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In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs [1] that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. [2] [3] They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres (4 + 1 ⁄ 2 inches) in length.
The number of renal lobes is reduced, and the kidney size is less than two standard deviations from the average, with the weight often being over 50g in adults and 12–25g in children. This type of hypoplasia can be either unilateral or bilateral and is more prevalent in females by 72%.
The size of the renal pelvis plays a major role in the grading of hydronephrosis. Normally, the anteroposterior diameter of the renal pelvis is less than 4 mm in fetuses up to 32 weeks of gestational age and 7 mm afterwards. [2] In adults, 13% of the normal population have a transverse pelvic diameter of over 10 mm. [3]
The length of the adult kidney is normally 10–12 cm, and the right kidney is often slightly longer than the left kidney. The adult kidney size is variable due to the correlation with body height and age; however, normograms for pediatric kidney size are available. [1]
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 ...
The pronephros is a functioning kidney of the embryo in bony fish and amphibian larvae, [7] but in mammals it is most often considered rudimentary and not functional. [18] In some lungfish and bony fishes, the pronephros can remain functional in adults, including often simultaneously with the mesonephros. [7]
The nephron is the functional unit of the kidney. [3] This means that each separate nephron is where the main work of the kidney is performed. A nephron is made of two parts: a renal corpuscle, which is the initial filtering component, and; a renal tubule that processes and carries away the filtered fluid. [4]: 1024
The size of the kidneys increases with the mass of mammals, and the number of nephrons in the kidneys between mammals increases allometrically. [92] In mice, the kidneys are approximately 1 cm (0.4 in) long, weighing 400 mg, with 16,000 nephrons, while in the killer whale , the kidney length exceeds 25 cm (10 in), the mass is approximately 4.5 ...