Lecture 8: Electrophysiology

Question 1

go refresh RMP maintenance graphic

Answer 1

:)

Question 2

RMP describes the steady state of the cell, but what happens when the cell needs to either do work or communicate?

Answer 2

the membrane (Em) needs to change

Question 3

how can we change Em

Answer 3

changing the permeability of the membrane to specific ions

Question 4

why does changing Em matter?

Answer 4

changes in membrane potential are a major way that cells (especially in the nervous system) communicate

Question 5

what is depolarization?

Answer 5

the cell membrane potential becomes more positive +

Question 6

what is repolarization

Answer 6

the return of the cell membrane back to/toward RMP (becomes more negative -)

Question 7

what is hyperpolarization?

Answer 7

the cell membrane potential becoming even more negative (past RMP)

Question 8

what is an action potential?

Answer 8

a rapid sequence of changes in the cell membrane

Question 9

what is threshold?

Answer 9

the voltage at which an action potential can occur (often listed at -55mv)

Question 10

be able to label a graph with the terms

Answer 10

depolarization
repolarization
hyperpolarization
threshold
action potential

Question 11

what kind of ion would we use to depolarize a membrane, why?

Answer 11

opening Na+ channels would allow positively charged Na into the cell and depolarize it

Question 12

what kind of ion would we use to repolarize a membrane, why?

Answer 12

opening K+ channels allows the positive charge to flow out, repolarizing it

Question 13

excitatory graded potential

Answer 13

RMP (-70mv) to threshold (-55 mv)
-excitement!! ++
-excitatory post synaptic potential

Question 14

inhibitory graded potentials

Answer 14

RMP (-70mv) to -90mv
-inhibitory!! –
-inhibitory post synaptic potential

Question 15

what is temporal summation?

Answer 15

when one presynaptic neuron repeatedly stimulates one post synaptic neuron

mom mom mom mom mom

time after time

Question 15

summation of graded potentials

Answer 15

1. temporal summation
2. spatial summation

Question 15

know the diagram of how epsps and ipsps work in the synapses and the graph

Answer 15

:)

Question 16

what is spatial summation

Answer 16

multiple presynaptic neurons simultaneously stimulate one postsynaptic neuron

taking up space

Question 17

action potentials

Answer 17

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

Question 18

be able to diagram an action potential

Answer 18

;)
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

Question 19

what are the channels repsonsible for action potentials

Answer 19

1. voltage gated sodium channels
   -has an activation and inactivation gate
2. voltage gated potassium channels
   -only has an activation gate

Question 20

activation gates are ________ dependent, whereas inactivation gates are _____________dependent

Answer 20

voltage , time

Question 21

please know the activation gate graph****

Answer 21

:) optional worksheet on moodle

Question 22

what is the absolute refractory period?

Answer 22

the period of time in which another AP cannot occur

Question 23

what is the relative refractory period?

Answer 23

the period of time in which another AP can occur if the stimulus is strong enough