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17 questions
A second nerve impulse cannot be generated until ________.
all sodium gates are closed
proteins have been resynthesized
the Na ions have been pumped back into the cell
the membrane potential has been reestablished
An inhibitory postsynaptic potential (IPSP) is associated with ________.
lowering the threshold for an action potential to occur
opening of voltage-regulated channels
hyperpolarization
a change in sodium ion permeability
Collections of nerve cell bodies outside the central nervous system are called ________.
tracts
ganglia
nuclei
nerves
If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________.
the impulse would move to the axon terminal only, and the muscle contraction would occur
the impulse would move to the axon terminal only
the impulse would spread bidirectionally
muscle contraction would occur
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
negatively charged and contains more sodium
positively charged and contains less sodium
positively charged and contains more sodium
Schwann cells are functionally similar to ________.
oligodendrocytes
microglia
ependymal cells
astrocytes
The part of a neuron that conducts impulses away from its cell body is called a(n) ________.
dendrite
Schwann cell
axon
neurolemma
The substance released at axon terminals to propagate a nervous impulse is called a(n) ________.
cholinesterase
biogenic amine
neurotransmitter
ion
What are ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid called?
Schwann cells
oligodendrocytes
astrocytes
ependymal cells
What does the central nervous system use to determine the strength of a stimulus?
frequency of action potentials
type of stimulus receptor
origin of the stimulus
size of action potentials
What is the role of acetylcholinesterase?
amplify or enhance the effect of ACh
act as a transmitting agent
destroy ACh a brief period after its release by the axon endings
stimulate the production of acetylcholine
Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?
mechanically gated channel
leakage channel
ligand-gated channel
voltage-gated channel
Which of the choices below describes the ANS?
motor fibers that conduct nerve impulses from the CNS to skeletal muscles
motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands
sensory neurons that convey information from somatic receptors in the head, body wall, and limbs and from receptors from the special senses of vision, hearing, taste, and smell to the CNS
sensory and motor neurons that supply the digestive tract
Which of the following describes the nervous system integrative function?
responds to stimuli by gland secretion or muscle contraction
senses changes in the environment
analyzes sensory information, stores information, makes decisions
Which of the following is false or incorrect?
An inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyperpolarization of the membrane.
An excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold.
A nerve impulse occurs if the excitatory and inhibitory effects are equal.
Which of the following is not a function of astrocytes?
anchor neurons to blood vessels
guide the migration of young neurons, synapse formation, and helping to determine capillary permeability
control the chemical environment around neurons
support and brace neurons
provide the defense for the CNS
Which of the following is not true of graded potentials?
They are short-lived.
They can form on receptor endings.
They can be called postsynaptic potentials.
They increase amplitude as they move away from the stimulus point.
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