Question

Which of the following best describes the na and k concentrations across a neuron's plasma membrane?

a. the na concentration is higher inside the cell compared to outside.
b. the k concentration is higher outside the cell compared to inside.
c. the na concentration is higher outside the cell compared to inside.
d. the k concentration is higher inside the cell compared to outside.
e. both na and k concentrations are higher outside the cell compared to inside.
f. both na and k concentrations are higher inside the cell compared to outside.

Answer 1

The Na+ concentration is higher outside the neuron, while the K+ concentration is higher inside. This distribution is maintained by the sodium-potassium pump and is crucial for the neuron's resting membrane potential.

Step-by-step explanation:

The concentration of sodium (Na+) and potassium (K+) ions across a neuron's plasma membrane is crucial for the maintenance of the resting potential and for the generation of action potentials. In the resting state of a neuron, the Na+ concentration is higher outside the cell compared to the inside, whereas the K+ concentration is higher inside the cell compared to outside.

This is primarily due to the sodium-potassium pump, which actively transports three Na+ ions out of the neuron for every two K+ ions it moves in. As a result, the inside of the cell becomes slightly negatively charged in comparison to the outside, establishing the resting membrane potential. Therefore, the option that best describes these concentrations is C. the Na+ concentration is higher outside the cell compared to inside and D. The K+ concentration is higher inside the cell compared to outside.