Chapter 2 Flashcards Preview

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Flashcards in Chapter 2 Deck (211):
1

T/F Dendrites contain the nuclei, ribosomes, mitochondria, and other structures found in most cells.

False

2

T/F A small gap is usually present between neurons.

True

3

T/F Neurons receive information and transmit it to other cells.

True

4

T/F Axons are covered with an insulating material called a myelin sheath

True

5

T/F An afferent axon brings information into a structure.

True

6

T/F An efferent axon carries information away from a structure.

True

7

T/F Neurons can have any number of dendrites, but no more than one axon.

True

8

T/F The general rule among neurons is that the wider the branching, the fewer connections with other neurons.

False

9

T/F The greater the surface area of a dendrite, the more information it can receive from other neurons.

True

10

T/F Neurons are distinguished from other cells by their shape.

True

11

T/F Glial cells serve many functions.

True

12

T/F There are more glial cells than neurons in the human brain.

True

13

T/F Glial cells transmit information across long distances

False

14

T/F Astrocytes remove waste material created when neurons die and control the amount of blood flow to each brain area.

True

15

T/F Oligodendrocytes in the periphery are specialized types of glia.

False

16

T/F Schwann cells build the myelin sheaths in the periphery of the body.

True

17

T/F Most chemicals can easily cross the cell membrane of a neuron.

False

18

T/F The blood-brain barrier is made up of closely packed glial cells.

False

19

T/F One disadvantage of the blood-brain barrier is that it keeps out most forms of nutrition.

True

20

T/F The primary source of energy used by the brain is fat.

False

21

T/F At rest, the inside of a neuron's membrane is more negative than the outside.

True

22

T/F The difference in voltage in a resting neuron is called the resting potential.

True

23

T/F Increasing the electrical gradient for potassium would reduce the tendency for potassium ions to exit the neuron.

True

24

T/F The sodium-potassium pump is what normally brings the membrane back to its original state of polarization after the peak of the action potential.

False

25

T/F If a drug was given that temporarily inactivated the sodium-potassium pumps, action potentials would cease immediately.

False

26

T/F A prolonged increase in the permeability of the membrane to sodium ions would interfere with a neuron's ability to have an action potential.

True

27

T/F Additional stimulation beyond the threshold of excitation will result in a greater depolarization of the membrane during an action potential.

False

28

T/F Dendrites and cell bodies are capable of producing action potentials.

False

29

T/F In a myelinated axon, sodium channels are absent in the nodes of Ranvier.

False

30

The two kinds of cells in the nervous system are:
a. neurons and glia
b. dendrites and axons
c. ribosomes and lysosomes
d. neurons and axons

a. neurons and glia

31

What are the two kinds of cells in the nervous system?
a. neurons and glia
b. dendrites and axons
c. ribosomes and lysosomes
d. neurons and axons

a. neurons and glia

32

Santiago Ramon y Cajal demonstrated that:
a. at rest, the neuron has a negative charge inside its membrane.
b. neurons are separate from one another.
c. neurons communicate at specialized junctions called synapses.
d. action potentials follow the all-or-none law.

b. neurons are separate from one another.

33

Who was the first researcher to demonstrate that neurons are separate from one another?
a. Curt P. Richter
b. Santiago Ramon y Cajal
c. Charles S. Sherrington
d. Jose Delgado

b. Santiago Ramon y Cajal

34

Prior to the work of Santiago Ramon y Cajal, what did many investigators believe?
a. Nerves conducted impulses at the speed of light.
b. Transmission across a synapse was just as fast as transmission along an axon.
c. The tip of an axon physically merged with the next neuron.
d. All neurons were of similar size and shape.

c. The tip of an axon physically merged with the next neuron.

35

Which of the following contributed most to Cajal's ability to find that neurons are separate from one another?
a. Charles Sherrington's study of reflexes
b. Camillo Golgi's cell staining method
c. Perves & Hadley's dye injection method
d. Galileo's invention of the telescope

b.Camillo Golgi's cell staining method

36

The cell membrane is composed of two layers of:
a. protein.
b. fat.
c. carbohydrate.
d. plasma.

b.fat

37

Neurons differ most strongly from other body cells in their:
a. temperature.
b. shape.
c. osmotic pressure.
d. mitochondria.

b.shape

38

The ____ of neurons most strongly differentiate them from other cells in the body.
a. temperature.
b. shape.
c. osmotic pressure.
d. mitochondria.

b.shape

39

What structure is composed of two layers of fat molecules that are free to flow around one another?
a. the endoplasmic reticulum
b. a ribosome
c. a mitochondrion
d. the membrane

d.the membrane

40

Water, oxygen and ____ most freely flow across a cell membrane.
a. calcium
b. positively charged ions
c. magnesium
d. carbon dioxide

d. carbon dioxide

41

Which chemicals flow most freely across a cell membrane?
a. proteins, fats, and carbohydrates
b. positively charged ions
c. water, oxygen, and carbon dioxide
d. calcium and magnesium

c. water, oxygen, and carbon dioxide

42

Chemicals than cannot flow freely across a cell membrane enter a neuron through:
a. a Golgi complex.
b. specialized protein channels.
c. the endoplasmic reticulum.
d. gaps in the myelin sheath.

b. specialized protein channels.

43

The structure that contains the chromosomes is called the:
a. endoplasmic reticulum.
b. nucleus.
c. mitochondrion.
d. ribosome.

b. nucleus.

44

Which of the following is most likely to cross the cell membrane by simple diffusion?
a. large proteins
b. small, charged ions
c. small, uncharged molecules
d. large, charged ions

c. small, uncharged molecules

45

Small, charged molecules can cross the cell membrane through:
a. diffusion.
b. ribosomes.
c. mitochondria.
d. protein channels.

d.protein channels.

