Definition
The paired kidneys are part of the urinary system and are located at the level of the 11th and 12th rib below the diaphragm. A fat capsule envelops both kidneys and adrenal glands. Pain resulting from kidney disease usually projects onto the lumbar region of the middle back.
The function of the kidneys is based on a complex filter system that forms urine from the blood and its components. The most important tasks include the regulation of the water balance and the electrolyte and acid-base balance, the elimination of so-called urinary substances and the control of blood pressure. In addition, the kidneys produce important hormones such as renin and erythropoietin and are involved in sugar metabolism.
Function of the kidney marrow
The renal parenchyma describes the renal tissue in its entirety. It is composed of the outer renal cortex and the renal medulla adjacent to the inside. The renal medulla, also called medulla renalis, consists of about 15 to 20 individual pyramid-shaped, radiating units.
The base of the medullary pyramids adjoins the renal cortex. The pyramids merge and form about eight pyramid tips with very fine pores. The tapered end of the medullary pyramids points to the inside of the kidney and protrudes into the calix renalis.
The resulting urine flows from the medulla into the calices, which together form the renal pelvis (Pelvis renalis). The function of the renal medulla is based on the formation of secondary urine. The primary urine coming from the renal cortex flows through the tubule system, the renal tubules. Here, a large part of the fluid and the substances contained in the urine are absorbed and returned to the bloodstream. A smaller part is excreted in concentrated form as urine.
Function of the renal cortex
The renal cortex (Cortex renalis) is, like the renal medulla, a component of the kidney tissue. It borders the renal capsule on the outside and the renal medulla on the inside. As columnae renalis, renal columns, the cortex between the marrow pyramids moves towards the sinus renalis, the renal bay.
The cortex directly below the capsule is traversed by delicate medullary rays (Radii medullares), which are functionally assigned to the renal medulla. The renal cortex consists of about one million nephrons, which represent the functional units of the cortex. They play an important role in the filtration of toxins, electrolytes, proteins, sugar, water and many other components found in the blood.
A nephron is composed of the renal corpuscle and the renal tubules. While the former are located in the cortex, the majority of the tubules are located in the renal medulla. The function of the renal cortex is to form the primary urine and to cleanse the blood of toxic substances. Every day, about 180 liters of primary urine are produced in the renal corpuscles of the bark, which then flows through the renal tubules and is further concentrated. Every minute the vascular clusters of the renal corpuscles produce about 125 milliliters.
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