Chapter 5 : Neurohistology (2) Flashcards
1. 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
l-B. Peripheral nerve fibers regenerate at the rate of 3 mm/day.
2. 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) conduc tion velocity of 12-30 m/sec. Slow pain has a nerve fiber (C) conduction velocity of 0.5-2 m/sec.
- All of the following statements concerning neurons are correct EXCEPT
(A) they are of neuroectodermal origin
(B) they have lost the capacity to undergocell division
(C) they contain Nissl substance
(D) they are derived from the neural tubeand neural crest
(E) bipolar neurons are the most commontype of neuron
3-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.
4. All of the following statements concerningaxons are correct EXCEPT they (A) may arise from the perikaryon (B) may arise from a dendrite (C) arise from the axon hillock (D) contain rough endoplasmic reticulum (E) transmit action potentials
4r-D. Axons may arise from the perikaryon or from a dendrite. They always arise from the axon
hillock. Axons do not contain rough endoplasmic reticulum (Nissl substance). Axons generate and
transmit action potentials.
- All of the following statements concerningmyelin 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 myelinateonly one internode
(E) myelinating cells of the CNS myelinateseveral internodes of different axons
5-A. Myelin is produced by Schwann cells in the peripheral nervous system (PNS) and by oligo dendrocytes 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 statements concerningastrocytes are correct EXCEPT
(A) they possess many processes
(B) they are found in both white and graymatter
(C) they are considered to be the scavengercells of the CNS
(D) they have perivascular end feet
(E) in damaged brain tissue, astrocytes formglial scars
6-C. Astrocytes have many processes and are found in the gray and white matter. They have
perivascular end feet. In the damaged brain, astrocytes form glial scar tissue, known as gliosis or astrogliosis. The microglial cells are the scavenger cells of the central nervous system (CNS).
- All of the following statements concerning Schwann cells are correct EXCEPT
(A) they play an important role in peripheralnerve regeneration
(B) they are derived from the neural tube
(C) they may give rise to tumors of peripheralnerves
(D) one Schwann cell myelinates one internodeof an axon
(E) they are neurolemmal cells
7-B. Schwann cells (neurolemmal cells) play an important role in peripheral nerve regeneration.
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 concerningependymal cells are correct EXCEPT
(A) they are derived from the neural crest
(B) they line the central canal
(C) they are in contact with CSF
(D) they produce CSF
(E) they include tanycytes and choroid plexusCells
8-A. Ependymal cells are derived from the neural tube, line the central canal and ventricles,
and are in contact with cerebrospinal fluid (CSF). Ependymal cells include choroid plexus cells,
which produce CSF. Tanycytes are modified ependymal cells found in the wall of the third ventricle.
- All of the following statements concerningwallerian 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 disappearanceof axons and myelin sheaths
(E) it is characterized by the proliferation ofSchwann cells
9-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 axonal transport are correct EXCEPT
(A) fast anterograde axonal transport is200-400 mm/day
(B) mitochondria are transported at the rateof 5 mm/day
(C) fast retrograde axonal transport is associatedwith microtubules and dynein
(D) fast anterograde axonal transport isassociated with microtubules and kinesin
(E) slow anterograde transport is 1-6 mm/day
10-B. Mitochondria are transported at the rate of 50-100 mm/day.
- All of the following statements concerning sensory receptors are correct EXCEPT
(A) pain and thermal receptors utilize grouplb fibers
(B) Meissner’s corpuscles are found only inthe dermal papillae of glabrous skin
(C) Merkel’s tactile disks mediate the sensationof light touch
(D) pacinian corpuscles are acceleration detectorsthat respond to vibration sensation
(E) annulospiral endings project centrally viathe dorsal column-medial lemniscus pathway
11-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.
Match each of the descriptions below with thecorresponding type of nerve cell. (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
- Are a variety of ependymal cell found inthe wall of the third ventricle
12-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.
Match each of the descriptions below with thecorresponding type of nerve cell. (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
- Arise from monocytes
13-C. Microglial cells, the scavenger cells of the CNS, arise from monocytes and enter the CNS
via abnormal blood vessels.
Match each of the descriptions below with thecorresponding type of nerve cell. (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
- Are neural crest derivatives
14-D. Schwann cells are derived from the neural crest; they myelinate the axons of the PNS.
Match each of the descriptions below with thecorresponding type of nerve cell. (A) Astrocytes (B) Oligodendrocytes (C) Microglial cells (D) Schwann cells (E) Tanycytes
- Contain glial filaments and glycogen granules
15-A. Astrocytes are characterized by the presence of glial filaments and glycogen; glial filaments contain glial fibrillary acidic protein (GFAP), a marker for astrocytes.
