The nephron is not only the main structural but also the functional unit of the kidney. It is here that the most important stages of urine formation take place. Therefore, information about how the structure of the nephron looks like, and what functions it performs, will be very interesting. In addition, the features of the functioning of nephrons can clarify the nuances of the renal system
Structure of the nephron: renal corpuscle
It is interesting that in a mature kidney of a he althy person there are from 1 to 1.3 billion nephrons. The nephron is the functional and structural unit of the kidney, which consists of the renal corpuscle and the so-called loop of Henle.
The renal corpuscle itself consists of a malpighian glomerulus and a Bowman-Shumlyansky capsule. To begin with, it is worth noting that the glomerulus is actually a collection of small capillaries. Blood enters here through the inflow artery - plasma is filtered here. The rest of the blood is excreted by the efferent arteriole.
The Bowman-Shumlyansky capsule consists of two leaves - inner and outer. And if the outer sheet is an ordinary fabric of flatepithelium, then the structure of the inner leaf deserves more attention. The inside of the capsule is covered with podocytes - these are cells that act as an additional filter. They allow glucose, amino acids and other substances to pass through, but prevent the movement of large protein molecules. Thus, primary urine is formed in the renal corpuscle, which differs from blood plasma only in the absence of large molecules.
Nefron: structure of the proximal tubule and loop of Henle
The proximal tubule is a structure that connects the renal corpuscle and the loop of Henle. Inside the tubule has villi that increase the total area of the internal lumen, thereby increasing reabsorption rates.
The proximal tubule smoothly passes into the descending part of the loop of Henle, which is characterized by a small diameter. The loop descends into the medulla, where it goes around its own axis by 180 degrees and rises up - here the ascending part of the loop of Henle begins, which has a much larger size and, accordingly, a diameter. The ascending loop rises to approximately the level of the glomerulus.
Structure of the nephron: distal tubules
The ascending part of the loop of Henle in the cortex passes into the so-called distal convoluted tubule. It is in contact with the glomerulus and is in contact with the afferent and efferent arterioles. This is where the final absorption of nutrients takes place. The distal tubule passes into the final section of the nephron, which in turn flows into the collecting duct, which carries fluid into therenal pelvis.
Classification of nephrons
Depending on the location, it is customary to distinguish three main types of nephrons:
- cortical nephrons account for approximately 85% of all structural units in the kidney. As a rule, they are located in the outer cortex of the kidney, which, in fact, is evidenced by their name. The structure of this type of nephron is slightly different - the loop of Henle is small here;
- juxtamedullary nephrons - such structures are located just between the medulla and the cortical layer, have long loops of Henle that penetrate deep into the medulla, sometimes even reaching the pyramids;
- subcapsular nephrons - structures that are located directly under the capsule.
You can see that the structure of the nephron is fully consistent with its functions.
