lecture 4

Question 1

If a neurotransmitter attaches to a ligand-gated channel and creates a potential that causes the inside of the excitable cell membrane to become less negative, and this potential travels only a short distance before dying out, it is considered to be a(n)…

Answer 1

depolarizing graded potential

Question 2

when do graded potentials arise ?

Answer 2

when ion movement causes a minor change in the resting membrane potential

Question 3

Typically graded potentials occur in the…

Answer 3

dendrites and cell body

Question 4

If three depolarizing graded potentials and two hyperpolarizing graded potentials occur in a dendrite at the same instant, what is the summation of their potentials equivalent to?

Answer 4

one depolarizing graded potential

Question 5

what ion pass through the resting neuronal cell membrane most easily?

Answer 5

potassium

Question 6

A resting nerve fiber is polarized because the concentration of

Answer 6

na+ is higher on the outside and k+ is higher on the inside

Question 7

Voltage-gated channels participate in the generation and conduction of _____ in the axons of all types of neurons.

Answer 7

action potentials

Question 8

What is the typical resting membrane potential of a neuron?

Answer 8

-70 mv

Question 9

The differences in electrical charges on either side of the cell membrane results in what is referred to as

Answer 9

membrane potential

Question 10

When the inside of the membrane becomes less negative, the membrane potential is said to be

Answer 10

depolarized

Question 11

If the accumulation of graded potentials in the trigger zone reaches threshold, the result is

Answer 11

voltage-gated channels open

Question 12

When a neurotransmitter attaches to a chemically-gated sodium channel, the sodium channel briefly opens to allow sodium ions to diffuse in. This action produces what type of graded potential?

Answer 12

depolarizing graded potential

Question 13

When a neurotransmitter attaches to a chemically-gated sodium channel, the sodium channel briefly opens to allow sodium ions to diffuse in. This action produces what type of graded potential?

Answer 13

leak channels and sodium-potassium pumps

Question 14

Na+/K+–ATPase is considered to be an electrogenic pump because

Answer 14

it contributes to the negativity of the resting membrane potential

Question 15

When a graded potential summates to threshold at the axon hillock

Answer 15

voltage-gated na+ channels open rapidly

Question 16

Which of these allows more potassium to exit the neuron and helps in maintaining the resting membrane potential?

Answer 16

leak channel

Question 17

During an action potential’s ___________, a second stimulus will not produce a second action potential (no matter how strong that stimulus is). This event corresponds to the period when the __________ remain open and the sodium inactivation gates have not reopened

Answer 17

absolute refractory period; voltage gated sodium channels

Question 18

During an action potential’s ___________, a second stimulus can be produced only if the stimulus is greater than the threshold stimulus. This event corresponds to the period when the __________ remain open and sodium inactivation gates have reopened.

Answer 18

relative refractory period; potassium voltage gated channels