Exam 2: Neuro Flashcards
what are three divisions of the nervous system
sensory
integrative
motor
what is included in the sensory division of the nervous system
tactile
visual
auditory
olfactory
what is included in the integrative division of the nervous system
process information, creation of memory
what does the motor division of the NS allow us to do
respond to and move about in our environment
the precentral gyri is related to ___________ function
motor
the post central gyri is related to _______ function
sensory
the afferent direction is ____________ the nervous system
towards
the efferent direction is _________ from the nervous system
away
what nerve ending responds to pressure
pacinian copuscle
what nerve ending responds to touch
meissners corpuscle
what joint nerve endings send messages to the DRG
kinesthetic receptors
what nerve endings respond to pain, cold and warmth
free nerve endings
What is the role of the thalamus?
routes afferent sensory messages to correct portions of brain (muscle cortex, glands, memory etc)
what does the temporal lobe do
intellectual and emotional functions
memory like face recognition
hearing
what actions does the brainstem control
swallowing
breathing
heartrate
what does the wernickes area do
speech comprehension
words/thought
what does the cerebellum do
coordinates movement and balance
what does the occipital lobe do
visual
what does the parietal lobe do
comprehension of language
spanish to english
what does the frontal lobe do
judgement,
foresight,
voluntary movement
problem solving
organization
what does the brocas area do
speech
what does the frontal lobe/olfactory bulb do
smell
what are the three levels of CNS function
spinal cord
lower brain
higher brain
T/F the spinal cord is just a conduit
false
what is contained in the lower brain level
medulla,
pons,
mesencephalon,
hypothalmus,
thalamus,
cerebellum,
basal ganglia
what is contained in the spinal cord level
walking circuits
withdrawal circuits
support against gravity circuits
circuits for reflex control of organ function
what does the lower brain level control
subconscious
arterial pressure,
respiration,
equilibrium,
feeding reflexes,
emotional patters
what is the role of the higher brain/cortical level
-memory storehouse
-muscle memory
-thought processing
-opens the world up for ones mind
T/F the higher brain cortex usually functions alone
False
works with lower centers
what are the three major components of the neuron structure
soma
axon
dendrite
what is the main body of the neuron
soma
which part of the neuron from the soma to the effector part of the neuron
axon
which part of the neuron transmits the action potential
axon
what is the sensory portion of the neuron
dendrite
which part of the neuron conducts electrical charge, not action potentials
dendrite
Neuron Structure
the posterior portion of the spinal cord is the __________ NS
sensory (afferent)
the anterior portion of the spinal cord is the __________ NS
motor (efferent)
Where is the grey and white matter in the spinal cord?
grey inside
white outside
which root (anterior or posterior) has a ganglion
posterior (sensory)
in the brain where is the grey and white matter
White inside
grey outside
why is membrane charge close to Ek charge
membrane is very permeable to K
what is the nearnst equation
balance of concentration and electrical gradients creates resting potential
what two ions are in greatest concentration outside the cell
Na
Cl
what ion is in greatest concentration inside the cell
K
what offsets the + charge of K inside the cell to make it -
proteins
What is a subthreshold stimulus?
weak local depolarization that does not reach threshold
T/F subthreshold potentials summate
True
T/F action potentials summate
False
what an epsp
excitatory post synaptic potential
brings membrane charge closer to threshold (+)
this makes it easier for an AP to occur
what type of summation is from the same synapse
temporal summation
what type of summation is from different synapse
spatial summation
what is an IPSP
inhibitory post synaptic potential
makes membrane
harder to reach AP
what is an example of IPSP
seizure meds
temporal summation almost ____________ induces an AP
never (he said spatial but book says opposite)
how long does an EPSIS/IPSP last
15 mSec
each terminal on a dendrite account for _____ - _______ mV EPSP
0.5-1.0
the higher number of synapses the ________ likely you are to reach threshold
more
what is a facilitated neuron
another neuron fires bringing the potential closer to threshold so the next impulse builds off the first one (summation)
Do dendrites transmit action potentials?
no
they conduct electricity
why keeps the dendrites from having APs
leaky K and Cl channels keep charge low
No Na channels
T/F all neurons have the same activity and frequency
False
different neurons have different activity and frequency
what substances are used in ion channel postsynaptic membranes
cation/anion channels
ligand gated chanels (Ach, NE)
what type of response do ion channel postsynaptic membranes have
short lived
what substances are used in 2nd messenger system postsynaptic membranes
neuropeptides (G protein)
what type of responses do 2nd messenger system postsynaptic membranes have
multiple responses
prolonged responses
Where are gap junctions found?
