Nephron helps to excrete unwanted substances and also maintains the osmotic concentration of the blood plasma. The fluid comings out from the nephron, containing unwanted components is called urine.
The following three steps are involved in urine formation
- Glomerular filtration.
- Reabsorption of solutes / tubular reabsorption.
- Tubular secretion.
Glomerular Filtration
First step of urine production. Filtration of blood from glomerular capillary through glomerular capillary wall and wall of bowman’s capsule wall.
The filtration is produced in bowmen’s capsule called glomerular filtrate or ultra-filtrate.
Daily volume of glomerular filtrate in adults is : In females – 150 litersIn male – 180 liters
More than 99% of the glomerular filtrate back to the blood plasma via tubular reabsorption. Glomerular capillaries wall prevents the filtration of blood cells and platelets. Glomerular capillaries wall size permits all solutes in blood plasma to exit glomerular capillaries.
Average glomerular filtration rate (GFR) in adults is In male – 125 ml/min In female – 105 ml/min
 |
| Glomerular Filtration |
Tubular Reabsorption
The volume of glomerular filtrate entering the proximal convoluted tubules.Reabsorption-Return of most of the filtrated water and solutes to the bloodstream.
Filtrate are reabsorbed by both active and passive process. Solutes are reabsorbed includes water, glucose, amino acids, urea and ions such as sodium ion, potassium ion, calcium ion, chloride ion, bicarbonate ion and phosphate ion.
Tubular Secretion
Those substances, which are not required for body and secreted out by the nephron tubular.
Hydrogen ion, creatinine, uric acid, potassium ions and drug remains are secreted out by tubular. Glomerular filtration is converted into concentrated urine.
 |
| Tubular Secretion |
0 comments:
Post a Comment