Explain the MECHANISM OF URINE FORMATION?
Answers
Excretion can be defined as the process of removal of nitrogenous waste produced by the metabolic activity of the cells. In humans, urea is the major nitrogenous waste. Uric acid and creatinine are also expelled in the process of excretion.
Mechanism of urine formation: It occurs in three steps as follows:
1. Glomerular Filtration- the water, minerals, ions, and solutes are diffused out of the blood and move into the Bowman's capsule forming a filtrate.
2. Tubular reabsorption: the necessary substances such as water, glucose, amino acids, vitamins, mineral ions in the filtrate are reabsorbed by the tubules of the nephrons. The loop of Henle regulates the water reabsorption
3. Tubular secretion: K+, H+, creatinine and excessive water are secreted out from the tubules into the filtrate. Such a filtrate is called the urine.
Answer: #BAL
1. Ultrafiltration- Blood flows inside glomerulus under high pressure due to narrowness of efferent arteriole. As a result it undergoes pressure filteration or Ultrafiltration.
2. Selective reabsorption- The blood then passes through the tubular part of nephron where useful substances such as glucose, amino acid ,salt and major amount of water are selectively reabsorbed.
3. Tubular secretion - as the urine passes through the Tubule some ions such as K+, NH4+, and molecules like medicines ,drugs etc from Blood are actively secreted into the urine called tubular secretion.
4. The collecting duct collects the urine from DCT . Water is reabsorbed here under the influence of harmone ADH from pituitary.
5. The urine contain urea ,uric acid and ammonium salt and pigment urochrome which imparts yellow colour to urine.
Explanation: