Chapter 12 Spinal cord and spinal nerves

Neurotransmitter substances are stored in vesicles located in specialized portions of the

neuron cell body.
axon.
dendrite.
postsynaptic membrane

axon

Damage to a postsynaptic membrane would _______.

increase neurotransmitter release.
decrease the release of neurotransmitter.
increase neurotransmitter production.
interfere with the ability to respond to neurotransmitter.
destroy vesicles containing neurotransmitter

interfere with the ability to respond to neurotransmitter.

A reflex that protects limbs by removing them from painful stimuli is the ___________.

stretch reflex.
crossed extensor reflex.
Golgi tendon reflex.
alternating reflex.
withdrawal reflex

withdrawal reflex

If the ventral root of a spinal nerve were cut, the regions innervated by that spinal nerve would experience complete loss of ________.

sensation.
movement.
sensation and movement.
pain.
None of these choices is correct

movement

Neurotransmitters are stored in synaptic vesicles in the:

neuron cell body
dendrite terminals
axon terminals
myelin sheath
synaptic gutter

axon terminals

Chemical synapses

have a delayed impulse transmission.
utilize gap junctions.
occur when two nerve cells are in direct contact with each other.
do not require the release of neurotransmitters

have a delayed impulse transmission

Motor neurons and interneurons are ______________ neurons.

unipolar
bipolar
multipolar
afferent

multipolar

Leak ion channels

open in response to small voltage changes.
open when a ligand binds to its receptor.
are responsible for the ion permeability of the resting plasma membrane
allow substances to move into the cell but not out.
all of the above.

are responsible for the ion permeability of the resting plasma membrane

myelin sheaths of PNS neurons are produced by _________.

Schwann cells.
oligodendrocytes.
ependymal cells.
leukocytes.

Schwann cells

Presynaptic inhibition is the opposite of __________.

coding.
integration.
recruitment.
summation.
facilitation

facilitation

The cutaneous sensory distribution of a spinal nerve can be mapped as a __________.

dermatome.
plexitome.
microtome.
myotome.
superdome

dermatome

The branch of a spinal nerve that innervates deep muscles on the dorsal thorax is the _______.

ramus communicans.
lateral ramus.
dorsal ramus.
ventral ramus.
medial ramus.

dorsal ramus

The tendon reflex

causes a muscle that is being stretched to contract.
makes the contralateral motor neurons contract.
makes the ipsilateral motor neurons relax.
prevents overcontraction of a muscle.
causes a tendon to contract.

prevents over contraction of a muscle

Compared to the inside of the resting plasma membrane, the outside surface of the membrane is

positively charged.
electrically neutral.
negatively charged.
continuously reversing so that it is positive one second and negative the next.
negatively charged whenever the sodium-potasisium pump is operating.

positively charged

Action potential transmission in the PNS is decreased if which cells are damaged?

astrocytes
microglia
oligodendrocytes
Schwann cells

Schwann cells

Opening of ______ gates produces an ______.

chloride; IPSP
sodium; IPSP
calcium; IPSP
potassium; EPSP
calcium and sodium; IPSP

chloride; IPSP

A neuron that conducts pain sensations to the central nervous system would be classified as a(n) _________.

motor neuron.
sensory or afferent neuron.
efferent neuron.
association neuron.
interneuron.

sensory or afferent

Overproduction of cerebrospinal fluid could be the result of over-activity of the ________.

astrocytes.
microglial cells.
oligodendrocytes.
macrophages.
ependymal cells.

ependymal cells

Local hyperpolarization in a synapse is called a(an) ____________.

excitatory postsynaptic potential.
resting membrane potential.
inhibitory postsynaptic potential.
gap junction potential.
action potential.

inhibitory postsynaptic potential

If the dorsal root of a spinal nerve were to be cut, the individual would _______.

have no motor responses for that nerve.
have no sensory perception from that nerve.
have no reflexes involving that nerve.
Both have no sensory perception from that nerve and have no reflexes involving that nerve are correct

Both have no sensory perception from that nerve and have no reflexes involving that nerve are correct

In a chemical synapse,

action potentials in the presynaptic terminal cause voltage-gated Ca2+ channels to open.
neurotransmitters can cause ligand-gated Na+ channels to open.
neurotransmitters can be broken down by enzymes.
neurotransmitters can be taken up by the presynaptic terminal.
all of the above.

all

The same neurotransmitter may produce different effects on neurons because of differences in the _____________.

type of receptors on the postsynaptic membranes of neurons.
strength of the action potential.
amount of neurotransmitter.
size of the neurons.
potassium channels.

type of receptors on the postsynaptic membranes of neurons.

