Chapter 1

Question 1

What is meant by “monism”?

Answer 1

The idea that the mind is made of the same substance as the rest of the universe

Question 2

How do local neurons differ from other neurons?

Answer 2

They do not have axons.

Question 3

What is an example of an evolutionary explanation as opposed to a functional explanation?

Answer 3

People evolved a tendency to form long-term male–female bonds because human infants benefit from the help of two parents during their long period of dependence.

Question 4

What does a “minimalist” favor with regard to animal research?

Answer 4

Animal research is permissible but should be held to a minimum.

Question 5

Describe the reasons biological psychologists conduct much of their research on nonhuman animals.

Answer 5

Sometimes the mechanisms of behavior are easier to study in a nonhuman species. We are curious about animals for their own sake. We study animals to understand human evolution. Certain procedures that might lead to important knowledge are illegal or unethical with humans.

Question 6

What are the “three Rs” in the legal standards for animal research?

Answer 6

Reduction, replacement, and refinement.

Question 7

How does the “minimalist” position differ from the “abolitionist” position?

Answer 7

A “minimalist” wishes to limit animal research to studies with little discomfort and much potential value. An “abolitionist” wishes to eliminate all animal research regardless of how the animals are treated or how much value the research might produce.

Question 8

Why is diversity an important issue for some types of research on humans, and less for others?

Answer 8

The basic aspects of brain anatomy, nerve cells, synapses, and sensory function are the same for people throughout the world, and even for most other mammalian species. However, the effects of medications often differ based on people’s genes, and sometimes differ between males and females.

Question 9

Santiago Ramón y Cajal clearly demonstrated which of the following?

Answer 9

The nervous system is composed of separate cells.

Question 10

Which part of a neuron has the chromosomes?

Answer 10

The cell body.

Question 11

How do dendrites differ from axons?

Answer 11

Dendrites are short and tapered.

Question 12

What do dendritic spines do?

Answer 12

They increase the surface area available for synapses.

Question 13

What does an afferent axon do?

Answer 13

It brings information into a structure.

Question 14

Which of the following is a function of astrocytes?

Answer 14

They synchronize the activity of a group of neurons.

Question 15

Which of the following is a function of microglia?

Answer 15

They remove dead cells and weak synapses.

Question 16

Why are chemotherapy drugs ineffective against brain cancers?

Answer 16

Chemotherapy drugs do not cross the blood–brain barrier.

Question 17

Which of these chemicals cross the blood–brain barrier by active transport?

Answer 17

Glucose and amino acids

Question 18

What is the brain’s main source of fuel?

Answer 18

Glucose

Question 19

Why does the brain need thiamine (vitamin B1)?

Answer 19

To metabolize glucose

Question 20

Under what conditions do the intestinal bacteria produce more inflammatory chemicals?

Answer 20

Under stressful conditions that might lead to depression.

Question 21

Why would weakened mitochondria affect the brain more than other organs?

Answer 21

The brain uses more energy than any other organ.

Question 22

Of the three types of neurons—sensory, motor, and intrinsic—which would have the shortest axons?

Answer 22

Intrinsic; because an interneuron is contained entirely within one part of the brain, its axon is short.

Question 23

An ontogenetic explanation focuses on which of the following?

Answer 23

How a behavior develops.

Question 24

Why is an action potential a better way for an axon to transmit information than electrical conduction would be?

Answer 24

An action potential does not decrease its intensity over distance.

Question 25

When the membrane is at rest, where are the sodium and potassium ions, mostly?

Answer 25

Sodium is mostly outside the cell, and potassium is mostly inside.

Question 26

What does the sodium-potassium pump do?

Answer 26

It pumps sodium out of the cell, and potassium into the cell.

Question 27

When the membrane is at rest, which gradient or gradients tend to draw sodium ions into the cell?

Answer 27

When the membrane is at rest, which gradient or gradients tend to draw sodium ions into the cell?

Question 28

When the membrane is at rest, which gradient or gradients tend to draw potassium ions out of the cell?

Answer 28

The concentration gradient.

Question 29

What causes the rising portion of the action potential?

Answer 29

Sodium ions are moving into the cell.

Question 30

After the peak of the action potential, the membrane returns toward its resting level. What accounts for this recovery?

Answer 30

Potassium ions move out because of the concentration gradient.

Question 31

If a membrane is depolarized to twice its threshold, what happens?

Answer 31

The action potential is the same as usual.

Question 32

The all-or-none law applies to what part of a neuron?

Answer 32

The axon.

Question 33

What causes the absolute refractory period of an axon?

Answer 33

The sodium channels are shut.

Question 34

What does the myelin sheath of an axon accomplish?

Answer 34

It increases the velocity of action potentials.

Question 35

State the all-or-none law.

Answer 35

According to the all-or-none law, for a given axon, every depolarization beyond the threshold produces an action potential of about the same amplitude and velocity.

Question 36

23 Suppose researchers find that axon A can produce up to 1,000 action potentials per second (at least briefly, with maximum stimulation), but axon B can never produce more than 100 per second (regardless of the strength of the stimulus). What could we conclude about the refractory periods of the two axons?

Answer 36

Axon A must have a shorter absolute refractory period, about 1 ms, whereas B has a longer absolute refractory period, about 10 ms.

Question 37

In a myelinated axon, how would the action potential be affected if the nodes were much closer together? How might it be affected if the nodes were much farther apart?

Answer 37

If the nodes were closer, the action potential would travel more slowly. If they were much farther apart, the current might not be able to stimulate the next node enough to reach its threshold.