Ch 4

Question 1

Which of the following statements about glia is true?
A. Microglia arise from macrophages outside of the nervous system and are physiologically and embryologically similar to other neural cell types.
B. Glia do not undergo proliferation.
C. Protoplasmic astrocytes produce substances that are tropic
to neurons to help maintain the appropriate concentration of ions and neurotransmitters by taking up K+ and the neurotransmitters glutamate and GABA.
D. Oligodendrocytes and Schwann cells are involved in myelin formation around axons in the peripheral and central nervous systems, respectively.
E. Macroglia are scavenger cells that resemble tissue macrophages and remove debris resulting from injury, infection, and disease.

Answer 1

C. Protoplasmic astrocytes produce substances that are tropic
to neurons to help maintain the appropriate concentration of ions and neurotransmitters by taking up K+ and the neurotransmitters glutamate and GABA.

Question 2

Primary erythromelalgia, which may be due to a peripheral nerve sodium channelopathy, was diagnosed in a 13-year-old girl who was experiencing frequent episodes of red, painful, warm extremities. Which part of a neuron has the highest concentration of Na+ channels per square micrometer of cell membrane?

A. dendrites
B. cell body near dendrites
C. initial segment
D. axonal membrane under myelin 
E. node of Ranvier

Answer 2

E. node of Ranvier

Question 3

A 45-year-old woman who works in an office had been experiencing tingling in her index and middle fingers and thumb of her right hand. Recently, her wrist and hand had become weak. Her physician ordered a nerve conduction test to evaluate her for carpal tunnel syndrome. Which one of the following nerves has the slowest conduction velocity?

A. Aα fibers 
B. Aβ fibers 
C. Aγ  fibers 
D. B fibers 
E. C fibers

Answer 3

E. C fibers

Question 4

Which of the following is NOT correctly paired?
A. Synaptic transmission: Antidromic conduction
B. Molecular motors: Dynein and kinesin
C. Fast axonal transport: ~400 mm/day
D. Slow axonal transport: 0.5–10 mm/day
E. Nerve growth factor: Retrograde transport

Answer 4

A. Synaptic transmission: Antidromic conduction

Question 5

Which of the following ionic changes is correctly matched with a component of the action potential?
A. Opening of voltage-gated K+ channels: After-hyperpolarization
B. A decrease in extracellular Ca2+: Repolarization
C. Opening of voltage-gated Na+ channels: Depolarization
D. Rapid closure of voltage-gated Na+ channels: Resting
membrane potential
E. Rapid closure of voltage-gated K+ channels: Relative
refractory period

Answer 5

C. Opening of voltage-gated Na+ channels: Depolarization

Question 6

A man falls into a deep sleep with one arm under his head. This arm is paralyzed when he awakens, but it tingles, and pain sensation in it is still intact. The reason for the loss of motor function without loss of pain sensation is
A. A fibers are more susceptible to hypoxia than B fibers.
B. A fibers are more sensitive to pressure than C fibers.
C. C fibers are more sensitive to pressure than A fibers.
D. Motor nerves are more affected by sleep than
sensory nerves.
E. Sensory nerves are nearer the bone than motor nerves and
hence are less affected by pressure.

Answer 6

B. A fibers are more sensitive to pressure than C fibers.

Question 7

Which of the following statements about nerve growth factor is NOT true?
A. It is made up of three polypeptide subunits.
B. It is responsible for the growth and maintenance of adrenergic neurons in the basal forebrain and the striatum.
C. It is necessary for the growth and development of the sympathetic nervous system.
D. It is picked up by nerves from the organs they innervate.
E. It can express both p75 NTR and Trk A receptors.

Answer 7

B. It is responsible for the growth and maintenance of adrenergic neurons in the basal forebrain and the striatum.

Question 8

A 20-year-old female student awakens one morning with severe pain and blurry vision in her left eye; the symptoms abate over several days. About 6 months later, on a morning after playing volleyball with friends, she notices weakness but not pain in her right leg; the symptoms intensify while taking a hot shower. Which of the following is most likely to be the case?
A. The two episodes described are not likely to be related.
B. She may have primary-progressive multiple sclerosis.
C. She may have relapsing-remitting multiple sclerosis.
D. She may have a lumbar disk rupture.
E. She may have Guillain–Barre syndrome.

Answer 8

C. She may have relapsing-remitting multiple sclerosis.