-Priyanti, Subject Matter Expert at Edumarz
Solution: The production of urine is dependent upon the total amount of excess water remaining after reabsorption in the kidneys. In this water, other compounds such as nitrogenous wastes (mainly urea) and some salts are present. The volume of water excreted as urine is dependent upon the water content in the body. If an individual is deficient in water, they would produce a small volume of concentrated urine that is dark yellow in colour. On the other hand, someone drinking ample quantities of water will excrete a high volume of dilute urine (that is pale yellow to almost transparent).
Hormonal activity responsible for this regulation is mediated by the vasopressin or antidiuretic hormone (ADH), secreted by the posterior pituitary gland. Release of ADH enhances reabsorption of urine by the kidneys, thus reducing the amount of water lost through urine and making it more condensed. This hormone is useful in maintaining the water levels in the body under conditions of water stress, when the individual is dehydrated.
Other factors regulating the volume of urine include the amount of wastes that have to be excreted. More the concentration of wastes, higher will be the volume of water needed for its removal. Dietary and immediate environmental conditions of an individual also play a role in this regulation.