During the relative refractory period, an initial threshold-level depolarization is usually not sufficient to trigger an action potential. Why?
A) Some Na+ channels have returned to their resting position and K+ channels are still open, so Na+ entry is offset by K+ loss.
B) Only some Na+ channels have returned to their resting position.
C) Only K+ channels are still open, so Na+ entry is offset by K+ loss.
D) The statement is incorrect; a threshold-level depolarization always triggers an action potential.
E) Only a few K+ channels have returned to their resting position.
A) Some Na+ channels have returned to their resting position and K+ channels are still open, so Na+ entry is offset by K+ loss.
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Which of the following is the major positive ion outside cells?
A) nitrogen B) hydrogen C) potassium D) sodium
The refractory period:
1.prevents the retrograde propagation of Action Potentials along the neuronal membrane 2.prevents the retrograde propagation of Graded Potentials along the neuronal membrane 3.results from actions of the Na+/K+ pump 4.Both 1 and 3 are correct. 5.All of these are correct.
Match the enzyme or hormone with the organ that produces it.A. Salivary glandsB. StomachC. LiverD. Small intestineE. PancreasCarboxypeptidase
Fill in the blank(s) with the appropriate word(s).
During an action potential ________.
A. K+ influx causes after-hyperpolarization B. Na+ influx causes depolarization C. Na+ efflux causes depolarization D. K+ influx causes repolarization