cardiac and smooth muscle
what is the function of gap junctions
increased speed of conduction of APs between cells
what is a second messenger always bound to
G protein
second messenger system is a (shorter longer) process than ion
longer
what kind of messengers does the second messenger system use
hormones
what are the 4 functions of a second messenger system
1) opens channels
2) activates enzymes to produce cAMP or cGMP
3) activates intracellular enzymes
4)activates gene transcription
what are some class 1 neurotransmitters
acetylcholine
what are some class 2 neurotransmitters
norepinephrine
epinephrine
dopamine
serotonin
histamine
what are some class 3 neurotransmitters
gamma-aminobutyric acid (GABA)
glycine
glutamine
aspartate
what are some class 4 neurotransmitters
NO (nitric oxide)
how does acidosis affect synaptic transmission
depresses neuronal activity
ex. diabetic coma
ph change from 7.4-7.0 results in coma
how does alkalosis affect synaptic transmission
increased neuronal excitability
epileptic seizure
ph change from 7.4 to 8.0 results in seizure
how does hypoxia affect synaptic transmission
brain dependent on O2
interruption of brain blood flow for 5-10 seconds leads to unconsciousness
what do mechanoreceptors detect
deformation
(pressure changes formation of receptors)
what do thermoreceptors detect
changes in temperature
What do nociceptors respond to?
damage (pain)
what do electromagnetic receptors detect
light (like rods and cones in eye)
what do rods in eye detect
light
white and black, no color
What do chemoreceptors detect?
taste
smell
CO2
O2
What does the pacinian corpuscle do?
detects pressure
what determines the location of a receptor
their function (idk this is a direct quote)
what is a modality of sensation
each of the principal types of sensation: pain, touch, sight, sound
what is the the labeled line principle
nerve fibers transmit only one modality of sensation
how do all receptors work at a cellular level
they all change the membrane permeability to ions causing either hyper or hypo polarization
how does receptor stimulation affect sensation of surrounding receptors
stimulation of one nerve sends a message to surrounding nerves increasing the membrane potential (closer to threshold) so it is easier for the nerve to reach threshold and send AP (facilitated)
if a nerve has a node of ranvier it is a ____________ nerve
myelinated
how does an increase in stimulus intesity affect AP frequency
increased receptor potential,
which increases AP frequency
receptor potential
small changes in stimulus strength can be discerned when intensity is _______
low
only large changes in stimulus strength can be discerned when intensity is _______
high
an increased amplitude of observed receptor potential requires a _________ stimulus strength
increased
how does stimulus strength and receptor potential affect a sensation like pain
there is a threshold for how much pain is possible to be perceived
what is adaptation of receptors
Neurons stop responding to constant stimuli
the fact that your body stops sending you signals about wearing a shirt is an example of what principle
adaption of receptors
what are examples of two nerves that adapt very quickly
pacinian corpuscle (stretch)
hair receptor
what are examples of two nerves that have slow and limited adaptation
joint capsule receptors
muscle spindle receptors
touch sensation adaptation
what decreases the distortion force in pacinian corpuscles
fluid redistributes, this is fast adaptation
what allows photoreceptors to have fast adaptation
receptors change the amount of light sensitive chemicals
what kind of receptor is a pacinian corpuscle
mechanoreceptor
is a muscle spindle tonic or phasic?
tonic (slow adapting)
is a golgi tendon apparatus tonic or phasic?
tonic (slow adapting)
is a ruffini ending tonic or phasic?
tonic (slow adapting)
is a merkel disk tonic or phasic?
tonic (slow adapting)
is a macula receptor tonic or phasic?
tonic (slow adapting)
is a temperature receptor tonic or phasic?
tonic (slow adapting)
is a chemoreceptor tonic or phasic?
tonic (slow adapting)
is a baroreceptor tonic or phasic?
tonic (slow adapting)
is a pain receptor tonic or phasic?
tonic (slow adapting)
is a tonic receptor slow or fast adapting
slow
a tonic receptor transmits impulses to brain for a ________ period of time
long
what kind of receptor keeps us appraised of our surroundings
tonic
how long does it take tonic receptors to adapt
hours to days
when do phasic receptors respond to stimuli
only when change is happening
what affects the rate and response of a phasic receptor
rate and intensity of stimuli
what receptors are very important for balance and movement
phasic (fast adapting)
Is a Pacinian corpuscle tonic or phasic?
phasic (fast acting)
Is a meissners corpuscle tonic or phasic?
phasic (fast acting)
Is a semicircular canal receptor tonic or phasic?
phasic (fast acting)
what type of receptor continues to respond to stimuli
tonic
what type of receptor responds only at onset and offset of stimuli
phasic
an A class nerve is (myelinated unmyelinated
myelinated
a C class nerve is (myelinated unmyelelinated)
unmyelinated
the larger the diameter of the nerve, the _________ the velocity
higher
what are the divisions of A classification of nerves from fastest to slowest
A alpha
A beta
A gamma
A Delta
what are some of the sensory function of C classification of nerves (unmyelinated)
crude touch and pressure
tickle
aching pain
cold
warmth
what is a motor function of C classification nerves
sympathetic
a nerve of 20 micrometers moves at a velocity of
120 meters/sec
what receptor has the sensory function of proprioception
muscle spindle
what are the two ways to increase signal intensity
spatial summation
temporal summation
if a nerve is excited, this means it has an
action potential
if a nerve is facilitated its membrane potential is changed to be (closer/further) to/from threshold
closer
what is a neuronal pool
groups of neurons with special characteristics
what are the different types of neuronal pools
converging
diverging
reverberating
inhibitory
what are the two type of divergent neuronal paths
same tract
multiple tract
what is an example of divergence in same tract
pyramid cells in motor cortex
what are examples of divergence in multiple tracts
information from dorsal columns take two directions one to cerebellum and then to thalamus and cerebral cortex
what is an amplifying type of divergence
divergence in the same tract
what are the two types of convergence neuronal pathways
single source
multiple source
convergence from a single source is an example of
spatial summation
what controls the antagonistic pairs of muscles
reciprocol inhibition circuit (extensors and flexors have to alternate relaxation and tension)
what prevents over-activity in brain
inhibitory circuit
what kind of circuit continually fires
reverberatory
what are examples of reverberatory circuits
HR,
respiration,
vaso tone
what type of feedback do reverberatory circuits have
positive feedback
What stops a reverberatory circuit?
