SELF EVALUATION - CHAPTER 4
STRUCTURE OF THE NERVOUS SYSTEM
1. The myelin sheaths of nerve fibers in the central nervous system are cytoplasmic extensions of:
a. Schwann cells.
b. oligodendrocytes.
2. Nerve fiber is another name for:
a. nerve.
b. neuron.
c. axon.
d. dendrite.
3. Which one of the following statements about the neuronal synapse is false?
a. One-way conduction (axon to dendrite or soma)
b. Transmission by chemical means
c. Physical contact of one neuron with the next
d. Fatigue more readily than the neuron
4. Which one of the following statements about myelin sheaths is true?
a. The myelin sheath is formed by the cell body of the neuron of which it is a part.
b. There is no chance for extracellular fluid to be in contact with the nerve fiber throughout its length when a nerve fiber is myelinated.
c. Unmyelinated fibers may be nearly surrounded by myelin from adjacent myelinated fibers but maintain a direct association with extracellular fluid throughout their length.
d. Nodes of Ranvier are the lymphatic structures of the nervous system.
ORGANIZATION OF THE NERVOUS SYSTEM
5. The autonomic divisions having cell origins in the cranial and sacral (craniosacral) regions of the
spinal cord and the thoracic and lumbar (thoracolumbar) regions are the_______ and
______, respectively.
a. sympathetic, parasympathetic
b. parasympathetic, sympathetic
6. With the exception of the cervical and caudal vertebrae, spinal nerves:
a. emerge in front of the vertebrae of the same serial number and name.
b. emerge behind the vertebrae of the same serial number and name.
7. Afferent nerve fibers enter the spinal cord via the root and efferent nerve fibers leave via the root.
a. dorsal, ventral
b. ventral, dorsal
c. dorsal, dorsal
d. ventral, ventral
8. Parasympathetic stimulation increases intestinal muscle and secretory activity.
a. True
b. False
9. Which one of the following best describes the function of the hypothalamus?
a. Important in equilibrium
b. Large pools of neurons for performing complex semivoluntary movement (walking and running)
c. Central mechanism for most postural reflexes (hopping, righting, placing)
d. Senses need for anterior pituitary hormones, forms posterior pituitary hormones, integration of autonomic nervous system functions
0. Which one of the following is an appropriate function for the cerebellum?
a. Modulates (adjusts) motor activity
b. Provides for consciousness
c. Relay center to cerebral cortex
d. Site of production of several.hormones
11. Parasympathetic stimulation to the heart would decrease its activity.
a. True
b. False
.2. Which division of the autonomic nervous system is referred to as the cholinergic system?
a. Sympathetic
b. Parasympathetic
.3. Which one of the following brain structures is a subdivision of the brain stem, contains the pituitary gland, and assumes a major role in the integration of functions carried out by the autonomic nervous system?
a. Basal nuclei
b. Cerebral cortex
c. Hypothalamus
d. Thalamus
.4. A myelin sheath on a peripheral nerve fiber:
a. is uninterrupted throughout its length.
b. is produced by the neuron of which it is a part.
c. prevents contact of the nerve fiber with extracellular fluid throughout its length.
d. increases the velocity of impulse conduction.
1.5. The vagus nerve (cranial nerve X) supplies autonomic fibers to visceral structures in the thorax and abdomen. Which division of the autonomics has fibers in this nerve?
a. Sympathetic
b. Parasympathetic
.6. Sympathetic stimulation to the bronchi (air passages) of the lungs would,result in:
a. a decrease of their diameter.
b. an increase of their diameter.
17. How many neurons are associated with the transmission of an autonomic impulse from its cell of origin (in brain or spinal cord) to its organ of.influence?
a.
Oneb. Two
c. Three
d. Too numerous to count
8. Which division of the autonomic nervous system is known as the adrenergic nervous system (postganglionic neuron secretes norepinephrine)?
a. Sympathetic
b. Parasympathetic
THE NERVE IMPULSE AND ITS TRANSMISSION
.9. A stimulus increases the permeability of the neuron for the sodium ion.
a. True
b. False
:0. If a stimulus lowers the resting membrane potential of -80 mV to -70 mV and the threshold for an action potential is -65 mV, the nerve fiber will fire.
a. True
b. False
»1. Which one of the following contains the respective neurotransmitters for postganglionic sympathetic and parasympathetic neurons?
a. Acetylcholine, norepinephrine
b. Acetylcholine, acetylcholine
c. Norepinephrine, acetylcholine
d. Norepinephrine, norepinephrine
!2. The phenomenon of saltatory conduction is associated with:
a. the flow of cerebrospinal fluid.
b. unmyelinated nerve fibers.
c. myelinated nerve fibers.
d. nerve impulse transmission at a synapse.
