Question 1

Which of the following best describes where graded potentials occur in a neuron?

Accepted Answer

At the dendrites and cell body

Question 2

Graded potentials are essential for initiating an action potential because:

Accepted Answer

They can summate to reach threshold at the axon hillock

Question 3

Which statement about graded potentials is FALSE?

Accepted Answer

They open voltage-gated sodium channels

Question 4

During the depolarization phase of an action potential, which ion movement is primarily responsible?

Accepted Answer

Sodium influx

Question 5

What is the threshold voltage for opening voltage-gated sodium channels in most neurons?

Accepted Answer

$$-55\ \mathrm{mV}$$

Question 6

Which phase of the action potential is characterized by potassium channels opening and potassium ions leaving the cell?

Accepted Answer

Repolarization

Question 7

Why does the depolarization phase of the action potential occur so rapidly?

Accepted Answer

Due to positive feedback as sodium channels open

Question 8

Which of the following best explains why action potentials do not decrease in amplitude as they travel along the axon?

Accepted Answer

They are regenerated at each node of Ranvier

Question 9

What is the main effect of myelination on the conduction velocity of action potentials?

Accepted Answer

It speeds up conduction by allowing action potentials to jump between nodes of Ranvier

Question 10

During the absolute refractory period, which of the following is true?

Accepted Answer

No action potential can occur, regardless of stimulus strength

Question 11

How does the nervous system encode the intensity of a stimulus?

Accepted Answer

By increasing the frequency of action potentials

Question 12

Which of the following neurotransmitters is primarily involved in the 'fight-or-flight' response?

Accepted Answer

Epinephrine

Question 13

An excitatory postsynaptic potential (EPSP) causes __ of the postsynaptic membrane, which will __ the chance to produce an action potential.

Accepted Answer

depolarization; increase

Question 14

Which of the following is a correct example of hyperpolarization?

Accepted Answer

$$-71\ \mathrm{mV}$$

Question 15

Which ion movement will cause depolarization of the neuronal membrane?

Accepted Answer

Sodium influx

Question 16

What would happen to the resting membrane potential (RMP) if potassium permeability decreased and sodium permeability increased to equal levels?

Accepted Answer

Potential would depolarize

Question 17

Which of the following is responsible for neurotransmitter release at the presynaptic terminal?

Accepted Answer

Calcium influx

Question 18

Which of the following best describes the function of the axon hillock?

Accepted Answer

It is the trigger zone for action potential initiation

Question 19

Which of the following statements about action potentials is FALSE?

Accepted Answer

They are inhibited by IPSPs

Question 20

Which of the following best describes spatial summation?

Accepted Answer

Stimulation of a postsynaptic cell by multiple terminals at the same time

Nerve Impulses: Graded Potentials and Action Potentials Lecture 11:2 PP

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