Action Potential Wk 10/ 11 Flashcards
class notes only to S:14
At rest, cells reach balance btw electrical and concentration gradients so there is ______
no net flow
Resting membrane potential is usually ___ to ___
-65mV to -95mV
resting membrane potential of neurons in the CNS is ______
-70 mV
_____: changes in membrane potential that spread across the cell
action potentials
Changes in a membrane potential affect the prop’s of _____ion channels
voltage gates
- causes then to open and close
positive feedback from a membrane potential causes _____ of the membrane
depolarization
Changes in ____ channels affect the properties of the voltage gated channel
ligand chanels
- cause depolarization- the voltage channel feels this change
___: when the flow leads to depolarization and further AP regeneration along the neuronal axon, repeats until it reaches terminal
positive feedback loop
the opening of a NA+ channel creates a _____ current
Na+ current
Na+ will flow according to : (2)
- resting membrane potential
2. Na+ equilibrium potential
EPSP stands for =
Excitatory postsynaptic potential
what causes a faster current flow into/out of the cell?
by making the resting membrane potential MORE different than the equilibrium
IPSP stands for=
inhibitory postsynaptic potential
______ chanels (besides Na+ chanels) can also open in response to ligands
Cl- channels
Cl- channels opening in response to ligands will cause _____
hyperpolarization
hyperpolarization is caused by ___
cl- channels opening in response to ligands
leakage in the membrane prevents ____ from sticking around
EPSPs
excitatory postsynpatic potential
Threshold is considered to be ____ to ____ mV
15-20
_____: if EPSPs are summed to threshold (15-20 mV above resting potential), a spike is generated
action potential
An action potential is when _____ are summed to threshold
EPSPs
15-20mV above resting potential
reaching the _____ potential leads to massive depolarization
threshold
reaching the threshold potential leads to massive ______
depolarization
IPSP summation does what?
takes the membrane potential away from reaching threshold
A voltage gated ____ channel contains a region with a (+) charge
Na+
When there is a large enough threshold change what occurs?
there is a change in conformation and the channel opens
_______: is a property where a threshold is reached in one area, it causes local depolarization and threshold to be reached in adjacent areas
regenerative property (wave-like)
explain regenerative property
it is when the threshold is reached in one area, it causes local depolarization and threshold to be reached in adjacent areas
action potentials are ___ or __
all or none
What are action potentials all or none?
regenerative property: when the threshold is reached in one area, it causes local depolarization and threshold to be reached in adjacent areas
voltage-gated Na+ channels inactivative quickly via _______ mechanis,
ball and chain
When the membrane potential is too depolarized , the channel’s __________
own peptide side chain plugs up the opening of the pore
What plugs up the opening of the pore when the membrane potential is too depolarized
its own peptide side chain
____ woltage gated channels are “slower”
K+
_____ channels only opening after the cell has depolarize so much that the membrane potential is close to 30 mV
K
_____ channels only open after the cell has overshoot and depolarized
K
K+ equilibrium potential
-90mV
K+ flowing out causes the cell membrane to ____
repolarize
What occurs at “afterhyperpolarization”
so much K+ flows out od the cell that the cell is at an even lower membrane potential than at rest
________ begins working when it senses an increase in intracellular Na+concentrations
Na/K/ ATPase pump
When does the Na/K/ ATPase pump being to work?
when it sense and increase in intracellular Na+ concentration
the activity of ______ helps to being the cell back to resting potential again
Na/K/ATPase
Na+ channels open during ___ to ____mV. They close at ____mV
open -70mV - +30mV
close: +30 mV
Na+ is positive so it moves more positive
The Na+/K+ pump become after _____
“after hyperpolarization”
Voltage-gates Ca2+ channels contribute to the ____ phase
deparolarization phase
carbic action potential has a inward current of ____ & ___ and an outward current of ____
inward: Na+ and Ca+
outward: K+
In neurons, voltage gates __ channels are used in vesicle binding and release of neurotransmitters
Ca2+
Ca+2 voltage gates are used for _______ & ______ in neurons
vesicle binding and release of neurotransmitters
in muscles action potentials cause _____
muscle contractions
In neurons action potentials cause: ______
vesicles to fuse and release neurotransmitters
_____ is the point at which another action potential cannot be generated
absolute refractory period
_________: when the voltage gates Na channels will not open temporarily, regardless of stimulus strength
absolute refractory period
What occurs during relative refractory period
voltage gate K - force K+ to leave the cell is stronger than the Na+ force to enter the cell
_______: when the driving force of K+ to leave the cell is stronger than the driving force for Na+ to enter the cell
relative refractory period
During _______, it is impossible to elicit another action potential
relative refractory period