Which of the following statements concerning the structure of spinal nerves is true?

The ventral root contains motor or efferent fibers.
The ventral root has a prominent root ganglion.
Rootlets from the surface of the spinal cord form the dorsal and ventral rami.
Each spinal nerve is formed by the union of a cranial nerve and a spinal nerve.
Spinal nerves do not have specific cutaneous distributions.

The ventral root contains motor or efferent fibers.

Sensory neurons

are multipolar and carry impulses toward the CNS.
are pseudounipolar and carry impulses toward the CNS.
are bipolar and carry impulses away from the CNS.
are multipolar and carry impulses away from the CNS

are pseudounipolar and carry impulses toward the CNS

A nurse pricks your finger to type your blood. You flinch at the pain, pulling your hand back. This is called the

pain reflex.
stretch (myotatic) reflex.
flexor (withdrawal) reflex.
tendon reflex.
crossed extension reflex

flexor (withdrawal) reflex

Which of the following is a visceral sense modality?

pain
touch
temperature
proprioception
balance

pain

A dermatome

is the area of skin supplied by a pair of spinal nerves.
exists for each spinal nerve except C1
can be used to locate the site of spinal cord or nerve root damage.
all of the above.

all of the above

Which of the following branches of a spinal nerve have somas of solely sensory neurons?

posterior (dorsal) root
anterior (ventral) root
posterior ramus
anterior ramus
meningeal branch

posterior (dorsal) root

Which of the following is mismatched?

central nervous system - brain
autonomic nervous system - sympathetic and parasympathetic divisions
peripheral nervous system - spinal nerves
somatic nervous system - sensory division of PNS
peripheral nervous system - sensory and motor divisions

somatic nervous system - sensory division of PNS

Chemical synapses are characterized by ___________.

the release of neurotransmitter by the presynaptic terminal.
protein channels that connect the pre- and postsynaptic cells.
the presence of receptors for neurotransmitters on the presynaptic terminal.
the absence of gap junctions.
receptors located only on the presynaptic terminal

the release of neurotransmitter by the presynaptic terminal.

Arrange the events of synaptic transmission in correct sequence.

(1)sodium ions diffuse into the cell and cause a local potential
(2)neurotransmitter binds with receptor on postsynaptic cell
(3)neurotransmitter diffuses across the synaptic cleft
(4)membrane permeability to sodium ions on postsynaptic cell increases
(5)action potential causes release of neurotransmitter

5, 2, 3, 4, 1
5, 2, 3, 1, 4
5, 3, 4, 1, 2
5, 4, 3, 2, 1
5, 3, 2, 4, 1

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action potential causes release of neurotransmitter

neurotransmitter diffuses across the synaptic cleft

neurotransmitter binds with receptor on postsynaptic cell


membrane permeability to sodium ions on postsynaptic cell increases

sodium ions diffuse into the cell and cause a local potential

Stimulation of the Golgi tendon organs result in which of the following changes in the reflex arc?

stimulation of a stimulatory association neuron
stimulation of an inhibitory neuron
decreased action potentials in alpha motor neurons
contraction of skeletal muscle fibers
stimulation of an inhibitory neuron and decreased action potentials in alpha motor neurons

stimulation of an inhibitory neuron and decreased action potentials in alpha motor neurons

The brain and the spinal cord comprise the __________ nervous system.

somatic
parasympathetic
autonomic
peripheral
central

central

Which of the following is not true of neuromodulators? They may

Influence synaptic effectiveness
Act through second messengers
Be released with neurotransmitters
Be the same molecules as neurotransmitters
Be none of the choices

none of the choices

Axons of sensory neurons synapse with the cell bodies of interneurons in the _____________ of spinal cord gray matter.

anterior horn
lateral horn
posterior horn
gray commissure
lateral funiculi

posterior horn

Inhibitory postsynaptic potentials (IPSPs) are associated with ____________.

depolarization of the cell membrane.
repolarization of the cell membrane.
hyperpolarization of the cell membrane.
no change of the cell membrane potential.
no change of the threshold

hyperpolarization of the cell membrane

The spinal cord is divided into all of the following regions except ___________.