46

Protein channels allow ____ to cross the cell membrane.
a. large charged molecules
b. small charged molecules
c. large uncharged molecules
d. small uncharged molecules

b. small charged molecules

47

Where do the metabolic activities occur that provide energy for all of the other activities of the cell?
a. Mitochondria
b. Ribosomes
c. Lysosomes
d. Golgi complexes

a. Mitochondria

48

Ribosomes are the part of a cell that:
a. performs metabolic activities.
b. breaks down harmful chemicals.
c. transports proteins.
d. synthesizes new proteins.

d. synthesizes new proteins.

49

The sites at which the cell synthesizes new protein molecules are called:
a. mitochondria.
b. endoplasmic reticula.
c. ribosomes.
d. plasma membranes.

c. ribosomes.

50

The endoplasmic reticulum is a:
a. network of thin tubes that transport newly synthesized proteins.
b. site where the cell synthesizes new protein molecules.
c. structure that separates the inside of the cell from the outside.
d. structure that contains the chromosomes.

a.network of thin tubes that transport newly synthesized proteins.

51

The main feature that distinguishes a neuron from other animal cells is that a neuron has:
a. a larger nucleus.
b. a distinctive shape.
c. the ability to metabolize a variety of fuels.
d. a high internal concentration of sodium ions.

b.a distinctive shape.

52

One of the most distinctive features of neurons compared to other types of cells is their:
a. shape.
b. number of mitochondria.
c. lack of a cell membrane.
d. size.

a. shape.

53

What receives excitation from other neurons and conducts impulses to muscle or gland cells?
a. sensory neurons
b. motor neurons
c. dendrites
d. dendritic spines

b. motor neurons

54

Dendrites ____.
a. contain the nucleus, ribosomes, and other structures found in most cells
b. are branching fibers that get narrower near their ends
c. is a thin fiber of constant diameter
d. are an insulating material that cover an axon

b. are branching fibers that get narrower near their ends

55

The branching fibers that form the information-receiving pole of the nerve cells are called:
a. motor neurons.
b. dendrites.
c. sensory neurons.
d. axons.

b.dendrites.

56

The surface of a dendrite is lined with specialized junctions through which the dendrite receives information from other neurons. What are these junctions called?
a. synaptic receptors
b. axons
c. synaptic hillocks
d. glia

a.synaptic receptors

57

Which of the following is NOT a characteristic of a dendrite?
a. It tapers as it gets further from the cell body.
b. It is in contact with the dendrites of other neurons.
c. Its surface may be lined with synaptic receptors.
d. It receives information from other neurons or the environment.

b. It is in contact with the dendrites of other neurons.

58

The tree-like branches of a neuron that receive information from other neurons are called:
a. axons.
b. dendrites.
c. soma.
d. myelin.

b.dendrites.

59

Some dendrites contain additional short outgrowths. What are these outgrowths called?
a. hillocks
b. dendritic spines
c. dendritic roots
d. myelin sheaths

b.dendritic spines

60

Many dendrites contain short outgrowths called spines that:
a. increase the surface area available for synapses.
b. increase the speed of transmission.
c. eliminate cell waste products.
d. increase the symmetry of the cell.

a.increase the surface area available for synapses.

61

Dendrites often contain additional short outgrowths. These are believed to:
a. increase the surface area available for synapses.
b. increase the speed of transmission.
c. eliminate cell waste products.
d. help the cell maintain its shape.

a.increase the surface area available for synapses.

62

A greater amount of branching on dendrites allows them to:
a. manufacture more mitochondria.
b. have a larger surface area available for receiving information from other neurons.
c. increase their membrane permeability.
d. lower their resting potential.

b.have a larger surface area available for receiving information from other neurons.

63

Incoming synapses are primarily found on:
a. dendrites only.
b. cell bodies only.
c. axons only.
d. dendrites and cell bodies.

d. dendrites and cell bodies.

64

The information sender of the neuron, which conveys an impulse toward either other neurons or a gland or muscle, is called the:
a. axon.
b. dendrite.
c. soma.
d. myelin.

a. axon.

65

Which of the following is the correct order of transmission of information within a neuron?
a. cell body, dendrite, axon
b. dendrite, axon, cell body
c. axon, cell body, dendrite
d. dendrite, cell body, axon

d.dendrite, cell body, axon

66

Compared to dendrites, axons usually:
a. form the information-receiving pole of the neuron.
b. are shorter than the dendrites.
c. are covered with myelin.
d. taper in diameter toward their periphery.

c.are covered with myelin.

67

The insulating material which covers many vertebrate axons is called the:
a. dendrite.
b. myelin sheath.
c. cell body or soma.
d. presynaptic terminal.

b.myelin sheath.

68

Myelin covers:
a. all axons
b. most dendrites
c. some axons in vertebrates and none in invertebrates
d. all vertebrate axons and some invertebrate axons

c. some axons in vertebrates and none in invertebrates

69

What does myelin cover?
a. all axons
b. most dendrites
c. some axons in vertebrates and none in invertebrates
d. all vertebrate axons and some invertebrate axons

c.some axons in vertebrates and none in invertebrates

70

Nodes of Ranvier are:
a. gaps in the myelin of axons.
b. the same as the myelin sheath.
c. the spiny outgrowths on dendrites.
d. responsible for cell metabolism.

a.gaps in the myelin of axons.

71

Gaps in the insulating material that surrounds axons are known as:
a. interpeduncular nuclei.
b. nodes of Ranvier.
c. myelin synapses.
d. presynaptic terminals.

b. nodes of Ranvier.

