2.71 Ultrafiltration

2.71 Describe ultrafiltration in the Bowman's capsule and the composition of the glomerular filtrate.

- The same diagram here is being shown. It is the Nephron which carries out the filtration of our blood, which results in filtered blood with the waste products removed, and the waste known as urine.

Looking at how the urine is actually formed:

- Begins in the Bowman's capsule and is known as ultrafiltration - the filtration of mollecules. Explained using the larger diagram.

- Filtration of blood begins with blood arriving in the Kidney, in the Nephron in the Afferent Arteriole. This blood is under high pressure and as it comes in, and it starts to branch and become much much smaller. This twisted smaller structure is known as the glomerulas.

- The next part to notice is the blood coming out of the Bowman's capsule by the Efferent Arteriole. We should notice that the diameter of this blood vessel in which the blood leaves the Bowman's capsule, is much smaller than the Afferent Arteriole which leads the blood into the Bowman's capsule. Because of the smaller tube, this means the blood pressure increases, and it has a very high pressure. So the glomerulas function is to increase the pressure of the blood. So while the blood is in the glomerulas it is of a very high pressure.

- The consequence of this is that the high pressured blood forces the liquid within blood (plasma - contains components dissolved in blood (salts, water, amino acids, glucose and urea) which forces them out of the blood vessel.

- The high pressure of blood in these twisted tubes, forces the plasma into the space surrounding the glomerulas which is the inside of the Bowman's capsule. When this happens we call this Glomerula filtrate.

- So the blood has been filtered by pressure, due to the restricted space in the blood vessel at the twisted point, which forces the plasma into the Bowman's capsule. The cleaner blood then continues on to do it's job and the plasma travels down the Bowman's capsule and begins it's journey till excretion (See first diagram to understand).