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Flashcards in Nervous System Deck (78):
1

Functions of Nervous System

sensory function
integrative function (interpretation)
motor function

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consists of the brain and spinal cord, which occupy the dorsal body cavity and act as the integrating and command centers of the nervous system

Central Nervous System

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consists mainly of the nerves that extend from the brain and spinal cord

Peripheral Nervous System

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2 Divisions of Peripheral nervous sysem

Sensory/Afferent
Motor/Efferent

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conduct action potentials from sensory receptors to the CNS

Sensory/Afferent

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conduct action potentials from the CNS to effector organs such as muscles and glands; depends on neurons

Motor/Efferent

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2 subdivisions of Motor/Efferent Peripheral Nervous System

somatic
autonomic

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allows to control consciously or voluntarily control skeletal muscles

somatic nervous system

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regulates events that are autonomic or involuntary, such as activity of smooth and cardiac muscles and glands

autonomic nervous system

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2 parts of autonomic nervous system

sympathetic
parasympathetic

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aka nerve cells
highly specialized to transmit from one part of the body to another

neuron

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metabolic center of the neurons

cell body

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processes that convey messages toward the cell body

dendrites

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generate nerve impusles and conduct them away from the cell body

axon

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a membrane that encloses the axon; insulates axons; not all neurons have this; faster travel of impulses

myelin sheath

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specialized supporting cells that wrap tighly around the axon of PNS

schwann cells

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gaps or indentations in the myelin sheath located at regular intervals

nodes of ranvier

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site for CHON synthesis in neurons; contributes to grayish color of cell body

Nissl bodies

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trigger zone

axon hillock
initial segment

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electrical segments start here

trigger zone

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a cone-shaped elevation that joins the cylindrical portion of an axon

axon hillok

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1at part of an axon

initial segment

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types of neuron accdg. to function

afferent/sensory
efferent/motor
interneuron

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types of neuron accdg. to shape

multipolar
bipolar
unipolar

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transmits impulses from receptors to CNS

afferent/sensory

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CNS to effector organ

efferent/motor

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one neuron to another neuron

interneuron

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typical neuron shape; CNS; motor neurons
many processes - dendrites
one axon
can have collateral branch axons
angle of 90 degrees

multipolar

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shape of neurons in retina of eye, inner ear, olfactory area of brain

axon or dendrite on opposite sides
center is cell body

bipolar

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has bulbs; sensory neurons

unipolar

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effectors

gland
muscles

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dont conduct electrical impulses
non-neuronal cells o the CNS and PNS
supporting cells in the CNS
more numberous than neuons

neuroglia

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types of neuroglia

astrocyte
ependymal cells
microglia
oligodendrocytes

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located in CNS
star-shaped cells

provide structural support does not block alcohol
form a layer around blood vessels that contribute to blood-brain barrier

astrocyte

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squamous epethelial-like

lines ventricles of the brain
circulate cerebrospinal fluid
some form choroid plexus

ependymal cells

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produces CSF

choroid plexus

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small mobile cells

protects CNS from infection, become phagocytic in response to inflammation

microglia

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cell with processes that can surround several axons

cell processes for myelin sheaths around axons or enclose nmyelinated axons in the CNS

Oligodendrocytes

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a junction where the axon of one neuron interacts with another neuron or an effector organ such as the muscle or gland

Neuromuscluar junction or synapse

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end of the axon

pre-synaptic terminal

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the space that separates the presynaptic terminal and postsynaptic membrane

synaptic cleft

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the membrane of the dendrite or effector cell

post-synaptic terminal

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chemical substances stored in synaptic vesicles in presynaptic terminal

neurotransmitter

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resting state; there are fewer positive ions sitting on the inner face of the neuron's plasma membrane than there are on its outer surface in the tissue fluid that surrounds it

polarization

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the inward push of sodium ion that lead into the changes of the polarity of the neuron's membrane; causes electrical impulses when it reaches threshold (40-50 volts)

depolarization

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the outflow of positive ions from the cell that restores the electrical conditions at the membrane to the polarized or resting state; normal state

repolarization

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the faster type of impulse propagation along fibers that have myelin sheath; leaping junction

saltatory conduction

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3 fibrous connective tissue membranes that surround and protect the brain and spinal cord

meninges

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meninges

dura mater
arachnoid mater
pia mater

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hard mater; most superficial and thickest of the meninges
double layered membrane that lines the skull and the spine

dura mater

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dura mater

periostal layer
meningeal layer

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tightly attached to the inner surface of the skull forming the periosteum of the skull

periostal layer

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forms the outermost covering of the brain and continuous as the dura mater of the spinal cord

meningeal layer

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very thin, cobweb-like strands of fibrous connective tissue

arachnoid mater

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where excess CNS from brain exits

arachnoid villi

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space between the dura mater and arachnoid

subdural space

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gentle mater; innermost membrane, on surface of the brain and SC

pia mater

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space between the arachnoid and pia mater which is filled with cerebrospinal fluid (tissue fluid of CNS)

subarachnoid space

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a cylindrical, glistening white continuation of the brain stem enclosed within the vertebral column

extends from the foramen magnum of the skull to the first or second lumbar vertebra

spinal cord

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structural component of spinal cord

ascending pathways
descending pathways

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consist of axons that conduct action potentials toward the brain

ascending pathways

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consist of axons that conduct action potentials away from the brain

descending pathways

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arise along the spinal cord from the union of the dorsal roots and ventral roots

categorized by the region of the vertebral column from which they emerge: cervilca, thoracic, lumbar, sacral and coccygeal

spinal nerves

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an involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS

reflex

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the neuronal pathway by which the reflex occurs

the basic functional unit of the nervous system

reflex arc

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5 basic components of reflex arc

sensory receptor
sensory neuron
interneuron
motor neuron
effector organ

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simpelst reflex in which muscles contract in response to a stretching force applied to it

stretch reflex

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ex. of stretch reflex

when the patellar ligament is tapped, the quadriceps femoris muscle tendon and muscles themselves are stretched. sensory receptors within these muscles are also stretched and the stretch reflex is activate. consequently, contraction of the muscles extends the leg, producing the characteristic knee-jerk response

knee-jerk reflex/patellar reflex

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the function is to remove a limb or other body part from a painful stimulus

withdrawal reflex/flexor reflex

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neuroglial cells of PNS

schwann cells
satellite cells

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flattened cells arranged around the cell bodies of neurons in a ganglia

satellite cells

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collection of cell bodies

ganglia

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terminal portion of the spinal cord and the spinal nerves below the first lumbar nerve; resembles horse tail

cauda equina

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tapered, conical portion, inferior to lumbar enlargement of the spinal cord

conus medullaris

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extension of pia mater that extends inferiorly and achors the spinal cord to the coccyx; reason why spinal cord doesnt loosen when we age

filum terminale

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cell bodies of neurons

gray matter

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myelinated and unmyelinated nerves

white matter

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where CSF passes
from 4th ventricle to longitudinal area of spinal cord

central canal