Question

1. At resting membrane potential in a neuron, which is true of the forces responsible for the movement of potassium (directed into or out of the cell)?

Select one:

a. The chemical gradient is outward while the electrical gradient is inward

b. Chemical gradient is inward while the electrical gradient is outward

c. Chemical and electrical gradients are directed outward

d. Chemical and electrical gradients are directed inward

2. Multiple sclerosis is a devastating disease because it...

Select one:

a. produces degeneration of nerve terminals in unmyelinated axons.

b. stops the action of the Na+/K+ pump.

c. prevents neurotransmitter release in motor neurons.

d. produces a conduction block at the point of demyelination.

e. blocks action potentials by blocking voltage-gated K+ channels.

Answer 1

Ans 1 : a) the chemical gradient is outward while the electrical gradient is inward.

The difference in the concentration of the ions lead to chemical gradient , whereas difference in the charge across the membrane is called electrical gradient.

The inside of cell has higher concentration of potassium , so the chemical concentration is directed outwards.

The inside of the membrane is also negative as compared to the exterior , hence the electrical gradient is directed inwards.

The combined gradient (electrochemical ) drives the movement of ions across the membrane of cell.