ln response to an increase in GFR, the proximal tubule and the loop of Henle demonstrate an increase in the rate of Na+ reabsorption. This phenomenon is called ?
*Autoregulation refers to the relative constancy of renal blood flow and GFR despite changes in arterial blood pressure.
*Mineralocorticoid escape refers to the fact that the salt-retaining action of mineralocorticoids does not persist but is overpowered by factors that promote renal Na+ excretion.
*Saturation of transport occurs when the maximal rate of tubular transport is reached. Tubuloglomerular feedback results in afferent arteriolar constriction when fluid delivery to the macula densa is increased; it contributes to renal autoregulation..
Glomerulo-tubular balance:
More the filtered load, more the reabsorbed load (load-dependent reabsorption).
What is reabsorbed is a constant percentage and not a constant amount. This helps in preserving the solute.
Possible mechanism for glomerulo-tubular balance:
As more fluid comes out of the glomerulus (due to increase in GFR), the protein concentration and therefore the oncotic pressure in the plasma increases. When the plasma comes to the peritubular capillaries, there is an increased oncotic pressure; this results in pulling the excess water in the tubular lumen into the capillaries. Along with the flow of water, sodium is also reabsorbed (this is known as bulk flow or solvent drag).
Autoregulation
Glomerulotubular balance
Mineralocorticoid escape
Saturation of tubular transport