Anatomy and Physiology Chapter 11

Which of the following statements regarding glial cells is false?

Glial cells produce action potentials for skeletal muscles

Which inhibitory neurotransmitter is blocked in strychnine poisoning?

Glycine

Identify the statement that best differentiates gray matter and white matter.

Gray matter consists of cell bodies and dendrites whereas white matter consists mostly of myelinated axons

Inhibitory postsynaptic potentials (IPSPs) are associated with which of the following?

Hyperpolarization of the plasma membrane

The nervous system

Interprets or assesses informationMonitors internal and external stimuliTransmits information in the form of action potentialsMaintains homeostasis

The central nervous system

Is the site for processing information

A substance is found to have the same effect as acetylcholinesterase, but acts at a much faster rate. What effect would this substance have at a cholinergic synapse?

It would greatly reduce synaptic communication by depleting ACh levels in the synaptic cleft.

In hyperpolarization

K+ tend to diffuse out of the cell

Depolarization of the nerve plasma membrane occurs when there is a rapid influx (inflow) of __________.

Na+

Gaps or interruptions in the myelin sheath are called __________.

Nodes of Ranvier

What occurs during hyperpolarization of a neuron plasma membrane?

Potassium ions are leaving the cell.

Why isn't an action potential transmitted from a postsynaptic membrane to a presynaptic terminal?

Presynaptic terminals have no acetylcholine receptors

What type of neuroglial cells provide support and nutrition to sensory ganglia in the PNS?

Satellite cells

Schwann cells differ from oligodendrocytes in which of the following ways?

Schwann cells form a myelin sheath around a portion of only one axon, while oligodendrocytes can surround portions of several axons.

Theresa has been diagnosed with a disease that demyelinates the somatic motor neurons. This disease is destroying the __________ associated with neurons that control __________.

Schwann cells; skeletal muscle

If a neuron is prevented from sending a neurotransmitter across a synapse to another cell, which neuron property is being inhibited?

Secretion

Which of these does not contribute to the cessation of the signal in a synaptic transmission?

Synaptic vesicles secrete neurotransmitter by exocytosis.

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

Temporal summation occurs.

Most metabolic and regulatory functions in a neuron happen where?

The cell body or soma

Neurons that have a single axon and a single dendrite are __________.

bipolar

A local anesthetic such as Novocaine decreases membrane permeability to Na+. The use of this anesthetic will

block sensory input into the CNS.

The function of acetylcholinesterase is to

breakdown acetylcholine in the synapse.

White matter is composed of

bundles of myelinated axons

Neurotransmitters

cause the production of action potentials in the postsynaptic membrane.

The autonomic nervous system

has two sets of neurons in a series.

When two or more presynaptic neurons synapse with a single postsynaptic neuron in the CNS, a/an __________ pathway is formed.

convergent

Receptor molecules in synapses

have a high degree of specificity.

The enteric nervous system consists of plexuses within the walls of the ________

digestive tract

Sensory neurons carrying action potentials from pain receptors synapse within the spinal cord with interneurons. These interneurons synapse with motor neurons leading back to an effector and ascending neurons that carry action potentials toward the brain. This is an example of a/an __________ pathway.

divergent

Which type of neuronal pathway allows for a stimulus to be transmitted to the most number of cells?

divergent

Gap junctions are functionally __________ synapses.

electrical

Monamine oxidase inhibitors (MAO inhibitors)

enhance the binding of norepinephrine to its receptors.

Hydrocephaly is a condition whereby cerebrospinal fluid accumulates around the brain. What supportive cells continue CSF production despite it backing up in the subarachnoid space?

ependymal cells

A neuron is receiving a stimulus which gets stronger and stronger. The result is

frequency of occurrence of action potentials increases

Action potentials are conducted more rapidly when transmission is

from node to node on a myelinated axon.

Cell bodies of the peripheral nervous system are located in

ganglia

Groups of related nerve cell bodies located outside of the central nervous system are called

ganglia

Groups of related nerve cell bodies located outside of the central nervous system are called __________.

ganglia

Mr. Miller has been hospitalized for the flu. The flu virus increases membrane permeability to K+. You would expect his cells to __________.

hyperpolarize

The absolute refractory period ends when

inactivation gates of voltage-gated Na+ channels reopen.

Local hyperpolarization in a synapse is called a/an __________.

inhibitory postsynaptic potential

The opening of more and more Na+ channels during depolarization

is an example of a positive feedback cycle.

During the absolute refractory period, the cell

is insensitive to further stimulation

During the absolute refractory period, the cel

is insensitive to further stimulation.

In an EPSP (excitatory postsynaptic potential), there is a

local depolarization

Suppose both excitatory and inhibitory neurons synapse with a single postsynaptic neuron. What determines if an action potential is initiated in the postsynaptic neuron?

The number of EPSPs in relation to the number of IPSPs

Which of the following statements is not true of reverberating circuits?

The number of action potentials decreases the farther along the circuit due to inhibitor effects of collateral axons.

Frank has a microbial infection attacking his brain. Which cell type would you expect to proliferate and be most active during this time?

microglia

The same neurotransmitter binds to a postsynaptic cell but produces a variety of different effects. What does this mean?

The postsynaptic cell is expressing different types of receptors for the same neurotransmitter.

