chapter 11: the nervous system

Question 1

What division of the nervous system is most specifically responsible for voluntary motor control?

Answer 1

Somatic nervous system

Question 2

Which of the following is NOT one of the basic functions of the nervous system?
A. Decode sensory information from the environment.
B. Integrate sensory input for decision making. C. Generate direct, electrical signals.
D. Release hormones into the bloodstream that travel around the systemic blood circulation to communicate with cells in multiple locations within the body.

Answer 2

D. Release hormones into the bloodstream that travel around the systemic blood circulation to communicate with cells in multiple locations within the body.

Question 3

As you start working out, you notice that your heart rate and breathing rate start to increase. Which division of your nervous system is generating this response? Be as specific as possible.

Answer 3

The sympathetic division of the autonomic nervous system

Question 4

Which glial cells have the most diversity of function?

Answer 4

astrocytes

Question 5

__________ ______ monitors the health of neurons, and can transform into a special type of macrophage to protect endangered neurons.

Answer 5

microglial cells

Question 6

Ependymal cells line many open cavities in the central nervous system (CNS). Ependymal cells have cilia on the side of the cell that face these openings. What is the most likely function of these ciliated cells?

A. movement and circulation of cerebrospinal fluid
B. create myelin sheaths for CNS cells
C. act as macrophage cells to destroy microorganisms or neuronal debris
D. exchange of nutrients between the circulatory system and neurons

Answer 6

A. movement and circulation of cerebrospinal fluid

Question 7

What peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS?

Answer 7

Schwann cells

Question 8

What is the structure at A?

Answer 8

dendrites

Question 9

What structural classification describes this neuron?

Answer 9

multipolar

Question 10

Which areas of this neuron would be classified as receptive regions?

Answer 10

Both A and B

Question 11

Which of these materials or structures would be found in greatest amounts or numbers at E?

Answer 11

vesicles containing neurotransmitter

Question 12

In which area of the neuron is an action potential initially generated?

Answer 12

C

Question 13

Which is the main receptive portion of the neuron

Answer 13

the dendrite

Question 14

Which of the following pairings does not fit?

A. multipolar neurons: peripheral nervous
B. system sensory neurons
association neuron: interneurons
C. motor neurons: efferent neurons.
D. sensory neurons: afferent neurons

Answer 14

A. multipolar neurons: peripheral nervous

Question 15

Many neurons have many short, branching extensions called dendrites. What is the benefit of these structures for a neuron?

Answer 15

The dendrites provide a large surface area for connections from other neurons.

Question 16

A neuron can have _____ _____ axon, but the axon may have occasional branches along its length

Answer 16

only one

Question 17

Which criterion is used to functionally classify neurons?

Answer 17

the direction in which the nerve impulse travels relative to the central nervous system

Question 18

In the motor division of the PNS, the effector organs consist of the three types of muscle tissue and glands. Which of these effector organs would be under voluntary control and thereby fall into the somatic nervous system?
A. Cardiac muscle
B. Skeletal muscle
C. Smooth muscle
D. Glands

Answer 18

B. Skeletal muscle

Question 19

Which of the following membrane regions would have significant numbers of voltage-gated ion channels?

Answer 19

C and D

Question 20

What is the basic condition when a neuron is described as polarized?

Answer 20

There is a separation of positive and negative charges across a membrane.

Question 21

Which of the following statements is correct regarding the polarization of a neuronal membrane and the formation of a resting membrane potential?
A. A resting potential can be generated without the energy as an input.
B. As Na+ leaks across the membrane, that establishes a negative charge inside the membrane.
C. As sodium leaks into the cell, the inside of the cell becomes more negative.
D. Sodium/Potassium pumps maintain concentration gradients; sodium and potassium move down their concentration gradients through leakage channels.

Answer 21

D. Sodium/Potassium pumps maintain concentration gradients; sodium and potassium move down their concentration gradients through leakage channels.

Question 22

Which of the following does NOT describe conditions that occur during an action potential?
A. After initial depolarization, K+ now has both an electrical and a chemical gradient drawing it out of the cell.
B. Na+ is used to repolarize the membrane.
C. The Na+/K+ pump reestablishes resting concentration gradients.
D. Na+ enters the cell through voltage-gated channels, causing a reversal of the resting membrane potential.