cervical.
thoracic.
lumbar.
pelvic.
sacral.

pelvic

The peripheral nervous system includes the ___________.

brain.
spinal cord.
cranial nerves.
blood-brain barrier.
cerebellum.

cranial nerves

The motor (efferent) division of the peripheral nervous system ___________.

is a division of the CNS.
regulates the digestion of food.
transmits impulses from the CNS to skeletal muscle.
has nerve cell bodies located in ganglia near the spinal cord and brain.
detects a stimulus.

transmits impulses from the CNS to skeletal muscle

Ventral rami of some spinal nerves join with each other to form a _________.

ganglion.
dermatome.
cord.
plexus.
nerve.

plexus

Which of the following spinal nerve groups is incorrect?

cervical - 7
thoracic - 12
lumbar - 5
sacral 5

cervical - 7

ventral rami of the spinal nerves form nerve plexuses in all regions except

the thoracic region.
the brachial region.
the cervical region.
the lumbar region.
the sacral region

the thoracic region

Clusters of nerve cell bodies within the peripheral nervous system are

ganglia.
fascicles.
nuclei.
laminae

ganglia

Which of these events occurs when a person steps on a tack with the right foot?

The right foot is pulled away from the tack because of the Golgi tendon reflex.
The left leg is extended to support the body because of the stretch reflex.
The flexor muscles of the right thigh contract, and the extensor muscles of the right thigh relax because of reciprocal innervation.
Extensor muscles contract in both thighs because of the crossed extensor reflex.

The flexor muscles of the right thigh contract, and the extensor muscles of the right thigh relax because of reciprocal innervation.

Synaptic vesicles contain neurotransmitters and are present in the __________.

dendrites.
cell body.
axolemma.
presynaptic terminals or terminal boutons.
trigger zone.

presynaptic terminals or terminal boutons

A neuroglial cell that is a major component of the blood-brain barrier is the ___________.

astrocyte.
microglial cell.
oligodendrocyte.
ependymal cell.
macrophage.

astrocyte

Cells found in the choroid plexuses that secrete cerebrospinal fluid are

astrocytes.
microglia.
ependymal cells.
oligodendrocytes.
Schwann cells.

ependymal cells

Action potentials are conducted more rapidly

in small-diameter axons than in large-diameter axons.
in unmyelinated axons than in myelinated axons.
along axons that have nodes of Ranvier.
all of the above.

along axons that have nodes of Ranvier

If the permeability of the plasma membrane to K+ increases, resting membrane potential _____________. This is called _____________.

increases, hyperpolarization
increases, depolarization
decreases, hyperpolarization
decreases, depolarization

increases, hyperpolariations

In convergent pathways,

the response of the postsynaptic neuron depends on the summation of EPSPs and IPSPs.
a smaller number of presynaptic neurons synapse with a larger number of postsynaptic neurons.
information transmitted in one neuronal pathway can go into two or more pathways.
all of the above.

the response of the postsynaptic neuron depends on the summation of EPSPs and IPSPs

Presynaptic inhibition is the opposite of __________.

coding.
integration.
recruitment.
summation.
facilitation.

facilitation

The central nervous system includes the _________.

ganglia.
spinal cord.
spinal nerves.
cranial nerves.
sensory receptors.

spinal cord

When a neurotransmitter binds to its receptor and increases the permeability of the postsynaptic membrane to sodium ions, ____________.

the membrane will be hyperpolarized.
more chloride ions will also diffuse into the cell.
an excitatory postsynaptic potential (EPSP) will result.
the membrane will become impermeable to potassium ions.
the sodium ions diffuse out of the cell.

an excitatory postsynaptic potential (EPSP) will result.

If five action potentials arrive at the same synapse in very close succession, which of the following would occur?

The direction of the action potential is reversed.
Temporal summation occurs.
Spatial summation occurs.
Hyperpolarization occurs.
Depolarization always occurs

Temporal summation occurs

The motor root of a spinal nerve is also referred to as the ___________.

afferent root.
dorsal root.
posterior root.
ventral root.
sensory root

ventral root

The muscles of the back contract to straighten so that you sit at a more erect posture and subsequently the muscles are suddenly stretched as you nod off. Which of the following best represents the sequence of events when you start to nod off?

