Regulations of Urine Output Through Hormones

Hormonal Regulation of Urine

Human beings are made of 75% water. The huge percentage of water in the human body is attributed to the constant need to sustain fluid balance through drinking water. However, the quantity of ingested water needs to be balanced with the amount and concentration of urine generated so as to regulate the volume of fluid and osmolarity within an ordinary range. Urine is formed in the human body through three major processes that occur in the nephrons i.e. glomerular filtration, tubular reabsorption, and turbular secretion (McCann et. al., 2002, p.605). The quantities of substances reabsorbed and secreted in the nephrons are varied by the kidneys, which contributes to changes in the composition of excreted urine.

Urine output or excretion is usually regulated by several hormones that also play a crucial role in regulation of urine. Vasopressin is one of the hormones that regulate urine output and is regarded as the hormonal mechanism for controlling the output of urine. This hormonal mechanism is excreted from the posterior pituitary gland that is directly linked to the magnocellular cells of the supraoptic nucleus and paraventricular nucleus. Through activating aquaporins, vasopressin acts on the renal by gathering duct to improve the reabsorption of water. Aquaporins are proteins with water channels that enable water reabsorption across the membrane from gathering duct back into cells and then into the blood (Rubin & Pfaff, 2010, p.75).

The other hormones that regulate urine output are aldosterone and antidiuretic hormone, which also control urine quantity and concentration. Aldosterone is a steroid hormone that is created by the adrenal cortex while antidiuretic hormone is a posterior pituitary hormone that is excreted in response to the solute concentration of blood that flows via the hypothalamus. Aldosterone regulates urine output through controlling the rate of reabsorption of sodium from the tubules while antidiuretic hormone regulated the reabsorption of water from the gathering tubules. Through regulating sodium reabsorption, aldosterone helps in controlling the secretion of potassium through tubular epithelial cells, which results in regulating urine output. In contrast, antidiuretic hormone acts in the distal tubule where it gathers ducts to enhance reabsorption of water and concentration of urine. The deficiency of antidiuretic hormone decreases the reabsorption of water and causes dilute urine.