Question

How is nitrogenous waste excreted through saliva? ( As given in NCERT)

Answer 1

Yes, saliva has been shown to contain urea which is the final product of amino acid breakdown in the body. Ammonia is produced from amino acid breakdown and is detoxified in the liver (not the kidney) to form urea, a non-toxic substance. The majority of urea is excreted by the kidneys into the urine but a portion of urea is secreted into the digestive tract each day as a way of salvaging nitrogen that would otherwise be lost in urine. The nitrogen in urea can be used by the microbial population in the small intestine to make new amino acids which can then be absorbed and utilized for protein synthesis in the body.

Saliva is not essential for starch digestion but it does contain a number of enzymes, amylases, that begin the digestive process.

Salivary glands and lacrimal glands excrete small amounts of nitrogenous waste through saliva and tears.