Anatomy: Chapter 11 Nervous System

Which of the following is false or incorrect?

A nerve impulse occurs if the excitatory and inhibitory effects are equal.

Which of the following is true of axons?

A neuron can have only one axon, but the axon may have occasional branches along its length.

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?

A single type of channel will open, permitting simultaneous flow of sodium and potassium.

Which of the neuroglial cell types shown is the most abundant in the CNS?

Astrocytes

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

Axon

Which area would contain an abundance of vesicles containing neurotransmitter?

Axon Terminals

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

Dendrites and Soma

Which of the neuroglial cell types shown control the flow of cerebrospinal fluid within the CNS?

Ependymal Cells

Strong stimuli cause the amplitude of action potentials generated to increase.

False

The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.

False

The autonomic nervous system is under voluntary control; whereas, the somatic nervous system is involuntary.

False

The nodes of Ranvier are found only on myelinated, peripheral neuron processes.

False

The sodium-potassium pump ejects two Na+ from the cell and then transports three K+ back into the cell in order to maintain the concentration gradients for sodium and potassium.

False

Unmyelinated fibers conduct impulses faster than myelinated fibers.

False

Signals generated at a chemical synapse are said to move only in the direction of the presynaptic cell to the postsynaptic cell. Which of the following statements regarding the mechanisms determining this one way transmission is INCORRECT?

Ions diffusing out of the presynaptic cell can enter the postsynaptic cell, but cannot reenter the presynaptic cell.

Which of the following is NOT true of association neurons?

Most association neurons are confined within the peripheral nervous system (PNS).

Destruction of which of the neuroglial cell types leads to the disease multiple scleroses (MS)?

Oligodendroctyes

Which of the neuroglial cell types shown form myelin sheaths within the CNS?

Oligodendrocytes

Which of the neuroglial cell types shown are found in the PNS?

Satellite Cells and Schwann Cells

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

Schwann cells

Which of the following is true about the movement of ions across excitable living membranes?

Sodium gates in the membrane can open in response to electrical potential changes.

Which of the following is NOT a difference between graded potentials and action potentials?

Spatial summation is used to increase the amplitude of a graded potential; temporal summation is used to increase the amplitude of an action potential.

A patient is admitted to the hospital with exacerbation of multiple sclerosis (MS). She asks the nurse "Why did this have to happen to me again? I was doing so well." Why are some forms of MS characterized by periods of remission and exacerbation?

The axons are not damaged; growing numbers of sodium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume.

Select the correct statement regarding synapses.

The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.

Which of the following is not characteristic of neurons?

They are mitotic.

Which of the following is NOT true of an electrical synapse?

They are specialized for release and reception of chemical neurotransmitters.

Which of the following is not true of graded potentials?

They increase amplitude as they move away from the stimulus point.

Local anesthetics block voltage-gated Na+ channels, but they do not block mechanically gated ion channels. Sensory receptors for touch (and pressure) respond to physical deformation of the receptors, resulting in the opening of specific mechanically gated ion channels. Why does injection of a local anesthetic into a finger still cause a loss of the sensation of touch from the finger?

Touch stimulation of this sensory receptor will open the mechanically gated ion channels, but action potentials are still not initiated because propagation of an action potential requires the opening of voltage-gated Na+ channels.

A postsynaptic potential is a graded potential that is the result of a neurotransmitter released into the synapse between two neurons.

True

A stimulus traveling toward a synapse appears to open calcium ion channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane.

True

Axon diameter and degree of myelination determine nerve impulse conduction velocity.

True

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system.

True

During depolarization, the inside of the neuron's membrane becomes less negative.

True

Efferent nerve fibers may be described as motor nerve fibers.

True

Enkephalins and endorphins are peptides that act like morphine.

True

If bacteria invaded the CNS tissue, microglia would migrate to the area to engulf and destroy them.

True

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

True

Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers.

True

Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte.

True

Neurons are also called nerve cells.

True

Neurons in the CNS are organized into functional groups.

True

Opening K+ or Cl- channels in a postsynaptic membrane would produce an inhibitory postsynaptic potential (IPSP).

True

Reflexes are rapid, automatic responses to stimuli.

True

Some neurotransmitters can be either excitatory or inhibitory depending upon the receptor.

True

The action potential is caused by permeability changes in the plasma membrane.

True

The oligodendrocytes can myelinate several axons.

True

The overlapping functions of the nervous system are sensory input, integration, and motor output.

True

Unipolar neurons have axons structurally divided into peripheral and central processes.

