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The kidneys have two cells that help to maintain acid-base homeostasis: intercalated A and B cells. The intercalated A cells are stimulated when the body is experiencing acidic conditions. Under acidic conditions, the high concentration of CO 2 in the blood creates a gradient for CO 2 to move into the cell and push the reaction HCO 3 + H ↔ H ...
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 unipapillary kidney with a single renal pyramid is the simplest type of kidney in mammals, from which the more structurally complex kidneys are believed to have evolved. [17] [6] [18] Differences in kidney structure are the result of adaptations during evolution to variations in body mass and habitats (in particular, aridity) between species.
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 ...
Humans have two kidneys that are supplied with blood from the renal artery. The kidneys remove from the blood the nitrogenous wastes such as urea, as well as salts and excess water, and excrete them in the form of urine. This is done with the help of millions of nephrons present in the kidney.
Most animals have a single renal papilla. [69] In some animals, such as horses, the apices of the renal pyramids fuse with each other to form a common renal papilla, called the renal crest. [71] The renal crest usually appears in animals larger than rabbits. [68] The kidneys of bovines are multilobar with external lobation. [72]
The distal convoluted tubule has a different structure and function to that of the proximal convoluted tubule. Cells lining the tubule have numerous mitochondria to produce enough energy for active transport to take place. Much of the ion transport taking place in the distal convoluted tubule is regulated by the endocrine system.
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.