Question

Urinary excretion of Na is regulated by

• A. Anterior pituitary
• B. Posterior pituitary
• C. Adrenal cortex
• D. Adrenal medulla

Answer 1

Answer: (C)

Adrenal cortex

$N{a}^{+}$ is the predominant ion in the extracellular fluid. Nearly about 99% of filtered $N{a}^{+}$ is reabsorbed. The principal regulator of Na+ reabsorption is the steroid hormone aldosterone, which is produced in the zona glomerulosa of the adrenal cortex. Aldosterone works to increase $N{a}^{+}$ reabsorption by promoting the expression of all the channels and pumps that mediate $N{a}^{+}$ reabsorption.