True

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

a threshold level depolarization

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.

absolute refractory period

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

acetylcholine

Which of the following correctly describes a graded potential?

amplitude of various sizes

Which of the following describes the nervous system integrative function?

analyzes sensory information, stores information, makes decisions

Cold sores on the skin of the mouth occur when herpes simplex viruses that are dormant in neural ganglia become active and travel to the skin of the mouth. Which of the following is the mechanism by which these viruses travel from the ganglia (located within the head) to the skin of the mouth?

anterograde transport

Nerve cell adhesion molecules (N-CAMs) ________.

are crucial for the development of neural connections

A neuron that has as its primary function the job of connecting other neurons is called a(n) ________.

association neuron

Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ________.

astrocytes

Which neuroglia are the most abundant and versatile of the glial cells?

astrocytes

The part of a neuron that conducts impulses away from its cell body is called a(n) ________.

axon

Which of the following is the conducting region of the neuron?

axon

Which part of the neuron is responsible for generating a nerve impulse?

axon

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

axon hillock and down the axon

The term central nervous system refers to the ________.

brain and spinal cord

What part of the nervous system performs information processing and integration?

central nervous system

Which of the following is NOT one of the chemical classes into which neurotransmitters fall?

chlorides

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

degree of myelination of the axon

What is the role of acetylcholinesterase?

destroy ACh a brief period after its release by the axon endings

Which of the following neurotransmitters inhibits pain and is mimicked by morphine, heroin, and methadone?

endorphin

Which neurotransmitter(s) is/are the body's natural pain killer?

endorphins

What are ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid called?

ependymal cells

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

excitatory postsynaptic potential

Bipolar neurons are commonly ________.

found in the retina of the eye

What does the central nervous system use to determine the strength of a stimulus?

frequency of action potentials

Collections of nerve cell bodies outside the central nervous system are called ________.

ganglia

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________.

generator potential

An inhibitory postsynaptic potential (IPSP) is associated with ________.

hyperpolarization

Which of the following is not a function of the autonomic nervous system?

innervation of skeletal muscle

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

integration center

Which of the following types of glial cells monitors the health of neurons, and can transform into a special type of macrophage to protect endangered neurons?

microglia

Which of the following types of neurons carry impulses away from the central nervous system (CNS)?

motor

Which of the choices below describes the ANS?

motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

What structural classification describes this neuron?

multipolar

Which of the following is NOT a functional classification of neurons?

multipolar

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________.

negatively charged and contains less sodium

Which of the following are bundles of neurofilaments that are important in maintaining the shape and integrity of neurons?

neurofibrils

The substance released at axon terminals to propagate a nervous impulse is called a(n) ________.

neurotransmitter

Which of the following are gaps found along a myelin sheath?

nodes of Ranvier

Which of the following is not a chemical class of neurotransmitters?

nucleic acid

In multiple sclerosis, the cells that are the target of an autoimmune attack are the _________.

oligodendrocytes

Schwann cells are functionally similar to ________.

oligodendrocytes

Which of the following types of glial cells produces the myelin sheaths that insulate axons, or nerve fibers, in the central nervous system (CNS)?

oligodendrocytes

Immediately after an action potential has peaked, which cellular gates open?

potassium

Which of the following is NOT a type of circuit?

pre-discharge circuits

Which of the following is not a function of astrocytes?

provide the defense for the CNS

Which of the following is NOT one of the basic functions of the nervous system?

regulation of neurogenesis

The __________ is due to the difference in K+ and Na+ concentrations on either side of the plasma membrane, and the difference in permeability of the membrane to these ions.

resting membrane potential

Which neuron circuit pattern is involved in the control of rhythmic activities such as breathing?

reverberating circuit

Which of the following circuit types is involved in the control of rhythmic activities such as the sleep-wake cycle, breathing, and certain motor activities (such as arm swinging when walking)?

reverberating circuits

Which pattern of neural processing works in a predictable, all-or-nothing manner, where reflexes are rapid and automatic responses to stimuli in which a particular stimulus always causes the same response?

serial processing

Which of the following describes the excitatory postsynaptic potential?

short distance depolarization

An impulse from one nerve cell is communicated to another nerve cell via the ________.

synapse

Which criterion is used to functionally classify neurons?

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

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________.

the impulse would spread bidirectionally

A second nerve impulse cannot be generated until ________.

the membrane potential has been reestablished

Saltatory conduction is made possible by ________.

the myelin sheath

Which of the following allows us to consciously control our skeletal muscles?

the somatic nervous system

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?

voltage-gated channel