explain the mechanism of urine in brief ( short and important)
Answers
Answer:
The urinary system, also known as the renal system or urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine.[1] The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra.
Answer:
Mechanism of urine formation:
It has four steps. 1. Ultra filtration 2. Reabsorption 3. Secretion 4. Concentration of urine
1. Ultra filtration : As the blood passes through the afferent arteriole it gets ultra filtrated under pressure. All small volume solutes and water are filtered out and enter the Bowman's capsule. This product is called glomerular filtrate.
2. Reabsorption : Glomerular filtrate passes through the pct which is surrounded by peritubular capillaries. The latter reabsorb all the useful components of glomerular filtrate like glucose, amino acids, Na+, cl- , bicarbonate, water(75%). Selective reabsorption also occurs in the region of dct.
3. Secretion : It occurs in dct mostly and a little in pct. It is the process by which waste materials are absorbed from peritubular capillaries and secreted into the lumen of the nephron. Urea, uric acid, extra salts, k+, h+ ate secreted into urine to maintain the pH.
4. Concentration of urine : 75% of water is reabsorbed from glomerular filtrate in pct. About 10% is reabsorbed by osmosis in the area of loop of Henley. Anti diuretic hormone helps in reabsorption of water in dct. In absence of adh reabsorption doesn't take place in dct. Deficiency of ash causes excessive, repeated dilute urination. This process of passage of urine is called micturition.