Explain the Regulation of Blood Composition

Each part of the nephron has different types of cells with different properties. An understanding of this is important to know how the kidneys regulate the composition of the blood. The nephron has a unique blood supply as compared to the other organs. Let us now study what is the unique blood supply of the nephorons and ultimately play a major role in regulating the blood composition:

Afferent arterioles: Look at Figure and identify the afferent arterioles. These connect the renal artery with the glomerular capillaries.

Glomerular capillaries: There are the coiled capillaries that are inside the Bowman's capsule.

Efferent arterioles: Identify the efferent arterioles in Figure. As you would have noticed, these connect the glomerular capillaries with the peritubular capillaries.

Peritubuhr capillaries: These are located after the glomerular capillaries and surrounding the PCT, loop of Henle and the DCT.

Interlobular veins: These are the veins that drain the peritubular capillaries into the renal vein.

The above mentioned blood vessels (forming portal circulation) help in the regulation of blood composition by the kidneys. Kidney is the only organ of the body in which the two capillary beds, in a series, connect arteries with the veins. This arrangement is important for maintaining a constant blood flow through and around the nephron despite fluctuations in the systemic blood pressure.