Lecture 8: Electrophysiology Flashcards
go refresh RMP maintenance graphic
:)
RMP describes the steady state of the cell, but what happens when the cell needs to either do work or communicate?
the membrane (Em) needs to change
how can we change Em
changing the permeability of the membrane to specific ions
why does changing Em matter?
changes in membrane potential are a major way that cells (especially in the nervous system) communicate
what is depolarization?
the cell membrane potential becomes more positive +
what is repolarization
the return of the cell membrane back to/toward RMP (becomes more negative -)
what is hyperpolarization?
the cell membrane potential becoming even more negative (past RMP)
what is an action potential?
a rapid sequence of changes in the cell membrane
what is threshold?
the voltage at which an action potential can occur (often listed at -55mv)
be able to label a graph with the terms
depolarization
repolarization
hyperpolarization
threshold
action potential
what kind of ion would we use to depolarize a membrane, why?
opening Na+ channels would allow positively charged Na into the cell and depolarize it
what kind of ion would we use to repolarize a membrane, why?
opening K+ channels allows the positive charge to flow out, repolarizing it
excitatory graded potential
RMP (-70mv) to threshold (-55 mv)
-excitement!! ++
-excitatory post synaptic potential
inhibitory graded potentials
RMP (-70mv) to -90mv
-inhibitory!! –
-inhibitory post synaptic potential
what is temporal summation?
when one presynaptic neuron repeatedly stimulates one post synaptic neuron
mom mom mom mom mom
time after time
summation of graded potentials
- temporal summation
- spatial summation
know the diagram of how epsps and ipsps work in the synapses and the graph
:)
what is spatial summation
multiple presynaptic neurons simultaneously stimulate one postsynaptic neuron
taking up space
action potentials
are a way to change membrane potentials
-very brief (2ms) but cause large change
-does not diminish in strength across the length of the neuron (stays constant)
-arises from stimuli that bring membrane potential to threshold
-ALL OR NOTHING EVENTS
be able to diagram an action potential
;)
Depolarization
the voltage change from -70 to threshold aparks the voltage gated sodium channels to open and take the RMP from -55 to +30. Which then begins a chain reaction from other channels to depolarize the Em
Hyperpolarization:
the voltage change from the Na+ channel sparks the voltage gated K+ channels to open and let out K+ which hyperpolarizes the cell
what are the channels repsonsible for action potentials
- voltage gated sodium channels
-has an activation and inactivation gate - voltage gated potassium channels
-only has an activation gate
activation gates are ________ dependent, whereas inactivation gates are _____________dependent
voltage , time
please know the activation gate graph****
:) optional worksheet on moodle
what is the absolute refractory period?
the period of time in which another AP cannot occur
what is the relative refractory period?
the period of time in which another AP can occur if the stimulus is strong enough
