urethra; secretes an alka-
line fluid that becomes part of semen; its smooth muscle
contributes to ejaculation (Chapter 20).
Prostatic hypertrophy(prahs-TAT-ik high-PER-truh-fee)
Enlargement of the prostate gland; may be benign or
malignant (Chapter 20).
Proteasome(PROH-tee-ah-sohm) A cell organelle that
destroys misfolded or damaged proteins; contains
enzymes called proteases (Chapter 3).
Protein (PROH-teen) An organic compound made of
amino acids linked by peptide bonds (Chapter 2).
Proteinuria(PROH-teen-YOO-ree-ah) The presence of
protein in urine (Chapter 18).
Prothrombin(proh-THROM-bin) A clotting factor syn-
thesized by the liver and released into the blood; con-
verted to thrombin in the process of chemical clotting
(Chapter 11).
Proton(PROH-tahn) A subatomic particle that has a posi-
tive electrical charge; found in the nucleus of an atom
(Chapter 2).
Proton pump(PROH-tahn PUMP) An enzyme of the
parietal cells of the stomach lining; secretes a hydrogen
ion (in exchange for potassium), which unites with a
chloride ion to form HCl in gastric juice (Chapter 16).
Protozoa(PROH-tuh-ZOH-ah) (Sing.— protozoan) The
simplest animal-like microorganisms in the kingdom
Protista; usually unicellular, some are colonial; may be
free living or parasitic (Chapter 22).
Proximal(PROK-si-muhl) Closest to the origin or point of
attachment (Chapter 1).
Proximal convoluted tubule(PROK-si-muhl KON-voh-
LOO-ted) The part of a renal tubule that extends from
Bowman’s capsule to the loop of Henle (Chapter 18).Pruritus(proo-RYE-tus) Severe itching (Chapter 5).
Puberty(PEW-ber-tee) The period during life in which
members of both sexes become sexually mature and capa-
ble of reproduction; usually occurs between the ages of
10 and 14 years (Chapter 20).
Pubic symphysis(PEW-bik SIM-fi-sis) The joint between
the right and left pubic bones, in which a disc of cartilage
separates the two bones (Chapter 6).
Pubis(PEW-biss) The lower anterior part of the hip bone
(Syn.—pubic bone) (Chapter 6).
Pulmonary artery(PULL-muh-NER-ee AR-tuh-ree) The
artery that takes blood from the right ventricle to the
lungs (Chapter 12).
Pulmonary edema(PULL-muh-NER-ee uh-DEE-muh)
Accumulation of tissue fluid in the alveoli of the lungs
(Chapter 15).
Pulmonary semilunar valve(PULL-muh-NER-ee SEM-
ee-LOO-nar VALV) The valve at the junction of the
right ventricle and the pulmonary artery; prevents back-
flow of blood from the artery to the ventricle when the
ventricle relaxes (Chapter 12).
Pulmonary surfactant (PULL-muh-NER-ee sir-FAK-
tent) A lipoprotein secreted by the alveoli in the lungs;
reduces the surface tension within alveoli to permit infla-
tion (Chapter 15).
Pulmonary veins(PULL-muh-NER-ee VAYNS) The four
veins that return blood from the lungs to the left atrium
(Chapter 12).
Pulp cavity(PUHLP) The innermost portion of a tooth
that contains blood vessels and nerve endings (Chap-
ter 16).
Pulse(PULS) The force of the heartbeat detected at an
arterial site such as the radial artery (Chapter 12).
Pulse deficit(PULS DEF-i-sit) The condition in which the
radial pulse count is lower than the rate of the heartbeat
heard with a stethoscope; may occur in some types of
heart disease in which the heartbeat is weak (Chapter 13).
Pulse pressure(PULS PRES-shur) The difference be-
tween systolic and diastolic blood pressure; averages
about 40 mmHg (Chapter 13).
Punnett square(PUHN-net SKWAIR) A diagram used to
determine the possible combinations of genes in the off-
spring of a particular set of parents (Chapter 21).
Pupil(PYOO-pil) The opening in the center of the iris;
light rays pass through the aqueous humor in the pupil
(Chapter 9).
Purkinje fibers(purr-KIN-jee) Specialized cardiac muscle
fibers that are part of the cardiac conduction pathway
(Chapter 12).
Pyloric sphincter(pye-LOR-ik SFINK-ter) The circular
smooth muscle at the junction of the stomach and the
duodenum; prevents backup of intestinal contents into
the stomach (from the Greek “gatekeeper”) (Chapter 16).
Pyloric stenosis(pye-LOR-ik ste-NOH-sis) Narrowing of
the opening between the stomach and duodenum caused30Scanlon(p3) Glossary 8/17/06 11:08 AM Page 578