Describe how filtration of the blood occurs at the Kidney

Due to the afferent arteriole going towards the glomerulus having a having a larger diameter than the efferent arteriole leaving the glomerulus the pressure increases in the glomerulus. This causes the smaller molecules such as ions, glucose and urea to be pushed through the podocytes, basement membrane and endothelium complex, which restricts larger molecules from passing through into the nephron. This is called ultrafiltration, as the blood vessels lie very close to the distal convoluted tubule diffusion occurs between the two tubes, initially of all molecules and then selective reabsorption of glucose and some of the ions. Urea remains, more water is reabsorbed in the loop of henle by the the countercurrent mechanism and in the collecting duct due to aquaporins (depending on ADH content).

I should have chosen a less vague question.