Estrogens (ES-tro-jenz) Feminizing sex hormones produced by
the ovaries; govern development of oocytes, maintenance of
female reproductive structures, and appearance of secondary
sex characteristics; also affect fluid and electrolyte balance,
and protein anabolism. Examples are
-estradiol, estrone, and
Etiology (e'-te-OL-o-je) The study of the causes of disease, including
theories of the origin and organisms (if any) involved.
Eupnea (OP-ne-a) Normal quiet breathing.
Eversion (e-VER-zhun) The movement of the sole laterally at the
ankle joint or of an atrioventricular valve into an atrium during
Excitability (ek-sTt'-a-BIL-i-te) The ability of muscle fibers to receive
and respond to stimuli; the ability of neurons to respond to
stimuli and generate nerve impulses.
Excrement (EKS-kre-ment) Material eliminated from the body as
waste, especially fecal matter.
Excretion (eks-KRE-shun) The process of eliminating waste products
from the body; also the products excreted.
Exhalation (eks-ha-LA-shun) Breathing out; expelling air from the
lungs into the atmosphere. Also called expiration.
Exocrine gland (EK-so-krin) A gland that secretes its products into
ducts that carry the secretions into body cavities, into the lumen
of an organ, or to the outer surface of the body.
Exocytosis (ex'-o-sT-TO-sis) A process in which membrane-enclosed
secretory vesicles form inside the cell, fuse with the plasma
membrane, and release their contents into the interstitial fluid;
achieves secretion of materials from a cell.
Exogenous (ex-SOJ-e-nus) Originating outside an organ or part.
Expiratory reserve volume (eks-PT-ra-to-re) The volume of air in
excess of tidal volume that can be exhaled forcibly; about
1200 mL in males and 700 mL in females.
Extensibility (ek-sten'-si-BIL-i-te) The ability of muscle tissue to
stretch when it is pulled.
Extension (ek-STEN-shun) An increase in the angle between two
bones; restoring a body part to its anatomical position after
External Located on or near the surface.
External auditory canal (AW-di-tor-e) or meatus (me-A-tus) A curved
tube in the temporal bone that leads to the middle ear.
External ear The outer ear, consisting of the pinna, external auditory
canal, and tympanic membrane (eardrum).
External nares (NA-rez) The external nostrils, or the openings into
the nasal cavity on the exterior of the body.
External respiration The exchange of respiratory gases between the
lungs and blood. Also called pulmonary respiration.
Exteroceptor (eks'-ter-o-SEP-tor) A sensory receptor adapted for the
reception of stimuli from outside the body.
Extracellular fluid (ECF) Fluid outside body cells, such as interstitial
fluid and plasma.
Extracellular matrix (MA-triks) The ground substance and fibers
between cells in a connective tissue.
Extrinsic (ek-STRIN-sik) Of external origin.
Extrinsic pathway (of blood clotting) Sequence of reactions leading
to blood clotting that is initiated by the release of tissue factor
(TF), also known as thromboplastin, that leaks into the blood from
damaged cells outside the blood vessels.
Exudate (EKS-oo-dat) Escaping fluid or semifluid material that oozes
from a space and that may contain serum, pus, and cellular
Eyebrow The hairy ridge superior to the eye.
Face The anterior aspect of the head.
Facilitated diffusion (fa-SIL-i-ta-ted dif-O-zhun) Diffusion in which a
substance not soluble by itself in lipids diffuses across a selective-
ly permeable membrane with the help of a transporter protein.
Fascia (FASH-e-a) A fibrous membrane covering, supporting, and
Fascicle (FAS-i-kul) A small bundle or cluster, especially of nerve or
muscle fibers (cells). Also called a fasciculus (fa-SIK-u-lus).
P lu r a l is
Fasciculation (fa-sik'-u-LA-shun) Abnormal, spontaneous twitch of all
skeletal muscle fibers in one motor unit that is visible at the skin
surface; not associated with movement of the affected muscle;
present in progressive diseases of motor neurons, for example,
Fauces (FAW-seTz) The opening from the mouth into the pharynx.
Feces (FE-sez) Material discharged from the rectum and made up of
bacteria, excretions, and food residue. Also called stool.
Feedback system A sequence of events in which information about
the status of a situation is continually reported (fed back) to a
Female reproductive cycle General term for the ovarian and uterine
cycles, the hormonal changes that accompany them, and cyclic
changes in the breasts and cervix; includes changes in the endo-
metrium of a nonpregnant female that prepares the lining of the
uterus to receive a fertilized ovum.
Fertilization (fer'-ti-li-ZA-shun) Penetration of a secondary oocyte
by a sperm cell, meiotic division of secondary oocyte to form an
ovum, and subsequent union of the nuclei of the gametes.
Fetal circulation The cardiovascular system of the fetus, including
the placenta and special blood vessels involved in the exchange
of materials between fetus and mother.
Fetus (FE-tus) In humans, the developing organism
in u te r o
beginning of the ninth week to birth.
Fever An elevation in body temperature above the normal tem-
perature of 37 °C (98.6 °F) due to a resetting of the hypothalamic
Fibrillation (fi-bri-LA-shun) Abnormal, spontaneous twitch of a single
skeletal muscle fiber (cell) that can be detected with electromy-
ography but is not visible at the skin surface; not associated with
movement of the affected muscle; present in certain disorders
of motor neurons, for example, amyotrophic lateral sclerosis
(ALS). With reference to cardiac muscle,
s e e
Atrial fibrillation and