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156 Cards in this Set

  • Front
  • Back
CNS
central nervous system: brain + spinal cord
PNS
peripheral nervous system:
cranial nerves
spinal nerves
(and branches)
(includes ANS)
ANS
AUTONOMIC NERVOUS SYSTEM:
part of the motor system controlling what are mostly involuntary functions (glands, smooth muscles of gut, bronchi and blood vessels and activity of heart)
Glia
asotrocytes
oligodendrocytes
microglia- supporting cells of the brain
Neurons
nerve cells
Soma
= cell body
(where the nucleous and most metabolic machinery of a neuron are located)
Nissl Substance
RER in neuron cell body
Dendrites
proceesse from neuron onto which synapses are made
Dendritic spines
processes off of dendrites for snyaptic connection
Dendritic arbor
the branching pattern of dendrites
Axon
neuronal process along which action potentials are propogated
Collateral branches
allow axons to transmit signal to different targets
Myelin
covering or axon that speeds conduction
Node of Ranvier
area of axon between myelein (where acon is not insulated)
Electronic signalling
passive spread of of electrical potential (voltage)

degrades with distance from site of generation
Action potential
propogated (regenerated) electrical potential that travels length of axon
Saltatory conduction
"jumping" action potential from one node of Ranvier to the next
Synapse
site of contact bt one neuron and the next, usually:
-axodendritic
-axosomatic
-axoaxonic
synapses are typically...
(hint: what are they bt?)
-axodendritic
-axosomatic
-axoaxonic
Neurotransmitter
chemical released from one neuron to influence the activity of another
Reuptake
one way of terminating action of a neurotransmitter

by taking it back into neuron
Axon Transport
flow of cellular material and constituents back and forth along axon
Synaptic vesicle
vesicle in presynaptic part of nerve terminal, released in response to axn potential
inhibitory (signal?)
anything that decreases the chance that a neuron with generate an action potential
excitatory (signal?)
anything that increases the chance that a neuron will generate an action potential
modulatory signal
anything that changes the likelihood of generating an action potential
Nucleus
collection of neurons within the CNS that have similar inputs, outputs and functions
Ganglia
collections of neurons outside the CNS

may be autonomic or sensory (such as dorsal root ganglia)
Tract/Fasciculus
collections of axons in the CNS that have similar origin, termination and fxn
Funiculus
the 3 areas of white matter in the spinal cord (anterior, lateral or posterior to the gray matter)

each funiculus contains several tracts
Pathway
a secried of tracts that convey a particular type of information through several relays in the CNS
1st order, 2nd order
sequence of neurons in a pathway, each neuron will have an axon that follows a different tract
origin/termination
term used with tracts to describe where tract strats and terminates (i.e. where cell bodies and synapses are)
Target
term used with tract to describe the site of termination
Relay
term used with pathway, site where one tract synapses on neurons that will give rise to the next tract
Decussation
term used with tract or pathway

describes a site of crossing to opposite side of the CNS
commissure
a connection between one side of the nervous system and the other
Ipsilateral
same side of the body or nervous system
Contralateral
opposite side of the body or nervous system
Afferent
going toward
Efferent
going away from
if no point of reference is given, point of reference for afferent/efferents
is the CNS

afferent then = sensory (toward CNS)
efferent = motor (from CNS)
Somatotopy
topographic respresentation of the body in the nervous system
Axial plane
horizontal

separates body into superior and inferior portions
Coronoal plane
separates body into anterior and posterior portions
sagittal plane
separates body into left and right portions
toward the nose
rostral (anterior part of brain)
brain stem is ...... to spinal cord
(spatial relationship)
rostral
brain stem consists of
medulla
pons
and midbrain

through which tracts pass from the spinal cord, containing nuclei of cranial nervs and centers for many involuntary functions
what passes through the brain stem?
tracts pass from the spinal cord, containing nuclei of cranial nervs and centers for many involuntary functions
cerebellum is ..... to the brainstem
(spatial relationship)
dorsal
cerebellum is involved in:
coordination
and learning of movement
diencephalon is .... to brain stem
(spatial relationship)
rostral
diencephalon consists of
hypothalamus
(dorsal) thalamus
and epithalamus
telencephalon is ... to thalamus
(spatial relationship)
rostral to thalamus
telencephalon consists of:
consists of cerebral cortex and basal ganglia (a misnomer)
nervous system is comprised of what cell types
neurons and glia
glia are responsible for:
-maintaining the internal milieu of the interstices of the brain

