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Nervous System
Organization, Nervous Tissue, CNS, etc.
74
Anatomy
12th Grade
10/26/2012

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Term
nervous system
Definition
fast-acting control system that employs nerve impulses to trigger muscle contraction or gland secretion
Term
central nervous system (CNS)
Definition
the brain and the spinal cord
Term
peripheral nervous system (PNS)
Definition
a system of nerves that connects the outlying parts of the body with the central nervous system
Term
afferent
Definition
carrying to or toward a center
Term
afferent neurons
Definition
nerve cells that carry impulses toward the central nervous system
Term
efferent
Definition
carrying away or away from
Term
efferent neurons
Definition
neurons that conduct impulses away from the central nervous system
Term
somatic nervous system
Definition
a division of the peripheral nervous system; also called the voluntary nervous system
Term
autonomic
Definition
self-directed; self-regulating; independent
Term
autonomic nervous system
Definition
the division of the nervous system that functions involuntarily; innervates cardiac muscle, smooth muscle, and glands
Term
neuroglia
Definition
the nonneuronal tissue of the central nervous system that performs supportive and other functions; also called glia
Term
glia
Definition
neuroglia
Term
neurons
Definition
cells of the nervous system specialized to transmit messages throughout the body
Term
dendrites
Definition
the branching extensions of neurons that carry electrical signals to the cell body; the receptive portion of a nerve cell
Term
axon
Definition
neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell
Term
neurotransmitter
Definition
chemical released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit them
Term
synapse
Definition
the region of communication between neurons
Term
synaptic cleft
Definition
the fluid-filled space at a synapse between neurons
Term
myelin
Definition
a white, fatty lipid substance
Term
nucleus
Definition
a dense central body in most cells containing the genetic material of the cell
Term
ganglion
Definition
a group of nerve cell bodies located in the peripheral nervous system
Term
tract
Definition
a collection of nerve fibers in the CNS having the same origin, termination, and function
Term
nerve
Definition
bundle of neuronal processes (axons) outside the central nervous system
Term
white matter
Definition
white substance of the central nervous system; the myelinated nerve fibers
Term
gray matter
Definition
the gray area of the central nervous system; contains unmyelinated nerve fibers and nerve cell bodies
Term
receptor
Definition
(1) a peripheral nerve ending specialized for response to particular types of stimuli; (2) molecule that binds specifically with other molecules, e.g., hormones and neurotransmitters
Term
proprioceptor
Definition
a receptor located in a muscle or tendon; concerned with locomotion, posture, and muscle tone
Term
interneurons
Definition
completes the pathway between afferent and efferent neurons; also called association neurons
Term
polarized
Definition
the state of unstimulated neuron or muscle cell in which the inside of the cell is relatively negative in comparison to the outside; the resting state
Term
depolarization
Definition
the loss of a state of polarity; the loss of a negative charge inside the plasma membrane
Term
graded potential
Definition
a local change in membrane potential that varies directly with the strength of the stimulus, declines with distance
Term
action potential
Definition
an electrical event occurring when a stimulus of sufficient intensity is applied to a neuron or muscle cell, allowing sodium ions to move into the cell and reverse the polarity
Term
nerve impulse
Definition
a self propagating wave of depolarization; also called action potential
Term
repolarization
Definition
restoration of the membrane potential to the initial resting (polarized) state
Term
reflex
Definition
automatic reaction to a stimulus
Term
reflex arc
Definition
neural pathway for reflexes
Term
ventricles
Definition
(1) discharging chambers of the heart
(2) cavities within the brain
Term
cerebrum
Definition
the largest part of the brain;
consists of right and left cerebral hemispheres
Term
sulcus
Definition
a furrow on the brain, less deep than a fissure
Term
gyrus
Definition
an outward fold of the surface of the cerebral cortex
Term
fissure
Definition
(1) a groove or cleft;
(2) the deepest depressions or inward folds on the brain
Term
parietal
Definition
pertaining to the walls of a cavity
Term
occipital
Definition
pertaining to area at the back of the head
Term
gray matter
Definition
an area of the central nervous system;
contains unmyelinated nerve fibers and nerve cell bodies
Term
white matter
Definition
substance of the CNS;
the myelinated nerve fibers
Term
basal nuclei
or
basal ganglia
Definition
gray matter areas deep within the white matter of the cerebral hemispheres
Term
diencephalon
Definition
that part of the forebrain between the cerebral hemispheres and the midbrain including the thalamus, the third ventricle, and the hypothalamus
Term
thalamus
Definition
a mass of gray matter in the diencephalon of the brain
Term
hypothalamus
Definition
the region of the diencephalon forming the floor of the third ventricle of the brain
Term
pituitary gland
Definition
the neuroendocrine gland located beneath the brain that serves a variety of functions including regulation of the gonads, thyroid, adrenal cortex, water balance, and lactation
Term
brain stem
Definition
the portion of the brain consisting of the medulla, pons, and midbrain
Term
cerebral aqueduct
Definition
the slender cavity of the midbrain that connects the third and fourth ventricles; also called the _________ of Sylvius
Term
pons
Definition
(1) any bridgelike structure or part;
(2) the brain area connecting the medulla with the midbrain, providing linkage between upper and lower levels of the CNS
Term
cerebellum
Definition
part of the hindbrain;
involved in producing smoothly coordinated skeletal muscle activity
Term
meninges
Definition
the membranes that cover the brain and spinal cord
Term
meningitis
Definition
inflammation of the meninges of the brain or spinal cord
Term
dura mater
Definition
the outermost and toughest of the three membranes (meninges) covering the brain and spinal cord
Term
arachnoid
Definition
weblike;
specifically, the weblike middle layer of the three meninges
Term
cerebrospinal fluid
Definition
the fluid produced by choroid plexi;
fills the ventricles and surrounds the CNS
Term
blood-brain barrier
Definition
a mechanism that inhibits passage of materials from the blood into brain tissues
Term
hemiplegia
Definition
paralysis of one side of the body
Term
peripheral nervous system
Definition
a system of nerves that connects the outlying parts of the body with the central nervous system
Term
nerve
Definition
bundle of neuronal processes (axons) outside the CNS
Term
endoneurium
Definition
a delicate connective tissue sheath that surrounds each fiber in a nerve
Term
fascicle
Definition
a bundle of nerve or muscle fibers bound together by connective tissue
Term
epineurium
Definition
a tough, fibrous sheath that binds together the fascicles in a nerve
Term
mixed nerves
Definition
nerves containing the processes of motor and sensory neurons;
their impulses travel to and from the CNS
Term
spinal nerves
Definition
the 31 pairs of nerves that arise from the spinal cord
Term
plexus
Definition
a network of interlacing nerves, blood vessels, or lymphatics
Term
autonomic nervous system
Definition
the division of the nervous system that functions involuntarily;
innervates cardiac muscle, smooth muscle, and glands
Term
preganglionic (presynaptic) neuron
Definition
a neuron of the autonomic nervous system having its cell body in the brain or spinal cord and its axon terminating in a ganglion
Term
postganglionic (postsynaptic) neuron
Definition
a neuron of the autonomic nervous system having its cell body in a ganglion and its axon extending to an organ or tissue
Term
sympathetic division
Definition
a division of the autonomic nervous system;
opposes parasympathetic functions;
called the fight-or-flight division
Term
parasympathetic division
Definition
a division of the autonomic nervous system;
also referred to as the craniosacral division
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