fatigue of synaptic junction
Do all reverberatory circuits fatigue?
no (vascular tone, gut tone, HR, resp etc)
what are examples of tactile mechanoreceptor sensations
touch,
pressure,
vibration,
tickle,
itch
what are examples of proprioceptive mechanoreceptor sensations
static position
rate of change
what do thermoreceptors detect
heat and cold
What do nociceptors respond to?
pain and any factor that damages tissue
what is the location of Meissner corpuscles
non-hairy skin close to surface
-fingertips
-lips
-eyelids
-nipples
-external genetalia
what is the function of meissner corpuscles
Motion detection, grip control
what is the stimuli for meissner corpuscles
skin motion, low frequency vibration
what is the nerve type of meissner corpuscles
type A beta nerve fibers
what is the location of merkel discs
tip of epidermal ridges
what is the function of merkel disks
form and texture perception
what is the stimuli for merkel disks
edges, points, corners, curvature
what tactile receptors help you differentiate between picking up a ball or block
merkel disks
what is the nerve type of merkle disks
type A beta fibers
what is the location of pacinian corpuslce
dermis and deeper tissues
what is the function of pacinian corpuslces
perception of distant events through transmitted vibrations
what is the stimuli of pacninian corpuscles
vibration
what is the nerve type of pacinian corpuscles
type A beta nerve fibers
what is the location of ruffini corpuscles
dermis (joint capsules)
what is the function of ruffini corpuscle
tangential force,
hand shape,
motion detection
what is the stimuli of ruffini corpuscle
skin stretch
what is the nerve type of ruffini corpuscle
type A beta fibers
what is the location of free nerve endings (myelinated)
surface of body and elsewhere
what is the function/stimuli of free nerve endings (myelinated)
pain
temp
what is the nerve type of free nerve endings (myelinated)
type A delta
what is the location of free nerve endings (unmyelinated)
surface of body and elsewhere
what is the function/stimuli of free nerve endings (unmyelinated)
pain
temp
itch
tickle
what is the nerve type of free nerve endings (unmyelinated)
type C
what are the two pathways for sensory afferents
anterolateral system
dorsal column-medial lemniscal system
where do all sensory afferents first go to on spinal cord
posterior root ganglion
dorsal column-medial lemniscal system has _________ (#) of nerves in the spinal cord
1, goes straight up to medulla oblongata
the anterolateral system enters the dorsal root and has a synapse that crosses the ____________ and goes up the __________
anterior commissure
anterolateral tract
the anterolateral system has ___ (#) of nerves in the spinal cord
2, crosses the anterior commissure
white matter is made up of
pathways
dorsal column-medial lemniscal pathway is made up of ________ myleninated nerve fibers
large
What is decussate?
where sensory nerves cross over to the opposite side of the nervous system
how many neurons are involved in the dorsal column-medial lemniscal pathway
3
where does the dorsal column-medial lemniscal pathway decussate
medulla oblongata (lower)
after crossing over in the medulla oblongota the dorsal column-medial lemniscal pathway goes through the _____________ to the ____________
medial lemniscus
ventrobasal complex of thalamus
where does almost all sensory afferents go
ventrobasal complex of thalamus
where does the third nerve of the dorsal column-medial lemniscal pathway synapse
ventrobasal complex of thalamus,
terminate in cortex
what type of mechanoreceptor information is transmitted in the dorsal column-medial lemniscal pathway
discrete types with a high degree of spatial fidelity
(touch, vibration, position, fine pressure)
what kind of neurons are in the anterolateral system
smaller myelinated and unmylinated fibers for slow transmission
how many neurons are involved in the anterolateral system
3
where does the anterolateral system decussate
spinal cord
the anterolateral system has a ______ degree of spatial orientation
low
what sensations are transmitted in the anterolateral system
pain,
thermal,
crude touch,
pressure,
tickle,
itch,
sexual sensations
where does the third neuron of the anterolateral system synapse
ventrobasal and intralaminar nuclei of the thalamus, terminates in cortex
what is the greatest area of representation of somatosensory cortex
1- lips
2- face
3- tongue
what areas have the least representation of somatosensory cortex
trunk and lower body
what determines where a sensation goes in brain
thalmus
what layer do all incoming signals go
4
how many layers does the structure of the cerebral cortex have
6
layers can have _________ columns of modality
multiple
where is layer 1 in the cortex
near the surface
where is layer 6 in the cortex
deep
what layers receive diffuse input from the lower brain centers
layer 1 and 2
what layers send axons to closely related portion of the cortex for communicating between similar areas
2 and 3
what layers send axons to more distant parts of the nervous system
5 and 6
where does layer 5 send signals
brainstem
where does layer 6 send signals
thalamus
a column in the cortex represents what
a specific sensory modality (stretch, pressure, touch, etc)
a small stimuli on a single point will stimulate (less/more) receptors than a large single point stimimuli
less
what is lateral inhibition
when an excited neuron reduces the activity in neighboring neurons
narrows area of sensation
what disease follows a dermatome
varicella (shingles)
dermatomes
what is a dermatome
area of skin supplied by a sensory neuron that arise from a spinal nerve ganglion
what kind of stimuli cause fast pain
knife cut, needle poke, burn
where is fast pain stimuli usually felt
surface of body
where is slow pain usually felt
body surface and deeper tissue
what kind of stimuli cause slow pain
throbbing/aching
what type of pain is bradykinin associated with
slow pain
fast pain travels on _______ nerves
myelinated
what is the main cause of pain from tissue damage
bradykinin
slow pain travels on ______ or ______ nerves
small myelinated or unmyelinated
what are the three signs of inflammation
heat, redness, swelling
what are some inflammatory mediators
bradykinin, prostaglandin,
what kind of receptors are pain receptors
free nerve endings
where are free nerve endings located
skin,
arterial wall,
joint surfaces,
periosteum,
falx and tentorium of cranial vault
do pain receptors adapt to stimuli?
no
what is intensity of pain related to
rate of tissue damage
what contributes to pain resulting from tissue damage (slow pain)
bradykinin
potassium
proteolytic enzymes (neutrophils)
What causes emphysema?
neutrophils dissolving elastin around alveoli,
what is ischemia
lack of blood flow
what is hypoxia
lack of o2
what causes ischemic pain
lactic acid build up (death of tissue)
bradykinin
proteolytic enzymes
how long does it take for pain to occur in arterial occlusion of limb
15-20 seconds
what kind of pain travels in the neospinothalamic tract
fast pain
what fibers transport the fast pain
type A delta
what fibers transport slow pain
type C fibers
what kind of pain travel in the paleospinothalamic tract
slow pain
where does the first neuron of the neospinothalamic tract travel
into posterior horn, up or down 1-2 segments, terminates in posterior horn in lamina marginalis
what is the path of the second neuron in the neospinothalamic tract
- starts in posterior horn lamina marginalis
- immediately crosses over the anterior commissure to the anteriolateral column
- travel up to the reticular formation of the ventrobasal complex of the thalamus
what is the neurotransmitter for A-delta fiber of neospinothalamic tract
glutamate
what lamina is the lamina marginalis in
1
what lamina is the substantia gelatinosa in
2-3
what lamina do Ad pain nerves (neospinothalamic) dessucate in
1 Lamina marginalis
what part of the spinal cord does the 2nd neuron of the neospinothalamic tract travel on
anterolateral column
where do most 2nd order neospinothalamic tract nerves terminate
ventrobasal complex of the thalamus
where do 3rd order neurons of the neospinothalamic tract travel to
cortex
can fast, sharp pain (neospinalthalamic) be localized well?
yes, when other tactile receptors are also stimulated
what happens with pain receptors in retricular formation
pain sensations get dissipated to trigger other portions of brain
what pathways use the anterolateral pathway
tactile,
neospinothalamic,
paleospinalthalamic
how many neurons are in the neospinothalamic tract
3
where does the neospinothalamic tract decassate
within spinal cord
what stimulates the tactile plate? what does it do
pain
releases endogenous pain relief
what type of nerve fiber is used in the paleospinothalamic tract
C fiber
what type of pain is transmitted in the paleospinothalamic tract
slow, burning pain
where does first neuron of the paleospinothalamic tract synapse
2 and 3 (substantia gelatinoa), or lamina 5
majority will go synapse in 5 first
where do all neurons of the paleospinothalamic tract synapse before crossing to the anterolateral pathway
lamina 5
what is the neurotransmitter for type C fibers of the paleospinothalamic tract
substance p
does the paleospinothalamic tract localize well
no
just to affect limb
where do most nerves of the paleospinothalamic tract terminate
reticular nuclei of medulla, pons, mesencephalon, and tectal area of mesencephalon and periaqueductal gray area
10-25% in thalamus
what types of pain does substance P mediate
lower back pain
arthritis
fibromyalgia
how does capsaicin work
depletes substance P from local nerve endings to relieve pain
if you remove the somatic sensory sensory area of the cortex will you still feel pain?