(1)muscles of the back are stretched
(2)the muscle spindle is stretched
(3)action potentials in sensory neurons of the muscle spindles increase
(4)action potentials in alpha motor neurons of skeletal muscle fibers increase
(5)skeletal muscle of the back contract

1, 2, 3, 4, 5
1, 5, 2, 3, 4
1, 5, 3, 2, 4
5, 2, 3, 4, 1
4, 5, 3, 2, 1

(1)muscles of the back are stretched
(2)the muscle spindle is stretched
(3)action potentials in sensory neurons of the muscle spindles increase
(4)action potentials in alpha motor neurons of skeletal muscle fibers increase
(5)skeletal muscle of the back contract

Which of these statements about ion movement through the plasma membrane is true?

Movement of Na+ out of the cell requires energy (ATP).
When Ca2+ binds to proteins in ion channels, the diffusion of Na+ into the cell is inhibited.
There are specific ion channels that regulate the diffusion of Na+ through the plasma membrane.
All of the above.

all

Hyperpolarization in the postsynaptic cell is caused by ___________.

excitatory postsynaptic potentials.
inhibitory postsynaptic potentials.
movement of K+ out of the cell.
Both inhibitory postsynaptic potentials and movement of K+ out of the cell are correct

Both inhibitory postsynaptic potentials and movement of K+ out of the cell are correct

The bundle of nerve roots that occupy the vertebral canal from L2 to S5 is called the _________.

medullary cone.
cauda equina.
lumbar enlargement.
cervical enlargement.
spinal cord.

cauda equina

Overproduction of cerebrospinal fluid could be the result of over-activity of the ________.

astrocytes.
microglial cells.
oligodendrocytes.
macrophages.
ependymal cells

ependymal cells

Which of the following is false?

The dorsal root of the spinal cord conveys sensory (afferent) nerve impulses to the spinal cord.
The posterior horn of the cord contains the cell bodies of motor neurons.
The ventral root is formed by the axons of neurons in the lateral and anterior horns.
The dorsal and ventral roots unite to form spinal nerves.
The ventral root of the spinal cord conveys motor (efferent) nerve impulses away from the spinal cord.

The posterior horn of the cord contains the cell bodies of motor neurons

The absolute refractory period

limits how many action potentials can be produced during a given period of time.
prevents an action potential from starting another action potential at the same point on the plasma membrane.
is the period of time when a strong stimulus can initiate a second action potential.
both a and b.
all of the above

both a and b

Given these components of a reflex arc:
(1) effector organ
(2) interneuron
(3) motor neuron
(4) sensory neuron
(5) sensory receptor
Choose the correct order an action potential follows after a sensory receptor is stimulated.

5,4,3,2,1
5,4,2,3,1
5,3,4,1,2
5,2,4,3,1
5,3,2,1,4

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sensory receptor
sensory neuron
interneuron
motor neuron
effector organ

Which of the following statements concerning the structure of spinal nerves is true?

The ventral root contains motor or efferent fibers.
The ventral root has a prominent root ganglion.
Rootlets from the surface of the spinal cord form the dorsal and ventral rami.
Each spinal nerve is formed by the union of a cranial nerve and a spinal nerve.
Spinal nerves do not have specific cutaneous distributions.

The ventral root contains motor or efferent fibers.

The peripheral nervous system includes the:

sensory nerves and motor nerves
brain and spinal cord
medulla oblongata and meninges
limbic system and parasympathetic division
none of the above

sensory nerves and motor nerves

In the patellar tendon reflex arc, the patellar ligament is stretched, which stretches the quadriceps femoris muscle of the thigh. This reflex will cause the quadriceps femoris to

contract and the antagonist muscles, the hamstrings, to relax.
contract and the hamstrings also to contract.
relax and the hamstrings to contract.
relax and the hamstrings also to relax.
relax without any effect on the hamstrings

contract and the antagonist muscles, the hamstrings, to relax

A reflex response accompanied by the conscious sensation of pain is possible because of

convergent pathways.
divergent pathways.
a reflex arc that contains only one neuron.
sensory perception in the spinal cord

divergent pathways

Rapid removal or destruction of neurotransmitter in the synaptic cleft ____________.

may affect the ability of the postsynaptic membrane to generate action potentials.
generates local potentials in the presynaptic terminal.
is necessary for synaptic transmission.
may lead to action potentials.
may stop exocytosis.

may affect the ability of the postsynaptic membrane to generate action potentials

Receptor molecules ___________.

are nonspecific.
are always lipids.
attach to the synaptic cleft.
determine whether a neurotransmitter will be excitatory or inhibitory.
are not attached to ligand-gated channels.

determine whether a neurotransmitter will be excitatory or inhibitory.