72

A presynaptic terminal is also known as:
a. an end bulb
b. a node of Ranvier
c. myelin
d. a spine

a. an end bulb

73

Which of the following is NOT true of axons?
a. They can vary greatly in length.
b. They carry information toward the soma.
c. They release chemicals that cross the synapse.
d. Some of them are covered with myelin sheaths.

b. They carry information toward the soma.

74

What is the point from which an axon releases chemicals into the synapse?
a. the myelin sheath
b. the presynaptic terminal
c. a dendritic spine
d. the endoplasmic reticulum

b. the presynaptic terminal

75

An axon has many branches, each of which swells at its tip. These are known as:
a. presynaptic terminals.
b. efferent axons.
c. afferent axons.
d. intrinsic neurons.

a. presynaptic terminals.

76

Chemicals are released by axons:
a. into the presynaptic terminal.
b. into the junction between neurons.
c. through the efferent terminals.
d. to the mitochondria.

b. into the junction between neurons.

77

An axon releases chemicals:
a. into the presynaptic terminal.
b. into the junction between neurons.
c. through the efferent terminals.
d. to the mitochondria.

b. into the junction between neurons.

78

A neuron can have any number of ____, but no more than one ____.
a. dendrites; axon
b. axons; dendrite
c. cell bodies; axon
d. cell bodies; dendrite

a. dendrites; axon

79

Neurons typically have one ____, but many ____.
a. dendrite; axons
b. axon; dendrites
c. cell body; axons
d. dendrite; cell bodies

b. axon; dendrites

80

Which of the following is NOT a characteristic of an axon?
a. It can be up to a meter long.
b. It has a constant diameter.
c. It carries information toward the cell body.
d. It may be covered with a myelin sheath.

c. It carries information toward the cell body.

81

As a general rule, where do axons convey information?
a. toward dendrites of their own cell
b. toward their own cell body
c. away from their own cell body
d. to surrounding glia

c. away from their own cell body

82

If you were to accidentally touch a hot stove with your hand, you would quickly pull your hand away. The information carried to the muscles in your arm to make them contract was carried by:
a. efferent neurons.
b. afferent neurons.
c. intrinsic neurons.
d. sensory neurons.

a. efferent neurons.

83

If all of a neuron's dendrites or axons were contained within the spinal cord, it would be considered a(n) ____ neuron.
a. efferent
b. afferent
c. intrinsic
d. Purkinje

c. intrinsic

84

What would a neuron in the pons be called that receives information only from other cells in the pons and sends information only to other cells in the pons?
a. afferent
b. efferent
c. intrinsic
d. inter-synaptic

c. intrinsic

85

Which of these is true of glial cells?
a. They are larger than neurons
b. They transmit information over long distances.
c. They do not transmit information over long distances.
d. They are less numerous then neurons.

c. They do not transmit information over long distances.

86

Which of the following is a characteristic of glial cells in the human brain?
a. They are larger than neurons.
b. They are capable of transmitting impulses when neurons fail to do so.
c. They are more numerous than neurons.
d. They are like neurons, except that they lack axons.

c. They are more numerous than neurons.

87

Glial cells:
a. are less numerous than neurons in the human brain.
b. transmit information over long distances within the central nervous system.
c. occupy about ten times more space in the brain than do neurons.
d. occupy about the same total space as do neurons.

d. occupy about the same total space as do neurons.

88

Which function is NOT performed by glia?
a. removing waste materials
b. building myelin sheaths
c. transmitting information
d. guiding the growth of axons and dendrites

c. transmitting information

89

One type of glia helps synchronize the activity of axons. They are called:
a. oligodendrocytes.
b. astrocytes.
c. radial glia.
d. Schwann cells.

b. astrocytes.

90

Which of the following is NOT true of astrocytes?
a. They wrap around the presynaptic terminals of several axons.
b. They help synchronize the activity of the axons.
c. They remove waste material.
d. They make up the myelin sheaths in the periphery of the body.

d. They make up the myelin sheaths in the periphery of the body.

91

Which type of glia remove waste material in the nervous system?
a. astrocytes
b. Schwann cells
c. oligodendrocytes
d. radial glia

a. astrocytes

92

What type of glial cells myelinate axons in the brain and spinal cord?
a. oligodendrocytes
b. Schwann cells
c. radial glia
d. astrocytes

a. oligodendrocytes

93

Which type of glia release chemicals that modify the activity of neighboring neurons?
a. astrocytes
b. Schwann cells
c. oligodendrocytes
d. radial glia

a. astrocytes

94

Which type of glia builds myelin sheaths around axons in the periphery of the body?
a. astrocytes
b. Schwann cells
c. oligodendrocytes
d. radial glia

b. Schwann cells

95

____ in the brain and spinal cord and ____ in the periphery are specialized types of glia that build the myelin sheaths that surround neurons.
a. Oligodendrocytes; Schwann cells
b. Schwann cells; oligodendrocytes
c. Microglia; oligodendrocytes
d. Radial glia; Schwann cells

a. Oligodendrocytes; Schwann cells

96

Glial cells whose function most closely resembles that of the immune system are called:
a. oligodendrocytes.
b. Schwann cells.
c. microglia.
d. radial glia.

c. microglia.

97

Radial glia:
a. guide the migration of neurons during embryonic development.
b. synchronize the activity of axons.
c. wrap around the presynaptic terminals of several axons.
d. build the myelin sheaths that surround and insulate certain axons.

a.guide the migration of neurons during embryonic development.

98

Of the following, the most important consideration in developing a drug that will act in the brain is:
a. if the drug can be inexpensively manufactured.
b. if the drug will cross the blood-brain barrier.
c. how long the drug will act.
d. the number of people who will use the drug.

b. if the drug will cross the blood-brain barrier.

