Nervous System Flashcards
Which of the following statements regarding axons and/or axonal transport is FALSE?
a. Single nerve cells can be over 1 m in length.
b. Fast axonal transport is responsible for movement of proteins from the cell body to the
axon.
c. Anterograde transport is accomplished by the protein kinesin.
d. The motor proteins, kinesin and dynein, are associated with microtubules.
e. A majority of the ATP in nerve cells is used for axonal transport.
Correct answer: e
Explanation: While axonal transport does require energy, it is not the primary consumer of ATP in neurons. Most ATP is used for maintaining ion gradients, neurotransmitter release, and general cellular homeostasis. Thus, option e is incorrect.
Which of the following statements is not characteristic of Schwann cells in Wallerian
degeneration?
a. Schwann cells provide physical guidance needed for the regrowth of the axon.
b. Schwann cells release trophic factors that stimulate growth.
c. Schwann cells act to clear the myelin debris with the help of macrophages.
d. Schwann cells increase synthesis of myelin lipids in response to axonal damage.
e. Schwann cells are responsible for myelination of axons in the peripheral nervous
system
Correct answer: d
Explanation: While Schwann cells remyelinate regenerating axons, the synthesis of myelin lipids is not significantly increased during Wallerian degeneration, which is a breakdown process. Hence, d is not characteristic.
Prenatal exposure to ethanol can result in mental retardation and hearing deficits in the
newborn. What is the cellular basis of the neurotoxicity?
a. neuronal loss in cerebellum.
b. acute cortical hemorrhage.
c. microcephaly.
d. loss of hippocampal neurons.
e. degeneration of the basal ganglia.
Correct Answer: c. microcephaly
Explanation:
Prenatal ethanol exposure is most associated with microcephaly, a condition marked by reduced brain growth and head size due to impaired neurogenesis during development. While loss of specific neurons (e.g., hippocampal) can occur, microcephaly represents the overarching and hallmark anatomical consequence of fetal alcohol exposure, encompassing widespread cortical and subcortical damage. The answer “d. loss of hippocampal neurons” is true but not as encompassing or representative of the primary neurodevelopmental impact as “c”.
Which of the following characteristics is LEAST likely to place a neuron at risk of toxic
damage?
a. high metabolic rate.
b. ability to release neurotransmitters.
c. long neuronal processes supported by the soma.
d. excitable membranes.
e. large surface area.
Correct answer: b
Explanation: While neurons do release neurotransmitters, this trait is not directly associated with toxic vulnerability. In contrast, high energy demands, excitability, and large surface area increase susceptibility to toxins.
The use of meperidine contaminated with MPTP will result in a Parkinson’s disease-like
neurotoxicity. Where is the most likely site in the brain that MPTP exerts its toxic effects?
a. cerebellum.
b. cerebral cortex.
c. brainstem.
d. substantia nigra.
e. hippocampus.
Correct answer: d
Explanation: MPTP selectively damages dopaminergic neurons in the substantia nigra pars compacta, mimicking Parkinson’s disease.
Which of the following statements regarding the PNS and the CNS is TRUE?
a. Nerve impulse transduction is much faster in the CNS than in the PNS.
b. PNS axons can regenerate, whereas CNS axons cannot.
c. Remyelination does not occur in the CNS.
d. Oligodendrocytes perform remyelination in the PNS.
e. In the CNS, oligodendrocyte scarring interferes with axonal regeneration.
Correct answer: b
Explanation: Unlike the CNS, axons in the PNS can regenerate due to the presence of supportive Schwann cells. CNS axons are limited in their regenerative capacity.
Platinum (cisplatin) results in which of the following neurologic problems?
a. peripheral neuropathy.
b. trigeminal neuralgia.
c. spasticity.
d. gait ataxia.
e. tremor.
Correct answer: a
Explanation: Cisplatin is known for inducing peripheral neuropathy through sensory neuron damage, especially in dorsal root ganglia.
Which of the following is NOT characteristic of axonopathies?
a. There is degeneration of the axon.
b. The cell body of the neuron remains intact.
c. Axonopathies result from chemical transaction of the axon.
d. A majority of axonal toxicants cause motor deficits.
e. Sensory and motor deficits are first noticed in the hands and feet following axonal
degeneration.
Correct Answer: d. A majority of axonal toxicants cause motor deficits.
Explanation:
Axonopathies often involve sensory neurons more than motor neurons, particularly because of the long axons of sensory neurons, which make them more vulnerable to toxic damage. Thus, it’s incorrect to say that a majority of axonal toxicants cause motor deficits — many actually cause sensory or mixed deficits first.
Other choices are accurate: axon degeneration occurs (a), the neuron’s soma remains intact (b), the injury often starts chemically at the axon (c), and the “glove and stocking” sensory pattern of degeneration (e) is classic.
All of the following statements regarding lead exposure are true EXCEPT:
a. Lead exposure results in peripheral neuropathy.
b. Lead slows peripheral nerve conduction in humans.
c. Lead causes the transection of peripheral axons.
d. Segmental demyelination is a common result of lead ingestion.
e. Lead toxicity can result in anemia.
Correct answer: c
Explanation: Lead does not cause actual transection (cutting) of axons. It causes functional and structural disruption like demyelination, impaired neurotransmission, and anemia, but not physical transection.
Regarding excitatory amino acids, which of the following statements is FALSE?
a. Glutamate is the most common excitatory amino acid in the CNS.
b. Excitotoxicity has been linked to conditions such as epilepsy.
c. Overconsumption of monosodium glutamate (MSG) can result in a tingling or burning
sensation in the face and neck.
d. An ionotropic glutamate receptor is coupled to a G protein.
e. Glutamate is toxic to neurons
Correct answer: d
Explanation: Ionotropic glutamate receptors are ligand-gated ion channels, not G protein–coupled receptors (which define metabotropic receptors). So option d is FALSE.