Which of the following statements concerning resting membrane potential is true?

The resting membrane potential is proportional to the tendency for K+ to diffuse out of the cell.

If you cut bundles of axons and their myelin sheaths in the PNS, you cut __________.

nerves

Compounds classified as __________ alter synaptic transmission by changing neurotransmitter receptor numbers or affecting the breakdown and/or removal of neurotransmitter.

neuromodulators

Viagra is used to treat erectile dysfunction by prolonging the effects of _____ on blood vessels.

nitric oxide (NO)

Clusters of gray matter deep within the brain are called __________.

nuclei

Which type of neural circuit is best for producing a prolonged output

reverberating circuit

Neurons arranged in a circular pathway form

reverberating circuits

Neurotransmitters are released from the ________.

presynaptic terminal

Synaptic vesicles contain neurotransmitters and are present in the __________.

presynaptic terminal

A decrease in the number of voltage-gated Ca2+ ion channels in the presynaptic terminal would

reduce or inhibit transmission across the synapse.

If a neuron is prevented from sending a neurotransmitter across a synapse to another cell, which neuron property is being inhibited?

secretion

Saltatory conduction of an action potential means that

an action potential is conducted from one node of Ranvier to the next node.

When a neurotransmitter binds to its receptor and increases the permeability of the postsynaptic membrane to Na+,

an excitatory postsynaptic potential (EPSP) will result.

Nissl bodies are __________.

areas of rough endoplasmic reticulum

LouAnn is being treated for a neurological condition with a specific drug that target neurons deep within the brain. Which glial cell must be bypassed by this drug in order for it to be effective?

astrocyte

Which of the following is mismatched

somatic nervous system - sensory division of PNS

The junction of a neuron with another cell is a/an __________.

synapse

A change in the resting membrane potential has the following characteristics: non-propagated, graded, can summate. This type of change can

be a local potential and a consequence of an increase in the permeability to Na+

All of the following are typical characteristics of neurotransmitters except

they are released into the bloodstream before reaching the postsynaptic cell.

The motor (efferent) division of the peripheral nervous system

transmits impulses from the CNS to effectors, such as skeletal muscle.

Which of the following statements accurately describe events that occur as the result of a local potential reaching threshold?

A positive feedback cycle develops in which depolarization causes activation gates of Na+ ion channels to open.

Which of the following descriptions of glial cells is mismatched?

A. microglia - provide support for the neuron cell body

Continuous conducts of action potentials means that

An action potential in one site generates local currents causing depolarization to threshold at the adjacent site

Which of the following will cause the plasma membrane to hyperpolarize when at its resting membrane potential?

An inflow of Cl−

Which of the following analogies best represents a parallel after-discharge circuit?

An instructor instructs all students to solve the same problem.

Dendrites

Are the input part of the neuron

Which of the following events is NOT a characteristic of an action potential

As Na+ enter, the inside of the plasma membrane becomes more negative.

The strength of a stimulus is communicated through

Both "the frequency of action potentials" and "the length of time action potentials are produced" are correct.

Voltage-gated Na+ channels are sensitive to changes in the extracellular concentration of __________.

Ca2+

Which ion is necessary for the release of neurotransmitter from synaptic vesicles?

Ca2+

Which of the following situations occurs in electrically excitable cells?

Depolarization causes voltage-gated Na+ channels to open

Which of the following is NOT true about astrocytes?

They can aid in the regeneration of injured neurons.

Which of the following statements concerning myelination is true?

Unmyelinated axons rest in invaginations of Schwann cells or oligodendrocytes.

If the extracellular fluid around a neuron is replaced with an isotonic saline solution that contains K+ and other solutes at concentrations very close to the extracellular fluid concentrations of a normal cell, the result is

a resting membrane potential close to its normal value.

Which neurotransmitter is released at neuromuscular junctions?

acetylcholine

A stimulus either causes an action potential or it doesn't. This is called __________.

all-or-nothing response

Which of the following is responsible for problem-solving skills?

central nervous system

Identify the type of synapse that includes a presynaptic cell, synaptic cleft, and postsynaptic cell.

chemical

The gray matter of the cerebrum is composed of neuron cell bodies and makes up both the __________ and the __________.

cortex; deep cerebral nuclei

The peripheral nervous system includes the __________.

cranial nerves

Enkephalins produce presynaptic inhibition in neurons transmitting pain signals. Increased levels of enkephalins will

decrease awareness of pain

When repolarization of a neuron is complete, the

original polarity of the neuron is restored.

Which type of circuit is associated with complex neuronal processes, such as solving mathematical equations?

parallel after-discharge

Digestion of food is regulated by the

parasympathetic division of the ANS

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

sensory or afferent neuron

When two action potentials arrive simultaneously at two different presynaptic terminals that synapse with the same postsynaptic neuron,

spatial summation occurs

The central nervous system includes the __________.

spinal cord

The junction between two neurons is a __________.

synapse

Gray matter on the surface of the brain is called __________.

the cortex

Chemical synapses are characterized by

the release of neurotransmitter by the presynaptic terminal.

Axons contain __________.

the trigger zone

Nervous tissue of the CNS that is composed primarily of myelinated axons is often referred to as __________ matter

white