:3. When a resting membrane potential of -85 mV is being measured in a nerve fiber at a particular point and the threshold for firing is -70 mV, which one of the following is false?
a. There is a high concentration of Na+ on the outside and a low concentration of Na + on the inside.
b. There is a relative impermeability of the fiber for diffusion of Na+.
c. There is no current flow at that point.
d. A stimulus that would decrease the resting membrane potential (from -85 to -80) would cause the nerve to fire.
:4. Repolarization of a nerve fiber:
a. is accomplished by Na+ being actively transported from the inside to the outside.
b. is accomplished by diffusion of K+ from the inside of the fiber to the outside.
:5. Which one of the following statements about impulse transmission velocity is false?
a. Fastest impulse transmission in the body would be a small-diameter, nonmyelinated fiber.
b. Where high velocity is required, greater space reduction would be achieved by myelination rather than by increased fiber size.
:6. Acetylcholine is an excitatory neurotransmitter and accordingly increases the permeability of the nerve fiber membrane for Na+.
a. True
b. False
>7. A stimulus applied to a neuron causes depolarization of the membrane. This means that the membrane:
a. becomes positive on the outside because of the outflow of Na+.
b. becomes positive on the inside and negative on the outside because Na+ flows inward.
c. will not be able to propagate a nerve impulse.
:8. A stimulus of sufficient strength to cause an action potential means that the magnitude of depolarization was sufficient to:
a. demyelinate the fiber.
b. incite a riot.
c. reach threshold.
d. raise or lower the threshold.
:9. The period of time when a nerve fiber cannot be caused to fire is known as:
a. repolarization.
b. saltatory conduction.
c. leakage.
d. the refractory period.
REFLEXES
0. Muscle tone:
a. is a state of complete muscle,relaxation.
b. is a state of muscle tension (contraction) that enables an animal,to assume and remain in an erect position.
c. refers to the sound made by contracting muscle.
d. is an autonomic nervous system function.
μ. A muscle spindle is best described as:
a. a reflex center located in the spinal cord for the purpose of muscle control.
b. the point on a bone over which a muscle passes.
c. a specialized receptor for maintaining muscle tone that, when stretched, causes contraction of the muscle in which it is located.
d. a specialized receptor found in tendons that, when stimulated, causes the muscle of the tendon to be relaxed.
,2. The ability of a cat to land on its feet when dropped from a position of its feet in a skyward direction is known as:
a. an attitudinal reflex.
b. hopscotch.
c. a righting reflex.
d. a placing reflex.
[3. Lifting the head of a horse in a standing position permits greater activity of the hind legs (attitudinal reflex).
a. True
b. False
14. Which reflex is the fundamental element of muscle tone?
a. Stretch
b. Attitudinal
c. Righting
d. Crossed extensor
THE MENINGES AND CEREBROSPINAL FLUID
15. Cerebrospinal fluid pressure:
a. would increase if there were resistance to venous blood flow from the head.
b. would decrease if there were resistance to venous blood flow from the head.
c. is independent of any change in venous blood pressure.
[6. Cerebrospinal fluid is produced:
a. by the choroid plexus in cavities (ventricles) within the brain.
b. by the ciliary processes in the posterior chamber of the eye.
c. as a neurosecretion by neurons in the hypothalamus.
d. by the nerve cell bodies in the cerebrum and spinal cord.
J7. Which one of the following does NOT apply to cerebrospinal fluid?
a. Provides a watery cushion for the brain and spinal cord
b. Assists in maintaining volume of cranial contents at a constant level
c. Contains numerous blood cells
d. Secreted by choroid plexus and returned to blood via arachnoid villi
CENTRAL NERVOUS SYSTEM METABOLISM
8. The blood-brain barrier:
a. exists for all substances in the blood.
b. applies to all areas of the brain.
c. excludes transport of some substances from blood to brain and permits transport of others. [9. Brain injury occurs when it is deprived of blood for (select the most appropriate time interval):
a. seconds.
b. minutes.
c. hours.
d. days.