What is the kidney medulla?
The kidneys are a complex system of detoxification. Filtering processes take place in the renal cortex, the outer layer of the kidneys. Above all, the darker renal medulla is home to the duct system of the kidneys, through which the filtered-out urine can drain off. Each kidney is thus composed of renal medulla and the renal cortex and thus consists of two different layers.
The renal medulla forms the inner part of the kidneys. It is located between the renal pelvis and the renal cortex and is made up of individual kidney pyramids. Ten to twelve renal pyramids meet in the renal medulla and form a complex drainage system. With their base, the pyramids point outward and with their tip point to the hilum of the kidney. In this area, blood vessels leak out of the kidney and into the kidney.
Anatomy & Construction
The renal cortex directly adjoins the renal medulla and surrounds it to the hilum. The renal medulla is pyramid-like. The individual kidney pyramids make up the structure of the renal medulla and point with their tips ever to the hilum of the kidneys. Single kidney pyramids may grow together. Each of the ten to twelve pyramids consists of a variety of papillae. These papillae are each a kidney of their own.
The papillae each open into an open renal calyx. At the top of the kidney pyramids carry so-called urinary pores. In the direction of flow of the urine, the renal cups are narrowed. In the renal pelvis, they meet and unite. This renal pelvis is located in the renal artery, which acts as a distributor for all structures of the Nirenhilus. At the end of the kidney bay lies as a final spur of the ureter.
Function & Tasks
To form urine, kidneys are called nephrons. Each kidney has about 1.2 million of them. They are located in the renal cortex surrounding the renal medulla. A nephron consists of a kidney body and a renal tubule. The renal tubule connects the renal cortex with the renal medulla and is for the most part already in the market share of the kidneys. The renal corpuscles each form the primary urine.
This formation of urine corresponds to a selective filtering process, which is particularly effective through the principle of permselectivity. The primary urine flows from the renal corpuscles through the renal tubules. When crossing the renal tubules, the body resorbs various substances and fluids from the primary urine. Above all, the re-absorption affects a large part of the water. So, before the primary urine reaches the renal medulla, reabsorption has already taken place. What flows into the renal medulla is therefore no longer primary urine, but so-called secondary urine and thus the actual urine, which is actually excreted in the end.
In the renal medulla, the secondary urine is collected in the renal calyces. One to three renal papillae drain into a renal calyx and release the urine to the renal pelvis. The pyradmids of the renal medulla are crossed by the renal tubules. Each of the kidney pyradmids consists of several collecting tubes. In the collection tube, water is withdrawn from the urine. The renal pores at the top of the pyramids thus allow the urine to pass from the individual collecting tubes in the direction of the renal calyces.
Thus, the urine reaches the common renal pelvis and flows from there via the renal pelvis into the ureter. In this way the urine reaches the bladder and is excreted. Overall, about 1.5 liters of urine are excreted per day through the process described. Produced is much more urine. Most of the filtered urine is, however, reabsorbed by the organism.
As part of various kidney diseases, the papillae can become inflamed in the renal medulla. In the worst case, the papillae even die as a result of this inflammation. This process is also known as papillary necrosis. The phenomenon is accompanied by pain, blood in the urine and blockages of the urinary tract.
Primary Disease in this condition is all too often the metabolic disease diabetes, which can be associated with kidney damage. The ability of the kidneys to concentrate is often lost or diminished as a result of papillary necrosis. The renal medulla is also prone to inflammatory processes. In this context, nephritis often occurs in the renal medulla. Mostly this inflammation is a bacterial nephritis originating in the urinary tract. Because of the ammonia concentration of the renal medulla, the body's defense systems in this area are weakened.
Frequently, infection of the renal medulla is preceded by deposition of calcium salts or uric acid in this anatomical structure. Uric acid deposits can occur, for example, in the context of special diets or as a result of a disturbed uric acid metabolism. Also diseases like the safe cell anemia can affect the renal medulla.
For example, in the context of this disease, vascular occlusions in the renal medulla can occur, which in turn can trigger renal infarction. Renal infarction is equivalent to an ischemic-related decline of kidney tissue and may result in renal insufficiency. Renal cancer may also affect the renal medulla. Kidney tumors, however, are rather rare and occur especially in old age after a renal insufficiency.