Neurophysiology

Question 1

Axon terminals and cell bodies communicate at a _______

Answer 1

synapse

Question 2

When a neuron is at rest, what is it doing? What is the term for it?

Answer 2

maintaining a balance of electrical charge across cell membrane

resting membrane potential

Question 3

What are the 3 primary ions responsible for maintaining electrical potential?

Answer 3

sodium
potassium
chloride

Question 4

Ions are maintained across both intra and extra-cellular compartments by what 3 things?

Answer 4

1) impermeable cell membranes
2) transports/channels
3) ion pumps

Question 5

Alteration in ion concentration/channels can manifest as…

Answer 5

neurological/neuromuscular disease

Question 6

What is the concept of equilibrium potential? Which equation describes this?

Answer 6

two forces (charge and concentration) control ion distribution and movement

Nernst equation

Question 7

What 2 gradients effect the movement of ions in a cell?

Answer 7

concentration
electrical

Question 8

When at rest, the ion concentrations do what?

Answer 8

leak potassium outside cell down concentration gradient

Na-K pump moves potassium back in

Question 9

The drift in the resting potential of a cell is due to…

Answer 9

potassium leak channel

Question 10

What occurs when threshold potential is reached and stimulus follows?

Answer 10

action potential

Question 11

Action potential is caused by what 4 channels working?

Answer 11

1) voltage gated Na channel
2) voltage gated K channel
3) resting K channel
4) calcium activated K channels

Question 12

What are the 5 steps of action potential?

Answer 12

1) stimulus occurs
2) rapid depolarization via Na channels
3) repolarization via K channels opening
4) hyperpolarization
5) restoration and maintenance of Na/K pump

Question 13

What are the 3 types of stimuli that activate action potentials?

Answer 13

1) chemical
2) electrical
3) mechanical

Question 14

Sodium channels open at about ____ mV (charge of cell)

Answer 14

-55

Question 15

What is the mV of resting membrane potential?

Answer 15

-70

Question 16

What is the mV of membrane threshold potential?

Answer 16

-55

Question 17

As Na channels close, which channel opens? At what mV?

Answer 17

potassium channels

+30 to +40

Question 18

As potassium leaves cell, the neuron potential drops and causes what?

Answer 18

the sodium channel to reset and activate again

Question 19

What is absolute refractory period?

Answer 19

the sodium channel inactivates and takes a long time to reactivate

Question 20

What is relative refractory periods?

Answer 20

hyperpolarization causes higher voltage to reactivate

Question 21

What is the name of the conduction that occurs in neurons?

Answer 21

saltatory conduction (jumping)

Question 22

_______ in an insulator of neurons

Answer 22

myelin

Question 23

What doesn’t occur in neurons wrapped tightly with myelin?

Answer 23

action potentials

Question 24

__________ _ ________ are breaks in myelin where you get action potentials

Answer 24

nodes of ranvier

Question 25

Action potential is determine by the summation of ____ ______

Answer 25

input signals

Question 26

For a signal to be transmitted, ________ must be released at synapse through the opening of _______ channels

Answer 26

neurotransmitters calcium

Question 27

When there in a change in membrane potential to be more negative, what is it called?

Answer 27

hyperpolarizing stimulus

Question 28

When there in a change in membrane potential to be more positive, what is it called?

Answer 28

depolarizing stimulus

Question 29

Release of transmitters from innervating neurons leads to a response on __________ _________ _________

Answer 29

dendritic plasma membrane

Question 30

What is IPSP and EPSP?

Answer 30

inhibitory postsynaptic potentials excitatory postsynaptic potentials

Question 31

Where is the axon hillock? What can happen at this location with sufficient membrane depolarization?

Answer 31

proximal axon terminal region initiate an action potential