Nervous System Flashcards
Functions of Nervous System
sensory function integrative function (interpretation) motor function
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
consists mainly of the nerves that extend from the brain and spinal cord
Peripheral Nervous System
2 Divisions of Peripheral nervous sysem
Sensory/Afferent
Motor/Efferent
conduct action potentials from sensory receptors to the CNS
Sensory/Afferent
conduct action potentials from the CNS to effector organs such as muscles and glands; depends on neurons
Motor/Efferent
2 subdivisions of Motor/Efferent Peripheral Nervous System
somatic
autonomic
allows to control consciously or voluntarily control skeletal muscles
somatic nervous system
regulates events that are autonomic or involuntary, such as activity of smooth and cardiac muscles and glands
autonomic nervous system
2 parts of autonomic nervous system
sympathetic
parasympathetic
aka nerve cells
highly specialized to transmit from one part of the body to another
neuron
metabolic center of the neurons
cell body
processes that convey messages toward the cell body
dendrites
generate nerve impusles and conduct them away from the cell body
axon
a membrane that encloses the axon; insulates axons; not all neurons have this; faster travel of impulses
myelin sheath
specialized supporting cells that wrap tighly around the axon of PNS
schwann cells
gaps or indentations in the myelin sheath located at regular intervals
nodes of ranvier
site for CHON synthesis in neurons; contributes to grayish color of cell body
Nissl bodies
trigger zone
axon hillock
initial segment
electrical segments start here
trigger zone
a cone-shaped elevation that joins the cylindrical portion of an axon
axon hillok
1at part of an axon
initial segment
types of neuron accdg. to function
afferent/sensory
efferent/motor
interneuron
types of neuron accdg. to shape
multipolar
bipolar
unipolar
transmits impulses from receptors to CNS
afferent/sensory
CNS to effector organ
efferent/motor
one neuron to another neuron
interneuron
typical neuron shape; CNS; motor neurons many processes - dendrites one axon can have collateral branch axons angle of 90 degrees
multipolar
shape of neurons in retina of eye, inner ear, olfactory area of brain
axon or dendrite on opposite sides
center is cell body
bipolar
has bulbs; sensory neurons
unipolar
effectors
gland
muscles
dont conduct electrical impulses
non-neuronal cells o the CNS and PNS
supporting cells in the CNS
more numberous than neuons
neuroglia
types of neuroglia
astrocyte
ependymal cells
microglia
oligodendrocytes
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
squamous epethelial-like
lines ventricles of the brain
circulate cerebrospinal fluid
some form choroid plexus
ependymal cells
produces CSF
choroid plexus
small mobile cells
protects CNS from infection, become phagocytic in response to inflammation
microglia
cell with processes that can surround several axons
cell processes for myelin sheaths around axons or enclose nmyelinated axons in the CNS
Oligodendrocytes
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
end of the axon
pre-synaptic terminal
the space that separates the presynaptic terminal and postsynaptic membrane
synaptic cleft
the membrane of the dendrite or effector cell
post-synaptic terminal
chemical substances stored in synaptic vesicles in presynaptic terminal
neurotransmitter
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
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
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
the faster type of impulse propagation along fibers that have myelin sheath; leaping junction
saltatory conduction
3 fibrous connective tissue membranes that surround and protect the brain and spinal cord
meninges
meninges
dura mater
arachnoid mater
pia mater
hard mater; most superficial and thickest of the meninges
double layered membrane that lines the skull and the spine
dura mater
dura mater
periostal layer
meningeal layer
tightly attached to the inner surface of the skull forming the periosteum of the skull
periostal layer
forms the outermost covering of the brain and continuous as the dura mater of the spinal cord
meningeal layer
very thin, cobweb-like strands of fibrous connective tissue
arachnoid mater
where excess CNS from brain exits
arachnoid villi
space between the dura mater and arachnoid
subdural space
gentle mater; innermost membrane, on surface of the brain and SC
pia mater
space between the arachnoid and pia mater which is filled with cerebrospinal fluid (tissue fluid of CNS)
subarachnoid space
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
structural component of spinal cord
ascending pathways
descending pathways
consist of axons that conduct action potentials toward the brain
ascending pathways
consist of axons that conduct action potentials away from the brain
descending pathways
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
an involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS
reflex
the neuronal pathway by which the reflex occurs
the basic functional unit of the nervous system
reflex arc
5 basic components of reflex arc
sensory receptor sensory neuron interneuron motor neuron effector organ
simpelst reflex in which muscles contract in response to a stretching force applied to it
stretch reflex
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
the function is to remove a limb or other body part from a painful stimulus
withdrawal reflex/flexor reflex
neuroglial cells of PNS
schwann cells
satellite cells
flattened cells arranged around the cell bodies of neurons in a ganglia
satellite cells
collection of cell bodies
ganglia
terminal portion of the spinal cord and the spinal nerves below the first lumbar nerve; resembles horse tail
cauda equina
tapered, conical portion, inferior to lumbar enlargement of the spinal cord
conus medullaris
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
cell bodies of neurons
gray matter
myelinated and unmyelinated nerves
white matter
where CSF passes
from 4th ventricle to longitudinal area of spinal cord
central canal
