Tag: zoology

ADH regulates the water balance in body by decreasing the excretion of free water from kidney (antidiuretic effect). It does so by increasing the permeability of ADH responsive cells in linings of distal convoluted tubules and collecting ducts of renal nephrons. 

Anti-diuretic hormone or the vasopressin is secreted by the hypothalamus and is stored and released by the posterior pituitary. This hormone is responsible for maintaining blood volume. When salty food is consumed, it increases the ions in the bloodstream and reduces the volume of the blood. The ADH will be released in this condition, that will directly act on the water reabsorbing channels in the collecting ducts of the nephrons. So, water will be reabsorbed from the filtrate and restored back to the blood. 

Diabetes insipidus is a rare condition that occurs when the kidneys are unable to conserve water during the process of filtering blood. Diabetes insipidus is caused by a lack of antidiuretic hormone (ADH), also called vasopressin, which prevents dehydration, or the kidney's inability to respond to ADH. ADH enables the kidneys to retain water in the body. The hormone is produced in the hypothalamus. It is stored and released from the pituitary gland.

ADH is secreted by pituitary gland. It increases the water permeability of distal convoluted tubules and collecting tubules, hence, plays a significant role in water re-absorption. The absence of ADH will reduce water reabsorption which may lead to water diuresis or diabetes insipidus.

 A fall in glomerular blood flow/glomerular blood pressure/GFR can activate the JG cells to release renin which converts angiotensinogen in blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR. Angiotensin II also activates the adrenal cortex to release Aldosterone. Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule. This also leads to an increase in blood pressure and GFR. This complex mechanism is generally known as the Renin-Angiotensin mechanism. Hence Angiotensin  II and aldosterone regulate solute reabsorption during urine formation.

Aldosterone is the hormone produced by the adrenal gland. Aldosterone balance sodium and potassium in our body. When Excess of aldosterone is produced by the adrenal gland causes the body to lose potassium and retain sodium. It leads to excretion of dilute urine.

During the summer season, The hormone whose concentration is maintained at a high level is Vasopressin or ADH(antidiuretic hormone). When excess water is lost through urine the blood volume is decreased and its osmolarity is increased which stimulates the posterior pituitary to release ADH.ADH decreases the volume of urine by increasing the reabsorption of water by kidneys and prevents diuresis. Hence it is also called antidiuretic hormone.

The term diuresis refers to the excessive production of urine. When excess water is lost through urine the blood volume is decreased and its osmolarity is increased which stimulates the posterior pituitary to release ADH.ADH decreases the volume of urine by increasing the reabsorption in the later parts of the tubule and prevents diuresis.