Hormone produced by different glands and its function-3

Adrenal Glands

The adrenal (suprarenal) glands are paired yellowish masses of tissue situated at the superior pole of each kidney and enclosed within the renal fascia. Each adrenal gland is about 5 cm (2 in) long 3 cm wide (1.2 in) 'and weighs about 4 gram. Each gland consists of two parts: an outer adrenal cortex and an inner adrenal medulla. A thin wall of connective tissue separates the glands from the kidneys. The adrenal glands are directly below the diaphragm.

Adrenal Medulla

The adrenal medulla is the inner part of the adrenal gland. It is more like a nervous tissue which is the part of the sympathetic nervous system. The cells of the adrenal medulla secretes two major hormones: epinephrine and norepinephrine, which are collectively called catecholamines and sympathomimetic. The secretion of the both hormone is stimulated by sympathetic impulses from the hypothalamus. These two hormones function to defend cells against stress situation and prepare the body for "fight, fright or flight". They play a great role in activation of the autonomic nervous system as well. When fear, pain, hemorrhage, trauma, or other stressors are influencing the body, epinephrine and norepinephrine are released in response to the release of acetylcholine (which is released when the sympathetic nervous system is activated).

Functions of the Epinephrine and Norepinephrine

• Norepinephrine increases blood pressure through causing vasoconstriction in the skeletal muscle, viscera, and skin.
• Additionally, it widens the pupils, raises heart activity, and reduces GI tract motility.
• Epinephrine increases blood flow to the skeletal muscles, cardiac excitation and contractility, and the mobilization and utilization of glucose.
• Additionally, it widens the bronchioles, lessens peristalsis, and stimulates the liver's conversion of glycogen to glucose.

Adrenal Cortex

The adrenal cortex is the outer part of the adrenal gland. It consists of the bulk of the gland and is true glandular tissue. There are three layers or zones in the adrenal cortex. The superficial layer (zona glomerulsoa) secrete mineralocorticoids, middle layer (zona fasciculate) secretes glucocorticoids and inner layer (zona reticularis) secrets mostly gonadocorticoids (sex steroids).

Mineralocorticoids

The main mineral steroid is aldosterone. Its activities are connected to the body's maintenance of electrolytes and water. It promotes potassium excretion in the urine and sodium reabsorption by the renal tubules through a negative feedback loop.

Blood pressure and volume of blood are both controlled by aldesterone. Additionally, it encourages H+ excretion in the urine.

Angiotensin II, low sodium, and high potassium levels in the blood enhance the mineralocorticoid's production. Aldestorone encourages potassium excretions and sodium retention through acting on the kidneys. Aldosterone secretion is controlled by the renin-angiotensin-aldosterone system.