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Sodium is reabsorbed in the thick ascending limb of loop of Henle, by Na-K-2Cl symporter and Na-H antiporter.It goes against its chemical driving force, but the high electrical driving force renders the overall electrochemical driving force positive anyway, availing some sodium to diffuse passively either the transcellular or paracellular way.
On top of each kidney is an adrenal gland. The upper parts of the kidneys are partially protected by the 11th and 12th ribs. Each kidney, with its adrenal gland is surrounded by two layers of fat: the perirenal fat present between renal fascia and renal capsule and pararenal fat superior to the renal fascia.
This illustration demonstrates the normal kidney physiology, including the Proximal Convoluted Tubule (PCT), Loop of Henle, and Distal Convoluted Tubule (DCT). It also includes illustrations showing where some types of diuretics act, and what they do. Renal physiology (Latin renes, "kidneys") is the study of the physiology of the kidney.
The glomerulus (pl.: glomeruli) is a network of small blood vessels (capillaries) known as a tuft, located at the beginning of a nephron in the kidney. Each of the two kidneys contains about one million nephrons. The tuft is structurally supported by the mesangium (the space between the blood vessels), composed of intraglomerular mesangial cells.
The urinary system refers to the structures that produce and transport urine to the point of excretion. In the human urinary system there are two kidneys that are located between the dorsal body wall and parietal peritoneum on both the left and right sides. The formation of urine begins within the functional unit of the kidney, the nephrons.
Mammalian kidneys are susceptible to ischemic injury because mammals lack a renal-portal system, and as a result, vascular vasoconstriction in the glomeruli can lead to decreased blood supply to the entire kidney. The kidneys are susceptible to toxic injury, since toxins are reabsorbed in the tubules along with most of the filtered substances. [47]
Unlike mammals, the kidneys of reptiles do not have a clear distinction between cortex and medulla. [43] The kidneys lack the loop of Henle, have fewer nephrons (from about 3,000 to 30,000), and cannot produce hypertonic urine. [3] [21] Nitrogenous waste products excreted by the kidneys may include uric acid, urea and ammonia. [55]
Nephrin is a zipper-like protein that forms the slit diaphragm, with spaces between the teeth of the zipper big enough to allow sugar and water through but too small to allow proteins through. Nephrin defects are responsible for congenital kidney failure. CD2AP regulates the podocyte cytoskeleton and stabilizes the slit diaphragm. [4] [5]