Deck 13: A: Nervous System Cells

Question 1

The afferent nervous system consists of all outgoing motor pathways.

Answer 1

False

Question 2

When a neuron is resting,the inner surface of its plasma membrane is slightly positive compared with its outer surface.

Answer 2

False

Question 3

In an adult,brain cells do not undergo mitosis,except to replace neurons that have been damaged or destroyed.

Answer 3

False

Question 4

Ependymal cells engulf and destroy microbes and cellular debris in inflamed or degenerating brain tissue.

Question 5

Most of the neurons in the brain and spinal cord are unipolar.

Question 6

If a motor neuron is damaged,it can cause the muscle it innervates to atrophy because of lack of stimulation.

Question 7

In a contralateral reflex arc,the receptors and effectors are located on opposite sides of the body.

Question 8

Nerve fibers with many Schwann cells forming a thick myelin sheath are called myelinated fibers,or gray fibers.

Question 9

The nervous system consists of the brain,spinal cord,and nerves.

Question 10

Multiple sclerosis is the most common primary disease of the CNS.

Question 11

The magnitude of the action potential peaks when the sodium channels close.

Question 12

The sodium-potassium pump actively pumps three potassium ions out of the neuron and two sodium ions into the neuron.

Question 13

Regeneration of nerve fibers will occur only if the cell body is intact and the fibers have a neurilemma.

Question 14

Oligodendrocytes form myelin sheaths around nerve fibers in the CNS.

Question 15

If the threshold potential is surpassed,the full peak of the action potential is always reached.

Question 16

Neurons are the only living cells that maintain a difference in the concentration of ions across their membranes.

Question 17

Most injuries to the brain and spinal cord cause permanent damage.

Question 18

Small,lipid-soluble molecules can diffuse easily across the blood-brain barrier.

Question 19

Groups of cell bodies located in the brain or spinal cord are referred to as ganglia.

Question 20

In an ipsilateral arc,the effectors and receptors are on opposite sides of the body.

Question 21

In depolarization the membrane potential moves toward zero,whereas in hyperpolarization the membrane potential moves away from zero.

Question 22

In a myelinated fiber,the action potential jumps from one node of Ranvier to the next.

Question 23

When a neuropeptide is secreted with one or two other neurotransmitters,it is thought to serve as a neuromodulator,regulating the effects of the other neurotransmitters.

Question 24

In a myelinated neuron,the impulse can travel under the myelin between nodes of Ranvier.

Question 25

A neurotransmitter can be excitatory or inhibitory,not both.

Question 26

A neurotransmitter can be either excitatory or inhibitory depending on the postsynaptic receptor.

Question 27

Excitatory neurotransmitters are most likely to initiate an action potential.

Question 28

Enkephalins and endorphins are subclasses of amines that are pain relievers.

Question 29

The speed of a nerve impulse depends on the neuron's resting potential.

Question 30

Myelinated fibers conduct impulses faster than unmyelinated fibers.

Question 31

Spatial summation is the effect produced by a rapid succession of stimuli on a single postsynaptic neuron.

Question 32

When epinephrine and norepinephrine are released into the bloodstream,they are called hormones instead of neurotransmitters.

Question 33

The neurotransmitter acetylcholine always has an excitatory effect.

Question 34

An inhibitory postsynaptic potential is produced through the hyperpolarization of the postsynaptic membrane.

Question 35

The receptors embedded in the plasma membrane of a postsynaptic neuron are protein molecules.

Question 36

Whether an impulse is continued through the neuron depends on the magnitude of the voltage in the axon hillock.

Question 37

The action potential is called an all-or-none response because if the threshold potential is surpassed,the full peak of the action is always reached; if the threshold potential is not surpassed,no action potential will occur.

Question 38

Many anesthetics produce their effects by inhibiting the opening of the potassium channels,blocking the repolarization of nerve impulses.

Question 39

The difference in electrical charge between the inside and outside of a membrane is called the membrane potential.

Question 40

The sensory fibers from the skin generally conduct impulses up to about 130 meters per second.

Question 41

The nervous system can be divided according to structure,direction of information flow,and speed of conduction.

Question 42

Cocaine produces a temporary feeling of well-being by blocking the release of dopamine.

Question 43

The nervous system is designed to detect stimuli from both the internal and external environment.

Question 44

A membrane that exhibits a membrane potential is said to be depolarized.

Question 45

Small,distinct regions of gray matter within the CNS are called nuclei.

Question 46

Action potential and membrane potential are synonymous terms.

Question 47

Glutamate is the most common excitatory neurotransmitter in the CNS.

Question 48

Many biologists believe that amino acids are among the most common neurotransmitters in the CNS.

Question 49

When "central" and "peripheral" are used as directional terms in the nervous system,a nerve fiber may be called peripheral if it extends from the cell body toward the central nervous system.

Question 50

The efferent division of the nervous system consists of mostly sensory pathways.

Question 51

Spinal nerves are considered part of the peripheral nervous system.

Question 52

There are differences between the central and peripheral nervous systems concerning the repair of damaged fibers.

Question 53

Neurons have,at best,a limited ability to repair themselves.

Question 54

Cranial nerves are considered part of the central nervous system.

Question 55

Most nerves in the human nervous system are mixed.

Question 56

Regeneration of nerve fibers is impossible,even if the cell body is intact and the fibers have a neurilemma.

Question 57

During the nerve impulse,the internal charge of the neuron becomes briefly positive.

Question 58

Bundles of unmyelinated fibers make up what is referred to as white matter.

Question 59

Action potentials travel in only one direction along a nerve fiber.

Question 60

Rapid succession stimulation of a postsynaptic neuron by a synaptic knob is called an ipsilateral reflex.

Question 61

When a neuron is resting,its membrane potential is zero.

Question 62

Cell body and perikaryon are interchangeable terms.

Question 63

In neurons,microtubules are called neurofibrils.

Question 64

Microglia are functionally and developmentally very close to neurons.

Question 65

The name for the astrocyte comes from its shape.

Question 66

Oligodendrocytes are found only around dendrites of neurons of the central nervous system.

Question 67

Whether a group of nerve fibers is called a nerve or a tract depends on its location.

Question 68

Gray fibers have no association with Schwann cells.

Question 69

Pathways from the autonomic nervous system that form the thoracic region of the spinal cord would be sympathetic pathways.

Question 70

The central nervous system is composed of efferent nerves only.

Question 71

Pathways from the autonomic nervous system that leave the central nervous system from the brain would be sympathetic pathways.

Question 72

If a membrane exhibits a membrane potential,it is said to be polarized.

Question 73

The microglia engulf and destroy microorganisms and cellular debris.

Question 74

Nerves are usually made up of a single large neuron.

Question 75

Astrocytes attempt to assist the neurons of the central nervous system in healing and regrowth.

Question 76

Part of the function of the astrocyte is to help feed the neurons.

Question 77

The peripheral nervous system includes both efferent and afferent nerves.

Question 78

Unipolar neurons have no axons.

Question 79

When "central" and "peripheral" are used as directional terms in the nervous system,a nerve fiber may be called peripheral if it extends from the cell body away from the central nervous system.

Question 80

Gray fibers probably do not have nodes of Ranvier.