Anatomy and Physiology chapter 11-13

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

sense the internal and external environments

integrate sensory information

direct long-term functions, such as growth

control peripheral effectors

coordinate voluntary and involuntary activities

direct long-term functions, such as growth

The ________ nervous system is composed of the brain and spinal cord.

efferent

afferent

central

peripheral

autonomic

central

The ________ nervous system controls the skeletal muscles.

afferent

somatic

parasympathetic

sympathetic

autonomic

somatic

The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.

automatic

autonomic

sensory division of the peripheral

somatic

special sensory

autonomic

The basic functional unit of the nervous system is the

nerve.

neuron.

brain.

spinal cord.

glial cell.

neuron

The plasma membrane of an axon is called the

axokaryon.

axon terminal.

axoplasm.

axon hillock.

axolemma.

axolemma

The cytoplasm that surrounds the nucleus of a neuron is called the

perikaryon.

protoplasm.

neuroplasm.

sarcoplasm.

nucleoplasm.

perikaryon

Clusters of RER and free ribosomes in neurons are called

neurofilaments.

Nissl bodies.

neurofibrils.

microglia.

perikaryon.

Nissl bodies

The axon is connected to the cell body at the

axon hillock.

telodendria.

synapse.

collateral branches.

synaptic knobs.

axon hillock

Branches that may occur along an axon are called

synapses.

hillocks.

collateral branches.

dendrites.

synaptic knobs.

collateral branches

Axons terminate in a series of fine extensions known as

knobs.

dendrites.

synapses.

telodendria.

collateral branches.

telodendria

Neurotransmitter for release is stored in synaptic

knobs.

mitochondria.

neurosomes.

vesicles.

telodendria.

vesicles

The site of intercellular communication between neurons is the

synapse.

telodendria.

collateral branch.

hillock.

synaptic knob.

synapse

Most CNS neurons lack centrioles. This observation explains

why CNS neurons cannot regenerate.

the ability of neurons to generate an action potential.

the ability of neurons to communicate with each other.

the ability of neurons to produce a resting potential.

why CNS neurons grow such long axons.

why CNS neurons cannot regenerate

The most common neurons in the CNS, including the motor neurons that control skeletal muscles, are:

anaxonic neurons.

bipolar neurons.

multipolar neurons.

unipolar neurons.

multipolar neurons

Most sensory neurons of the PNS are of which type?

bipolar neurons

anaxonic neurons

unipolar neurons

multipolar neurons

unipolar neurons

________ monitor the position of skeletal muscles and joints.

Exteroceptors

Interoceptors

Proprioceptors

Somatic sensory receptors

Special sensory receptors

Proprioceptors

________ provide information about the external environment.

Interneurons

Interoceptors

Exteroceptors

Somatic sensory receptors

Proprioceptors

Exteroceptors

The most abundant class of neuron in the central nervous system is

unipolar.

multipolar.

pseudopolar.

bipolar.

anaxonic.

multipolar

Which of the following activities or sensations is not monitored by interoceptors?

cardiovascular activities

sight

activities of the digestive system

joint movement

urinary activities

sight

Neuron cell bodies in the PNS are clustered together in masses called

nucleii.

ganglia.

peripheral nerves.

nerves.

the spinal cord

ganglia

Which glial cells form an epithelium that lines a fluid-filled passageway within the spinal cord and brain?

ependymal cells

astrocytes

oligodendrocytes

microglia

ependymal cells

Oligodendrocytes:

are the myelin-producing glial cells in the CNS.

maintain the blood-brain barrier.

assist in producing, circulating, and monitoring the CSF.

are the myelin-producing glial cells in the PNS.

are the myelin-producing glial cells in the CNS

The glial cells in the central nervous system that form scar tissue after central nervous system injury are the

satellite cells.

microglia.

oligodendrocytes.

ependymal cells.

astrocytes.

astrocytes

Small, wandering cells that engulf cell debris and pathogens in the CNS are called

microglia.

astrocytes.

ependymal cells.

satellite cells.

oligodendrocytes.

microglia

The largest and most numerous neuroglia in the CNS that absorb and recycle neurotransmitters are the

astrocytes.

tanycytes.

oligodendrocytes.

microglia.

ependymocytes.

astrocytes

Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because

the astrocytes isolate the CNS by forming a blood-brain barrier.

