Question

How do golmeruli contribute to renal function in vertebrates?

Answer 1

The glomerulus is the main site of Ultrafiltration of the blood to get rid of the wastes and rest of the fluid to flow on.It filtrates the blood entering the kidney through the renal artery to make it a filtrate. The afferent arteriole enering to the functional unit nephron's bowman's capsule will be branched out into numerus minute vessels to form a ball of veassels with less diameter and a high blood pressure to force the plasma to be leaked out as the interstitial fluid with some of the salts,water,waste products etc.The filtered fluid will be collected into the bowmans space.This purposeful leakage occurs due to the specialized character of the vessel lining endothelium and cells lining bowman's capsule. The endothelial cells lining the gomerulus is lined by fenestrations (gap present). These holes will facilitate the slipping out of the molecules to basement membrane which will allow small molecules to be passed throgh it like Na+,glucose,aminoacids etc. Proteins(like albumin) will bounce back to the vessel due to large size and repulsion to the same charged vasement membrane(-ve). The filtrate will be brought into the bowman's space using a specialized cells lining the capsule called the Podocytes.This whole filtration membrane including the vessel endothelium, basement membrane, and the podocytes is the key factor in the ultrafiltration of the blood into the space.The normal rate of the glomerular filtration is 125ml/min(GFR).

Composition of the filtrate: Blood- (formed elements RBC,WBC,Platelets,Large proteins,fat)

composition of filtrate- Amino acids,vitamins,glucose,electrolytes(Na+,K+,Cl-,HCO3-,H+,Ca2+),Urea,creatinine,Water

Out of these amino acids and glucose will be reabsorbed,Much of the water soluble vitamins will be excreted throgh the kidney.The ions will be reabsorbed. Creatinine will be eliminated.