Action Potential

Question 1

What is an action potential?

Answer 1

A process in which neurons are dynamically changing their membrane potentials as they communicate with another

Question 2

Is Na always going in to out of neurons?

Answer 2

In

Question 3

Is Cl normally going in or out of neurons?

Answer 3

In

Question 4

What is local potential?

Answer 4

Change in potential difference in a small portion of the neuron (dendrite)

Question 5

How can local potentials be generated?

Answer 5

At synapses or by sensory stimuli in the periphery

Question 6

what are local potentials?

Answer 6

Reversible
Graded
Excitatory or inhibitory
Additive

Question 7

What does graded mean in terms of local potentials?

Answer 7

depends on amount strength and length of the stimulus

Question 8

What is depolarization?

Answer 8

resting membrane potential becomes less negative -> depolarization

Question 9

What is hyperpolarization?

Answer 9

resting membrane potential becomes more negative

Question 10

What is threshold?

Answer 10

Membrane potential that must be reached for an axon to send an electrical signal

Question 11

What is summation?

Answer 11

Integration of signals that determines if an action potential will fire

Question 12

What does excitatory mean in terms of signals?

Answer 12

Likely to fire an action potential

Question 13

What does inhibitory mean in terms of signals?

Answer 13

Prevents the firing of an action potential

Question 14

What do signals depend on?

Answer 14

The receptor a neurotransmitter binds to
Glutamate- excitatory, passes cations
GAB- inhibitory, passes anions

Question 15

what is spatial summation?

Answer 15

Multiple dendrites stimulated at once

Question 16

What is temporal summation?

Answer 16

One dendrite stimulated several times over time

Question 17

An action potential will only be initiated when…

Answer 17

A “threshold potential” of -55 mV is reached at the axon hillock

Question 18

What happens to local potentials that fail to reach threshold?

Answer 18

They will dissipate over time

Question 19

Which channels open faster Na or K?

Answer 19

Na opens and closes faster

Question 20

How are Na channels controlled?

Answer 20

Voltage gated

Question 21

How are K channels controlled?

Answer 21

Voltage gated

Question 22

What is the refractory period?

Answer 22

The ability for a patch of membrane to fire an action potential is altered

Question 23

What is the absolute refractory period?

Answer 23

Na channels have not yet returned to resting state; cannot be reactivated

Question 24

what is the relative refractory period?

Answer 24

Membrane is hyperpolarized, stronger signal is necessary to re-fire an action potential

Question 25

How do action potentials move faster?

Answer 25

Myelin

Question 26

What does myelin do?

Answer 26

Insulates the axon, preventing current leak, guaranteeing travel of longer distances and speeding up conduction

Question 27

Refresher: what is myelin produced by in the CNS?

Answer 27

Oligodendrocytes (myelinate multiple axons)

Question 28

Refresher: what is myelin produced by in the PNS?

Answer 28

Schwann cells (myelinate single axon)

Question 29

If the current cant move through myelin how is a signal transmitted?

Answer 29

Nodes of ranvier

Question 30

What is saltatory conduction?

Answer 30

When the ion influx “speeds” through myelinated portion of axon without being lose, initiating an action potential at the adjacent node of Ranvier