-producing the blood brain barrier (astrocytes)

-producing myelin (oligodendrocytes)

-phagocytic/immune fxns (microglia are parts of the monocyte/M0 system)
components of neurons
dendrites (with spines)
cell bodies (with normal cellular components)
axons
neurons have resting membrane potential that is due to...
-selective ion permeabilities
and
-ionic gradient
neuronal membranes contain:
ion channels

and

various receptors
when are neuronal ion channels open?
-some are open ALL THE TIME
-some (voltage gated) are open when there are changes in membrane potential
-some (ligand gated) are only upon when a transmitter binds to them
voltage gated ion channels are open
are only open when there are changes in membrane potential
ligand gated ion channels are open
when a transmitter is bound to them
neurons are electricially excitable due to:
their ion channels

these channels allow neurons to be depolarized or hyperpolarized

this electrical change spreads electronically (the change in potential diminishes further from the site of generation)
neurons have threshold for opening...
voltage gated ion channels
what is responsible for generating an action potential
voltage gated ion channels
how are action potentials propogated?
they are regenerated at intervals down axons all the way to their terminals

(therefore it does not change in amplitude)
why does the amplitude of an action potential NOT change?
it is propogated(regenerated) at intervals down axons all the way to their terminals
how does myelin effect conduction?
allows small axons to conduct more rapidly via "saltatory" conduction (depolarization only occurs at intervals)
what is bidirectional axonal transport?
the movement of cellular organelles, vesicles and various chemical constituents up and down the axon
synapses
sites of contact between neurons
most synapeses are...
chemical
a few synapses allow direct conduction of ions via
GAP JUNCTIONS
at chemical synapses axon terminals contain
synaptic vesicles with neurotransmitter
what causes chemical neurotransmitters to be released?
CALCIUM that enters the nerve terminal
(via voltage-gated channels when the nerve terminal is depolarized by an axn potential)
how do neurotransmitters have an effect?
act on receptors (may be ION CHANELS or MEMBRANE PROTEINS coupled to enzyme mechanism)
postsynaptic receptors
ION CHANNELS- may be open or closed by neurotransmitter axn

MEMBRANE PROTEINS coupled to ENZYME mechanisms (eg GDP coupled receptors)
neurotransmitters may do what to the postsynaptic neuron?
INHIBIT or EXCITE
inhibitory neurotrasmittors
decrease the chance that a neuron will generate an action potential
excitatory neurotransmittors
increase the chance for axn potential generation
What is summation?
combination of excitatory or inhibitory effects on a neuron

producing a net effect of either:
-reaching threshold (producing an ACTION POTENTIAL) or
-failing to reach threshold (no action potential)
what is meant by the fact that the output of neuron is binary?
ALL or NOTHING

either reaches threshold and produces action potential

or does NOT
Action of a neurotransmitter is terminated by:
a)
b)
c)
a) enzyme breakdown
b) diffusion away from the site
c) reuptake into a terminal
nervous system is comprised of:
PNS and CNS
PNS is the
SOMATIC nervous system (motor and sensory nerves)

and the

AUTONOMIC nervous system
somatic nervous system is part of the...
PNS
autonomic nervous system is part of the...
PNS
motor nerve fibers
a) type
b) origin of axons
c) termination of axons
d) axons pass through
a) EFFERENT fibers
b) axons begin in motor neurons of the nervous system
c) axons end synapses on msucles of the head or body
d) passing through:
-ventral nerve roots
-nerve plexi and..
-peripheral nerves
sensory nerve fibers
a) type
b) begin
c) traverse
d) cell body location
e) continue as
f) end where
a) AFFERENT
b) begin in periphery in receptive ending
c) traverse the peripheral or cranial nerves back toward the spinal cord
d) cell body in dorsal root ganglion
e) anotehr axon continues from neuron through the dorsal root into the posterior (dorsal part) of spinal cord
# of spinal nerve pairs
31
# of cranial nerve pairs
12
Autonomic Nervous System
motor system

involved in controlling visceral fxns (got or blood vessel smooth muscle, glands, edc..)
ANS characterized by
2-neuron pathway

