Glossary 581covered opening of the inner ear that bulges to prevent
pressure damage to the organ of Corti (Chapter 9).
Rugae(ROO-gay) Folds of the mucosa of organs such as
the stomach, urinary bladder, and vagina; permit expan-
sion of these organs (Chapter 16).—S—
Saccule(SAK-yool) A membranous sac in the vestibule of
the inner ear that contains receptors for static equilib-
rium (Chapter 9).
Sacroiliac joint(SAY-kroh-ILL-ee-ak) The slightly mov-
able joint between the sacrum and the ilium (Chapter 6).
Sacrum(SAY-krum) The five fused sacral vertebrae at the
base of the spine (Chapter 6).
Saddle joint(SA-duhl) The carpometacarpal joint of the
thumb, a diarthrosis (Chapter 6).
Sagittal section(SAJ-i-tuhl SEK-shun) A plane or cut from
front to back, separating right and left parts (from the
Latin “arrow”) (Chapter 1).
Saliva(sah-LY E-vah) The secretion of the salivary glands;
mostly water and containing the enzyme amylase
(Chapter 16).
Salivary glands(SAL-i-va-ree) The three pairs of exocrine
glands that secrete saliva into the oral cavity; parotid,
submandibular, and sublingual pairs (Chapter 16).
Salt(SAWLT) A chemical compound that consists of a pos-
itive ion other than hydrogen and a negative ion other
than hydroxyl (Chapter 2).
Saltatory conduction (SAWL-tah-taw-ree kon-DUK-
shun) The rapid transmission of a nerve impulse from
one node of Ranvier to the next; characteristic of myeli-
nated neurons (Chapter 8).
Saprophyte(SAP-roh-fight) An organism that lives on dead
organic matter; a decomposer (Syn.—saprobe) (Chap-
ter 22).
Sarcolemma(SAR-koh-LEM-ah) The cell membrane of a
muscle fiber (Chapter 7).
Sarcomere(SAR-koh-meer) The unit of contraction in a
skeletal muscle fiber; a precise arrangement of myosin
and actin filaments between two Z lines (Chapter 7).
Sarcoplasmic reticulum(SAR-koh-PLAZ-mik re-TIK-
yoo-lum) The endoplasmic reticulum of a muscle fiber; is
a reservoir for calcium ions (Chapter 7).
Saturated fat(SAT-uhr-ay-ted) A true fat that is often
solid at room temperature and of animal origin; its fatty
acids contain the maximum number of hydrogens
(Chapter 2).
Scapula(SKAP-yoo-luh) The flat bone of the shoulder that
articulates with the humerus (Syn.—shoulder blade)
(Chapter 6).
Schwann cell(SHWAHN SELL) A cell of the peripheral
nervous system that forms the myelin sheath and neu-
rolemma of peripheral axons and dendrites (Chapter 4).
Sclera(SKLER-ah) The outermost layer of the eyeball,made of fibrous connective tissue; the anterior portion is
the transparent cornea (Chapter 9).
Scoliosis(SKOH-lee-OH-sis) A lateral curvature of the
vertebral column (Chapter 6).
Scrotum(SKROH-tum) The sac of skin between the upper
thighs in males; contains the testes, epididymides, and
part of the ductus deferens (Chapter 20).
Sebaceous gland(suh-BAY-shus) An exocrine gland in the
dermis that produces sebum (Chapter 5).
Sebum(SEE-bum) The lipid (oil) secretion of sebaceous
glands (Chapter 5).
Secondary infection(SEK-un-DAR-ee) An infection made
possible by a primary infection that has lowered the
host’s resistance (Chapter 22).
Secondary sex characteristics(SEK-un-DAR-ee SEKS)
The features that develop at puberty in males or females;
they are under the influence of the sex hormones but are
not directly involved in reproduction. Examples are
growth of facial or body hair and growth of muscles
(Chapter 20).
Secretin(se-KREE-tin) A hormone secreted by the duode-
num when food enters; stimulates secretion of bile by the
liver and secretion of bicarbonate pancreatic juice
(Chapter 16).
Secretion(see-KREE-shun) The production and release of
a cellular product with a useful purpose (Chapter 4).
Section(SEK-shun) The cutting of an organ or the body to
make internal structures visible (Chapter 1).
Selectively permeable(se-LEK-tiv-lee PER-me-uh-buhl)
A characteristic of cell membranes; permits the passage
of some materials but not of others (Chapter 3).
Self-limiting disease(self-LIM-i-ting) A disease that typi-
cally lasts a certain period of time and is followed by
recovery (Chapter 22).
Semen(SEE-men) The thick, alkaline fluid that contains
sperm and the secretions of the seminal vesicles, prostate
gland, and bulbourethral glands (Chapter 20).
Semicircular canals(SEM-eye-SIR-kyoo-lur) Three oval
canals in the inner ear that contain the receptors that
detect motion (Chapter 9).
Seminal vesicles(SEM-i-nuhl VESS-i-kulls) The glands
located posterior to the prostate gland and inferior to the
urinary bladder; secrete an alkaline fluid that enters the
ejaculatory ducts and becomes part of semen (Chap-
ter 20).
Seminiferous tubules(sem-i-NIFF-er-us) The site of
spermatogenesis in the testes (Chapter 20).
Sensation(sen-SAY-shun) A feeling or awareness of condi-
tions outside or inside the body, resulting from the stim-
ulation of sensory receptors and interpretation by the
brain (Chapter 9).
Sensory neuron(SEN-suh-ree NYOOR-on) A nerve cell
that carries impulses from a receptor to the central nerv-
ous system. (Syn.—afferent neuron) (Chapter 8).
Septic shock(SEP-tik SHAHK) A type of circulatory shock30Scanlon(p3) Glossary 8/17/06 11:08 AM Page 581