Schwann cells form a capsule around neurons.

ependymal cells restrict the flow of interstitial fluid between the capillaries and the neurons.

oligodendrocytes form a continuous myelin sheath around the axons.

the neurilemma is impermeable to most molecules.

the astrocytes isolate the CNS by forming a blood-brain barrier

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.

grey

dark

yellow

clear

white

white

Regions of the CNS where neuron cell bodies dominate constitute the ________ matter.

dark

clear

yellow

white

grey

grey

What is the first step in Wallerian degeneration?

The Schwann cells wrap around the axon as it elongates.

The Schwann cells proliferate along the path of the original axon.

The axon regrows into the site of injury.

The axon and myelin degenerate and fragment.

The axon and myelin degenerate and fragment.

Which glial cells are found only in the PNS?

Schwann cells

ependymal cells

oligodendrocytes

microglia

Schwann cells

Glial cells that surround the neurons in ganglia are

astrocytes.

microglia.

ependymal cells.

oligodendrocytes.

satellite cells.

satellite cells

______ are sensory structures that detect changes in the internal or external environment.

Receptors

_____ _____ _____ monitor internal organs.

Visceral sensory receptors

Which division of the PNS brings information to the CNS?

sensory division

______ ______ ______ provide position, touch, pressure, pain, and temperature sensations.

Somatic sensory receptors

_______ _____ ______ provide sensations of smell, taste, vision, balance, and hearing.

Special sensory receptors

The _____ ______ of the PNS carries motor commands from the CNS to peripheral tissues and systems.

motor division

The _____ ______ _____ controls skeletal muscle contractions.

somatic nervous system (SNS)

The _____ _____ _____ automatically regulates smooth muscle, cardiac muscle, glands, and adipose tissue.

autonomic nervous system (ANS)

______ are target organs whose activities change in response to neural commands.

Effectors

______ receive stimuli from the environment or from other neurons.

Dendrites

The _____ of a neuron contains the nucleus and other organelles.

cell body

Which part of a neuron carries information toward other cells?

axon

The ______ is a specialized portion of the plasma membrane that surrounds the cytoplasm of the axon.

axolemma

The ______ contains neurofibrils, neurotubules, small vescicles, lysosomes, mitochondria, and various enzymes.

axoplasm

The cytoplasm surrounding the nucleus is called:

perikaryon

The main axon trunk ends in a series of fine extensions, or ______.

telodendria

_____ ______ is where the neuron communicates with other cells.

axon terminals (synaptic terminals)

What is a synapse?

It is a specialized site of the axon terminal where the neuron communicates with another cell.

Why is a CNS neuron not usually replaced after it is injured?

Most CNS neurons lack centrioles and cannot divide.

______ _____ are small and lack anatomical features that distinguish dendrites from axons; their functions are poorly understood.

Anaxonic neurons

______ ______ have two distinct processes; they are rare but occur in special sense organs, where they relay information about sight, smell, or hearing from receptor cells to other neurons.

Bipolar neurons

In a _____ ______ the dendrites and axon are continuous, and the cell body lies off to the side.

unipolar neuron

______ ______ have two or more dendrites and a single axon; most common neurons in the CNS.

Multipolar neurons

_______ fibers carry sensory information to the CNS.

- afferent

- efferent

Afferent

______ fibers are axons that carry instructions from to CNS to peripheral tissues.

- afferent

- efferent

Efferent

A ______ is a collection of neuron cell bodies in the PNS.

ganglion

_____ _____ _____ innervate skeletal muscles.

Somatic motor neurons

______ _____ innervate skeletal muscle fiber at neuromuscular junctions.

Peripheral nerve

_____ _____ ____ innervate all peripheral effectors other than skeletal muscles.

Visceral motor nerves

These type of cells support and protect neurons in the PNS and CNS and make up about half the volume of the nervous system.

neuroglia

What are the different neuroglia of the CNS?

ependymal cells, microglia, astrocytes, and oligodendrocytes

Which glial cell protects the CNS from chemicals and hormones circulating in the blood?

astrocytes

______ are embryologically related to monocytes and macrophages.

Microglia

_______ provide a structural framework within the CNS by stabilizing the positions of axons.

Oligodendrocytes

What are the function of Shwann cells?

insulate, maintain, and myelinate axons

_______ _____ surround neuron cell bodies in PNS ganglia. They regulate the environment around the neurons, much as astrocytes do in the CNS.