yes, pain has branching pathways (reticular areas)
what area of the brain is important for determining the quality of pain
cortex
where does endogenous analgesia begin
reticular formation
periventricular nuclei
periaqueductal gray
what does the raphe magnus/nucleus release when stimulated
serotonin
what stimulates the enkephalin system
serotonin
when nucleus raphe magnus is stimulated and releases serotonin what happens next
the enkephalin neuron inhibits pain transmission in spinal cord
what does naloxone do,
stops the enkephalin neuron from tying up pain receptor neuron
what 4 sites can stimulate endogenous analgesia by blocking the anterior lateral pathway
parabrachial nucleous
medullary reticular formation
raphe nuclei
locus coerleus
where is serotonin released from in endogenous analgesia pathway
raphe nuclei
what can cause both presynaptic and postsynaptic inhibition of incoming type C and tybe A delta fibers where they synapse in in dorsal horn
enkephalin
what is an example of higher brain centers controlling pain
placebo affect
what are the major endogenous opiates
beta-endorphin,
dynorphin
met-enkephalin,
leu-enkephalin,
where are enkephalins and dynorphins found
brain stem
spinal cord
where are beta-endorphins found
hypothalamus and pituitary
when is the endogenous opiate system activated
pain suppression during stress
response to emergency
defense, predation, dominance
adaptation to environmental challenges
what is the gate theory of pain
stimulation of type A-beta fibers from peripheral tactile receptors can decrease transmission of pain signals
what are examples of using the gate theory of pain
electrical stim
massage
liniments
what form of gate theory of pain can reduce labor pain
audioanalgesia
how many pain receptors do visceral tissues have
few
what are common causes of visceral pain
ischemia
chemical irritation
spasm of a hollow viscus
over-distension of a hollow viscus
where is pain from internal organ often felt
distant area of skin, this is referred pain
what is phantom pain
pain in a missing limb
what is the mechanism of referred pain
intermingling second order neurons in dorsal horn of spinal cord from skin and viscera (relatedto embyronic development)
why do MIs cause L arm pain
referred pain
what causes the specific location of referred pain of an organ on the skin
dermatome of embryonic development
where is heart pain localized
neck
left shoulder
left arm
where is stomach pain localized
above umbilicus
where is colon pain localized
below umbilicus
does headache pain come from the actual brain
no, brain tissue is insensitive to pain
where are the pain senstive areas in the head that are related to HA
dura
blood vessels of the dura
venous sinuses
middle meningeal artery
what causes eye headaches
computer use
needing glasses
what causes sinus HA
sinusitis
HA pain form the superior surface of the tentorum cerbellum forward manifests as what kind of HA
cerebral vault HA (top and side of head) meningitus, middle meningeal artery
HA pain from the inferior surface of the tentorum cerebellum backward manifests as what kind of HA
brain stem and cerebellar vault HA
what causes intracranial HAs
meningitis
migraine
hangovers
what causes migranes
vasospasm followed by prolonged vasodilation
vasodilitation stretching of blood vessels
what causes hangover HA
irritation of meninges by alcohol breakdown products
what causes extracranial HAs
muscular spasm (tension HA like TMJ, also emotional tension)
sinus HA
eye strain
we have more (hot/cold) receptors that we do (hot cold) receptors
cold
hot
where is the highest density of cold receptors
lips
T/F freezing cold and burning hot are the same sensations
T, when intense it stimulates pain so it feels the same
how does cold and hot stimulate nerves
changes the metabolic rate around receptor, so changes rate of intracellular reactions and ion interactions
cold changes ____________ metabolic rate
decrease
heat changes __________- metabolic rate
increase
what are the three sub areas of the motor cortex
primary motor cortex
premotor area
supplemental motor area
What does the primary motor cortex do?
controls the primary movement (like raising arm to climb up ladder)
What does the premotor area do?