PREGANGLIONIC NEURONS have
-cell bodies in the CNS and
-terminations in a ganglion by synapsing on a postganglionic neuron

POSTGANGLIONIC NERVE FIBER= axon that extends from the ganglion to the organ
sympathetic component of ANS is aka
THORACOLUMBAR OUTFLOW
preganglionic neurons found in teh spinal cord from T1 to L2 (w/ axons leaving the cord in those nerve roots)
sympathetic ganglia are located..
in a chain along the sides of the spine (??paravertebral) with connections back and forth to the spinal nerves or in front of the spine (prevertebral) situated along the aorta
component of nervous system for fight/flight and ejaculation
sympathetic nervous system
parasympathetic component of ANS is aka
craniosacral outflow

has cell bodies in the brain stem and the sacral spinal cord
parasympathetic nervous system has cell bodies in
has cell bodies in:
the brain stem and
the sacral spinal cord
preganglionic parasympathetic axons leave the nervous system via
several of the cranial nerves
(specifically: III, VII, IX and X)
parasympathetic ganglia consist of
4 ganglia in the head
and
Scattered tiny ganglia near or within each organ innervated
involved in pupil and lens accommodation
CNIII
involved in salivary, lacrimal gland and nose
CNVII
involved in salivary gland
CNIX
involved in thoracic and most abdominal organs
CNX
nerves involved in parasympathetic control of pelvic organs
S2-S4
Parasympathetic nerve fibers basically:
increase digestion (secretion/motility)
slow heart
involved in producing bladder contractions
erection
nasal and respiratory congestion and secretion
CNS consists of
brain and spinal cord
CNS is composed of
White matter (axons/tracts)
and collections of neurons
within the CNS a nucleus is:
a group fo nuerons having the same function
the cortex
(cerebellum and cerebral cortex) are neuronal cells spread over the surface of the brain in a thin layer
tracts
groups of axons that connect a group of neurons in the gray matter of one part of the brain (eg the cortex or a nucleus) with another part of the nervous system

axons can be thought of as wires and the tract can be thought of as conveying info from one part of the nervous system to another
damage to a tract will cause
loss of whatever fxn that tract is subserving
beginning of a sensory tract is
its receptor
beginning of a motor tract is
whatever part of the nervous system is generating the motor signal (eg: for voluntary movement that would be the motor cortex)
tracts have an ending at...
a synapse with another neuron (perhaps in a nucleus or the cortex)
every group of neurons (ie every nucleus or part of the cortex) can be thought of as having:
-afferent input from other areas of the nervous system (synapse on the neurons of the region) and

-efferent output to other parts of the nervous system (axons that leave the area as tracts projecting to other parts of the nervous system... these efferents become afferents to these other brain regions)
a pathway consists of a series of
tracts that convey information through the nervous system in several relays, relay sites are usually in nuclei with the anatomical substrate of the relay consisting of the synapse bt the tract and the neurons of the nucleus
parts of the CNS
spinal cord
medulla
pons
cerebellum
midbrain
diencephalon
telencephalon
basic architecture of spinal cord
-CENTRAL CANAL
-GRAY MATTER on inside (H-shaped, with dorsal and ventral horns)
-WHITE MATTER on the outside (axons making tracts and connections)
ventral horn contains
motor neuron cell bodies
dorsal horn contains
many senssory processing neurons
lateral horn contains
in thoracic and upper lumbar cord: preganglionic sympathetic neurons

