Write the process of urine formation.
Answers
Urine is formed through a combination of four basic processes: 1) glomerular filtration, 2) tubular reabsorption, 3) tubular secretion, and 4) water conservation. Blood is under high pressure in the glomerulus; thus, plasma (except for plasma proteins) moves into the glomerular capsule. This fluid is called filtrate. As the filtrate moves along the tubules, it is referred to as tubular fluid. Most of the water and many other molecules are reabsorbed into the blood, while some substances are secreted into the tubular fluid. Once the fluid moves into the collecting, duct it is called urine. While in the collecting duct, additional water is removed from the urine, concentrating the wastes.
Bowman's capsule has semi permeable membrane with pores. The molecules of water and some other molecules can passes through these pores. The solution remaining in the Bowman's capsule enters the uriniferous tube or nephron. Nephron has four parts, Proximal convoluted tubule, Loop of Henle, Distal convoluted tubule and Collecting duct. Water and useful molecules are reabsorbed into the blood whereas remaining toxic substances along with some water is sent ahead for elimination. This solution later forms urine.
The urine produced in the kidney is then taken through the ureters and deposited in urinary bladder.
The urinary bladder is muscular and it is under the control of voluntary nerves.
From urinary bladder urine goes out of the body through urethra.
Kidneys are the main organs of excretion in human beings but the skin and lungs also help in the process of excretion.