nerve impulse: Resting Potential, Threshold, Action Potential , Depolarization, Repolarization

Question 1

What is the resting potential of a neuron?

Answer 1

The resting potential of a neuron is typically around -70 mV.

Question 2

True or False: The resting potential is the state when a neuron is actively transmitting an impulse.

Answer 2

False

Question 3

What ion is primarily responsible for maintaining the resting potential?

Answer 3

Potassium (K+)

Question 4

Fill in the blank: The threshold potential is usually around _____ mV.

Answer 4

-55 mV

Question 5

What happens when the threshold potential is reached?

Answer 5

An action potential is triggered.

Question 6

True or False: Depolarization involves the influx of sodium ions (Na+).

Answer 6

True

Question 7

What is depolarization?

Answer 7

Depolarization is the process where the membrane potential becomes less negative (more positive).

Question 8

During an action potential, what is the maximum membrane potential typically reached?

Answer 8

Around +30 mV.

Question 9

What occurs during repolarization?

Answer 9

The membrane potential returns to a more negative value after depolarization.

Question 10

Which ion channels open first during depolarization?

Answer 10

Sodium (Na+) channels.

Question 11

Fill in the blank: After repolarization, the membrane may experience a brief period called _____.

Answer 11

hyperpolarization

Question 12

True or False: Hyperpolarization makes a neuron more likely to fire an action potential.

Answer 12

False

Question 13

What is the role of the sodium-potassium pump?

Answer 13

To maintain the resting potential by moving Na+ out and K+ into the cell.

Question 14

True or False: An action potential is an all-or-nothing response.

Answer 14

True

Question 15

What is the refractory period?

Answer 15

The time during which a neuron cannot fire another action potential.

Question 16

Fill in the blank: The rapid change in membrane potential during an action potential is primarily due to the movement of _____ ions.

Answer 16

sodium (Na+)

Question 17

What is the sequence of events during an action potential?

Answer 17

Depolarization, repolarization, and hyperpolarization.

Question 18

What role do voltage-gated ion channels play in action potentials?

Answer 18

They open or close in response to changes in membrane potential, allowing ion flow.

Question 19

Fill in the blank: The resting potential is maintained by the _____ of ions across the membrane.

Answer 19

differential distribution

Question 20

What happens during the overshoot phase of an action potential?

Answer 20

The membrane potential becomes positive.

Question 21

What is the function of myelin sheaths?

Answer 21

To insulate axons and increase the speed of action potential conduction.

Question 22

True or False: Action potentials can vary in size.

Answer 22

False

Question 23

What is the effect of a stronger stimulus on action potential generation?

Answer 23

It increases the frequency of action potentials, not their size.

Question 24

What is the significance of the threshold potential?

Answer 24

It is the critical level to which a membrane potential must be depolarized to initiate an action potential.

Question 25

Fill in the blank: The period during which a neuron is less likely to fire another action potential is called the _____ period.

Answer 25

refractory

Question 26

What causes the falling phase of an action potential?

Answer 26

The efflux of potassium ions (K+) out of the neuron.

Question 27

True or False: During depolarization, the interior of the neuron becomes more negative.

Answer 27

False

Question 28

What is the role of calcium ions (Ca2+) in neurotransmitter release?

Answer 28

Calcium ions trigger the release of neurotransmitters at the synapse.

Question 29

What happens to sodium channels during repolarization?

Answer 29

They close, stopping the influx of sodium ions.

Question 30

Fill in the blank: The term _____ refers to the time it takes for a neuron to recover after firing an action potential.

Answer 30

refractory period

Question 31

What type of signaling occurs when a neurotransmitter binds to a receptor on a postsynaptic neuron?

Answer 31

Chemical signaling.

Question 32

True or False: Action potentials can propagate without the need for myelin.

Answer 32

True

Question 33

What is saltatory conduction?

Answer 33

The jumping of action potentials from node to node in myelinated axons.

Question 34

Fill in the blank: The return to the resting potential after an action potential is primarily due to the movement of _____ ions.

Answer 34

potassium (K+)

Question 35

What is the primary difference between graded potentials and action potentials?

Answer 35

Graded potentials vary in magnitude, while action potentials are all-or-nothing.

Question 36

What initiates the depolarization phase of an action potential?

Answer 36

The opening of voltage-gated sodium channels.

Question 37

Fill in the blank: The membrane potential becomes more positive during _____ and more negative during _____ .

Answer 37

depolarization; repolarization

Question 38

True or False: The action potential travels down the axon by continuous conduction in unmyelinated fibers.

Answer 38

True

Question 39

What is the typical duration of an action potential?

Answer 39

About 1-2 milliseconds.

Question 40

What happens to the potassium channels during the peak of the action potential?

Answer 40

They begin to open, allowing K+ to exit the neuron.

Question 41

Fill in the blank: The _____ phase of an action potential is characterized by the rapid influx of sodium ions.

Answer 41

depolarization