GLOSSARY
or the adrenal medulla of the
adrenal gland.
Meninges Three thin layers
covering the brain and spinal
cord, and also making and
containing cerebrospinal
fluid. They are known as the
dura mate
r,
arachnoid
, and
pia mater
.
Meiosis Part of special type
of cell division, when the
chromosomes are not copied
and only one set (not a
double-set) moves into
each resulting cell.
Metabolism All of the
body’s thousands of chemical
processes, changes, and
reactions, such as breaking
apart blood sugar to release
energy, and building up
amino acids into proteins.
Mineral A simple chemical
substance, usually a metal
such as iron or calcium, or
a salt-type chemical, such as
phosphate, which the body
needs in small quantities from
food to stay healthy.
Mitosis Part of normal
cell division, when the
chromosomes have been
copied and one full double-
set moves into each resulting
cell.
Motor nerve A nerve that
carries messages from the
brain to a muscle, telling it
when to contract, or to a
gland, telling it when to
release its content.
Mucus Thickish, sticky, slimy
substance made by many
body parts, often for
protection and lubrication,
such as inside the nose and
within the stomach.
Myo- Having to do with
muscles, such as myocardium
or heart muscle.
Nephron Microscopic
filtering unit in the kidney for
cleaning the blood.
Neuron A nerve cell, the
basic unit of the nervous
system.
Olfactory Having to do
with the nose and smell.
Optic Having to do with the
eye, especially the optic
nerve carrying messages
from the eye to the brain.
Papillae Small bumps on a
body part, such as the tongue.
Peripheral nerves The
bodywide network of nerves,
excluding the central nervous
system.
Peristalsis Wave-like
contractions of muscles in the
wall of a body tube, such as
the small intestine, ureter
(from kidney to bladder),
or oviduct (from ovary to
womb).
Pulmonary Having to do
with the lungs.
Renal Having to do with the
kidneys.
Sebum Natural waxy
substance, made in sebaceous
glands associated with hair
follicles, that keeps skin
supple and fairly waterproof.
Sensory nerve A nerve
that carries messages to the
brain from a sense part, such
as the eye, the ear, the tiny
stretch sensors in muscles
and joints, and the blood
pressure sensors in main
arteries.
Skeletal Having to do with
the skeleton.
System In the body, a set of
major parts and organs that
all work together to fulfil one
main task, such as the
respiratory system, which
transfers oxygen from the
air around to the blood.
Tendon The string,
fibrous, rope-like end
of a muscle, where it
tapers and joins to
a bone.
Thoracic Having to do with
the chest, called the
thorax
.
Thrombosis The process of
blood going lumpy to form a
clot, also known as a
thrombus
.
Tissue A group of very
similar cells all doing the
same job, such as muscle
tissue, adipose, or fat tissue,
epithelial (covering or lining)
tissue, and connective tissue
(joining and filling in gaps
between other parts).
Valve A flap, pocket, or
similar part that allows
a substance to pass one way
but not the other.
Vein A blood vessel that
conveys blood toward the
heart.
Vertebra A single bone of
the row of bones called the
backbone
,
spine
, or
vertebral
column
.
Villi Tiny finger-like objects
from the microscopic cells in
various body parts, including
the inner lining of the small
intestine.
Visceral Having to do with
the main parts or organs
inside the abdomen (the
lower part of the torso),
mainly the stomach,
intestines, kidneys, bladder,
and in females, reproductive
parts.
Vitamin Substance needed
in fairly small amounts from
food for the body to work
well and stay healthy.
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Abdomen The lower part
of the main body or torso,
below the chest, that mainly
contains digestive and
excretory organs, and in
females, reproductive parts.
Artery A blood vessel that
conveys blood away from the
heart.
Axon The very long, thin
part of a nerve cell or neuron,
also called a
nerve fibe
r.
Bladder Bag-like sac or
container for storing fluids.
The body has several,
including the urinary
bladder, often just called
the
bladder
, and gall bladder.
Blood sugar Also called
glucose
, the body’s main
energy source, used by all
its microscopic cells to carry
out their life processes and
functions.
Capillary The smallest type
of blood vessels, usually less
than 0.02 in. long and too
thin to see except through a
microscope.
Cardiac Having to do with
the heart.
Cartilage Tough, light,
slightly bendy and
compressible body
substance, often called
gristle
, that forms parts
of the skeleton, such as the
ears and nose, and also
covers the ends of bones
in joints.
Cell The basic microscopic
“building block” of the body,
a single living unit, with most
cells being 1/1,000 in.
across. The body contains
over 10 trillion cells.
Central nervous system
The brain and spinal cord.
Cerebral Having to do with
the cerebrum, the largest part
of the brain that forms its
wrinkled domed shape.
Cerebrospinal fluid Liquid
surrounding the brain and
spinal cord, to protect and
cushion them as well as
helping provide nourishment
and taking away waste.
Cilium Microscopic hair,
usually sticking out from
the surface of
a cell, that can wave
or bend, and
perhaps sense
substances, such as
the olfactory epithelium
of the nose and in the taste
buds on the tongue. (Plural:
cilia.)
Clone A living thing with
exactly the same genes as
another living thing.
Collagen Tiny, tough, strong
fibers found in body parts
such as skin and bones.
Cortex The outer part or
layer of a body part, such
as the renal cortex of the
kidney or the cerebral
cortex of the brain.
Cranium The upper domed
part of the skull that covers
and protects the brain.
Cermis The inner layer of
skin, under the epidermis,
that contains the touch
sensors, hair follicles, and
sweat glands.
DNA Deoxyribonucleic acid,
the chemical substance
that forms the genetic
information, called
genes
.
Embryo The name for a
developing human body,
from fertilization as a
single cell to eight weeks later.
Endocrine Having to do
with hormones and the
hormonal system (
see
hormone).
Enzymes Substances
that alter the speed of a
chemical change or reaction,
usually speeding it up, but
remain unchanged
themselves at the end of
the reaction.
Epidermis The protective
outer layer of skin, which is
always being worn away but
continually replacing itself.
Excretory Having to do
with removing waste
substances from the body.
The main excretory system is
made up of the kidneys,
bladder and their linking
tubes.
Fertilization When an egg
cell joins a sperm cell to start
the development of a new
human body.
Fetus A developing human
body, from eight weeks after
fertilization until birth.
Fovea The small area in the
retina of the eye where vision
is most detailed and clearest,
due to the large number of
cone cells.
Gastric Having to do with
the stomach.
Gland A body part that
makes a substance that it
then releases, such as the
tear glands that make tear
fluid for the eyes, and the
sweat glands in the skin.
Glucose
See
blood
sugar.
Gustatory Having to do
with the tongue and taste.
Hepatic Having to do with
the liver.
Hormone A natural
chemical messenger that
circulates in the blood and
affects how certain body
parts work, helping the
nervous system to control
and coordinate all body
processes.
Humor Old word used to
describe various body fluids,
still used in some cases. For
example, to describe the
fluids inside the eye, the
vitreous humor and aqueous
humor.
Immunity Protection or
resistance to microbial
germs and other harmful
substances.
Integumentary Having to
do with the skin and other
coverings, including nails
and hair.
Ligament A stretchy, strap-
like part that joins the bones
around a joint, so the bones
do not move too far apart.
Medulla The central region
of a body part, such as the
renal medulla of the kidney,
GLOSSARY
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