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The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure called Bowman's capsule. The renal tubule extends from the capsule.
This filtrate then flows along the length of the nephron, which is a tubular structure lined by a single layer of specialized cells and surrounded by capillaries. The major functions of these lining cells are the reabsorption of water and small molecules from the filtrate into the blood, and the secretion of wastes from the blood into the urine.
The glomerular basement membrane of the kidney is the basal lamina layer of the glomerulus.The glomerular endothelial cells, the glomerular basement membrane, and the filtration slits between the podocytes perform the filtration function of the glomerulus, separating the blood in the capillaries from the filtrate that forms in Bowman's capsule. [1]
Blood filtration, as in other vertebrates, occurs in the renal glomeruli, where pressurized blood passes through a permeable barrier that filters out blood cells and large protein molecules, forming primary urine. The filtered primary urine is osmotically and ionically the same as blood plasma.
Mass movement of sodium occurs through the cells, by secondary active transport on the apical membrane, followed by active resorption across the basolateral membrane via the Na + /K +-ATPase. [10] The solutes are absorbed isotonically , in that the osmotic potential of the fluid leaving the proximal tubule is the same as that of the initial ...
Diagram showing Bowman's capsule as part of the renal corpuscle. The process of filtration of the blood in the Bowman's capsule is ultrafiltration, and the normal rate of filtration is 125 ml/min, equivalent to 80 times the daily blood volume. [citation needed] It is a major site for blood filtration (including glomerulus)
The filtrate includes water, small molecules, and ions that easily pass through the filtration membrane. However, larger molecules such as proteins and blood cells are prevented from passing through the filtration membrane. The amount of filtrate produced every minute is called the glomerular filtration rate or GFR and amounts to 180 litres per ...
This active transport enables the kidney to establish an osmotic gradient that is essential to the kidneys ability to concentrate the urine past isotonicity. K + is passively transported along its concentration gradient through a K + leak channel in the apical aspect of the cells, back into the lumen of the ascending limb.