USMLE: Medical Science MCQs (Practice-Test 24 of 135)

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1. Excessive polarization due to GABA is created due to the opening of ____ channels.

   1. Ca + +

   2. Cl-

   3. K +

   4. Na +

   Answer: b

2. Valium has an effect on ____ to inhibit neural transmission.

   1. Epinephrine

   2. Norepinephrine

   3. GABA

   4. Dopamine

   Answer: c

3. The drug ____ blocks the reuptake of serotonin into presynaptic axons.

   1. Prozac

   2. Valium

   3. Xanax

   4. Deprenyl

   Answer: a

4. Which of the following toxins blocks Sodium Channels?

   1. Srychnine

   2. Neostigmine

   3. Tetrodotoxin

   4. Curare

   Answer: c

5. Clostridium botulinum releases this enzyme that destroys peptide bonds.

   1. Amylase

   2. Endopeptidases

   3. Exopeptidases

   4. Protein kinase

   Answer: b

6. Multiple sclerosis is a disease that attacks the _______ of neurons in the CNS.

   1. Myelin sheaths

   2. Axon terminals

   3. Sodium channels

   4. Nicotinic receptors

   Answer: a

7. Which of the following is not considered a type of synapse?

   1. Dendrodendritic

   2. Axosomatic

   3. Axoaxonic

   4. Denoaxonic

   Answer: d

8. The progression of a nerve impulse with the nodes of Ranvier is called _______.

   1. Saltatory conduction

   2. Transmission

   3. Unmyelinated conduction

   4. Relative conduction

   Answer: a

9. Supporting cells located within the CNS are collectively called _____.

   1. Neuroglia

   2. Astrocytes

   3. Perikaryon

   4. Satellite cells

   Answer: a

10. Which of the following types of cells line the ventricles and spinal cord?

    1. Astrocytes

    2. Schwann cells

    3. Ependymal cells

    4. Oligodendrocytes

    Answer: c