Kidney

The function of the kidneys is to filter waste products from the bloodstream and recycle nutrients and ions. Additionally, kidneys play a significant role in regulating blood pressure, electrolyte balance, and red blood cell production.

The kidney structure is complex, multilayered and the functional unit for fine-tuned filtration is called a nephron.

In short, oxygenated blood enters the kidney through the renal artery. In the kidney, the blood is passed through nephrons, where waste product and excess water are filtered out from the bloodstream and directed toward the ureter and ultimately the bladder.

This way, the kidney processes up to 180 liters a day in humans, the vast majority of the filtrate being reabsorbed in the bloodstream resulting in a typical urine volume of only 3-5 three to five liters a day on average.

Figure 1. Internal Structure of a Kidney