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70 terms

Chapter 11

Fundamentals of the Nervous System and Nervous Tissue
STUDY
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False
The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.
True
Reflexes are rapid, automatic responses to stimuli.
True
Efferent nerve fibers may be described as motor nerve fibers.
False
Saltatory conduction occurs because of the presence of salt (NaCl) around the neuron.
True
Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system.
True
Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte.
True
During depolarization, the inside of the neuron's membrane becomes less negative.
T
Neurons in the CNS are organized into functional groups.
F
Strong stimuli cause the amplitude of action potentials generated to increase.
T
The oligodendrocytes can myelinate several axons.
T
Enkephalins and endorphins are peptides that act like morphine.
T
A synapse formed between the axon ending of one neuron and the cell body of another neuron is called an axosomatic synapse.
T
In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.
F
Action potentials can be generated by virtually all cells of the body because all cells possess cell membranes.
T
Voltage is always measured between two points and may be called the potential between these two points.
False
Neurons that are far away from the center of the neuron pool and that are not easily excited by an incoming stimulus are in the discharge zone.
True
Acetylcholine is not a biogenic amine.
False
The two major classes of graded potentials are transmitter potentials and receptor potentials.
True
A graded potential that is the result of a neurotransmitter released into the synapse between two neurons is called a postsynaptic potential.
True
Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers.
False
The nodes of Ranvier are found only on myelinated, peripheral neural processes.
True
Unipolar neurons have axons structurally divided into peripheral and central processes.
True
A stimulus traveling toward a synapse appears to open calcium channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane.
False
A positive feedback cycle is the main force in the generation of graded potentials at receptor ends.
True
If bacteria invaded the CNS tissue, microglia would migrate to the area to engulf and destroy them.
open ion channels to provoke rapid responses
Direct-acting neurotransmitters ________.
Current is directly proportional to the voltage
Which of the following is correct relative to Ohm's law?
ependymal cells
Ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid are called ________.
neurilemma
The sheath of Schwann is also called the ________.
found in the retina of the eye
Bipolar neurons are commonly ________.
acetylcholine
An excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle is ________.
reverberating circuit
A neural circuit in which a single impulse is transmitted over and over is a ________.
absolute refractory period
The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.
converging circuit
A neuronal circuit that concentrates or directs a large number of incoming impulses to a rather small number of neurons is called a(n) ________.
synaptic cleft
Which of the following is not a structural feature of a neuron?
axon
The part of a neuron that conducts impulses away from its cell body is called a(n) ________.
Ca2+
The chemically gated channel, NMDA, allows ________ ions entry into the nerve cell.
synapse
The point at which an impulse from one nerve cell is communicated to another nerve cell is the ________.
destroy ACh a brief period after its release by the axonal endings
The role of acetylcholinesterase is to ________.
innervation of skeletal muscle
Which of the following is not a function of the autonomic nervous system?
ganglia
Collections of nerve cell bodies outside the central nervous system are called ________.
brain and spinal cord
The term central nervous system refers to the ________.
neurotransmitter
The substance released at axon terminals to propagate a nervous impulse is called a(n) ________.
association neuron
A neuron that has as its primary function the job of connecting other neurons is called a(n) ________.
the myelin sheath
Saltatory conduction is made possible by ________.
Na
Which of these ions is actively transported through the cell membrane to establish a resting potential?
a dendrite
The part of the neuron that normally receives stimuli is called ________.
Voltage would be measured by placing one electrode inside the membrane and another outside the membrane.
Choose the statement that is most correct about membrane potential.
pumps three sodium ions outside the cell and two potassium ions inside
The sodium-potassium pump ________.
is essential for impulse propagation
An action potential ________.
The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.
Select the correct statement about synapses.
nitric oxide
Which of the following is a good example of a neuromodulator?
group C fibers
Which group of fibers spreads impulses at up to 1 meter per second?
autonomic nervous system
The sympathetic and parasympathetic are subdivisions of the ________.
help to circulate the cerebrospinal fluid
Ependymal cells ________.
astrocytes
Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ________.
oligodendrocytes
Schwann cells are functionally similar to ________.
potassium
Immediately after an action potential has peaked, which cellular gates open?
are crucial for the development of neural connections
Nerve cell adhesion molecules (N-CAMs) ________.
hyperpolarization
An inhibitory postsynaptic potential (IPSP) is associated with ________.
A single type of channel will open, permitting simultaneous flow of sodium and potassium.
Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?
generator potential
When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________.
increase amplitude as they move away from the stimulus point
All of the following are true of graded potentials except that they ________.
Some ions are prevented from moving down their concentration gradients by ATP-driven pumps.
Which of the following is true about the movement of ions across excitable living membranes?
Serotonin
________ is an indolamine.
the membrane potential has been reestablished
A second nerve impulse cannot be generated until ________.
negatively charged and contains less sodium
In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________.
the impulse would spread bidirectionally
If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________.
Group C fibers are not capable of saltatory conduction.
Neurons may be classified according to several characteristics. Which of the following is correct?
Spinal reflexes are an example of serial processing.
Select the correct statement about serial processing.