25. Which of the following choices correctly fills in the blanks? After repolarization, the sodium ions are found- A -the neuron and the potassium ions are found -B -of the neuron. This reversal of ions can be fixed by the action of -C,D- sodium ions are taken out and- E -potassium ions are brought in.
A. A )outside B) inside C) NA+ K exchange pump D) two E) three
B. A )outside B) inside C) Voltage gated channels D) two E) three
C. A )inside B) outside C) NA+ K exchange pump D) three E) two
D. A )inside B) outside C)voltage gated channels D) three E) two
26. The nerve impulses always travel in one direction from dendrites to axon terminals. What prevents an action potential from travelling backward?
Select one:
a. Hyperpolarization of the neuron makes the membrane more positive and prevents another action potential.
b. After repolarization, the reversal of ions prevents another action potential as there would not be enough sodium ions outside the cell to rush in.
c. After repolarization, the refractory period occurs, where the sodium ions are found outside the cell.
d. The refractory period prevents another action potential by lowering the threshold potential. My answer is B but not sure if its correct or not.
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