stimulates related muscle groups to allow the primary movement
(shoulder and elbow and hand movement to raise arm when climbing ladder)
what are mirror neurons
anterior portion- builds image of action while posterior portion puts it into affect (part of premotor)
mirror neurons are part of which area of the motor cortex
premotor area
what does the supplemental motor area do
works with premotor area to elicit bilateral movement
(when climbing a ladder tells the rest of the body how to get into position to support primary movement)
sensory is the ___________ gyrus
posterior
motor is the __________ gyrus
anterior
what supples the broca area
first branch of the middle cerebral artery
what happens when broca area is damaged like in stroke
decreased speech capacity
what are specilized areas of the motor cortex
broca area
eye fixation and head rotation
hand skills area
what does the eye fixation and head rotation area do
for coordinated head and eye movement
what does damage to the hand skills area lead to
motor ataxia,
inability to perform fine hand movements
what transmits corticol motor signals on the direct pathway
corticospinal tract
what pathway transmits discrete detailed movement
direct pathway/corticospinal tract
what does the indirect pathway of cotricol motor signal
basal ganglia,
cerebellum,
brainstem nuclei
what percent of the corticospinal tract comes from the primary motor cortex
30
what percent of the corticospinal tract comes from the supplementary motor areas
30
what percent of the corticospinal tract comes from the somatic sensory areas
40
where do the majority of the fibers of the corticospinal tract dessucate
pyramid of medulla oblongota
after dessucating in the medulla where do corticospinal tract fibers travel
lateral corticospinal tracts
the majority of every type of nerve fiber dessucate in the
medulla oblongota
what type of fibers come out of the giant pyramidal cells (betz cells)
large fibers with fast transmission (70 m/sec)
lateral corticospinal tract crosses over at the
medulla oblongata
ventral corticospinal tract crosses over at the
cervical or spinal area
betz cells make up about ______ percent of total fibers
3%
how many muscle fibers do we have
1 million
why do we have large betz cell fibers for the motor transmission
creates immediate muscle response
what is the collateral response of the betz cells
send message back to cortex to sharpen the boundaries of the excitatory signal
what do motor fibers to caudate nucleus and putamen do
controls body posture (spinae erectae)
what does the reticular formation do
reacts to pain stimuli
what connects the hemispheres of the brain
corpus callosum
how many ways do somatosensory side comunicate to motor side
5
what tract does the red nucleous work with
rubrospinal tract
where does the red nucleous and rubrospinal tract receive input from
primary motor cortex
what is contained in the magnocellular portion of the red nucleus
large nuerons similar to betz cells
the magnocellular portion of the red nucleus gives rise to the
rubrospinal tract
the magnocellular portion of the red nucleus has somatotopic organization similar to the
primary motor cortex
what kind of movement does red nucleus stimulate
relatively discrete movement
which is more discrete primary motor cortex or red nucleous
primary motor cortex
what gives sensory feedback for motor control system
muscle spindles,
tactile receptors,
propioceptors
what does sensory feedback from motor control system do
fine tunes muscle movement (how tight to hold a can)
what causes auto correction in muscle spindle
length mismatch
what is an example of compression of skin provides sensory feedback to motor cortex on degree of effectiveness of intended action
holding an object, how tight to hold
how many giant pyramidal cells are need to cause muscle contraction
50-100
what layer of the cortex are motor neurons in
layer 5
what does a lesion in the primary motor cortex cause
loss of voluntary control of discrete movement of the distal segments of the limbs
what do lesions of the basal ganglia cause
muscle spasticity from loss of inhibitory input from accessory areas of the cortex that inhibit excitatory brainstem motor nuclei
what part of body does brainstem area contol
motor and sensory functions of face and head (cranial nerves)
the brainstem is an extension of the
spinal cord
where are centers for stereotypic movement and equilibrium contained
brainstem
what muscles support the body against gravity
muscles of spinal column and the extensor muscles of the legs
what excites the antigravity muscles
pontine reticular nuclei
what inhibits the antigravity muscles
medullary reticular nuclei
what tract does the medullary reticular nuclei use to oppose antigravity
medullary reticulospinal tract
where does the medullary reticulospinal tract receive input
corticospinal tract,
rubrospinal tract,
other motor pathways
muscles that support the body against gravity are under the influence of the
brainstem nuclei
what are the components of the vestibular apparatus
semicircular ducts (canals)
utricle
saccule
where are the maculae located
utricle and saccule of the vestibule
what does the vestibular apparatus do
maintains equilibrium/balance
the maculae of the urtical responds to _________- movement
horizontal
the maculae of the saccule responds to _________ movement
verticle
what are the layers of the maculae
statoconia (weighted pebbles)
gelatinous layer
hair tufts (in gelatin layer)
hair cells
nerve fibers
weighted stataconia move in the (same/opposite) direction of movement
opposite
Where are crista ampullaris/cupula located?
in the ampulla of each semicircular canal
How many semicircular canals are there?
3 (anterior, posterior, lateral)
What are the semicircular canals filled with?
endolymph
what are the small protrusions of the hair cell called
stereocilia
what is the one large protrusion of the hair cell
kinocilium
movement towards the kinocilium of the hair cell causes cellular
depolarization (opens pores)
movement away from the kinocilium of the hair cell causes
hyperpolarization
what connects the steriocilia and kinocilium
filament attachements
each semicircular canal has an _________ where the cupula and cristae ampullaris are located
ampulla
all the semicircular canals are at a _____ degree angle to eachother
90
what structures tell our brain about equilibrium
vestibular apparatus
what nerve transmitts the information from the vestibular appartus
vestibular nerve
where does the vestibular nerve travel
vestibular nucleus in medulla oblongata
what motor systems use the autonomic nervous systme
visceral organs,
blood vessels,
secretory glands
where are cell bodies of preganglionic ANS located
brain stem or spinal cord
axon of the visceral motor neuron is ___________ myelinated and projects to the ____________ ganglia
thinly
autonomic
cell body of the postganglionic neuron of the ANS are located within the ___________ ganglia and the _____myleninated axon projects to visceral effector cell
autonomic
UN
what are the divisions of the ANS
sympathetic and parasympathetic
sympathetic have ________ preganglionic fibers and _______ postganglionics
short
long
parasympathetics have __________preganglionic fibers and _______ postganglionics
long
short
All postganglionic parasympathetic neurons release ______.
acetylcholine
All preganglionic axons of the autonomic nervous system release
acetycholine
what is pathway of norepi synthesis
tyrosine-DOPA-dopamine-norepi
what is acetylcholine made up of
acetyl CoA and choline
what receptors does norepinephrine stimules
alpha and beta adrenergic
where are alpha receptors located
blood vessels (vasoconstriction)
Where are beta 1 receptors located?
heart (increase HR and contractility)
where are beta 2 receptors located
skeletal muscle,
lungs
bronchial dilation
vasodilation in muscle
calorigensis
glycogenolysis
what receptors does acetylcholine activate
nicotinic and muscarinic
Where are nicotinic receptors found?
neuromuscular junction, synapses between pre and post ganglionic neurons
Where are muscarinic receptors found?
all effector cells stimulated by postganglionic parasympathetic fibers (glands?)
what does sympathetic stimulation of the eye cause
pupillary dilation
what does parasympathetic stimulation of the eye cause
pupillary constriction and accommodation (focusing) of lense
what glands does the parasympathetic stimulate
nasal,
lacrimal,
salivary,
GI glands
what glands does the sympathetic stimulate
sweat
how does sympathetic affect the GI
none
how does parasympathetic affect the GI
stimulates overall activity and GI smooth muscle
how does sympathetic affect the heart
increased HR and contractility
how does parasympathetic affect the heart
decreased HR
how does sympathetic affect blood vessels
vasoconstriction
how does parasympathetic affect blood vessels
SOME vasodilation, but this is mostly done by suppressing sympathetic
parasympathetic has __________ receptors
cholinergic
sympathetic has _______- receptors
adrenergic
which part of the ANS is the adrenal medulla related to
sympathetic
what percent of epi and norepi is released from adrenal medulla
80% epi
20% norepi
What is the role of the adrenal medulla?
facilitates sympathetic
helps body deal with stress
where does sympathetic affect “tone”
venous system-constant tone
where does parasympathetic affect tone
GI
where do parasympathetic nerves come from
discrete brain stem and sacral 2-4
what causes the bodies stress response
sympathetic ANS
what is affect of SNS response (fight or flight)
increased BP, HR, Contractility, blood flow to muscles, blood glucose, metabolic rate, muscle strength, mental activity, blood coagulation
what are examples of adrenergic/sympathomimetic drugs
phenlyephrine (alphas)
isoproterenol (beta 1 and beta 2)
albuterol (beta 2)
what drug can treat collapsing trachea
isoproterenol
what does the splachnic nerve stimulate
viscera
where does the splachnic nerve come from
sympathetic chain ganglion
what are the three pathways in the sympathetic chain ganglion
1) enter via the white ramus and terminate
2)enter the sympathetic chain and go up or down a few segements and terminate
3)enter via the white ramus and exit via the splachnic nerve and terminate in a prevertebral ganglia
what cranial nerves do the parasympathetic nerves come from
3
7
9
10
what is cranial nerve 3
Occulomotor (eye movement) pupillary sphincter and ciliary muscles
what is cranial nerve 7
Facial (nerves to nasal, lacrimal, and submandibular gland)
what is cranial nerve 9
glossopharyngeal (parotid gland)
what is cranial nerve 10
vagus
what is another name for the parasympathetic splachnics
sacral segments (2-4)
where do the sacral segments of PNS go
fibers go to colon, rectum, bladder, genitalia
what postganglionic SNS nerves dont release norepi
sweat glands,
piloerector muscles,
and select blood vessels
what breaks down acetylcholine
acetylcholinesterase
what drugs increase the release of norepi from storage terminals
ephedrine, tyramine, amphetamine
where are nicotinic receptors located
muscles
ANS preganglion
what drug do you not give in glaucoma
atropine, use pilocarpine instead
what are examples of antimuscarinics
atropine, scopolamine
what are examples of cholinesterase inhibitors
neostigmine, pyridostigmine, ambenonium
cessation of cerebral blood flow for ______ to ______ seconds results in LOC
5-10
what percent of blood goes to brain
15% (750-900 ml min)
what are the metabolic factors that effect blood flow
Co2, H, O2
what are the 4 arteries that supply the circle of willis
internal carotids and vertebral arteries
The brain has a ___ metabolic rate
high
how can we measure Cerebral blood flow
functional MRI
positron emission tomography
why do we have the cerebral circle
if there is an occlusion on one part, blood flow can still continue from other parts of the circle
What is the body’s main source of energy?
glucose
does the brain require insulin?
no
what can too much insulin cause in the brain
decreased blood glucose, leads to psychosis and coma
how long of a glucose supply does the brain have
2 min
where is the brains supply of glucose
glycogen in neurons
increased CO2 casues vaso___________
dilation
what does an increase in CO2 leading to an increase in H in brain lead to
increased blood flow
decreased neuronal activity
nueral activity of the brain is increased during what acid base condition
alkaline
how do astocytes increase blood flow
nervous activity = glutamate
glutamate = calcium wave
calcium wave = prostaglandins
prostaglandins= dilation
what pressures does CBF autoregulation keep
60-140
what can pressure of >160mm hg in brain lead to
blood vessel stretch, eventual rupture and stroke
how much CSF is formed each day
500 ml (600?)