Which portion of a reflex arc is most likely to be located entirely within the central nervous system?

sensory neuron
motor neuron
effector cell
interneuron
receptor cell

interneuron

Intercostal nerves are formed from the ________.

thoracic plexus.
ventral rami of thoracic spinal nerves.
dorsal rami of thoracic spinal nerves.
rami communicans of the thoracic spinal nerves.
cervical plexus.

ventral rami of thoracic spinal nerves.

This figure shows a dermatome map. A patient with no sensation in the left thumb would probably have a nerve damaged in _____________.
T1.
T5.
C5.
C6.
L3.

c6

Monamine oxidase inhibitors (MAO inhibitors) ________.

prevent synaptic transmission.
enhance the breakdown of norepinephrine.
enhance the binding of norepinephrine to its receptors.
prevent the release of norepinephrine by the presynaptic terminal.
have no effect on the action of norepinephrine.

enhance the binding of norepinephrine to its receptors

Reflex arcs __________.

require the actions of the brain.
do not utilize somatic motor nerves.
generally rely on the actions of the hypothalamus.
may have a single synapse.

may have a single synapse

You go to the movies after a long day and you begin to nod off as soon as the movie starts. Your head starts to lower a little but this reflex causes your head to rise. This is called the

tendon reflex.
crossed extension reflex.
withdrawal reflex.
stretch (myotatic) reflex.
flexor (withdrawal) reflex

stretch myotatic reflex

Neuroglia that are phagocytic within the central nervous system are

oligodendrocytes.
microglia.
ependymal cells.
astrocytes.
Schwann cells

microglia

The resting membrane potential results when the tendency for _____________ to diffuse out of the cell is balanced by its attraction to opposite charges inside the cell

K+

Decreasing the extracellular concentration of K+ affects the resting membrane potential by causing

hyperpolarization

Which of these terms is correctly matched with its definition or description
a. depolarization; membrane potential becomes more negative
b. hyperpolarization; membrane potential becomes more negative
c. hypopolarization ; membrane potential becomes more negative

b

The major function of the sodium-potassium pump is to ;
a. pump Na+ into the K+ out of the cell
b. generate the resting membrane potential
c maintain the concentration gradients of Na+ and K+ across the plasma membrane
d. oppose any tendency of the cell to undergo hyperpolarization

c

Graded potentials
a. spread over the plasma membrane in decremental fashion.
b. are not propagated for long distances
c. are confined to a small region of the plasma membrane
d. can summate
e. all of these are correct

all

During the depolarization phase of an action potential, the permeability of the membrane
a. to K+ is greatly increased
b to Na+ is greatly increased
c. to Ca2+ is greatly increased
d. unchanged

b

During repolarization of the plasma membrane
a. Na+ diffuses into the cell
b. Na+ diffuses out of the cell
c. K+ diffuses into the cell
d. K+ diffuses out of the cell

d

A subthreshold stimulus
a. produces an afterpotential
b. produces a graded potential
c. causes and all-or-none response
d. produces more action potentials than a submaximal stimulus

produces a graded potential

An inhibitory presynaptic neuron can affect a postsynaptic neuron by
a. producing an IPSP in the postsynaptic neuron
b. hyperpolarizing the plasma membrane of the postsynaptic neuron
c. causing K+ to diffuse out of the postsynaptic neuron
d. causing Cl- to diffuse into the postsynaptic neuron
e. all of these are correct

all

In convergent pathways
a. the response of the postsynaptic neuron depends on the summation of EPSPs and IPSPs
b. a smaller number of presynaptic neurons synapse with a larger number of postsynaptic neurons
information transmitted in ne neuronal pathway can go into two or more pathways
d. all are correct

the response of the postsynaptic neuron depends on the summation of EPSPs and IPSPs

Summation
a. is caused by combining two or more graded potentials
b. occurs at the trigger zone of the postsynaptic neuron
c. results in an action potential if it reaches the threshold potential
d. can occur when two action potentials arrive in close succession at a single presynaptic terminal
e. all of these are correct

all of these are correct