G-8
Glossary
Endoderm
(en
9
do-derm) Embryonic germ layer; forms the lining of the
digestive tube and its associated structures.
Endogenous
(en-doj
9
ĕ-nŭs) Originating or produced within the organ-
ism or one of its parts.
Endometrium
(en
0
do-me
9
tre-um) Mucous membrane lining of the
uterus.
Endomysium
(en
0
do-mis
9
e-um) Tin connective tissue surrounding
each muscle cell.
Endoplasmic reticulum (ER)
(en
0
do-plaz
9
mik rĕ-tik
9
u-lum) Membra-
nous network of tubular or saclike channels in the cytoplasm of a cell.
Endosteum
(en-dos
9
te-um) Connective tissue membrane covering in-
ternal bone surfaces.
Endothelium
(en
0
do-the
9
le-um) Single layer of simple squamous cells
that line the walls of the heart, blood vessels, and lymphatic vessels.
Energy
Te capacity to do work; may be stored (potential energy) or in
action (kinetic energy).
Energy intake
Energy liberated during food oxidation.
Energy output
Sum of energy lost as heat, as work, and as fat or glyco-
gen storage.
Enzyme
(en
9
zīm) A protein that acts as a biological catalyst to speed up a
chemical reaction.
Eosinophil
(e
0
o-sin
9
o-fil) Granular white blood cell whose granules
readily take up an acid stain called eosin.
Ependymal cell
(ĕ-pen
9
dĭ-mul) A type of CNS supporting cell; lines the
central cavities of the brain and spinal cord.
Epidermis
(ep
0
ĭ-der
9
mis) Superficial layer of the skin; composed of kera-
tinized stratified squamous epithelium.
Epididymis
(ep
0
ĭ-dĭ
9
dĭ-mis) Tat portion of the male duct system in
which sperm mature. Empties into the ductus (or vas) deferens.
Epidural space
Area between the bony vertebrae and the dura mater of
the spinal cord.
Epiglottis
(ep
0
ĭ-glot
9
is) Elastic cartilage at the back of the throat; covers
the opening of the larynx during swallowing.
Epileptic seizures
Abnormal electrical discharges of groups of brain
neurons, during which no other messages can get through.
Epimysium
(ep
0
ĭ-mis
9
e-um) Sheath of fibrous connective tissue sur-
rounding a muscle.
Epinephrine
(ep
0
ĭ-nef
9
rin) Chief hormone produced by the adrenal me-
dulla. Also called adrenaline.
Epiphyseal plate
(e
0
pĭ-fis
9
e-ul) Plate of hyaline cartilage at the junction
of the diaphysis and epiphysis that provides for growth in length of a
long bone.
Epiphysis
(e-pif
9
ĭ-sis) Te end of a long bone, attached to the shaF.
Epithalamus
Most dorsal portion of the diencephalon; forms the roof
of the third ventricle with the pineal gland extending from its posterior
border.
Epithelium (epithelial tissue)
(ep
0
ĭ-the
9
le-ul) Pertaining to a primary tissue
that covers the body surface, lines its internal cavities, and forms glands.
Erythrocytes
(e-rith
9
ro-sīts) Red blood cells.
Erythropoiesis
(ĕ-rith
0
ro-poi-e
9
sis) Process of erythrocyte formation.
Erythropoietin (EPO)
(ĕ-rith
0
ro-poi
9
ĕ-tin) Hormone that stimulates
production of red blood cells.
Esophagus
(ĕ-sof
9
ah-gus) Muscular tube extending from the laryngo-
pharynx through the diaphragm to join the stomach; collapses when not
involved in food propulsion.
Eccrine glands
(ek
9
rin) Sweat glands abundant on the palms, soles of
feet, and the forehead.
Ectoderm
(ek
9
to-derm) Embryonic germ layer; forms the epidermis of
the skin and its derivatives, and nervous tissues.
Edema
(ĕ-de
9
mah) Abnormal increase in the amount of interstitial fluid;
causes swelling.
Effector
(ef-ek
9
ter) Organ, gland, or muscle capable of being activated by
nerve endings.
Efferent
(ef
9
er-ent) Carrying away or away from, especially a nerve fiber
that carries impulses away from the central nervous system.
Elastic cartilage
Cartilage with abundant elastic fibers; more flexible
than hyaline cartilage.
Elastic fiber
±iber formed from the protein elastin, which gives a rub-
bery and resilient quality to the matrix of connective tissue.
Electrical energy
Energy formed by the movement of charged particles
across cell membranes.
Electrocardiogram (ECG
or
EKG)
(e-lek
0
tro-car
9
de-o-gram
0
) Graphic
record of the electrical activity of the heart.
Electrochemical gradient
Te combined difference in concentration
and charge; influences the distribution and direction of diffusion of ions.
Electroencephalogram (EEG)
(e-lek
0
tro-en-sef
9
ah-lo-gram
0
) Graphic
record of the electrical activity of nerve cells in the brain.
Electrolyte
(e-lek
9
tro-līt) Chemical substances, such as salts, acids, and
bases, that ionize and dissociate in water and are capable of conducting
an electrical current.
Electrolyte balance
Refers to the balance between input and output of
salts (sodium, potassium, calcium, magnesium) in the body.
Electromagnetic radiation
Emitted photons (wave packets) of energy,
e.g., light, X ray, infrared.
Electron
Negatively charged subatomic particle; orbits the atom’s
nucleus.
Electron shells (energy levels)
Regions of space that consecutively sur-
round the nucleus of an atom.
Element
One of a limited number of unique varieties of matter that
composes substances of all kinds; e.g., carbon, hydrogen, oxygen.
Embolism
(em
9
bo-lizm) Obstruction of a blood vessel by an embolus
(blood clot, fatty mass, bubble of air, or other debris) floating in the blood.
Embryo
(em
9
bre-o) Developmental stage extending from fertilization to
the end of the eighth week.
Emesis
Reflexive emptying of the stomach through the esophagus and
pharynx; also known as vomiting.
Encephalitis
(en
0
seh-fuh-lī-
9
tis) Inflammation of the brain.
Endergonic reaction
Chemical reaction that absorbs energy, e.g., an
anabolic reaction.
Endocardium
(en
0
do-kar
9
de-um) Endothelial membrane that lines the
interior of the heart.
Endochondral ossification
(en
0
do-kon
9
dral) Embryonic formation of
bone by the replacement of calcified cartilage; most skeletal bones are
formed by this process.
Endocrine glands
(en
9
do-krin) Ductless glands that empty their hor-
monal products directly into the blood.
Endocrine system
Body system that includes internal organs that secrete
hormones.
Endocytosis
(en
0
do-si-to
9
sis) Means by which fairly large extracellular
molecules or particles enter cells, e.g., phagocytosis, pinocytosis,
receptor-mediated endocytosis.
previous page 1184 Human Anatomy and Physiology (9th ed ) 2012 read online next page 1186 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off