What is glomerular filtrate?
Kidneys are able to filter our blood for excreting nitrogenous waste products. The filtrate that accumulates immediately after filtering the blood is called Glomerular filtrate.
For this purpose a structure called glomerulus is present associated with Bowman's capsule. The capsule is first part of nephron, structural and functional unit of kidney. Glomerulus is a tuft of capillaries supplied by afferent arteriole and drained by narrower efferent arteriole.
Difference in the diameter of the two arterioles help in building high blood pressure in glomerular capillaries. Visceral lining of Bowman's capsule is made up of special cells forming a sieve like structure around capillaries. This allows fluid from blood to accumulate as filtrate in surrounding Bowman's capsule.
Glomerular filtrate contains a lot of water, but also important molecules like glucose, amino acids, salts and excretory material, urea. Thus selective reabsorption is necessary along the length of nephron, to reabsorb necessary materials from filtrate which are not meant for excretion.