99

The risk of having part of the brain unprotected by the blood-brain barrier is that:
a. it is invisible to brain imaging techniques.
b. it takes longer for drugs to work.
c. viruses or toxic chemicals are more likely to damage it.
d. the blood is poorly oxygenated.

c. viruses or toxic chemicals are more likely to damage it.

100

What is the mechanism that prevents or slows some chemicals from entering the brain, while allowing others to enter?
a. a threshold
b. a blood-brain barrier
c. an endoplasmic wall
d. a differential-drug inhibitor

b. a blood-brain barrier

101

In the brain, an arrangement of endothelial cells:
a. has gaps large enough to allow the passage of molecules.
b. synthesizes neurotransmitters.
c. does not allow most molecules to pass because the cells are so tightly packed.
d. has gaps that are filled with enzymes that attack most blood chemicals.

c. does not allow most molecules to pass because the cells are so tightly packed.

102

What happens to a virus that manages to cross the blood-brain barrier and enter the brain?
a. It is destroyed by natural killer cells.
b. It gets trapped in a neuron, then both are destroyed by natural killer cells.
c. It gets trapped in a glial cell, then both are destroyed by natural killer cells.
d. It stays in the nervous system throughout the person's life.

d. It stays in the nervous system throughout the person's life.

103

Which of the following is an important function of the blood-brain barrier?
a. It enables more nutrients to reach the brain.
b. It maintains an electrical gradient.
c. It aids in the production of neurotransmitters.
d. It protects the brain from most viruses.

a. It enables more nutrients to reach the brain.

104

Which of the following molecules would be able to passively cross the blood-brain barrier?
a. small, uncharged molecules
b. large, charged molecules
c. glucose
d. amino acids

a. small, uncharged molecules

105

Molecules that can cross the blood-brain barrier are usually:
a. large, uncharged molecules, such as lactose.
b. large, charged molecules.
c. neurotransmitters, such as dopamine.
d. molecules that can dissolve in the fats of the capillary walls.

d. molecules that can dissolve in the fats of the capillary walls.

106

The major disadvantage of a blood-brain barrier is that:
a. many chemicals can easily diffuse into the brain.
b. it requires so much glucose to maintain it.
c. certain required chemicals must be actively transported.
d. viruses can’t escape.

c. certain required chemicals must be actively transported.

107

Glucose enters the brain via which type of transport?
a. indirect transport
b. direct transport
c. passive transport
d. active transport

d. active transport

108

Compared to passive transport, the major disadvantage of active transport is that it:
a. cannot transport chemicals out of the brain.
b. requires expenditure of energy.
c. transports glucose into the brain.
d. transports viruses into the brain.

b. requires expenditure of energy.

109

What is the main source of nutrition for vertebrate neurons?
a. Fats
b. Glucose
c. Sodium
d. Complex carbohydrates

b. Glucose

110

Why do neurons rely so heavily on glucose as their source of nutrition?
a. Neurons lack the enzymes necessary to metabolize other fuels.
b. Glucose is the only fuel that can be used even in the absence of vitamins.
c. Glucose is not used extensively by other parts of the body.
d. Other fuels do not readily cross the blood-brain barrier.

d. Other fuels do not readily cross the blood-brain barrier.

111

What are two requirements for the brain to metabolize glucose?
a. thiamine and oxygen
b. vitamin C and nitrogen
c. niacin and bicarbonate
d. riboflavin and iron

a. thiamine and oxygen

112

Why does the brain need thiamine?
a. to enable glucose to cross the blood-brain barrier
b. as a source of fuel in case there is not enough glucose
c. as a building block for making proteins
d. to enable it to metabolize glucose

d. to enable it to metabolize glucose

113

If the brain does not have enough thiamine, what is it unable to do?
a. maintain its blood-brain barrier
b. pump glucose across the blood-brain barrier
c. produce certain neurotransmitters
d. metabolize glucose

d. metabolize glucose

114

Which group is most likely to suffer from a thiamine deficiency?
a. alcoholics
b. heroin addicts
c. diabetics
d. infants

a. alcoholics

115

What leads to Korsakoff's syndrome?
a. thiamine deficiency resulting from alcoholism
b. glucose deficiency resulting from alcoholism
c. viruses that manage to cross the blood-brain barrier
d. glial cells that over-reproduce and increase pressure in the brain

a. thiamine deficiency resulting from alcoholism

116

Korsakoff's syndrome:
a. is marked by severe memory impairments.
b. results from too much thiamine.
c. results from lack of oxygen to the brain.
d. is due to a breakdown of the blood-brain barrier.

a. is marked by severe memory impairments.

117

The membrane of a neuron is specialized to:
a. keep all types of intercellular chemicals from moving out of the neuron.
b. keep all types of extracellular chemicals from moving into the neuron.
c. control the exchange of chemicals between the inside and outside of the cell.
d. produce chains of fatty acids and proteins.

c. control the exchange of chemicals between the inside and outside of the cell.

118

The membrane of a neuron is composed of ____ with ____ embedded in them.
a. carbohydrates; purines
b. fat molecules; proteins
c. proteins; neurotransmitters
d. benzene molecules; carbohydrates

b. fat molecules; proteins

119

What is the difference in voltage called that typically exists between the inside and the outside of a neuron?
a. concentration gradient
b. generator potential
c. resting potential
d. shock value

c. resting potential

120

When stating that the neuron's membrane is polarized, you are referring to a difference in electrical potential between:
a. the axons and the dendrites.
b. the axon hillock and the cell body.
c. sodium ions and potassium ions.
d. the inside and the outside of the membrane.

d. the inside and the outside of the membrane.

