Question

Explain the role of kidney’s vascular system in urine formation.

Answer 1

ROLE OF KIDNEY'S VASCULAR SYSTEM IN FORMATION OF URINE :

1) Role in ultrafiltration - Afferent renal arteriole divides into many small Glomerular capillary inside the renal corpuscles/Bowman's Capsule. This Glomerular capillary has many pores between the endothelium called filteration slits. Glomerular capillary reunite to form effernt arteriole which comes out the bowmans capsule. The diameter of afferent arteriole is larger than that of Efferent arteriole, this difference in the diameter of afferent and effernt arteriole creates a hydrostatic pressure gradient inside the Glomerular capillary. This hydrostatic pressure helps in ultrafiltration of the plsma.

2) Reabsorption of solute : Efferent arteriole continue further as vasa recta and forms Peritubular capillary network around the nephron. This Peritubular Network in PCT exchange the nutrients and solute from PCT by active reabsorption.

3) Mainatance of medullary Osmolarity by counter current exchange and couter current multiple system. This high Osmolarity of the medullary Interstitial fluid is responsible for the reabsorption of water in descending limb of loop of henle.

4) Role in secretion of solute - Peritubular capillary network around the DCT & CT help in salt and water reabsorption and secretion of H+ & K+ into the tubular fluid. By altering the H+ ion concentration it is responsible for changing urinary pH.

5) Autoregulation of Renal blood flow & hence GFR by myogenic mechanism. If the blood pressure increases there is stretch of the smooth muscle of afferent arteriole and hence it increases permiability of Calcium channel leading to calcium influx and vasoconstriction leading to decresed RBF and hence decrei GFR..

In this way kidneys vasculature has important role in formation of urine.