Answer 22

B. Na+ is used to repolarize the membrane.

Question 23

Which of the following events would be directly affected if a neuron had a mutation that prevented the production of voltage-gated Na+ channels?
A. generating the resting membrane potential
B. graded hyperpolarization
C. depolarization leading to action potentials
D. graded depolarization

Answer 23

C. depolarization leading to action potentials

Question 24

What type of event is required for an action potential to be generated?

Answer 24

A threshold level evaporation

Question 25

Which of the following is NOT a difference between graded potentials and action potentials?
A. The magnitude of action potentials decrease as the impulse travels further away from the start of the impulse while graded potentials do not decrease in magnitude.
B. Graded potentials can result from the opening of chemically gated channels; action potentials require the opening of voltage-gated channels.
C. Greater stimulus intensity results in larger graded potentials, but not larger action potentials.
D. Graded potentials occur along dendrites, whereas action potentials occur along axons.

Answer 25

A. The magnitude of action potentials decrease as the impulse travels further away from the start of the impulse while graded potentials do not decrease in magnitude.

Question 26

What is a factor that determines the rate of impulse propagation, or conduction velocity, along an axon?

Answer 26

The degree of myelination of the axon

Question 27

What ion is entering the axon terminal at A, and what effect does it have?

Answer 27

Ca2+, which then causes release of neurotransmitter from the axon terminal

Question 28

By which method does the structure at B release neurotransmitter

Answer 28

exocytosis

Question 29

Which of the following statements most accurately describes the effect caused by binding of the neurotransmitter (green dots) to the structure labeled C?

Answer 29

The membrane potential of the postsynaptic membrane changes.

Question 30

How would the receptors at C best be classified?

Answer 30

chemically gated

Question 31

Which of the following statements is true of both membrane potential responses shown in the graphs?

Answer 31

Both responses are examples of graded potentials

Question 32

Which of the following stimuli caused the reaction in the graph on the left

Answer 32

opening of gated Na+ channels

Question 33

Which of the following is expected to occur first if the membrane potential increase shown in the graph on the left were to reach the threshold value indicated at −55 mV?

Answer 33

opening of voltage-gated Na+ channels

Question 34

Suppose that both stimuli seen in these graphs happened equally at the same time on a postsynaptic membrane as a result of two different synapses. Which of the following best describes the result?

Answer 34

there would be little to no graded potential

Question 35

Which membrane potential occurs because of the influx of Na+ through chemically gated channels in the receptive region of a neuron?

Answer 35

excitatory postsynaptic potential

Question 36

Which of the following does NOT describe the process of summation?

A. One EPSP and one IPSP cancel each other out.
B. Two EPSPs are generated at the same time by two separate synapses, bringing the cell to threshold.
C. Two EPSPs occur close enough in time to bring the cell to threshold.
D. One EPSP fails to bring the cell to threshold.

Answer 36

D. One EPSP fails to bring the cell to threshold.

Question 37

What component of the reflex arc determines the response to a stimulus?

Answer 37

integration center

Question 38

Structures of the nervous system surrounding, but not part of the central nervous system are part of the
___________ __________ _________.

Answer 38

peripheral nervous system

Question 39

Supporting cells of the nervous system are collectively called
__________.

Answer 39

neuroglia

Question 40

When potassium channels have been open long enough to go below resting membrane potential, _____________ has occurred.

Answer 40

hyperpolarization

Question 41

When a neuron is stimulated and sodium channels open, the process of ___________ has begun

Answer 41

depolarization

Question 42

___________ are a group of natural chemicals that reduce the perception of pain.

Answer 42

endorphins

Question 43

Two consecutive neurons communicate at a
_______ , where they physically come together.

Answer 43

synapse

Question 44

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.

Answer 44

K+; Na+

Question 45

During depolarization, which gradient(s) move(s) Na+ into the cell?

Answer 45

both electrical and chemical gradients

Question 46

What is the value for the resting membrane potential for most neurons?

Answer 46

-70mv

Question 47

The Na+–K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

Answer 47

Na+ is pumped out of the cell and K+ is pumped into the cell

Question 48

The concentrations of which two ions are highest outside the cell.

Answer 48

Na+ and Cl–

Question 49

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?

Answer 49

The inside surface of the plasma membrane is much more negatively charged than the outside surface.

Question 50

The plasma membrane is much more permeable to K+ than to Na+. Why?

Answer 50

There are many more K+ leak channels than Na+ leak channels in the plasma membrane.

Question 51

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors.

Answer 51

The presence of concentration gradients and leak channels