At the normal resting membrane potential of a typical neuron, its sodium-potassium exchange pump transports
A) 1 intracellular sodium ion for 2 extracellular potassium ions.
B) 2 intracellular sodium ions for 1 extracellular potassium ion.
C) 3 intracellular sodium ions for 1 extracellular potassium ion.
D) 3 intracellular sodium ions for 2 extracellular potassium ions.
E) 3 extracellular sodium ions for 2 intracellular potassium ions.
Question 2
Which of the following is not true regarding the establishment of a neuron's resting membrane potential?
A) Chemical and electrical forces both favor sodium ions entering the cell.
B) Electrical forces do not push sodium ions into the cell.
C) The chemical gradient for potassium ions tends to drive them out of the cell.
D) Ion pumps in the plasma membrane eject sodium ions as fast as they cross the membrane.
E) Resting membrane permeability to Na+ is very low.
Question 3
Which of the following can cause demyelination?
A) arsenic poisoning
B) diphtheria
C) multiple sclerosis
D) mercury exposure
E) Demyelination can be caused by arsenic, diphtheria, multiple sclerosis and mercury.
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