Question

1. If a sensory neuron is voltage-clamped at -70 millivolts in normal saline (so all ion channels can work) you would expect to see:

a)relatively little current flow, since this is near the resting potential, where the membrane potential is mostly balancing the concentration gradients for the various ions

b)a large positive current inward as potassium enters the cell

c)a large positive current inward as sodium enters the cell

d)a large positive current outward as sodium leaves the cell

2. A nociceptor neuron with TRPV1 channels is bathed in normal saline so all ion channels can function. Then capsaicin (the active ingredient in hot peppers) is applied. You would expect to see:

a)no change in the membrane potential

b)depolarization of the cell as the open TRPV1 channels allows calcium entry

c)hyperpolarization of the cell as calcium flows out of the cell

d)depolarization of the cell as potassium enters the cell via potassium channels

Answer 1

Ans:- 1 ---- a) because at resting membrane potential net flow of ion is zero.

Ans2:- b)

TRPV1 receptors are activated by vanilloids like capsaicin . At negative holding potentials, this activation results in the influx of calcium and sodium, thereby depolarizing the cell.