121

The resting potential is mainly the result of:
a. negatively charged proteins inside the cell.
b. positively charged proteins inside the cell.
c. negatively charged proteins outside the cell.
d. positively charged proteins outside the cell.

a. negatively charged proteins inside the cell.

122

The resting potential of a neuron refers to:
a. the net positive charge on the inside of the neuron.
b. ions which rest in one place in the cell.
c. the movement of ions to the outside of the neuron.
d. the net negative charge on the inside of the neuron.

a. the net positive charge on the inside of the neuron.

123

What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?
a. -70 millivolts
b. +10 millivolts
c. 0 millivolts
d. +90 millivolts

a. -70 millivolts

124

The selectivity of a neuron membrane is analogous to:
a. the blood-brain barrier.
b. the action potential.
c. the resting potential.
d. myelin.

a. the blood-brain barrier.

125

Allowing only certain people to cross the street, and only at certain times, is comparable to a neuron’s ____ with respect to ions.
a. threshold of excitation
b. all-or-none law
c. resting potential
d. selective permeability

d. selective permeability

126

When a neuron's membrane is at rest, which of the following molecules crosses through it MOST slowly?
a. potassium
b. sodium
c. water
d. carbon dioxide

a. potassium

127

When the neuronal membrane is at rest, the potassium channels:
a. permit potassium ions to pass quickly and easily.
b. permit potassium ions to pass slowly.
c. prohibit any movement of potassium ions.
d. help to open up the sodium channels.

b. permit potassium ions to pass slowly.

128

When the neuronal membrane is at rest, the sodium channels:
a. permit sodium ions to pass quickly and easily.
b. permit potassium ions to cross instead of sodium.
c. are closed.
d. fluctuate rapidly between open and closed.

c. are closed.

129

Which of the following describes selective permeability?
a. Ions can only travel in certain directions across the membrane.
b. Only certain molecules are allowed to cross the membrane freely.
c. Only certain types of stimulation will result in an action potential.
d. All molecules must pass through designated channels.

b. Only certain molecules are allowed to cross the membrane freely.

130

When a neuron’s membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell.
a. into, into
b. into, out of
c. out of, into
d. out of, out of

a. into, into

131

When a neuron’s membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell.
a. into, into
b. into, out of
c. out of, into
d. out of, out of

c. out of, into

132

The sodium-potassium pump repeatedly transports ____ sodium ions out of the cell while drawing ____ potassium ions into it.
a. three; two
b. two; three
c. one; three
d. one; two

a. three; two

133

The sodium-potassium pump repeatedly transports three ____ ions out of the cell while drawing two ____ ions into it.
a. calcium; potassium
b. potassium; calcium
c. potassium; sodium
d. sodium; potassium

d. sodium; potassium

134

Electrical gradients lead to what kind of movements?
a. the general movement of ions into the neuron
b. the general movement of ions out of the neuron
c. the movement of ions to areas having the same electrical charges
d. the movement of ions to areas having the opposite electrical charges

d. the movement of ions to areas having the opposite electrical charges

135

Under which conditions would the sodium-potassium pump be far less effective in creating a concentration gradient?
a. if dendrites were generally longer than axons
b. if the glia-to-neuron ratio were higher
c. if selective permeability of the membrane did not exist
d. if it were an active transport system that required energy

c. if selective permeability of the membrane did not exist

136

The net effect of each cycle of the sodium-potassium pump is to:
a. decrease the number of positively charged ions within the cell.
b. increase the number of positively charged ions within the cell.
c. decrease the number of positively charged ions outside the cell.
d. increase the number of negatively charged ions within the cell.

a. decrease the number of positively charged ions within the cell.

137

What is one major cause for the resting potential of a neuron's membrane?
a. a difference in size between axons and dendrites
b. a high permeability of the membrane to water molecules
c. the refractory period of the membrane
d. the sodium-potassium pump

d. the sodium-potassium pump

138

The sodium-potassium pump pumps sodium ions ____ and potassium ions ____.
a. into the cell; into the cell
b. into the cell; out of the cell
c. out of the cell; out of the cell
d. out of the cell; into the cell

d. out of the cell; into the cell

139

The concentration gradient refers to:
a. the fact that the concentration of ions is greater on the inside of a neuron.
b. the fact that the concentration of ions is greater on the outside of a neuron.
c. the difference in distribution for various ions between the inside and outside of the membrane.
d. the negatively charged proteins inside the cell.

c. the difference in distribution for various ions between the inside and outside of the membrane.

140

What is meant by the term "concentration gradient" with respect to neurons?
a. Sodium is more concentrated in the dendrites and potassium in the axon.
b. Negative charges are more concentrated outside the cell.
c. Sodium and potassium ions are more concentrated on opposite sides of the membrane.
d. Potassium is more concentrated in the dendrites and sodium in the axon.

c. Sodium and potassium ions are more concentrated on opposite sides of the membrane.

141

Concentration gradients lead to what kind of movements?
a. the general movement of ions into the neuron
b. the general movement of ions out of the neuron
c. the movement of ions to areas of their highest concentrations
d. the movement of ions to areas of their lowest concentrations

d. the movement of ions to areas of their lowest concentrations

142

Which of the following events would increase the concentration gradient of sodium?
a. decreased permeability to potassium ions
b. increased activity of the sodium potassium pump
c. increased membrane permeability to sodium ions
d. increased membrane permeability to chloride ions

b. increased activity of the sodium potassium pump

143

The concentration gradient for potassium tends to:
a. draw potassium into the cell.
b. push chloride out of the cell.
c. push sodium out of the cell.
d. push potassium out of the cell.

d. push potassium out of the cell.

