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

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