List the major steps involved in formation of urine and state in brief their function??
Answers
kideney's cells are known as nephrons
nephorns consist of mainly 4 parts
and the nephorn's third part,the loop of henle helps in formation of urine
Answer:
The process of urine formation involves three steps:
(i) Ultra filtration of blood
(ii) Selective re-absorption of substances
(iii) Tubular secretion
(i) Ultra filtration of blood:
The blood containing waste materials and excess water from the body enters the glomerulus.
The blood is filtered from the blood capillaries into the Bowman’s capsule due to the pressure of the glomerulus.
All substances from the blood are filtered out except the large protein molecules. This fluid is called Glomerular filtrate.
(ii) Selective re-absorption of substances
The glomerular filtrate contains lot of useful materials like water, urea, salts, glucose, amino acids, uric acid, sodium, potassium and chloride ions.
These substances are selectively absorbed by blood capillaries surrounding the nephron from the renal tubule.
The amount of water re-absorbed depends on how much excess water and dissolved salts are there in the body.
(iii) Tubular secretion
This occurs mainly in the renal tubule and the collecting duct of the nephron.
The cells of the tubules secrete additional wastes like potassium, hydrogen, creatinine etc from the blood stream into the filtrate by active transport.
The fluid which now flows through the collecting duct is called Urine.
Human urine consists of 95% water and 5% nitrogenous substances like urea, uric acid and mineral ions like sodium, potassium and chloride etc.
Finally the urine moves through the ureters and collects in the urinary bladder till thrown out of the body through urethra.