Homework3

Question 1

What is the typical resting membrane potential of a neuron?

Answer 1

-70 mV

Question 2

What is the typical threshold potential of a neuron?

Answer 2

-50 to -55 mV

Question 3

Which of the following are true of graded potentials?

Answer 3

(A) Vary in magnitude, (B) Sum spatially, (E) Sum temporally

Question 4

To hyperpolarize the dendritic membrane, which channels must open?

Answer 4

(E) Chloride or potassium channels

Question 5

What happens when the axon hillock reaches threshold?

Answer 5

(E) All of the above: neuron fires, action potentials begin, Na+ and K+ channels start opening

Question 6

How does an action potential propagate?

Answer 6

(B) It generates a local current that depolarizes adjacent membrane to threshold

Question 7

True or False – If a neuron fires, it should release neurotransmitter.

Answer 7

True

Question 8

Which of the following is not a target for a firing neuron?

Answer 8

(C) A bone

Question 9

What directly signals the exocytosis of neurotransmitters at the axon terminal?

Answer 9

(E) An influx of Ca²⁺

Question 10

A neuron encodes signal strength through the _____ of its action potentials.

Answer 10

Frequency

Question 11

What causes the depolarization at region A on an action potential graph?

Answer 11

Summation of graded potentials

Question 12

What happens at point B of the action potential graph?

Answer 12

Voltage-gated Na⁺ channels open

Question 13

What happens at point C of the action potential graph?

Answer 13

Na⁺ channels close; K⁺ channels open

Question 14

What happens at point D of the action potential graph?

Answer 14

K⁺ channels close

Question 15

What happens in region E of the graph?

Answer 15

Ion concentrations reset via Na⁺-K⁺ pumps

Question 16

What is the typical duration (F) of an action potential?

Answer 16

1–2 msec

Question 17

True or False – The absolute refractory period prevents backward signal movement.

Answer 17

True

Question 18

True or False – An axon can fire backwards if voltage-gated Na⁺ channels are triggered at the terminal end.

Answer 18

True

Question 19

Which channels open during an EPSP on a postsynaptic neuron?

Answer 19

(C) Chemically-gated cation channels

Question 20

What do oligodendrocytes do?

Answer 20

(D) Increase speed of conduction and cause saltatory conduction

Question 21

What does proprioception allow you to perceive?

Answer 21

(C) The location of body parts

Question 22

True or False – Nociceptors are sensory neurons for pain.

Answer 22

True

Question 23

What do baroreceptors monitor?

Answer 23

(B) Blood pressure

Question 24

True or False – Sensory information from the foot uses multipolar neurons.

Answer 24

False (uses pseudounipolar neurons)

Question 25

What neurotransmitter is released by all preganglionic autonomic neurons?

Answer 25

Acetylcholine (ACh)

Question 26

How many neurons are involved in somatic signaling, and what is released at the synapse?

Answer 26

One neuron; Acetylcholine (ACh)

Question 27

True or False – Most efferent neurons are multipolar.

Answer 27

True

Question 28

Muscarinic receptors are found on which types of tissue?

Answer 28

(A) Cardiac muscle, (B) Glands, (C) Smooth muscle

Question 29

What nervous system division dominates during strenuous activity?

Answer 29

Sympathetic; releases epinephrine and norepinephrine

Question 30

True or False – Sweat gland stimulation involves adrenergic receptors.

Answer 30

False (uses muscarinic receptors)

Question 31

What would a muscarinic antagonist do?

Answer 31

(E) Block parasympathetic stimulation (and A at sweat glands)

Question 32

What effects might a muscarinic antagonist have?

Answer 32

(C) Decrease sweat, (E) Dilate airways

Question 33

What happens when dopamine is released and causes hyperpolarization?

Answer 33

Chemically-gated K⁺ channels open

Question 34

What causes local depolarization by glutamate?

Answer 34

Opening of chemically-gated cation channels

Question 35

What is the summation of different channel effects called?

Answer 35

Spatial summation

Question 36

What causes greater depolarization due to repeated firing of a presynaptic neuron?

Answer 36

Temporal summation

Question 37

What opens first when threshold is reached at -40 mV?

Answer 37

Voltage-gated Na⁺ channels

Question 38

What opens more slowly and causes repolarization?

Answer 38

Voltage-gated K⁺ channels

Question 39

What restores resting ion concentrations?

Answer 39

Na⁺-K⁺ ATPase pumps

Question 40

What opens at the axon terminal to release neurotransmitter?

Answer 40

Voltage-gated Ca²⁺ channels