Unit IV Review Guide
Chapter 13 – True or False
The nervous system consists of the brain, spinal cord, and nerves.
The afferent nervous system consists of all outgoing motor pathways.
Ependymal cells engulf and destroy microbes and cellular debris in inflamed or degenerating brain tissue.
Oligodendrocytes form myelin sheaths around nerve fibers in the CNS.
Nerve fibers with many Schwann cells forming a thick myelin sheath are called myelinated fibers, or gray fibers.
Most of the neurons in the brain and spinal cord are unipolar.
In a contralateral reflex arc, the receptors and effectors are located on opposite sides of the body.
In an ipsilateral arc, the effectors and receptors are on opposite sides of the body.
Groups of cell bodies located in the brain or spinal cord are referred to as ganglia.
Most injuries to the brain and spinal cord cause permanent damage.
Regeneration of nerve fibers will occur only if the cell body is intact and the fibers have a neurilemma.
If a motor neuron is damaged, it can cause the muscle it innervates to atrophy because of lack of stimulation.
Neurons are the only living cells that maintain a difference in the concentration of ions across their membranes.
When a neuron is resting, the inner surface of its plasma membrane is slightly positive compared with its outer surface.
If the threshold potential is surpassed, the full peak of the action potential is always reached.
The magnitude of the action potential peaks when the sodium channels close.
The difference in electrical charge between the inside and outside of a membrane is called the membrane potential.
In depolarization the membrane potential moves toward zero, whereas in hyperpolarization the membrane potential moves away from zero.
The action potential is called an all-or-none response because if the threshold potential is surpassed, the full peak of the action is always reached; if the threshold potential is not surpassed, no action potential will occur.
Myelinated fibers conduct impulses faster than unmyelinated fibers.
Excitatory neurotransmitters are most likely to initiate an action potential.
A neurotransmitter can be either excitatory or inhibitory depending on the postsynaptic receptor.
When epinephrine and norepinephrine are released into the bloodstream, they are called hormones instead of neurotransmitters.
The nervous system is designed to detect stimuli from both the internal and external environment.
The nervous system can be divided according to structure, direction of information flow, and speed of conduction.
The efferent division of the nervous system consists of mostly sensory pathways.
Small, distinct regions of gray matter within the CNS are called nuclei.
Most nerves in the human nervous system are mixed.
Neurons have, at best, a limited ability to repair themselves.
Regeneration of nerve fibers is impossible, even if the cell body is intact and the fibers have a neurilemma.
There are differences between the central and peripheral nervous systems concerning the repair of damaged fibers. 50.
Bundles of unmyelinated fibers make up what is referred to as white matter.
Action potential and membrane potential are synonymous terms.
During the nerve impulse, the internal charge of the neuron becomes briefly positive.
Action potentials travel in only one direction along a nerve fiber.
Glutamate is the most common excitatory neurotransmitter in the CNS.
Cranial nerves are considered part of the central nervous system.
Spinal nerves are considered part of the peripheral nervous system.
When “central” and “peripheral” are used as directional terms in the nervous system, a nerve fiber may be called peripheral if it extends from the cell...
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