what produces CSF
the choroid plexus in the lateral (2), third and fourth ventricles
what cushions the brain and allows it to float
CSF
how much CSF is in the head usually
150ml
how much volume can the cranial vault hold
1600mls
all fluids in body (including csf) end up in
venous system and then urinated out
CSF is similar to
plasma
similar concentration
where is CSF and vessels in brain
sub arachnoid space
Where is the perivascular space?
space between blood vessel that goes into brain and pia.
what is perivascular space
specialized lymphatic system of the brain for CSF
what med do we use to treat cerebral edema
mannitol
what happens to CSF in increased ICP
CSF is lost
what causes papilledema
elevated ICP
what is normal ICP
8-15 mmHg
What does the BBB protect the brain from?
changes in ions,
AA,
peptides that occur in blood
where is BBB located
capillary endothelial cells
can H go through BBB
NO
can lipid soluble things go though BBB
yes
can CO2 go through BBB
yes
a gas
what are causes of ischemic stroke
thrombosis (local clot)
emobolism (clot from somewhere else)
hypotension (schock)
venous thrombosis
what are the two types of strokes
ischemic and hemorrhagic
What percent of strokes are ischemic?
87%
where do most ischemic strokes come from
carotid, cause of carotid sinus
what is synaptic fatigue
exhaustion of stores of transmitter in synaptic terminals
excitatory synapses are repetitively stimulated at a rapid rate until post synaptic discharge becomes progressively less
what is result of synaptic fatigue
loss of excitability
what does synaptic fatigue protect against
excess neuronal activity
what is post-tetanic facilitation
enhanced responsiveness following repetitive stimulation
what ion causes post-tetanic facilitation
Ca ions in presynaptic termininal
causes more vesicular release of transmitter
what is synaptic delay
the process of neurotransmision takes time, from the delay can calculate the number of neurons in a circuit
what does electrical stimulation of periaqueductal gray area do
relieves pain
inhibits nociceptive projection neurons in dorsal horn of cord
analgesia system diagram
what nerve fibers does enkephalin inhibit
type C
type A delta
T/f the cortex functions alone
False
Cortex never functions alone, always in association with lower centers
What are functions of cortex
Large memory story
Essential for thought processes
Takes information body gains, processes it and gives response for body
What’s another name for the soma
Cell body
What is the effector part of the neuron
Axon
What is the sensory portion of the neuron
Dendrite
Which. Channels and ions create an epsp
Cations
Na K Ca
What does glutamate do
Opens cation channels
Chief excitatory transmitter in CNS
What does GABA do
Opens Cl- channels
Chief inhibitory transmitter in adult CNS
Which ions are involved in creating ipsp
K or Cl-
What are 4 functions of G protein?
-open channels
-activate enzymes (membrane enzymes)
-activate one or more intracellular enzymes
-activates gene transcription
What is the inhibitory transmitter mainly in the cord
Glycine
Classes of neuropeptides
Hypothalamic releasing hormones
Pituitary peptides
Peptides that act on gut and brain
Peptides that work on other tissues
What sensory receptors are in the epidermis
Free nerve endings
Meissner corpuscle
Merkel cells
What sensory neurons are in the dermis
Ruffini corpuscles
What sensory neurons are in the subq layer
Pacinian corpuscles
Why is there no action potential except in the axon?
No Na channels except in the axon
What causes sudden cessation of reverberation?
Fatigue of synaptic junctions
What is the mechanism of fatigue
Transmission depletion
Receptor inactivation
Abnormal ion concentration in axon
what receptor function is proprioception
muscle spindle
what receptor function is touch
merkel
meissner
pacinian
ruffini
what are neuronal pools?
groups of neurons with special characteristics of organization
Meissner corpuslces location, function, stimuli, adaptation and type
location: nonhair skin close to surface
function: motion detection, grip control
stimuli: skin motion, low frequency vibration
adaptation: rapid adaptation
type: A beta
merkel location, function, stimuli, adaptation, type
location: tip of epidermal ridges
function: form and texture perception
stimuli: edges, points, corners, curvature
adaptation: slow
type: A beta
Pacinian corpuscle location function stimuli adaptation receptive field and type
location: dermis and deeper tissues
function: perception of distant events through transmitted vibrations
stimuli: vibrations
adaptation: very rapid
receptive field: entire finger or hand
type A beta
Ruffini corpuscle location function stimuli adaptation and type
location: dermis
function: tangential force; hand shape; motion detection
stimuli: skin stretch
adaptation: slow
type A beta
what type of nerve fibers are myelinated free nerve endings
type A delta
What does substance P do
Excited pain fiber nerve ending
What does substance P do
Excited pain fiver nerve ending
What does substance P do
Excited pain fiver nerve ending
Where do paleospinothalmi. Tract fibers terminate
Diffuser in reticular nuclei of medulla pons and mesencephalon
Tectal area of mesencephalon
Periaqueductal gray area
What is the mechanism of referred pain
Intermingling of second order neurons in dorsal horn of spinal cord from skin and viscera
Muscle spindle axon type
Ia and II
Muscle spindle axon type
Ia and II
