Question

Regulation of urine formation is under hormonal control. Comment.

Answer 1

Hint: Chemical secretions produced by the endocrine gland control and coordinates the life processes. Various hormones are involved in urine formation.

Complete answer:
The kidneys aren't sensitive to only chemical composition and osmolarity of blood and plasma but also are influenced by hormones. The foremost important hormone that directly regulates kidney function is the Antidiuretic Hormone (ADH). Aside from ADH, the parathormone also influences excretion.
- When the water levels within the body fall below a particular level, the receptors referred to as osmoreceptors present throughout the body are activated. Osmoreceptors are a kind of receptors that detect a change within the pressure of the blood and plasma.
- Once these osmoreceptors are activated, they send impulses to the posterior lobe of the pituitary to stimulate the secretion of ADH. ADH stimulates the kidneys to reabsorb water from the urine to revive the water levels within the body.
- A similar mechanism is seen when the vital sign falls. When there's a fall in vital sign, the quantity of blood passing through the glomeruli is a smaller amount then there's less filtration rate. thanks to this, a kind of cells referred to as juxtaglomerular cells present around the glomerulus, are activated, and that they release an enzyme called renin.
- Renin within the blood converts angiotensinogen to angiotensin I, which is eventually converted to angiotensin II. Angiotensin II acts on the blood vessels and capillaries to cause their construction thereby increasing the vital sign. The angiotensin II also stimulates the cortex to release aldosterone which has an impact on sodium levels within the blood.
- Aldosterone is primarily liable for reabsorption of sodium from the urine. Reabsorption of sodium results in an increase in water reabsorption also. Both these together help to revive the vital sign. This complete mechanism where the hormones are acting towards restoring the vital sign is understood because of the Renin- Angiotensin- Aldosterone mechanism or RAAS mechanism.

Note: While the first function of our excretory system is the elimination of waste, there's another important factor it must consider. This is often the balance of fluids and electrolytes in our bodies. Our bodies must maintain a healthy internal environment, and therefore the regulation of excretion plays an enormous part therein, RAAS is an important mechanism of this.