Chapters 11
Plasma membrane exhibits voltage gated Ca channels
secretory region
axon terminal release neurotransmitters
secretory zone
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
Which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS?
shwann cells
Enkephalins and endorphins are peptides that act like morphine.
t
Neurons in the CNS are organized into functional groups. t/f
t
Unipolar neurons have axons structurally divided into peripheral and central processes.
t
Which of the following is NOT true of association neurons?
Most association neurons are confined within the peripheral nervous system (PNS).
The velocity of the action potential is fastest in which of the following axons?
a small myelinated axon
During depolarization, which gradient(s) move(s) Na+ into the cell?
both the electrical and chemical gradients
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
One incoming fiber triggers responses in everincreasing numbers farther and father along the circuit involved in activating fibers of a skeletal muscle
diverging
Binding of the neurotransmitter to its receptor causes the membrane to __________.
either depolarize or hyperpolarize
Which of the neuroglial cell types shown control the flow of cerebrospinal fluid within the CNS?
ependymal cells
The nodes of Ranvier are found only on myelinated, peripheral neuron processes. t/f
f
Bipolar neurons are commonly ________.
found in the retina
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
What characterizes depolarization, the first phase of the action potential?
he membrane potential changes from a negative value to a positive value.
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 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.
What conditions will increase the diffusion of molecules, such as neurotransmitters?
An increase in the amount of neurotransmitter exocytized by the presynaptic axon.
Strong stimuli cause the amplitude of action potentials generated to increase.
F
During an action potential, hyperpolarization beyond (more negative to) the resting membrane potential is primarily due to __________.
K+ ions diffusing through voltage-gated channels
Predict the possible effect of a drug that totally blocks the neurotransmitter receptor on the postsynaptic membrane. For example, curare is a neurotoxin used by several South American cultures. The primary effect of curare is that acetylcholine, a major neuromuscular neurotransmitter, cannot bind at its receptor because curare is blocking it. Predict the possible effects of curare on the postsynaptic membrane and muscle.
Local graded potentials and action potential transmission is blocked and there is no response by the postsynaptic cell, the muscle.
Which of the neuroglial cell types shown form myelin sheaths within the CNS?
Oligodendrocytes form myelin sheaths within the white matter of the CNS.
Tetraethylammonium (TEA) blocks voltage-gated K+ channels such that K+ cannot pass even when the channels are open. However, TEA leaves K+ leakage channels largely unaffected. How would you expect the action potential to change if you treated a neuron with TEA?
The action potential would depolarize as usual, but the repolarization phase would take longer, causing the action potential to be more broad in time.
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.
You are going to record RMP from a cell using an electrode. You place your electrode and record a resting membrane potential every millisecond. You record an initial value of -70mV; however, over time you notice that your recordings become more and more positive until the RMP reaches 0mV. Assuming that Na+ and K+ are the major determinants of RMP in this cell, which of the following could best explain your results?
The cell's Na+−K+ ATPase pumps have stopped functioning.
Destruction of which of the neuroglial cell types leads to the disease multiple scleroses (MS)?
The defects in nerve transmission associated with MS are caused by a loss of myelin within the CNS. Myelin within the CNS is primarily produced by the oligodendrocytes shown in A.
Hypothetically, what would be the most immediate effect of doubling the number of Na+ leakage channels in the plasma membrane?
The resting membrane potential would become less negative (more positive).
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
Suppose a drug is developed that blocks K+ leakage channels. The drug prevents ions from passing through those channels. If this drug was applied to a neuron, what would be the most immediate effect on that neuron?
The resting membrane potential would become less negative (more positive).
Which of the neuroglial cell types shown are found in the PNS?
The satellite cell shown by E wraps and insulates the soma of neurons within ganglia in the PNS.
Which of the following correctly describes a graded potential?
amplitude of various sizes
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
Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ________.
astocytes
Which of the neuroglial cell types shown is the most abundant in the CNS?
astrocytes
different types of sensory input can have the same ultimate effect
converging circuit
What is the major role of the Na+-K+ pump in maintaining the resting membrane potential?
maintaining the concentration gradients for Na+ and K+ across the cell membrane
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 choices below describes the ANS?
motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands
Complete the following sentence. The operation of the Na+−K+ ATPase pump __________.
moves 3 Na+ to the ECF and 2 K+ to the cytoplasm
Which of the following are bundles of neurofilaments that are important in maintaining the shape and integrity of neurons?
neurofibrils
Which of the following is not a chemical class of neurotransmitters?
nucleic acid
may be involved in complex, exacting types of mental processing
parallel after discharge
Which of the following is NOT a type of circuit?
pre-discharge circuits
Which neuron circuit pattern is involved in the control of rhythmic activities such as breathing? 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
Hyperpolarization results from __________.
slow closing of voltage-gated K+ channels
Which criterion is used to functionally classify neurons?
the direction in which the nerve impulse travels relative to the central nervous system
Imagine you changed the concentration of K+ outside a neuron such that the resting membrane potential changed to -80 mV (from the normal resting value of -70 mV). What have you changed?
the electrical gradient for K+ and the concentration gradient for K+
An action potential in one segment of axon causes adjacent sections of axon membrane to reach threshold through what mechanism?
the generation of local currents
A second nerve impulse cannot be generated until ________.
the membrane potential has been reestablished
If a signal from a sending neuron makes the receiving neuron more negative inside,
the receiving neuron is less likely to generate an action potential.
What change in a neuron is being measured in the graph?
the voltage measured across the axon membrane at a specific point as an action potential travels past
An action potential releases neurotransmitter from a neuron by opening which of the following channels?
voltage-gated Ca2+ channels
When an action potential arrives at the end of the axon terminal, a series of events take place that result in the release of neurotransmitter from the presynaptic axon. Select the answer that correctly describes the primary stimulus for vesicles to move towards the cell membrane and eventually release their contents.
voltage-gated membrane channels open, and Ca+2 enters the cytoplasm, increasing intracellular calcium