61) A node of Ranvier (myelin sheath gap)
A) occurs only in ganglia.
B) is one segment of the myelin sheath.
C) occurs in the PNS but not in the CNS.
D) is a bare region of axonal membrane in myelinated axons only.
62) The difference between myelinated and unmyelinated axons is that
A) Schwann cells are not associated with unmyelinated axons.
B) Schwann cells form more widely spaced nodes of Ranvier in unmyelinated axons.
C) Schwann cells simultaneously surround multiple axons in myelinated axons.
D) Schwann cells wrap around myelinated axons in concentric layers.
63) An axon collateral from one neuron that circles back and synapses with a previous neuron describes
A) a converging circuit.
B) parallel processing.
C) a reverberating circuit.
D) serial processing.
64) In the region of the spinal cord, the cell bodies of most interneurons lie in
A) sensory ganglia.
B) the PNS.
C) the dorsal half of the gray matter.
D) the ventral half of the white matter.
65) A monosynaptic reflex arc is an example of
A) a converging circuit.
B) parallel processing.
C) a reverberating circuit.
D) serial processing.
66) Ciliated neuroglial cells that form an epithelium and play an active role in forming and moving cerebrospinal fluid are
A) ependymal cells.
B) Schwann cells.
C) oligodendrocytes.
D) astrocytes.
67) The chemical substance that is released at axon terminals is called a
A) hormone.
B) neurotransmitter.
C) synaptic vesicle.
D) Nissl body.
68) The covering of a fascicle within a nerve is the
A) endoneurium.
B) perineurium.
C) ectoneurium.
D) epineurium.
69) The entire nerve is surrounded by a tough fibrous sheath called the
A) endoneurium.
B) perineurium.
C) ectoneurium.
D) epineurium.
70) The peripheral nerve fibers that speed up the movement of the digestive tract are classified as
A) general visceral sensory (afferent).
B) special visceral sensory.
C) general visceral motor (efferent).
D) special somatic motor.
71) Regeneration of peripheral axons requires
A) construction of a collateral that branches from the point of damage.
B) deposition of neurofilaments to bridge the gap between the original axon fragments.
C) formation of a tube by Schwann cells to guide growth.
D) migration of neural stem cells from the hippocampus.
72) Vesicles containing neurotransmitters are located in
A) a synaptic cleft.
B) axon terminals.
C) the postsynaptic region of dendrites.
D) the nodes of Ranvier.
73) The type of axon that conducts impulses most slowly is
A) thick, myelinated.
B) thick, unmyelinated.
C) thin, myelinated.
D) thin, unmyelinated.
74) During embryo development, neurons that make "bad" connections
A) are inhibited by chemicals released from astrocytes.
B) are turned off by inhibitory synapses in reverberating circuits.
C) develop collaterals that seek out appropriate target cells.
D) die by apoptosis.
75) Gray matter in the CNS contains all of the following
except
A) neuron cell bodies.
B) neuroglia.
C) dendrites.
D) fiber tracts.