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efrain12
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what is ATP involved in? (3)
-excitatory or inhibitory
-found both in CNS and PNS
-pain modulation
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what does the adenosine of the ATP do? (2)
-inhibits
- -induces sleep
- *caffeine blocks this
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what is NO involved in?
-learning and memory
-strengthening synapse formation when learning
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what are excitatory NTs?
cause action potential on post synaptic neuron
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what are inhibitory NTs?
cause suppression of action potential on post synaptic neuron
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what determines the excitation or inhibitory response?
depends on the receptors that are present at the post synaptic neuron
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By which 2 ways can the excitation and inhibition be accmplished?
-direct
-indirect
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description of receptors with direct
- -often open ion channels directly after binding of NT
- **ex of channel-linked receptor
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description of receptors with indirect
use the secondary messengers to open ion channels and also initiate other intracellular effects
- *ex) g-prtein linked receptor
- ***usually found in hormones
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description of excitatory post synaptic potentials (EPSP) (2)
-often located on dendrites
-often involve sodium
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description of inhibitory post synaptic potentials (IPSP)
-often at the cell body
- -open chloride channels
- *hyperpolarizes
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what is temporal summation?
- -multiple impulses sent rapidly to post synaptic neuron
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what is spatial summation?
- several presynaptic neurons send impulses to post synaptic neuron simultaneously
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what are the 3 types of circuits?
-convergent
-divergent
-oscillating
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what is divergent circuit?
- amplifying
- *1 input results in alot of outputs
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what is convergent circuit
- -concentrating
- *multiple inputs result in single output
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what is oscillating?
- -reverberating
- *circuits go round and round
- *sleep and wake cycle
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how are higher level mental functions performed?
by parallel circuits
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what are reflex arcs?
serial sensation pathways that are rapid, automatic responses to stimuli
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6 components to reflex arc
-stimulus
-receptr
-sensory neuron
-integration center
-motor neuron
-effector
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in a reflex arc, what does the receptor do?
- translates stimulus into AP
- *must have it in order to perceive it
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in a reflex arc, what does sensory neruron do?
carries AP to CNS
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in a reflex arc, what is the integration center?
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in a reflex arc, what does motor neuron do?
carries AP to effector, muscle
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in a reflex arc, what does effetor do?
executes appropriate repsonse
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what are the two types of reflexes?
-visceral
-somatic
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what is visceral reflex involved in?
glands
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what is somatic reflex involved in?
skeletal msucles
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somatic reflex) description of stretch reflex (2)
-embedded in skeletal muscle
- -muscle spindles
- *made up of modified skeletal muscle called intrafusal fibers
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in an intrafusal fiber, what occurs in the middle?
sensory fibers synapse at the non-contractile area
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in a intrafusal fiber, what occurs at both ends?
synapses by gamma motor neurons, this area is contractile area
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what occurs if the large skeletal muscle is stretched?
spindle (intrafusal fibers) also stretch
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when the spindle is stretched, what does this prompt the sensory nerve fibers to do?
fire an AP to the spinal cord
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what happens at the spinal cord with the signals coming in from the sensory nerve fibers?
they synapse with the alpha motor neurons that are outgoing towards the skeletal msucle that was stretched and antagonist
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what is the result from the AP heading towards the skeletal msucle that was stretched?
the stimulated(stretched) skeletal muscle contracts as the antagonist relaxes
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what maintains the spindle tension?
APs from gamma motor neurons
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why must the spindle tension be maintained?
- so that when skeletal muscle is stretched the spindle fiber is stretched enough to irritate the sensory nerves
- *if they become too loose then no mechanical irritation will occur
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what organ is involved with deep tendon relfex?
golgi tendon organ
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what are golgi tendon organ?
collagen fibers in tendon with sensory nerve endings attched that synapse to the spinal cord
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what happens in response to the streth of tendon?
GTO is stimulated and AP fires off along sensory nerve
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does the nerve synapses on both stretched muscles and antagonistic muscle in GTO reflex?
yes
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what does the GTO reflex do?
- -causes relaxation of stretched muscle and contraction of antagonist
- ***prevents tearing
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what is flexor reflex?
withdrawal due to painful stimulus
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what is the crossed extensor reflex?
- ipsilateral withdrawal and contralateral extension
- *so withdrawal of limb and extension of limb
- **step on sharp thing, quickly withdraw foot and the other will extend to keep uprigth
- ***postural
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what are the 2 superficial relfexes?
-plantar
-abdominal
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superficial reflexes) what does the plantar test?
integrity of L4-S2
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superficial reflexes) what is normal for plantar?
downward flexion of toes
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superficial reflexes) what is abnormal for plantar?
- babinski sign
- *toes will dorsiflex
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superficial reflexes) what does the abdominal test?
T8-T12
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superficial reflexes) what is normal abdominal ?
umbillicus moves to the stimulated side due to abdominal muscle contraction
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superficial reflexes) what is abnormal for abdominal?
if it does not move to the stimulated side
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