Satellite cells

Schwann cells participate in the repair of damaged nerves in the PNS. the repair process, which ofther fails to restore full function, is known as ______ ______.

Wallerian degeneration

Identify the neuroglia of the PNS.

Schwann cells and satellite cells

Describe the neurilemma.

The outer suface of the Schwann cell

In which part of the nervous system does Wallerian degeneration occur?

PNS of damaged nerves

The separation of plus and negative charges across the membrane creates a ________ difference, or voltage.

potential

kinetic

graded

concentration

gradient

potential

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?

Threshold potential

Resting membrane potential (RMP)

Action potential

Positive membrane potential

Resting membrane potential (RMP)

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

Sodium-potassium ATPases

Voltage-gated channels

Ligand-gated channels

Leak channels

Leak channels

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

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

There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.

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

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

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

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

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

The Na+-K+ pumps transport more K+ into cells than Na+ out of cells.

Ligand-gated cation channels favor a greater influx of Na+ than K+.

There are many more voltage-gated K+ channels than voltage-gated Na+ channels

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

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.

The presence of concentration gradients and leak channels

The presence of concentration gradients and voltage-gated channels

The presence of a resting membrane potential and leak channels

The presence of concentration gradients and Na+-K+ pump

The presence of concentration gradients and leak channels

What prevents the Na+ and K+ gradients from dissipating?

H+-K+ ATPase

Na+ and K+ leaks

Na+ cotransporter

Na+-K+ ATPase

Na+-K+ ATPase

In a typical undisturbed cell, the extracellular fluid (ECF) contains high concentrations of sodium ions and chloride ions, whereas the cytosol contains ______.

high concentrations of potassium ions and negatively charged proteins

low concentrations of potassium ions and negatively charged proteins

low concentrations of potassium ions and high concentrations of chloride ions

high concentrations of both potassium ions and sodium ions

high concentrations of potassium ions and negatively charged proteins

In an undisturbed cell, which of the following can diffuse through leak channels?

K+ and Pr-

Na+ and K+

Na+ and Pr-

Pr-

Na+ and K+

The sodium-potassium ion exchange pump

moves sodium and potassium opposite to the direction of their electrochemical gradients.

depends on a hydrogen gradient for energy.

transports potassium ions out of the cell during repolarization.

is not involved in producing the resting membrane potential.

transports sodium ions into the cell during depolarization.

moves sodium and potassium opposite to the direction of their electrochemical gradients

________ channels open or close in response to binding specific molecules.

Activated

Mechanically-gated

Leak

Voltage-gated

Chemically gated

Chemically gated

The resting potential of an undisturbed neuron occurs under which of the following conditions?

+30 mV

+10 mV

-70 mV

-90 mV

-70 mV

Which of the following would occur in a resting membrane after a stimulus is applied?

The closing of potassium channels will cause hyperpolarization.

The opening of sodium channels will cause hyperpolarization.

The opening of sodium channels will cause depolarization.

The opening of potassium channels will cause depolarization.

The opening of sodium channels will cause depolarization.

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons?

The axon would be unable to generate action potentials.

Action potentials would lack a repolarization phase.

Neurons would depolarize more rapidly.

The absolute refractory period would be shorter than normal.

None, because the chemically gated sodium channels would still function.

The axon would be unable to generate action potentials.

