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The mysterious factory of the kidney: Do you know the surprising secret of the brush border of the renal tubule?
The renal tubule is an important tissue in the kidney, responsible for regulating the electrolyte and acid-base balance in the body. Especially in the proximal renal tubule, the structural and functional complexity is stunning. The proximal renal tubule extends from the renal pole of the glomerular capsule to the beginning of the loop of Henle. Here, the epithelial cells of the renal tubules present a stunning brush edge, which helps in effective material reabsorption and secretion.
The brush edge of the proximal renal tubule is a special structure composed of dense microvilli, which greatly increases the luminal area of the cell and facilitates the reabsorption of materials.
Structure of renal tubules
The proximal renal tubule can be further divided into two parts: the proximal convoluted tubule (PCT) and the proximal straight tubule (PST). The characteristic structure of these cells includes a mitochondria-rich cytoplasm, so they often have an eosinophilic appearance. The number of mitochondria enables cells to generate the energy needed to activate and transport sodium ions and maintain kidney function.
The cells of the proximal renal tubule are known for their unique side-wall interactions, which make the edges of the cells indistinct and difficult to discern with the naked eye.
Segmentation of proximal renal tubule
At low magnification, the proximal renal tubule can be divided into two main regions: the proximal convoluted tubule and the proximal straight tubule. Based on electron microscopy observations, these segments can be further subdivided into S1, S2, and S3 segments, each with different cell shapes and functions.
Function of the proximal convoluted tubule
The proximal convoluted tubule is mainly responsible for regulating acids and bases in filtered liquids. It can excrete about 80% of filtered bicarbonate, which is the key to maintaining the acid-base balance in the body.
The proximal renal tubule realizes sodium reabsorption through active transport and relies on Na+/K+-ATPase to help it function.
Secretory function of proximal renal tubule
In addition to resorption, these cells are also involved in the secretion of drugs and elements. For example, most ammonia is formed in the proximal tubule through the breakdown of amino acids, which is essential for excretion and maintenance of nitrogen balance.
Clinical significance
Proximal tubular epithelial cells play a key role in kidney disease, and studies have shown that these cells are affected in many kidney diseases.
Renal cell carcinoma, the most common form of kidney cancer, usually originates in the convoluted tubules.
Kidney functions and diseases
For example, acute tubular necrosis usually results from drug poisoning or other toxins that directly damage the proximal renal tubules. This will lead to morphological changes in the cells and may even affect their normal functions.
Future research directions
Future kidney research may focus on understanding the role of these tubules in disease development and finding new treatments.
Behind all this, the proximal renal tubule is like a mysterious factory, responsible for important metabolism and maintaining balance in our body. Will you start to pay attention to this "little factory" that works silently in your kidneys?