in sacral cord: has parasympathetic neurons
brainstem consists of:
medulla
pons
midbrain
cerebellum
connected to the dorsum of the brainstem by several large bundles of white matter, called peduncles that comprise the tracts connecting to and from the cerebellum
diencephalon
hypothalamus
(dorsal) thalamus
epithalamus
telencephalon
basal ganglia
cerebral cortex
hippocampus
amygdala
cerebral cortex
frontal, temporal, parietal and occipital lobes
most important function of
SPINAL CORD:
final site of integration of motor and autonomic output;
spinal reflexes;
initial processing of sensory signals; white matter contains:
-ascending sensory tracts from the body (mediating the transmission of sensations from body) and
-descending motor tracts (allowing control of motion)
most important function of
medulla/pons/midbrain
site of cranial nerve nuclei; control of CN fxns including reflexes (blinking, reflex eye mvmts, gagging); integration of involuntary fxns (blood pressure regulation, respiration vomiting, swallowing, coughing); provides pathway for tracts and pathways connecting the spinal cord to other parts of the nervous system; connections to and from the cerebellum
most important function of
cerebellum
processing machinery for learning and performance of skilled movements, may be involved in other forms of learning and emotional control as well.
most important function of
hypothalamus:
mainsite of synthesis and coordination of endocrine and autonomic functions as well as some emotional behaviors
most important function of
(dorsal) thalamus:
main function is as a relay nucleus for pathways that are going to the cerebral cortex
most important function of
BASAL GANGLIA
involved in the control of motor tone, postures and stereotypes movements as well as initiation of voluntary movements.
also contributes to emotional tones and postures
most important function of
the HIPPOCAMUS:
critical to recent memory
most important function of
the AMYGDALA:
critical to integrated emotional response and memory (e.g. fear reactions and anxiety)
most important function of the
CEREBRAL CORTEX
highest level of integrative function

some areas control highly specific functions and some are higher order processing (called association cortex)
coverings of the brain:
DURA
ARACHNOID
PIA
DURA
tough layer adhered to skull
ARACHNOID
thin watertight layer, bt dura and pia
PIA
intimately covering the brain
Subdural space
potential space between the dura and arachnoid
Subarachnoid space
space between the arachnoid and pia
Major arteries of the brain run in what space?
in the subarachnoid space
(veins cut ax it)
Circulation of the brain
4 major vessels
carotid arteries divide into:
-arterior cerebral arteries
-middle cererbral arteries
two vertebral arteries joint to make the
-basilar artery, which divides to the
-posterior cerebral arteries, which are connected to the internal carotid arteries by the posterior communicating arteries
-anterior communicating artery connects the two anterior cerebral arteries
CIRCLE OF WILLIS
anastomotic path that blood can follow to bypass blockage of any of the four major blood vessels supplying the brain
venous dural sinuses are between
layers of dura
bridged by veins from the brain
main sinuses:
superior sagittal
inferior sagittal
straight sinus
transverse sinuses
sigmoid sinuses
cavernous sinuses
sigmoid sinuses
drain into what?

communicate with what?
drain into internal jugular vein

communicate with transverse sinuses and cavernous sinuses
largest vein draining the internal part of the brain
GREAT CEREBRAL VEIN (of GALEN)
great cerebral vein communicates with what?
straight sinus posteriorly
inferior sagittal sinus anteriorly
ventricular system of brain
system of cavities inside the brain
what makes CSF
choroid plexus
path of CSF
passes from the LATERAL VENTRICLES
through the FORAMEN OF MONROE into the THIRD VENTRICLE (midline) then through the CEREBRAL AQUEDUCT OF THE MIDBRAIN to the FOURTH VENTRICLE (dorsal to pons and rostral medulla) which communicates with the CENTRAL CANAL of the spinal cord and with subarachnoid space via the FORAMEN OF MAGENDI (midline) and LUSKA (laterally)
How does the 4th VENTRICLE communicate with the central canal of the spinal cord and with subarachnoid space?
FORAMEN OF MAGENDI (midline)
and
FORAMEN OF LUSHKA (laterally)
How is CSF resorbed into the venous system?
by the arachnoid granulations