Waste products created after metabolic activity are toxic for the body. They can harm all vital functions so their removal is necessary from the body.

Osmoreceptors in the body get in action when the blood pressure falls below a certain limit. They trigger action of Anti Diuretic Hormones which maintain osmotic pressure of the blood.

Renin converts angiotensin to angiotensin I and finally to angiotensin II. Angiotensin II increases glomerular filtration rate.

Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working.

Adrenal glands, also known as suprarenal glands, are small, triangular-shaped glands located on top of both kidneys.

Malpighian tubules are found in phylum arthropoda, which includes the largest number of animals, the animals of this phylum are known as insects, which possess jointed feet or appendages. Animals of this phylum also possess green glands.

The excretory organs of Platyhelminthes are flame cells.

In certain land animals and birds the excretory product is uric acid. The main advantage with this type of excretion is of water conservation. Animals living in extreme temperature need to conserve water. In birds less weight helps in flight adaptation so uricotelic excretion is the preferred mode.

When ammonia is the main excretory product, this type of excretion is called ammonotelic.

(i) Urea is formed by ornithine cycle. It occurs in liver.
(ii) The process of excreting nitrogenous waste as ammonia is known as ammonotelic. During excretion, such animals excrete ammonia so they are known as ammonotelic animals.
Ammonotelic creatures include protozoans, crustaceans, platyhelminths, cnidarians, poriferans, echinoderms, fishes, and amphibian larvae/tadpoles.

As urine collects in the urinary bladder, the muscular walls of the bladder distend to accomodate it.The stretch receptors on the wall of the bladder send signals to the CNS by stimulating the sensory nerve ending in the bladder.It causes an urge to pass out the urine.So if the stretch receptors are totally removed from the bladder, urine will not be collected in the bladder and urination will keep continuing.

The counter current mechanism has been evolved in higher vertebrates (birds and mammals including man) to excrete hypertonic urine(urine is more concentrated than blood) for conserving body water so necessary for land life.

Atrial Natriuretic Factor(ANF) is secreted by the atria of heart, when blood flow increases. It causes vasodilation (dilation of blood vessels) and thereby, decrease the blood pressure. ANF works antagonistically to RAAS.

Alcohol inhibits the release of ADH and caffeine interferes with ADH action and sodium reabsorption.Thus both of these artifically dilute the urine.Such compounds which dilute urine are called diuretic substances.

Excessive loss of fluid from the body activates osmoreceptors, which stimulate the hypothalamus to release ADH from the neurohypophysis. ADH facilitates water reabsorption from posterior parts of tubule.This decreases osmolarity of blood.
An increase in body fluid volume can switch off the osmoreceptors and suppress the ADH release to complete the feedback.ADH also causes constrictory effects on blood vessels.