Module 4

Question 1

Which ion channels are required to conduct an AP?

Answer 1

Na+ and K+ voltage gated channels

Leak channels

Question 2

Na+ voltage gated channels open ____. K+ voltage gated channels open ___.

Answer 2

Fast (Na)

Slow (K)

Question 3

The rising phase is also known as ___. Which voltage gated channel opens?

Answer 3

Depolarization

Na+ voltage gated channels

Question 4

The falling phase is also known as ___. Which voltage gated channel opens?

Answer 4

Repolarization

K+ voltage gated channels

Question 5

During the after-hyperpolarization phase which channel is responsible for bringing the membrane potential back to -70mv?

Answer 5

Leak channels

Question 6

What does the activation gate open in response to?

Answer 6

Depolarization

Question 7

What does the inactivation state close in response to?

Answer 7

Depolarization

Question 8

Contrast between absolute and relative refractory periods.

Answer 8

Absolute refractory period: a second AP cannot be generated

Relative refractory period: a second AP can be initiated but requires a larger than normal GP

Question 9

Which channel is inactivated during the absolute refractory period?

Answer 9

Na+ channels

Question 10

What is the purpose of a refractory period?

Answer 10

Ensuring the AP travels in one direction
Limit the frequency of firing
Prevent excitotoxicity

Question 11

in terms of action potential, what does conduction mean?

Answer 11

Action potentials travelling over long distances without losing energy

Question 12

what will repolarize the membrane?

Answer 12

Loss of K+

Question 13

What are the two parameters that determine the velocity of conduction?

Answer 13

Diameter of the axon

Resistance of the axon membrane to leakage

Question 14

Which of the following would we expect to have the highest velocity of conduction?

a) myelinated, small diameter, leaking axon
b) myelinated, large diameter, non-leaking axon
c) unmyelinated, small diameter, leaking axon
d) unmyelinated, larger diameter, non-leaking axon

Answer 14

b) myelinated, large diameter, non-leaking axon

Question 15

The majority of synapses in the nervous system are ____ synapses.

Answer 15

Chemical

Question 16

A chemical that is released, acts on a postsynaptic cell in close vicinity and causes a rapid response in the postsynaptic cell is a ____.

a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine

Answer 16

a) neurotransmitter

Question 17

Where would we expect to find electrical synapses?

Answer 17

Few in the CNS
Cardiac muscle
Smooth muscle

Question 18

A chemical that is released, acts on a postsynaptic cell in close vicinity and causes a slow response in the postsynaptic cell is a ____.

a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine

Answer 18

b) neuromodulator

Question 19

Which neurocrine is secreted into the blood stream and acts on a target in the body?

a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine

Answer 19

c) neurohormone

Question 20

Which neurocrine receptor elicits a slower response but lasts longer and ligand binding leads to a g-protein mediated cellular response?

Answer 20

Metabotropic receptors

Question 21

Which neurocrine receptor opens in a channel when ligand binding leads to a conformational change and mediates fast responses?

Answer 21

Ionotropic receptors

Question 22

Large neurotransmitters are synthesized and packaged into vesicles at the ____, where as small neurotransmitters are synthesized and packaged at the ____.

Answer 22

Soma

Axon terminal

Question 23

Neurotransmitters are released by which structure and which ion will induce release?

Answer 23

Vesicles

Calcium

Question 24

What are the 3 ways neurotransmitter activity is terminated?

Answer 24

Returned to axon terminal for reuse
Enzyme inactivation
Diffusion

Question 25

Which of the following would lead to increased neurotransmitter release?

a) increased firing of AP
b) decreased firing of AP
c) it doesnt matter, neurotransmitters are released when needed
d) none of the above

Answer 25

a) increased firing of AP

Question 26

What is the idea of spatial summation?

Answer 26

summation of several subthreshold signals that results in an AP

Question 27

What is the idea of synaptic inhibition?

Answer 27

one inhibitory postsynaptic potential sums with two excitatory postsynaptic potentials to prevent an AP

Question 28

What is the idea of temporal summation?

Answer 28

two graded potentials from one presynaptic neuron occur close together in time