144

Which of the following is NOT true for sodium ions when the cell is at resting potential?
a. Sodium ions remain outside the cell because the sodium- potassium pump drives them out.
b. Sodium gates are tightly closed.
c. Sodium tends to be driven into the neuron by the concentration gradient.
d. Sodium tends to be driven out of the neuron by the electrical gradient.

d. Sodium tends to be driven out of the neuron by the electrical gradient.

145

When the neuron is at rest, what is responsible for moving potassium ions OUT of the cell?
a. a concentration gradient
b. an electrical gradient
c. both a concentration gradient and an electrical gradient
d. the sodium-potassium pump

a. a concentration gradient

146

When the neuron is at rest, what is responsible for moving potassium ions into the cell?
a. concentration gradient
b. an electrical gradient
c. the sodium-potassium pump
d. both the sodium-potassium pump and electrical gradient

d. both the sodium-potassium pump and electrical gradient

147

When a membrane is at rest, what attracts potassium ions to the inside of the cell?
a. an electrical gradient
b. a concentration gradient
c. both an electrical gradient and a concentration gradient
d. neither an electrical gradient nor a concentration gradient

a. an electrical gradient

148

When a membrane is at rest, what attracts sodium ions to the inside of the cell?
a. an electrical gradient
b. a concentration gradient
c. both an electrical gradient and a concentration gradient
d. neither an electrical gradient nor a concentration gradient

c. both an electrical gradient and a concentration gradient

149

When the neuron is at rest, what is responsible for moving sodium ions out of the cell?
a. a concentration gradient
b. an electrical gradient
c. both a concentration gradient and an electrical gradient
d. the sodium-potassium pump

d. the sodium-potassium pump

150

Which of the following is an advantage of having a resting potential?
a. The toxic effects of sodium are minimized inside the cell.
b. No energy is required to maintain it.
c. The cell is prepared to respond quickly to a stimulus.
d. All of the ions are maintained in equal concentrations throughout the cytoplasm.

c. The cell is prepared to respond quickly to a stimulus.

151

Negatively charged ions like ____ are mostly located outside the cell.
a. sodium
b. chloride
c. calcium
d. potassium

b. chloride

152

Ordinarily, stimulation of a neuron takes place:
a. through hyperpolarization.
b. at the synapse.
c. in the mitochondria.
d. in the endoplasmic reticulum.

b. at the synapse.

153

What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
a. Hyperpolarization
b. Depolarization
c. an action potential
d. a threshold

a. Hyperpolarization

154

Hyperpolarization is:
a. increased polarization.
b. decreased polarization.
c. the threshold of the cell.
d. the resting potential of the cell.

a. increased polarization.

155

Which of the following would produce a hyperpolarization of a neuron?
a. applying a negative charge inside the neuron with a microelectrode
b. applying a positive charge inside the neuron with a microelectrode
c. increasing the membrane's permeability to sodium
d. decreasing the membrane's permeability to potassium

a. applying a negative charge inside the neuron with a microelectrode

156

What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a potential slightly closer to zero?
a. hyperpolarization
b. depolarization
c. selective permeability
d. a refractory period

b. depolarization

157

The neuron will produce an action potential only if the depolarization exceeds what level?
a. the threshold of excitation
b. the resting potential
c. hyperpolarization
d. the refractory period

a. the threshold of excitation

158

A membrane produces an action potential whenever the potential across it reaches what level?
a. the resting potential
b. -90 mV
c. the threshold of excitation
d. the refractory period

c. the threshold of excitation

159

If there is a depolarizing effect on a neuron, the result will be that the neuron will fire:
a. no matter how slight the effect.
b. forever.
c. only if it reaches threshold.
d. only if the cell is in its relative refractory period.

c. only if it reaches threshold.

160

The sodium gates in the axon are usually closed. Which of the following opens them?
a. depolarization of the membrane
b. increased concentration of socium outside the cell
c. increased concentration of sodium inside the cell
d. increased activity of the sodium-potassium pump

a. depolarization of the membrane

161

What tends to open the sodium gates across a neuron's membrane?
a. hyperpolarization of the membrane
b. depolarization of the membrane
c. increase in the sodium concentration outside the neuron
d. passing the peak of the action potential and entering the refractory period

b. depolarization of the membrane

162

What happens to the ion gates when the membrane of a neuron starts to be depolarized?
a. Potassium gates close.
b. Chloride gates open.
c. Sodium gates close.
d. Sodium gates open.

d. Sodium gates open.

163

Stimulus A depolarizes a neuron just barely above the threshold. Stimulus B depolarizes a neuron to 10 mV beyond threshold. What can we expect to happen?
a. Stimulus B will produce an action potential that is conducted at a faster speed than A.
b. Stimulus B will produce an action potential of greater magnitude than stimulus A.
c. Stimulus B will produce an action potential but stimulus A will not.
d. Stimulus A and stimulus B will produce the same response in the neurons.

d. Stimulus A and stimulus B will produce the same response in the neurons.

164

If depolarization is less than the cell's threshold:
a. sodium is prevented from crossing the membrane.
b. potassium is prevented from crossing the membrane.
c. sodium crosses the membrane only slightly more than usual.
d. the cell will still produce an action potential.

c. sodium crosses the membrane only slightly more than usual.

