Author Question: When a cell membrane of an excitable cell is exposed to a depolarizing current, which of the ... (Read 101 times)

xroflmao · **on:** Jul 16, 2018

When a cell membrane of an excitable cell is exposed to a depolarizing current, which of the fol-lowing occurs?

a. Increased influx of calcium into the cell
b. Rapid influx of sodium ions into the cell
c. Increased efflux of potassium out of the cell
d. Rapid efflux of protein molecules out of the cell

Question 2

Phase 1 of a single-breath CO2 curve represents which of the following?

a. Anatomic dead space
b. Physiologic dead space
c. Transition between airway and alveolar exhaled gas
d. Anatomic shunt

stano32 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: B
An action potential begins when the cell membrane of the excitable cell is exposed to a depolar-izing current and eventually reaches its excitation threshold potential. The initial phase of this type of action potential consists of a rapid upstroke or depolarization. This change in membrane potential to a more positive value occurs because of a rapid influx of sodium ions into the cell.

Answer to Question 2

ANS: A
Anatomic dead space has no CO2; the mixed expired CO2 (FECO2) = 0 during that phase.