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110 terms

nervous tissue the brain

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gyrus
an elevated ridge of cerebral tissue
neuron cell bodies
gray matter is composed of
association tract
a fiber tract that provides for communication between different parts of the same cerebral hemisphere
basal nuclei
the lentiform nucleus plus the caudate nucleus collectively
hypothalamus
site of regulation of body temperature and water balance, most important autonomic center
cerebral hemisphere
consciousness depends on the function of this part of the brain
corpora quadrigemina
located in the midbrain; contains reflex centers for vision and audition
cerebellum
responsible for regulation of posture and coordination of complex muscular movements
thalamus
important synapse site for afferent fibers traveling to the sensory cortex
afferent fibers
Axons that carry information inward to the central nervous system from the periphery of the body
medulla oblongata
contains autonomic centers regulating blood pressure, heart rate, and respiratory rhythm as well as couging, sneezing, and swallowing centers
corpus callosum
large commisure connecting the cerebral hemispheres
commisure
Areas in brain where fibers cross
fornix
fiber tract involved with olfaction
cerebral aqueduct
connects the third and fourth ventricles
thalamus
encloses the third ventricle
forebrain
embryonic origin: the diencephalon, including the thalamus, optic chiasma, and hypothalamus
hindbrain
embryonic origin: the medulla, pons, and cerebellum
forebrain
embryonic origin: the cerebral ganglia
basal ganglia (function)
they are involved in the regulation, modulation, and refinement of voluntary motor activity
corpus callosum
in split brain experiments, the main commisure connecting the cerebral hemispheres is cut. What's the name of this commisure?
dura matter
outetmost meninx covering the brain; composed of tough fibrous connective tissue
pia matter
innermost meninx covering the brain; delicate and highly vascular
arachnoid villi
structures instrumental in returing cerebrospinal fluid to the venous blood in the dural sinuses
choroid plexus
structure that forms the csf
arachnoid mater
middle meninx; like a cobweb in structure
dura mater
its outer layer forms the periosteum of the skull
falx cerebri
a dural fold that attaches the cerebrum to the crista galli of the skull
tentorium cerebelli
a dural fold separating the cerebrum from the cerebellum
acessory XI
name the name and # of crainial nerves involved; rotating the head
olfactory I
name the name and # of crainial nerves involved; smelling a flower
oculomotor III
name the name and # of crainial nerves involved; raising the eyelids; focusing the lens of the eye for accommodation; and constricting the pupils of the eye
vagus X
name the name and # of crainial nerves involved; slowing the heart; increasing the motility of digestive tract
facial VII
name the name and # of crainial nerves involved;
trigeminal V
name and # of crainial nerves involved; chewing food
vestibulocochlear VIII
name the name and # of crainial nerves involved; listening to music; seasickness
facial VII
name the name and # of crainial nerves involved; secreting saliva; tasting well-seasoned food
III, IV, VI
name the name and # of crainial nerves involved; involved in rolling the eyes (3 nerves, provide #'s only)
trigeminal V
name the name and # of crainial nerves involved; feeling a toothache
optic II
name the name and # of crainial nerves involved; reading the newspaper
I, II, VIII
name the name and # of crainial nerves involved; exclusively or primarily sensory in function
sensory input
information gathered by sensory receptors about internal and external changes
integration
interpretation of sensory input
motor output
activation of the effector organs, produces a response
sensory input, integration, motor output
3 functions of the nervous system
central and peripheral nervous systems
divisions of the nervous system
central nervous system
brain and spinal cord, integration and command center
peripheral nervous system
paired spinal and crainial nerves carry messages to and from the cns
sensory and motor
two functional divisions of the peripheral nervous system
sensory division
contains somatic and visceral afferent fibers
motor division
transmits impulses from the cns to effector organs
somatic afferent fibers
convey impulses from skin, skeletal muscles, and joints
visceral afferent fibers
convey impulses from visceral organs
somatic nervous system
(voluntary) conscious control of skeletal muscles
autonomic nervous system
contains visceral motor nerve fibers, regulates smooth muscle, cardiac muscle and glands. two functional subdivisions; sympathetic and parasympathetic
neurons
excitable cells that transmit electrical signals
neuroglia
supporting cells
neurons and neuroglia
two principal cell types
astrocytes
largest, most numerous glial cells; maintain blood-brain barrier to isolate CNS from general circulation; provide structural support for CNS; regulate ion and nutrient concentrations; perform repairs to stabilize tissue and prevent further injury
microglia
phagocytize microorganisms and neuronal debris, small ovoid cells with thorny processes
ependymal cells
range in shape, line the central cavities of the brain and spinal column, separate cnss interstitial fluid from csf
oligodendrocytes
branced cells, processes wrap cns nerve fibers, forming insulating myelin sheaths
satellite cell
surround neuron cells bodies in the pns
schwann cells
also called neurolemmocytes, surround peripheral nerve fibers and form myelin sheaths, vital to regeneration of damaged peripheral nerve fibers
cell body (perikaryon or soma)
biosynthetic center of a neuron
processes
dendrites and axons, bundles of processes are called tracts in cns and nerves in pns
dendrites
short, tapering and diffusely branched, convey electrical signals toward the cell body as graded potentials
axon
conducting region of a neuron, generates and transmits nerve impulses away from cell body
myelin sheath
segmented protein lipoid sheath around most long or large diameter axons, functions to protect electrically insulate axon, increase speed of nerve impulse transmission
nodes of raniver
myelin sheath gaps between adjacent schwann cells, sites where axon collaterals can emerge
white matter
dense collections of myelinated fibers
gray matter
mostly neuron cell bodies and unmyelinated fibers
multipolar
1 axon and several dendrite
bipolar
1 axon and 1 dendrite
unipolar
single short process that has two brances, peripheral process and central process
sensory (afferent)
transmit impulses from sensory receptors toward the cns
motor (efferent)
carry impulses from the cns to effectors
interneurons
shuttle signals through cns pathways; most are entirely witin the cns
voltage (V)
measure of potential energy generated by separated charge
potential difference
voltage measured between two points
current (I)
the flow of electrical charge (ions) between two points
resistance (R)
hindrance to charge flow provided by the plasma membrane
insulator
substance with high electrical resistance
conductor
substance with low electrical resistance
leakage (nongated) channels
always open
chemically gated (ligand gated) channels
open with binding of a specific neurotransmitter
voltage gated channel
open and close in response to changes in membrane potential
mechanically gated channels
open and close in response to physical deformation of receptors
depolarization
a reduction in membrane potential toward zero, inside of the membrane becomes less negative than the resting potential. increases the probability of producing a nerve impulse
hyperpolarization
an increase in membrane potential away from zero. inside of the membrane becomes more negative than the resting potential. reduces the probability of producing a nerve impulse
graded potentials
short lived, localiazed changes in the membrane potential, can be depolarizations or hyperpolarizations, graded potential spreads as local currents change the membrane potential of adjacent regions
action potential
brief reversal of membrane potential with a total amplitude of 100mv, occurs in muscle cells and axon of neurons
subthreshold stimulus
weak local depolarization that does not reach threshhold
threshold stimulus
strong enough to push the membrane potential toward and beyond threshold
absolute refractory period
nothing can make it fire. time from the opening of the Na channels until the resetting of the channels.
relative refractory period
strong enough will fire, follows the absolute refractory period, most of the Na channels have returned to their resting state, some K channels are still open, repolarization is occuring
repolarizing phase
Na channel slow inactibation gate close, membrane permeability to Na declines to resting levels, slow voltage-sensitive K gates open, K exits the cell and internal negativity is restored
hyperpolarization
some K channels remain open, allowing excessive K efflux, this causes after-hyperpolarization of the membrane
repolarization
restores the resting electrical conditions of the neuron, does not restore the resting ionic conditions
saltatory conduction
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
group a fibers
large diameter, myeloinated somatic sensory and motor fibers
group b fibers
intermediate diameter, lightly myelinated ans fibers
group c fibers
smallest diameter, unmyelinated ans fibers
synapse
a junction that mediates information transfer from one neuron to another or to an effector cell
presynaptic neuron
conducts impulses toward the synapse
postsynaptic neuron
transmits impulses away from the synapse
axodendritic synapse
between the axon of one neuron and the dendrite of another
axosomatic synapse
between the axon of one neuron and the soma of another
synaptic cleft
a chemical event, involves release, diffusion, and binding of neurotransmitters. ensures unidirectional communication between neurons
synaptic delay
time needed for neurotransmitter to be released, diffuse across the synapse, and bind to receptors. rate-limiting step of neural transmission