Topic.5.TheNeuron.powerpoint.5.1.ion.channels.and.action.potentials

Question 1

T/F A resting neuron can conduct an action potential

Answer 1

No

Question 2

What are the 3 characteristics about a resting neuron

Answer 2

-voltage gated k+ and Na+ are closed
-K+ leak channels
-k+/Na+/ATPase channels 3 Na out and 2 K in

Question 3

What are the four types of ion channels in neurons?

Answer 3

-ungated channels (leak),
-Voltage-gated channels (in axon membranes)
-Ligand-gated channels (primarily at synapses)
-Mechanically gated (in sensory receptors)

Question 4

T/F At rest there are more Na+ channels open than K+

Answer 4

False, more ungated k+ channels open

Question 5

What is an example of ligand-gated channel?

Answer 5

neurotransmitter bind and create a conformational change

Question 6

What is an example of mechanically gated channel?

Answer 6

hair cell in the inner ear-involved with hearing

Question 7

T/F Generally with neurons, ion channels size matters matter

Answer 7

Yes, even if you are smaller than the ion size channel still can’t go through

Question 8

What is a voltage gated ion channel?

Answer 8

They are integral membrane proteins
-alpha-helical transmembrane segments that can form pores where ion can pass-through
-voltage sensing than can inactivate pore

Question 9

Volted gated ion channels are sensitive to ___

Answer 9

membrane potential

Question 10

Goldman equation predicts

Answer 10

membrane potential of membranes permeable to more than one ion
-depends on concentration of ions and permeability

Question 11

t/F Ion channels do not always open and close independently

Answer 11

true

Question 12

The rate of ionic flow through the channel is determined by…

Answer 12

-maximum channel conductance
-the electrochemical driving force for that ion

Question 13

Action potential

Answer 13

The abrupt and transient change in membrane potential that occurs when a neuron (other electrically excitable cell) conducts an electrical impulse

Question 14

hyperpolarization

Answer 14

membrane potential goes lower than resting membrane potential

Question 15

What are the steps for action potential

Answer 15

1. stimulus
2. Depolarization occurs until a threshold potential of 10-20 mV more positive than -70mV
3. Peak of action potential
4. repolarization
   5.hyperpolarization
   .6Returns to resting membrane potential

Question 16

What is all or nothing?

Answer 16

nonstop action potential firing, once reaches threshold regardless of stimulus strength

Question 17

Write a summary of Na+/k+ channels opening in an action potential

Answer 17

k+ closed & Na+ open(flow in)|Action potential |Na+ inactivated and K+ open (flow out)

Question 18

What are the 3 keys features of AP in neurons?

Answer 18

-All or none
-Maintain the size of magnitude of the action potential as it travels along the axon(voltage)
-Propagation of action on neighboring
stretches of membrane

Question 19

What is a refractory period?

Answer 19

Sensitivity of area to further
stimulation decreases for a time

Question 20

What is the difference between absolute and relative refractory period?

Answer 20

Absolute: Complete insensitivity exists to
another stimulus
-From beginning of action potential
until near end of repolarization.
Relative: A stronger-than-threshold stimulus can initiate another action potential

Question 21

Which of the following is true
regarding the refractory period?
A. It only lasts for a few milliseconds
B. During the relative refractory period, the threshold
required for generating an action potential is much higher
than normal.
C. It keeps impulses from traveling in both directions in
neurons
D. All of the above
E. None of the above

Answer 21

D All of the Above

Question 22

What would be the primary basis for
the absolute refractory period?
A. Not enough sodium ions left outside
B. Sodium channels closed
C. Sodium channels inactivated
D. Voltage gated potassium channels open
E. Membrane is depolarized

Answer 22

C. Sodium channels inactivated
D. Voltage-gated potassium channels open

Question 23

In an absolute refractory period, how do we know it began, end, restart?

Answer 23

-Voltage-gated Na+ channels are either already open or have proceeded to the inactive stat
-once closed the channels can open to a second stimulus once the membrane is repolarized and pore is closed

Question 24

What would be the basis for the
relative refractory period?
A:Not enough sodium ions left outside
B. Sodium channels closed
C. Some sodium channels still inactivated
D. Voltage-gated potassium channels open
E. Membrane hyperpolarized

Answer 24

C. Some sodium channels still inactivated
D. **Voltage-gated potassium channels open (contributes
most)
E. Membrane hyperpolarized

Question 25

What are some trait of relative refractory period?

Answer 25

-some but not all Na+ are closed
-some k+ still open

Question 26

During a relative refractory period, new stimulus can depolarize the membrane above threshold BUT ONLY IF.

Answer 26

1.The stimulus is large in magnitude
2. The stimulus outlasts the relative refractory period

Question 27

If new action potenial is started during relative refractory period, we can expect the AP to be ___ than the original

Answer 27

smaller
-K+ is still going out
-some Na+ channels are still inactivated,
rather than closed

Question 28

During relative refractory period, the threshold required for the generation of an action potential is ___. Meaning you need greater ___

Answer 28

higher than normal; depolarization

Question 29

T/F The duration of a relative refractory period is not variable

Answer 29

False

Question 30

Strength stimuls gradually lowers over time in relative refractory period due to

Answer 30

Na+ channels recover from inactivation and
as K+ permeability returns to its resting level.

Question 31

the intensity of a stimulus is indicated by
the

Answer 31

frequency of action potentials