165

Which of the following actions would depolarize a neuron?
a. decreasing membrane permeability to calcium
b. increasing membrane permeability to potassium
c. decreasing membrane permeability to sodium
d. increasing membrane permeability to sodium

d. increasing membrane permeability to sodium

166

Stimulation of a neuron beyond a certain level is called the:
a. firing threshold
b. hillock threshold
c. threshold of excitation
d. threshold of inhibition

c. threshold of excitation

167

The action potential of a neuron depends mostly on what movement of ions?
a. sodium ions entering the cell
b. sodium ions leaving the cell
c. potassium ions entering the cell
d. potassium ions leaving the cell

a. sodium ions entering the cell

168

In the normal course of an action potential:
a. sodium channel remain open for long periods of time.
b. the concentration of sodium equalizes across the membrane.
c. sodium remains much more concentrated outside than inside the neuron.
d. subthreshold stimulation intensifies the action potential.

c. sodium remains much more concentrated outside than inside the neuron.

169

Voltage-activated channels are channels for which a change in the voltage across the membrane alters their:
a. permeability.
b. length.
c. number.
d. threshold.

a. permeability.

170

At the peak of the action potential, the electrical gradient of potassium:
a. is the same as during the resting potential.
b. pulls sodium into the cell.
c. pushes potassium out of the cell.
d. pulls potassium into the cell.

c. pushes potassium out of the cell.

171

When the potential across a membrane reaches threshold, the sodium channels:
a. open to let sodium enter the cell rapidly.
b. close to prevent sodium from entering the cell.
c. open to let sodium exit the cell rapidly.
d. close to prevent sodium from exiting the cell.

a. open to let sodium enter the cell rapidly.

172

Suppose we applied a drug to a neuron that caused its sodium gates to suddenly open wide. What would happen?
a. hyperpolarization of the membrane
b. an increase in the threshold
c. an action potential
d. nothing, because potassium gates would compensate

c. an action potential

173

During the entire course of events from the start of an action potential until the membrane returns to its resting potential, what is the net movement of ions?
a. sodium in, potassium in
b. sodium out, potassium out
c. sodium in, potassium out
d. sodium out, potassium in

c. sodium in, potassium out

174

A drug that blocks the sodium gates of a neuron's membrane would:
a. decrease the threshold.
b. block the action potential.
c. cause repeated action potentials.
d. eliminate the refractory period.

b. block the action potential.

175

After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
a. There is no longer a concentration gradient for sodium.
b. The sodium-potassium pump greatly increases its rate of activity.
c. All the available sodium ions have already entered the cell.
d. The sodium gates in the membrane close.

d. The sodium gates in the membrane close.

176

At what point do the sodium gates begin to close, shutting out further entry of sodium into the cell?
a. at the peak of the action potential
b. when the threshold is reached
c. at the end of the relative refractory period
d. when the concentration gradient for sodium is eliminated

a. at the peak of the action potential

177

Just after the peak of the action potential, what movement of ions restores the membrane to approximately the resting potential?
a. Sodium ions enter the cell.
b. Potassium ions enter the cell.
c. Potassium ions leave the cell.
d. Sodium ions travel down the axon.

c. Potassium ions leave the cell.

178

What causes potassium ions to leave the axon just after the peak of the action potential?
a. a continuing concentration gradient and the opening of the potassium gates
b. an increase in the concentration gradient across the membrane
c. increased tendency of the sodium-potassium pump to pump potassium out
d. binding of potassium ions to proteins that leave at this time

a. a continuing concentration gradient and the opening of the potassium gates

179

A drug that decreases the flow of potassium through the potassium gates of the membrane would:
a. block action potentials.
b. increase the threshold of the membrane.
c. slow the return of the membrane to its resting potential.
d. cause the membrane to be hyperpolarized.

c. slow the return of the membrane to its resting potential.

180

A drug would prevent an action potential if it:
a. lowers the threshold of the membrane.
b. blocks the movement of potassium across the membrane.
c. blocks the movement of sodium across the membrane.
d. increases the movement of sodium across the membrane.

c. blocks the movement of sodium across the membrane.

181

Local anesthetic drugs attach to the sodium channels of the membrane, which:
a. allows sodium ions to enter and stop action potential.
b. prevents potassium ions from entering and stopping action potential.
c. allows potassium ions to enter and stop action potential.
d. prevents sodium ions from entering and stopping action potential.

d. prevents sodium ions from entering and stopping action potential.

182

Local anesthetic drugs, such as Novocain, work by:
a. opening the potassium gates.
b. blocking the sodium gates.
c. inactivating the sodium-potassium pump.
d. decreasing blood flow to certain areas of the brain.

d. decreasing blood flow to certain areas of the brain.

183

Which of the following represents the all-or-none law?
a. Every depolarization produces an action potential.
b. Every hyperpolarization produces an action potential.
c. The size of the action potential is independent of the strength of the stimulus that initiated it.
d. Every depolarization reaches the threshold, even if it fails to produce an action potential.

c. The size of the action potential is independent of the strength of the stimulus that initiated it.

184

The all-or-none law states that:
a. a neuron produces an action potential of maximal strength, or none at all.
b. all neurons fire or none at all.
c. all neurons in a pathway fire at the same time, or none do.
d. all ions move in the same direction, or none do.

a. a neuron produces an action potential of maximal strength, or none at all.

185

The all-or-none law applies to:
a. cell bodies of neurons.
b. dendrites.
c. axons.
d. all parts of a neuron.

c. axons.

186

The presence of an all-or-none law suggests that neurons can only convey different messages by changing their:
a. rate or pattern of action potentials.
b. size of action potentials.
c. speed of action potentials.
d. sodium-potassium pump activity.

a. rate or pattern of action potentials.

187

According to the all-or-none law:
a. all neurons produce an action potential at the same time or none at all.
b. all of the extracellular sodium enters the axon, or none at all.
c. once an axon reaches threshold, the amplitude and velocity of an action potential are nearly equal each time.
d. neurons are either active all the time or not at all.

c. once an axon reaches threshold, the amplitude and velocity of an action potential are nearly equal each time.

