2.72 Describe ultrafiltration in the Bowman’s capsule and the composition of the glomerular filtrate

In your kidneys, there are thousands of little structures called nephrons. These are responsible for filtering the blood. It begins in the glomerulus.

The pressure in the glomerulus is high enough to squeeze some fluid out of the blood. This enters the Bowman's capsule and is known as the filtrate. It is made up of water, urea and smaller molecules and ions. But how exactly does this happen?

The blood comes in through the afferent arteriole at high pressure. It branches and becomes much smaller and the pressure increases further. The high pressure forces the plasma (liquid) into the space inside the bowman's capsule. It is now called filtrate.

Glomerular filtrate is composed of mainly water, ions (potassium, calcium, chlorine, etc.) and organic molecules.