Tubular reabsorption ::
Nearly 175 litres of deproteinised plasma is filtered out through glomeruli in 24 hours but only about one and a half litre of urine is finally excreted daily Hence it stands to reason that the rest of the fluid with many important constituents is reabsorbed back in the blood to body s advantage
The following substances are reabsorbed by the renal tubule at various levels and in varied proportions
Glucose : It is reabsorbed completely from the proximal tubules Along with glucose galactose and fructose are also absorbed
water: More than 85% of the water is reabsorbed from the tubule This takes place in the proximal distal and even in collecting tubules of the total reabsorption seven- eighth is reabsorbed by the proximal tubule
This reabsorption is controlled by the antidiuretic hormone of the posterior pituitary gland Antidiuretic hormone regulates extracellular water by adjusting the amount of water reabsorbed into the blood by the distal convoluted tubules and collecting tubules When this fails reabsorption does not occur and copious urination follows This disease is called Diabetes Insipidus
Salts : Sodium chloride is reabsorbed in the proximal and distal tubules Potassium is completely reabsorbed from the proximal tubule Bicarbonate is also completely reabsorbed by the tubule phosphate is reabsorbed in the proximal tubule Aldosterone regulates the extracellular fluid volume by adjusting the amount of sodium reabsorbed by the blood from the kidneys
Miscellaneous Substances :: These are uric acid sulphates vit C creatine amino acids acetoacetic acid beta-hydroxybutyric acid etc are also reabsorbed from the tubules by the loop of Henle
0 Comments