Synaptic transmission IL Flashcards
Define neuromuscular junction
(NMJ)
synapse point between the axon terminal and end of a motor neuron and the muscle its sending a signal to
a single axon can innervate multiple fibers in a muscle but each individual muscle fiber is controlled by only one ____
axon
at the site of the NMJ the motor neuron has Ca2+ induced release of _____
Acetylcholine (ACh)
how do we want to respond to motor impulses fast
Junctional folds that increase surface area + decrease distance between the motor neuron and the muscle membrane
which receptors are fast responding
ionotropic receptros
a myocyte is innervated by one axon but ____ neuron csn innervate multiple myocytes
a motor neuron
are metabotropic receptors found in NMJ
no
which receptors are stimulated by nicotine
attatched to an ion channel
2 ACh molecules bind to 1 receptor
demonstrate rapid desensitization
ionotropic receptors
an action potential will travel down the axon to the synaptic terminal
____ the membrane by an ____ flux of sodium and ____ flux of potassium
depolarizing
inward
outward
as the action potential reaches the axon terminal and Na+ reaches its reversal potential, voltage gates ____ channels will open and ____ will flow INTO the axon terminal
Ca2+
free cytoslic calcium causes synaptic vesciles to fuse on the ____ membrane
presynaptic
the ACh will diffuse across the synaptic cleft to the ____ membrane and binds to its receptor which causes an influx of sodium through depolarization of muscle cell, it produces End plate potential
postsynaptic
once EPP reaches threshold _____ potential is generated and we have contraction
an all or nothing action potential
T or F
an end plate potential is NOT an action potential
T
its a graded potential produced at the post synaptic level of the NMJ
strength of action potential directly influences the ____ of the inward ___ current
size
Ca2+ current
stronger action potential= longer time the membrane is depolarized = longer opening of the voltage gated calcium channels
EPP is graded, it is dependent on the amount of ACh that is released into the synaptic cleft. what ensures we always have enough vesicles released and can always guarantee muscle contraction
safety factor
what determines the amplitude of the EPP
strength of calcium current in the presynaptic cell
number of vesciles in the synapse
concentration of ACh in vesicle
concentration of ACh receptors on the post synaptic cell membrane
T or F
binding of ACh binds to its receptor opens an ion channel that allows Na and K to pass this ion channel is equally permeable to both Na and K
T
know the point of equal flux of sodium and potassium through Ach channel
Ach vesicles fuse with
presynaptic terminals and release ACh into synaptic cleft
ACh binds to AChR in the junctional folds on the post synaptic side causing ______
the nicotinic AChR to open a ligand gated ion channel
initial depolarization due to inward flux of Na+ causes ____-
the EPP
what happens when depolarization of the ligand gated channel depolarizes the membrane enough to open the voltage gated sodium channels located across the membrane
an action potential occurs
