Neurons, Synapses, and Signaling Part 2

Question 1

Gated channel

Answer 1

• causes a change in membrane potential to occur
  -Opens or closes in response to stimuli

Question 2

Voltage gated ion channel

Answer 2

Opens or closes in response to a shift in the volatage across the plasma membrane or the neuron

Question 3

When gated K+ channels open, K+ diffuses out which makes the inside of the cell more___

Answer 3

negative

Question 4

Hyperpolarization

Answer 4

an increase in magnitude of the membrane potential

Question 5

opening other types of ion channels triggers Depolarization.

Answer 5

a reduction in the magnitude of the membrane potential

Question 6

Graded potentials

Answer 6

changes in polarization where the magnitude of the change varies with the strength of the stimulus.
- Graded potentials decay with time and distance from the source

Question 7

If a depolarization shifts the membrane potential sufficiently, it results in a massive change in membrane voltage called

Answer 7

action potential

Question 8

Action potentials have a constant magnitude and transmit signals over

Answer 8

short and long distances

Question 9

Action potentials occur whenever a depolarization increases the membrane potential to a particular valve called a

Answer 9

threshold

Question 10

Action potentials are all or

Answer 10

none

Question 11

First stage of action potentials

Answer 11

Resting stage- Most Na+ channels are closed, but not all, of the volatage-gated potassium (k+) channels are also closed

Question 12

Second stage of action potentials

Answer 12

Depolarization-A stimulus opens some sodium channels. Na+ flows into the cell. If the stimulus is strong enough, more Na+ channels open increasing Na- diffusion even more. If the depolarization reaches the threshold, it triggers an action potential.

Question 13

Third stage of action potential

Answer 13

Once the threshold is crossed, this positive-feedback cycle rapidly
brings the membrane potential close to E N a
▪ This is called the rising phase

Deplorization opens most sodium channels while the potassium channels remain closed. Na+ influx makes the inside the membrane positive with respect to the outside

Question 14

The fourth stage of action potential: Falling stage

Answer 14

During the falling phase, voltage-gated Na+ Channels become inactivated;voltage-gated channels open,and flows out of the cell

Question 15

Refractory Period

Answer 15

During this period after an action
potential, a second action potential cannot be
initiated
* The refractory period is a result of a temporary
inactivation of the channels

Question 16

site where the action potential is initiated (usually the axon hillock)

Answer 16

an electrical current depolarizes the neighboring region of the axon
membrane

Question 17

Action potentials travel only toward the

Answer 17

synaptic terminals

Question 18

Inactivated channels behind the zone of depolarization___the action potential from traveling___

Answer 18

prevent
backward

Question 19

How long do action potentials last in neurons

Answer 19

less than 2 milliseconds

Question 20

Frequency of action potential conveys information
True or False

Answer 20

True

Question 21

Speed of an action potential increases with

Answer 21

the axon’s diameter