A shift of the resting transmembrane potential toward 0 mV is called

depolarization.

repolarization.

hyperpolarization.

hypopolarization.

non-polarization.

depolarization

Opening of sodium channels in the axon membrane causes

depolarization.

repolarization.

hyperpolarization.

increased positive charge inside the membrane.

both depolarization and increased positive charge inside the membrane.

both depolarization and increased positive charge inside the membrane

Where do most action potentials originate?

Cell body

Initial segment

Nodes of Ranvier

Axon terminal

Initial segment

What opens first in response to a threshold stimulus?

Voltage-gated K+ channels

Ligand-gated Cl- channels

Voltage-gated Na+ channels

Ligand-gated cation channels

Voltage-gated Na+ channels

What characterizes depolarization, the first phase of the action potential?

The membrane potential changes to a much more negative value.

The membrane potential changes to a less negative (but not a positive) value.

The membrane potential changes from a negative value to a positive value.

The membrane potential reaches a threshold value and returns to the resting state

The membrane potential changes from a negative value to a positive value.

What characterizes repolarization, the second phase of the action potential?

Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.

Before the membrane has a chance to reach a positive voltage, it repolarizes to its negative resting value of approximately -70 mV.

As the membrane repolarizes to a negative value, it goes beyond the resting state to a value of -80 mV.

Once the membrane depolarizes to a threshold value of approximately -55 mV, it repolarizes to its resting value of -70 mV.

Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.

What event triggers the generation of an action potential?

The membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV.

The membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV.

The membrane potential must return to its resting value of -70 mV from the hyperpolarized value of -80 mV.

The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.

The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.

What is the first change to occur in response to a threshold stimulus?

Voltage-gated K+ channels change shape, and their activation gates open.

Voltage-gated Na+ channels change shape, and their activation gates open.

Voltage-gated Na+ channels change shape, and their inactivation gates close.

Voltage-gated Ca2+ channels change shape, and their activation gates open.

Voltage-gated Na+ channels change shape, and their activation gates open.

The following are the main steps in the generation of an action potential.

1. Sodium channels are inactivated.

2. Voltage-gated potassium channels open and potassium moves

out of the cell, initiating repolarization.

3. Sodium channels regain their normal properties.

4. A graded depolarization brings an area of an excitable membrane to threshold.

5. A temporary hyperpolarization occurs.

6. Sodium channel activation occurs.

7. Sodium ions enter the cell and depolarization occurs.

What is the proper sequence of these events?

4, 6, 7, 1, 2, 3, 5

6, 7, 4, 1, 2, 3, 5

4, 2, 5, 6, 7, 3, 1

2, 4, 6, 7, 1, 3, 5

4, 6, 7, 3, 2, 5, 1

4, 6, 7, 1, 2, 3, 5

The all-or-none principle states that

only motor stimuli can activate action potentials.

all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

the greater the magnitude of the stimuli, the greater the magnitude of the action potential.

all stimuli will produce identical action potentials.

only sensory stimuli can activate action potentials.

all stimuli great enough to bring the membrane to threshold will produce identical action potentials

The minimum stimulus required to trigger an action potential is known as the

graded potential.

resting potential.

membrane potential.

threshold.

refractory period.

threshold

What type of conduction takes place in unmyelinated axons?

Synaptic transmission

Saltatory conduction

Continuous conduction

Electrical conduction

Continuous conduction

An action potential is self-regenerating because __________.

depolarizing currents established by the influx of Na+‎ flow down the axon and trigger an action potential at the next segment

repolarizing currents established by the efflux of Na+‎ flow down the axon and trigger an action potential at the next segment

repolarizing currents established by the efflux of K+‎ flow down the axon and trigger an action potential at the next segment

depolarizing currents established by the influx of K+‎ flow down the axon and trigger an action potential at the next segment

depolarizing currents established by the influx of Na+‎ flow down the axon and trigger an action potential at the next segment

Why does regeneration of the action potential occur in one direction, rather than in two directions?

The inactivation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just fired an action potential.

The activation gates of voltage-gated K+‎ channels open in the node, or segment, that has just depolarized.

The activation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just depolarized.

The inactivation gates of voltage-gated K+‎ channels close in the node, or segment, that has just fired an action potential.

The inactivation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just fired an action potential.