Questions: What ion enters a neuron causing depolarization of the cell membrane?
Select one:
a. PHOSPHATE
b. POTASSIUM
c. CHLORIDE
d. SODIUM
Transcript text: What ion enters a neuron causing depolarization of the cell membrane?
Select one:
a. PHOSPHATE
b. POTASSIUM
c. CHLORIDE
d. SODIUM
Solution
The answer is the last one (or D): SODIUM.
Explanation for each option:
a. PHOSPHATE: Phosphate ions do not play a primary role in the depolarization of the neuron cell membrane. They are more involved in energy transfer and storage within the cell.
b. POTASSIUM: Potassium ions (K+) are involved in repolarization and maintaining the resting membrane potential, but they do not cause depolarization. During depolarization, potassium ions actually move out of the cell.
c. CHLORIDE: Chloride ions (Cl-) are generally involved in hyperpolarization, making the inside of the cell more negative, which is the opposite of depolarization.
d. SODIUM: Sodium ions (Na+) enter the neuron during depolarization. When a neuron is stimulated, sodium channels open, allowing Na+ to flow into the cell, making the inside of the cell more positive and leading to depolarization.
Summary:
Depolarization of the neuron cell membrane is primarily caused by the influx of sodium ions (Na+). Therefore, the correct answer is D: SODIUM.