21 Which of the following statements regarding the propagation of an action pote

Question

21 Which of the following statements regarding the propagation of an action potential is most accurate? a) sodium ions that flow into the cell during one action potential diffuse and induce a new action potential in a neighboring membrane region; b) action potentials will propagate in all directions along an axon since sodium ions diffuse in all directions; c) sodium ions do not diffuse from the axon hillock into the perikaryon, thus ensuring one - way propagation of the action potential; d) action potentials propagate only toward cell membranes that are experiencing a refractory period; e) new action potentials are generated by depolarizations to -65 mv. 22. A postsynaptic cell a) must always be a neuron; b) possesses many synaptic vesicles near the synapse; c) releases neurotransmitter as a result of the influx of calcium; d) may possess receptor proteins that function as chemically regulated gates; e) always contains a membrane bound acetylcholinesterase The increase in excitability of a postsynaptic neuron following repeated stimulation is called a) inhibitory post synaptic potential; b) presynaptic inhibition; c) synaptic potentiation; d) excitatory post synaptic potential; e) neuromodulation. 23. 24. Biogenic amines a) are always found in the CNS; b) are never found in the CNS; c) are constructed from short chains of amino acids; d) are metabotropic (indirect) in function; e) include the neurotransmitter acetylcholine. 25. Which of the following does not appear to be a structural class of neurotransmitter? a) acetylcholine; b) disaccharides; c) peptides; d) purines; e) peptides.

Explanation / Answer

21. a and c; sodium ions flow in the cell to induce action potential in the next region of the membrane; sodium ions do not diffuse back from the hillock to the perikaryon ensuring a one way propogation

22. D

23. D

24. C

25. Disaccharide

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