CHAPTER 5 Flashcards
- Peripheral nerve fibers regenerate at the
rate of
(A) 0.1 mm/day (B) 3 mm/day (C) 100 mm/day (D) 200 mm/day (E) 400 mm/day
1-B. Peripheral nerve fibers regenerate at the rate of 3 mm/day.
- Fast pain has a conduction velocity of
(A) 1 m/sec (B) 5 m/sec (C) 15 m/sec (D) 30 m/sec (E) 100 m/sec
2- C. Fast pain has a nerve fiber (A delta) conduction velocity of 12-30 m/sec. Slow pain has a nerve fiber (C) conduction velocity of 0.5-2 m/sec.
3.A 10-year-old boy has severed his radial nerve. Which of the following cells plays a major role in axonal regrowth?
(A) Fibrous astrocytes (B) Fibroblasts (C) Oligodendrocytes (D) Protoplasmic astrocytes (E) Schwann cells
3- E. Schwann cells play a major role in axon regeneration (axon regrowth) in the peripheral nervous system (PNS).
- The muscle stretch reflex (MSR) is initiated
by which of the following receptors?
(A) End bulbs of Krause (B) Merkel disks (C) Muscle spindles (D) Ruffini end bulbs (E) Vater-Pacini corpuscles
4- C. The muscle stretch reflex is initiated by muscle spindles.
- All of the following statements concerning
neurons are correct EXCEPT
(A) they are of neuroectodermal origin (B) they have lost the capacity to undergo cell division (C) they contain Nissl substance (D) they are derived from the neural tube and neural crest (E) bipolar neurons are the most common type of neuron
5- E. Neurons are of ectodermal origin, contain Nissl substance, and have lost the capacity to undergo cell division. The neural tube and the neural crest both give rise to neurons. Multipolar neurons are the most common type. Bipolar neurons are found in the olfactory mucous membrane, in the ganglia of the vestibulocochlear nerve, and in the retina.
- All of the following statements concerning myelin are correct EXCEPT
(A) it is produced by the microglia
(B) it is produced by Schwann cells
(C) it is produced by oligodendrocytes
(D) myelinating cells of the PNS myelinate
only one internode
(E) myelinating cells of the CNS myelinate
several internodes of different axons
6- A. Myelin is produced by Schwann cells in the peripheral nervous system (PNS) and by oligodendrocytes in the central nervous system (CNS). Schwann cells myelinate only one internode;oligodendrocytes myelinate several internodes of different axons (up to 30). Microglial cells are the scavenger cells of the CNS; they do not produce myelin.
- All of the following sta ements concerning Schwann cells are correct EXCEPT
(A) they play an important role in peripheral
nerve regeneration
(B) they are derived from the neural tube
(C) they may give rise to tumors of peripheral
nerves
(D) one Schwann cell myelinates one inter-
node of an axon
(E) they are neurolemmal cells
7- B. Schwann cells (neurolemmal cells) play an important role in peripheral nerve regenera-
tion. They are derived from the neural crest. They may give rise to benign tumors called schwannomas. Schwann cells are the myelin-forming cells of the peripheral nervous system (PNS); they myelinate only one internode of an axon.
- All of the following statements concerning
wallerian degeneration are correct EXCEPT
(A) it occurs in the CNS
(B) it occurs in the PNS
(C) it is a retrograde degeneration
(D) it is characterized by the disappearance of
axons and myelin sheaths
(E) it is characterized by the proliferation of
Schwann cells
8- C. Wallerian degeneration is an anterograde degeneration of nerve fibers, characterized by the disappearance of axons and myelin and by Schwann cell proliferation.
- All of the following statements concerning
sensory receptors are correct EXCEPT
(A) pain and thermal receptors utilize group
lb fibers
(B) Meissner corpuscles are found only in the
dermal papillae of glabrous skin
(C) Merkel tactile disks mediate the sensa-
tion of light touch
(D) pacinian corpuscles are acceleration de-
tectors that respond to vibration sensa-
tion
(E) annulospiral endings project centrally via
the dorsal column—medial lemniscus pathway
9- A. Pain and thermal receptors utilize group A delta (fast pain) and C (slow pain) fibers. Pain and thermal sensation are mediated via the lateral spinothalamic tract.
10. Are a variety of ependymal cell found in the wall of the third ventricle (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
10- E. Tanycytes are a variety of ependymal cell found in the wall of the third ventricle. The processes of these cells extend from the lumen of the third ventricle to the capillaries of the hypophyseal portal system and also to the neurosecretory neurons of the arcuate nucleus.
11. Arise from monocytes (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
11- C. Microglial cells, the scavenger cells of the CNS, arise from monocytes and enter the CNS
via abnormal blood vessels.
12. Are neural crest derivatives (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
12- D. Schwann cells are derived from the neural crest; they myelinate the axons of the PNS.
13. Contain glial filaments and glycogen granules (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
13- A. Astrocytes are characterized by the presence of glial filaments and glycogen; glial filaments contain glial fibrillary acidic protein (GFAP), a marker for astrocytes.
14. Are perineuronal satellite cells in the central nervous system (CNS) (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
14- B. Oligodendrocytes are perineuronal satellite cells; they myelinate the axons of the central nervous system (CNS).
