Week 2, Neurophysiology

Question 1

The all-or-none principle states that

Answer 1

all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

Question 2

________ open or close in response to binding specific molecules.

Answer 2

Chemically gated channels.

Question 3

The fibre type in which propagation of an action potential will occur most quickly is,

Answer 3

myelinated type A fibre.

Question 4

The ________ division of the peripheral nervous system brings sensory information to the central nervous system.

Answer 4

afferent

Question 5

Rapid impulse conduction from “node” to “node” is called

Answer 5

saltatory propagation.

Question 6

The minimum stimulus required to trigger an action potential is known as the,

Answer 6

threshold.

Question 7

A shift of the resting transmembrane potential toward 0 mV is called;

Answer 7

depolarization.

Question 8

The site of intercellular communication between a neuron and another cell is the,

Answer 8

synapse.

Question 9

The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period.

Answer 9

relative refractory.

Question 10

In what ways do the two divisions of the autonomic nervous system interact?
Answers:
One division may counterbalance the other division.

Occasionally only one division communicates with an organ.

Both divisions may work together for the function of an organ or a process.

One division may increase function of an organ, while the other division inhibits it.

All of the answers are correct.

Answer 10

All of the answers are correct.

Question 11

All of the following are true of neural reflexes except that they
Answers:
are automatic motor responses.

are the simplest form of behavior.

help preserve homeostasis.

cannot be modified by the brain.

involve at least two neurons.

Answer 11

cannot be modified by the brain.

Question 12

A neuron that receives neurotransmitter from another neuron is called

Answer 12

the postsynaptic neuron.

Question 13

What triggers the release of acetylcholine from a synaptic terminal?

Answer 13

What triggers the release of acetylcholine from a synaptic terminal?

Question 14

A postsynaptic neuron will have an excitatory postsynaptic potential (EPSP) when

Answer 14

chemically regulated sodium channels are open and sodium is diffusing into the cell.

Question 15

A stimulus that changes a postsynaptic neuron’s membrane from resting potential to -85 mV is a(n) ________ stimulus.

Answer 15

inhibitory.

Question 16

Voltage-gated channels are present,

on the soma of neurons.

b.
in the membrane that covers axons.

c.
on the surface of dendrites.

d.
at the motor end plate.

Answer 16

in the membrane that covers axons.

Question 17

The ________ nervous system controls the skeletal muscles.

Answer 17

somatic

Question 18

Which type of synapse is most common in the nervous system?

Answer 18

chemical.

Question 19

Neurotransmitters are released into the

Answer 19

synaptic cleft.

Question 20

The presence of ________ dramatically increases the speed at which an action potential moves along an axon.

Answer 20

myelin.

Question 21

Sympathetic nerves

Answer 21

contains short preganglionic fibers and longer postganglionic fibers.

Question 22

Any stimulus that opens a ________ ion channel will produce a graded potential.
Answers:
voltage-gated

chemically gated

sodium

mechanically gated

All of the answers are correct.

Answer 22

All of the answers are correct.

Question 23

________ reflexes perform the simplest functions of the autonomic nervous system

Answer 23

somatic.

Question 24

The neurotransmitter ACh is,

Answer 24

always excitatory when used in the synapses of the sympathetic nervous system.

Question 25

What channels open or close in response to physical distortion of the membrane surface, such as vibrations or pressure?

Answer 25

mechanically-gated.

Question 26

The ion that triggers the release of acetylcholine into the synaptic cleft is,

Answer 26

calcium.

Question 27

Functions of astrocytes include all of the following except
Answers:
maintaining the blood-brain barrier.

conducting action potentials.

guiding neuron development.

responding to neural tissue damage.

forming a three-dimensional framework for the CNS.

Answer 27

conducting action potentials.

Question 28

The ________ division of the autonomic nervous system is said to function during “rest and digest.”

Answer 28

parasympathetic.

Question 29

Ion channels that are always open are called ________ channels.

Answer 29

leak

Question 30

The period during which an excitable membrane cannot respond to further stimulation is the ________ period.

Answer 30

absolute refractory.

Question 31

The site in the neuron where EPSPs and IPSPs are integrated is the

Answer 31

axon hillock.

Question 32

Graded potentials,

Answer 32

may be either a depolarization or a hyperpolarization.

Question 33

In which of the following would the rate of impulse conduction be the greatest?
Answers:

a myelinated fiber of 10-µm diameter

a nonmyelinated fiber of 20-µm diameter

a myelinated fiber of 1-µm diameter

a nonmyelinated fiber of 10-µm diameter

It would be the same in all because of the all-or-none principle.

Answer 33

a myelinated fiber of 10-µm diameter

Question 34

After acetylcholinesterase acts, the synaptic terminal,

Answer 34

reabsorbs the choline.

Question 35

Which of the following is not a neurotransmitter?

Answer 35

adrenaline

Question 36

If the permeability of a resting axon to sodium ion increases,

Answer 36

inward movement of sodium will increase and the membrane will depolarize.

Question 37

Cholinergic synapses release the neurotransmitter

Answer 37

acetylcholine.

Question 38

The ________ nervous system is composed of the brain and spinal cord.

Answer 38

central

Question 39

The ________ division of the peripheral nervous system brings sensory information to the central nervous system

Answer 39

afferent

Question 40

When potassium channels open and the ions diffuse through the membrane,

Answer 40

the inside of the membrane will become more negative.