Hole's Human Anatomy & Physiology (Shier), 12th Edition

Ph.I.L.S. 3.0 Quizzing 25: Ph.I.L.S. 3.0 Quizzing

Ph.I.L.S. 3.0 Quizzing

1
What was the relationship between the membrane potential and the concentration of sodium outside the cell?
A)The membrane potential depolarized (became less negative) when the level of sodium was decreased.
B)The membrane potential did not change when the extracellular level was decreased.
C)The membrane potential hyperpolarized (became more negative) when the level of sodium was decreased.
2
Look at your final graph. What is the slope of the line? The value has been written on the graph; the slope is the number immediately to the LEFT of 'x'?
A)0
B)About 8.
C)About 20.
D)About 33.
3
If you decreased the concentration of sodium in the Ringer's solution by a factor of 10 (say from 100 to 10mEq Na/L) this would produce:
A)a membrane depolarization of about 8 mV.
B)no change in the membrane potential.
C)a membrane hyperpolarization of about 8 mV.
4
Increasing the level of potassium in the Ringer's solution by a factor of 10 (say from 5 to 50) depolarizes the membrane by about 30 mV. This means that, when compared with sodium:
A)potassium has a greater effect on the membrane potential.
B)potassium has the same effect on the membrane potential.
C)potassium has less of an effect on the membrane potential.
5
A muscle contraction is initiated by an action potential, whose threshold is 15 mV depolarized with respect to resting. What do you think would happen if you changed the Ringer's solution from one with 20 mEq Na/L to one with 200 mEq Na/L?
A)The muscle would contract and shorten.
B)The muscle would lengthen.
C)The muscle would exhibit no visible response.
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