Question

1.

Astrocytes play a critical role in regulating the external levels of which ion?

	a.	Na+
	b.	K+
	c.	Cl-
	d.	Ca2+

2.

Depolarization will change the membrane potential to a more negative value while hyperpolarization will change the membrane potential to a less positive value.

True

False

Answer 1

1) The correct option is b. K⁺.

Astrocytes play an essential role in the regulation of the external levels of potassium ions. They have membrane potassium pumps, which concentrate potassium ions in their cytosol. When K⁺ increases, K⁺ enters the astrocyte through the potassium channels and causes astrocyte membrane to depolarize.

2) The given statement is false.

Depolarization occurs when the membrane potential becomes less negative or more positive whereas hyperpolarization occurs when the membrane potential becomes more negative.