188

The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the:
a. concentration gradient.
b. refractory period.
c. sodium potassium pump.
d. phospholipid bilayer.

b. refractory period.

189

Under what conditions is it impossible for a stimulus to produce an action potential?
a. if the membrane is in its absolute refractory period
b. if it occurs at the same time as a hyperpolarizing stimulus
c. if sodium ions are more concentrated outside the cell than inside
d. if the potassium gates have been blocked

a. if the membrane is in its absolute refractory period

190

Which feature of a neuron limits the number of action potentials it can produce per second?
a. the threshold
b. the refractory period
c. saltatory conduction
d. the length of the axon

b. the refractory period

191

What will NOT affect the speed of an action potential?
a. the presence of myelin
b. the diameter of the axon
c. the length of the axon
d. the number of sodium gates

c. the length of the axon

192

How is the speed of an action potential down an unmyelinated axon BEST described?
a. the speed of electricity, regardless of the size of the axon
b. less than 1 meter per second, regardless of the size of the axon
c. faster in thin axons than in thick ones
d. faster in thick axons than in thin ones

d. faster in thick axons than in thin ones

193

The presence of myelin and the diameter of the axon:
a. affect the strength and frequency of the stimulus
b. affect the speed of an action potential
c. affect the strength of an action potential
d. affect the frequency of an action potential

b. affect the speed of an action potential

194

Which two factors affect the speed of an action potential?
a. the strength and frequency of the stimulus
b. the location of the cell body and the length of the axon
c. the length and diameter of the axon
d. the presence of myelin and the diameter of the axon

d. the presence of myelin and the diameter of the axon

195

The function of a myelin sheath is to:
a. prevent action potentials from traveling in the wrong direction.
b. increase the velocity of transmission along an axon.
c. increase the magnitude of an action potential.
d. provide a store of nutrients for the neuron.

b. increase the velocity of transmission along an axon.

196

If you were to stub your toe and feel the pressure a second or two before you feel the pain, then which of the following statements is most likely true?
a. Pain sensitive neurons are large and myelinated.
b. Pain sensitive neurons are longer.
c. Pressure sensitive neurons are small and lightly myelinated.
d. Pressure sensitive neurons are large and myelinated.

d. Pressure sensitive neurons are large and myelinated.

197

What are the nodes of Ranvier?
a. gates in the membrane that admit all ions freely
b. gaps in the myelin sheath
c. branching points in an axon
d. places where dendrites join the cell body

b. gaps in the myelin sheath

198

The myelin sheath is interrupted periodically by short sections of axon called:
a. axon gaps
b. nodes of Cajal
c. axon nodes
d. nodes of Ranvier

d. nodes of Ranvier

199

In a myelinated axon, where are sodium gates abundant?
a. in the areas covered by myelin
b. at the nodes of Ranvier
c. throughout the axon
d. only in the axon hillock

b. at the nodes of Ranvier

200

To what does saltatory conduction refer?
a. the production of an action potential by the movement of sodium ions
b. the transmission of an impulse along a myelinated axon
c. the transmission of impulses along dendrites
d. the transmission of an impulse between one neuron and another

b. the transmission of an impulse along a myelinated axon

201

Saltatory conduction ____ the velocity of action potentials and ____ the amount of energy used by the neuron.
a. decreases; decreases
b. decreases; increases
c. increases; decreases
d. increases; increases

c. increases; decreases

202

How does saltatory conduction affect energy use in a neuron?
a. It eliminates the need for action potentials.
b. It increases the duration of the refractory period.
c. It reduces the frequency of action potentials.
d. It reduces the work load for the sodium-potassium pump.

d. It reduces the work load for the sodium-potassium pump.

203

What disease is related to the destruction of myelin sheaths?
a. multiple sclerosis
b. cystic fibrosis
c. myasthenia gravis
d. Parkinson's disease

a. multiple sclerosis

204

In what way is a myelinated axon that has lost its myelin (through disease) different from an axon that was never myelinated?
a. It has a smaller diameter.
b. It lacks sodium gates along parts of its surface.
c. It has a longer refractory period.
d. It has a much higher threshold.

b. It lacks sodium gates along parts of its surface.

205

Multiple sclerosis is one of several:
a. blood-brain disorders
b. neuron diseases
c. demyelinating diseases
d. movement disorders

c. demyelinating diseases

206

Which of the following is NOT governed by the all-or-none law?
a. unmyelinated axons
b. myelinated axons
c. motor neurons
d. local neurons

d. local neurons

207

In what direction does a local neuron transmit information?
a. through its dendrites to cell body to axon
b. through its axon to cell body to dendrites
c. only toward the cell body
d. equally well in any direction

d. equally well in any direction

208

Which of the following describes the transmission of information in a local neuron?
a. The signal decreases in strength as it travels.
b. The signal increases in strength as it travels.
c. The signal strength remains constant as it travels.
d. Local neurons do not transmit any information.

a. The signal decreases in strength as it travels.

209

Why are local neurons more difficult to study?
a. There are so few of them that they are difficult to find.
b. They are so small.
c. They exist only in humans, so there are ethical considerations.
d. They die if separated from other neurons.

b. They are so small.

210

Which of the following is TRUE of local neurons?
a. They exchange information with distant neurons.
b. They abide by the all-or-none principle.
c. The change in membrane potential increases as it travels.
d. They have short dendrites and axons.

d. They have short dendrites and axons.

211

A local neuron:
a. has an axon approximately a meter long.
b. conveys information to other neurons across great distances.
c. is a small neuron with no axon or a very short one.
d. has an axon with many branches far from the cell body.

c. is a small neuron with no axon or a very short one.