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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.
There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport , which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area ...
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.
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]
Each adult human kidney contains around 1 million nephrons, while a mouse kidney contains only about 12,500 nephrons. The kidneys also carry out functions independent of the nephrons. For example, they convert a precursor of vitamin D to its active form, calcitriol; and synthesize the hormones erythropoietin and renin.
This is an accepted version of this page This is the latest accepted revision, reviewed on 13 November 2024. This article is about the human urinary system. For urinary systems of other vertebrates, see Urinary systems of birds, urinary systems of reptiles, and urinary systems of amphibians. Anatomical system consisting of the kidneys, ureters, urinary bladder, and the urethra Urinary system 1 ...
Secondary active transport is when one solute moves down the electrochemical gradient to produce enough energy to force the transport of another solute from low concentration to high concentration. [ citation needed ] An example of where this occurs is in the movement of glucose within the proximal convoluted tubule (PCT).
Diagram outlining movement of ions in nephron, with the collecting ducts on the right. The collecting duct system is the final component of the kidney to influence the body's electrolyte and fluid balance. In humans, the system accounts for 4–5% of the kidney's reabsorption of sodium and 5% of the kidney's reabsorption of water. At times of ...