Distinguish between renin and rennin.

Renin and rennin are two distinct enzymes with different functions and contexts:

Renin:

Function: Renin is an enzyme produced and released by specialized cells in the kidneys called juxtaglomerular cells. Its primary function is to play a key role in regulating blood pressure and maintaining fluid and electrolyte balance in the body.
Action: Renin acts on angiotensinogen, a precursor protein produced by the liver, to convert it into angiotensin I. Angiotensin I is then further processed by other enzymes to ultimately produce angiotensin II, a potent vasoconstrictor that leads to increased blood pressure and stimulates the release of aldosterone from the adrenal glands.
Physiological Significance: The renin-angiotensin-aldosterone system is crucial for maintaining blood pressure, blood volume, and electrolyte balance. Dysregulation of this system can lead to hypertension (high blood pressure) and other cardiovascular disorders.
Rennin:

Function: Rennin (also known as chymosin) is an enzyme that is found in the stomachs of young mammals, including humans, during infancy. It aids in the digestion of milk proteins by coagulating milk and helping to form curds. This is particularly important in the digestion of mother's milk, as it allows the stomach to retain the milk for a longer period, facilitating better nutrient absorption.
Action: Rennin acts on the protein casein, which is present in milk, and helps convert it into solid curds. These curds are easier to digest than the liquid form of milk, and this enzymatic activity is especially important for the digestive system of young mammals.
Physiological Significance: Rennin is most active during early infancy when the digestive system is not yet fully developed. As mammals grow older, their bodies typically produce less rennin because they transition to other forms of nutrition beyond milk.
In summary, renin is an enzyme produced by the kidneys that plays a central role in regulating blood pressure and fluid balance, while rennin is an enzyme found in the stomachs of young mammals, aiding in the digestion of milk proteins. The two enzymes have distinct functions and operate in different physiological contexts.