The Action Potential

Question 1

What is the characteristic profile of action potentials

Answer 1

Properties of voltage gated Na and K channels

Question 2

how to neurons use electrical signals?

Answer 2

In the forms of action potentials to communicate with each other

Question 3

How is the communication between neurons done

Answer 3

By propagation of an electrical signal and release of neurotransmitters

Question 4

At rest, the cell membrane is much more permeable to which ion?

Answer 4

K+

- is the main ion the contributes to the RMP value

Question 5

At rest, which ion is the cell membrane slightly permeable to?

Answer 5

Na+

Question 6

What controls permeability of a neuron

Answer 6

gated channels

Question 7

What do mechanically gated ion channels do

Answer 7

Open in response to mechanical stimulation

Question 8

What do chemically gated ion channel do

Answer 8

Open in response to a chemical binding

Question 9

What do voltage-gated channels do

Answer 9

Open in response to a voltage change

Question 10

Difference between Na+ and K+ voltage gated channels

Answer 10

Na+ is faster to open where as K+ channel is lazy and slow to close

Question 11

What is depolariztiton

Answer 11

Cell becomes more positive

Question 12

What is repolarization

Answer 12

The depolarized membrane returns to RMP

Question 13

What is the threshold

Answer 13

The minimum depolarization that will initiate an action potential
-55mV

Question 14

What is hyperpolarization

Answer 14

Cell becomes more negative

Question 15

Where to graded potentials occur

Answer 15

neuron dentrites

Question 16

How do graded potential occur

Answer 16

Either depolarization or hyper polarization caused by opening voltage gated channels

Question 17

What is a graded potential proportional to

Answer 17

Amplitude of potential is directly proportional to the stimulus strength

Question 18

What are the 2 reasons why graded potentials can only travel a short distance and lose strength over time

Answer 18

1. Current leak

2. Cytoplasmic resistance

Question 19

In what part of the neuron does the stimulus have to reach in order to generate an action potential

Answer 19

axon hillock with at least -55mV

Question 20

What are the 3 important things about action potentials

Answer 20

1. All or none
2. Unidirectional
3. Always same amplitude and duration

Question 21

What is the absolute refractory period

Answer 21

When a a depolarized cell is returning back to the RMP, no action potentials can be generated until the channels are back to their resting position

Question 22

Which gate is responsible for the absolute refractory period

Answer 22

Inactivation gate

Question 23

What is the loss of K+ through the potassium channel responsible for?

Answer 23

hyper polarization of the cell

-action potentials can be generated here but has to be a strong enough stimulus to push it over the threshold