The kidneys are a paired organ of the genitourinary system. Their shape resembles beans. They are located at the back of the torso, on both sides of the lumbar spine, the right one slightly lower than the left one. However, they can be mobile—when we lie down, they move a few centimetres higher than when we stand.

Although they are small (one kidney weighs up to 200 grams and is up to 12 cm long), they play a significant role in our body. This is proven by the fact that 25% of the blood pumped through the heart flows through them. It is estimated that it is up to 1,800 litres per day, which corresponds to the capacity of 10 bathtubs!

Each kidney is made up of approximately 1,000,000 nephrons – microfilters that filter the blood, made of the glomerulus (a tangle of tiny vessels where primary urine is filtered) and an a tubule connected to it. They connect at the renal papilla where urine enters the calico-pelvic system to be excreted through the ureters into the bladder.

A healthy kidney produces up to 180 litres of primary urine per day! This one contains both wanted and harmful waste products. The wanted ones are reabsorbed in the tubules and retained in the body, and the toxic ones remain in the urine and are eliminated. Healthy kidneys eventually excrete only about 1.5-2 litres of primary urine.

The main function of the kidneys is to remove unnecessary and harmful metabolic products from the body (excretory function). The kidneys also maintain the internal balance of the body (homeostatic function). They also produce hormones responsible for, among others, blood formation, regulation of blood volume and blood pressure, and the body's calcium and phosphate balance, including the activation of vitamin D.

The kidneys are an extremely efficient organ. In order for the body to clearly feel disturbances in their functions, 75% of their parenchyma must be destroyed. This means that one properly functioning kidney is more than enough to stay healthy. This fact is used in transplantology—transplantation of one kidney ensures full recovery of proper functioning of the organism.

Take care of your kidneys! Their proper function is the basis of your health and well-being!