3. Action Potentials I Flashcards
large, rapid changes in membrane potential
action potentials
produced by excitable cells, like neurons and muscle cells in response to stimuli
action potentials
graded potentials are induced in 2 places
dendrites and cell body
dendrites receive neurotransmitters from other neurons and respond by producing small, localized changes in membrane potential
graded potentials
what do graded potentials do?
regulate action potential production @ the initial segment
Where are action potentials induced? what happens after this and what does it stimulate?
initial segment; it is propagated along the axon to each axon terminal, where it stimulates the release of neurotransmitters.
graded potentials are also known as
postsynaptic potentials
the cell body is AKA
soma
presynaptic terminal is aka
axon terminal
spike initiation zone is aka
initial segment
Every action potential produced by a particular cell is ________, showing the same changes in mem potential and same duration
identical
Action potentials have an ______________________________ response to a stimulus= it either produces an action potential or it doesn’t. Once it starts it can’t stop
all-or-none
action potentials are _________ __________ __________, meaning that the ap that occur at the axon terminals are identical to the one induced at the initial segment
transmitted without decrement
what is the typical resting potential for neurons?
-70 mV
A change in membrane potential to a less negative value than the resting potential. (-70mV changing to -50mV or +10mV)
depolarization
a change in mem pot to a more negative value than the resting potential (-70 to -90)
hyperpolarization
A return to the resting potential from a depolarized state (-50 to -70)
repolarization
Which gates are closed when a voltage-gated Na+ channel is in the inactivated state?
The inactivation gates only
The last of the voltage-gated K+ channels do not enter the closed state until
The end of the undershoot phase
K+ leak channels are open during an action potential (true or false(
True
During the depolarization phase, the membrane is less permeable to Na+ than it is to K+ (t or f)
True
If the membrane potential were -40mV, which of the following changes in membrane potential would be a hyper polarization?
-20 to -40
-40 to -70
-40 to -30
-60 to -40
Change from -40 to -70 mV
If the resting potential were -80 and the threshold potential were -60, which of the following depolarizations would be a threshold potential?
+20 mV
A voltage-gated Na+ channel can open in response to a hyper polarization (t or f)
True
The Hodgkin cycle is terminated by
The closing of the inactivation gate
K+ permeability during the undershoot phase is the same as the K+ permeability during the resting potential (t or f)
False
The inactivation gate is closed during the undershoot phase (t or f)
False