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what is ATP involved in? (3)
-excitatory or inhibitory
-found both in CNS and PNS
what does the adenosine of the ATP do? (2)
- -induces sleep
- *caffeine blocks this
what is NO involved in?
-learning and memory
-strengthening synapse formation when learning
what are excitatory NTs?
cause action potential on post synaptic neuron
what are inhibitory NTs?
cause suppression of action potential on post synaptic neuron
what determines the excitation or inhibitory response?
depends on the receptors that are present at the post synaptic neuron
By which 2 ways can the excitation and inhibition be accmplished?
description of receptors with direct
- -often open ion channels directly after binding of NT
- **ex of channel-linked receptor
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
description of excitatory post synaptic potentials (EPSP) (2)
-often located on dendrites
-often involve sodium
description of inhibitory post synaptic potentials (IPSP)
-often at the cell body
- -open chloride channels
what is temporal summation?
- -multiple impulses sent rapidly to post synaptic neuron
what is spatial summation?
- several presynaptic neurons send impulses to post synaptic neuron simultaneously
what are the 3 types of circuits?
what is divergent circuit?
- *1 input results in alot of outputs
what is convergent circuit
- *multiple inputs result in single output
what is oscillating?
- *circuits go round and round
- *sleep and wake cycle
how are higher level mental functions performed?
by parallel circuits
what are reflex arcs?
serial sensation pathways that are rapid, automatic responses to stimuli
6 components to reflex arc
in a reflex arc, what does the receptor do?
- translates stimulus into AP
- *must have it in order to perceive it
in a reflex arc, what does sensory neruron do?
carries AP to CNS
in a reflex arc, what is the integration center?
in a reflex arc, what does motor neuron do?
carries AP to effector, muscle
in a reflex arc, what does effetor do?
executes appropriate repsonse
what are the two types of reflexes?
what is visceral reflex involved in?
what is somatic reflex involved in?
somatic reflex) description of stretch reflex (2)
-embedded in skeletal muscle
- -muscle spindles
- *made up of modified skeletal muscle called intrafusal fibers
in an intrafusal fiber, what occurs in the middle?
sensory fibers synapse at the non-contractile area
in a intrafusal fiber, what occurs at both ends?
synapses by gamma motor neurons, this area is contractile area
what occurs if the large skeletal muscle is stretched?
spindle (intrafusal fibers) also stretch
when the spindle is stretched, what does this prompt the sensory nerve fibers to do?
fire an AP to the spinal cord
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
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
what maintains the spindle tension?
APs from gamma motor neurons
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
what organ is involved with deep tendon relfex?
golgi tendon organ
what are golgi tendon organ?
collagen fibers in tendon with sensory nerve endings attched that synapse to the spinal cord
what happens in response to the streth of tendon?
GTO is stimulated and AP fires off along sensory nerve
does the nerve synapses on both stretched muscles and antagonistic muscle in GTO reflex?
what does the GTO reflex do?
- -causes relaxation of stretched muscle and contraction of antagonist
- ***prevents tearing
what is flexor reflex?
withdrawal due to painful stimulus
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
what are the 2 superficial relfexes?
superficial reflexes) what does the plantar test?
integrity of L4-S2
superficial reflexes) what is normal for plantar?
downward flexion of toes
superficial reflexes) what is abnormal for plantar?
- babinski sign
- *toes will dorsiflex
superficial reflexes) what does the abdominal test?
superficial reflexes) what is normal abdominal ?
umbillicus moves to the stimulated side due to abdominal muscle contraction
superficial reflexes) what is abnormal for abdominal?
if it does not move to the stimulated side