Question

Name the main hormone secreted by adrenal glands? Give its function.

Answer 1

Adrenal glands also known as suprarenal glands are endocrine glands present one at the anterior part of each kidney. It is composed of two types of tissues, adrenal medulla, and adrenal cortex.

The adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine, these are commonly called catecholamines. These are rapidly secreted in response to the stress of any kind and during emergency situations and are called emergency hormones or hormones of fight or flight. Their functions are to increase the heartbeat, the strength of heart contraction and the rate of respiration. Also, they increase the sweating, piloerection, alertness and pupillary dilation. They stimulate the breakdown of glycogen resulting in an increased concentration of glucose in the blood. With this, they also, stimulate the breakdown of lipids and proteins.

The adrenal cortex is divided into three layers- zona reticularis (inner layer), zona fasciculata (middle layer) and zona glomerulosa (outer layer). The cortex secretes hormones called corticoids and divided into 3 major categories - mineralocorticoids, glucocorticoids, and sex corticoids. The hormone mineralocorticoid is aldosterone which controls the electrolyte and water metabolism, stimulating kidney tubules to reabsorb more Na${}^{+}$ and increases excretion of $K^{+}$. The hormone glucocorticoid provides general resistance of long-term stress by anti-inflammatory and anti-allergic responses. The sex corticoids are androgens and estrogen which help in the development of secondary sexual characteristics.