Question

1.

While a neuron is in its absolute refractory period, the amount of current required to depolarize the neuron is elevated above normal.

True

False

2.

Provide the number as your answer:

The sodium-potassium pump uses ATP in order to transport ............................ Na+ ions out of the cell and transport ........................... K+ ions in the cell.

Answer 1

1. true

During the relative refractory period, a stronger than normal stimulus is needed to elicit neuronal excitation. After the absolute refractory period, Na+ channels begin to recover from inactivation and if strong enough stimuli are given to the neuron, it may respond again by generating action potentials.

It is correct as more current is required for depolarization of neuron when it is in the refractory period.

2. three Na+ outside and two K+ inside.

these are the numbers.

The process of moving sodium and potassium ions across the cell membranes is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase. This process is responsible for maintaining the large excess of Na+ outside the cell and the large excess of K+ ions on the inside. A cycle of the transport process is sketched below. It accomplishes the transport of three Na+ to the outside of the cell and the transport of two K+ ions to the inside. This unbalanced charge transfer contributes to the separation of charge across the membrane. The sodium-potassium pump is an important contributor to action potential produced by nerve cells. This pump is called a P-type ion pump because the ATP interactions phosphorylate the transport protein and cause a change in its conformation.