Kidney (vertebrates)

Not to be confused with Human kidney.

The kidneys are a pair of organs of the excretory system in vertebrates, which maintain the balance of water and electrolytes in the body (osmoregulation), filter the blood, remove metabolic waste products, and, in many vertebrates, also produce hormones (in particular, renin) and maintain blood pressure.[1][2][3][4] In healthy vertebrates, the kidneys maintain homeostasis of extracellular fluid in the body.[5] When the blood is being filtered, the kidneys form urine, which consists of water and excess or unnecessary substances, the urine is then excreted from the body through other organs, which in vertebrates, depending on the species, may include the ureter, urinary bladder, cloaca, and urethra.[6]

All vertebrates have kidneys. The kidneys are the main organ that allows species to adapt to different environments, including fresh and salt water, terrestrial life and desert climate.[7] Depending on the environment in which animals have evolved, the functions and structure of the kidneys may differ.[8] Also, between classes of animals, the kidneys differ in shape and anatomical location.[9][10] In mammals, they are usually bean-shaped.[11] Evolutionarily, the kidneys first appeared in fish as a result of the independent evolution of the renal glomeruli and tubules, which eventually united into a single functional unit.[12] In some invertebrates, the nephridia are analogous to the kidneys but nephridia are not kidneys.[13] The metanephridia, together with the vascular filtration site and coelom, are functionally identical to the ancestral primitive kidneys of vertebrates.[14]

The main structural and functional element of the kidney is the nephron.[15] Between animals, the kidneys can differ in the number of nephrons and in their organisation.[16] According to the complexity of the organisation of the nephron, the kidneys are divided into pronephros, mesonephros and metanephros.[17] The nephron by itself is similar to pronephros as a whole organ.[18] The simplest nephrons are found in the pronephros, which is the final functional organ in primitive fish.[19] The nephrons of the mesonephros, the functional organ in most anamniotes called opisthonephros,[20] are slightly more complex than those of the pronephros.[19] The main difference between the pronephros and the mesonephros is that the pronephros consists of non-integrated nephrons with external glomeruli.[7] The most complex nephrons are found in the metanephros of birds and mammals.[19][21][22] The kidneys of birds and mammals have nephrons with loop of Henle.[23]

All three types of kidneys are developed from the intermediate mesoderm of the embryo.[24] It is believed that the development of embryonic kidneys reflects the evolution of vertebrate kidneys from an early primitive kidney, the archinephros.[6] In some vertebrate species, the pronephros and mesonephros are functional organs, while in others they are only intermediate stages in the development of the final kidney, and each next kidney replaces the previous one.[7] 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 mesonephros is the final kidney in amphibians and most fish.[25]

  1. ^ Skadhauge, E. (2012-12-06). Osmoregulation in Birds. Springer Science & Business Media. pp. 53–54. ISBN 978-3-642-81585-0.
  2. ^ Florkin, Marcel (2014-04-24). Deuterostomians, Cyclostomes, and Fishes. Elsevier. p. 575. ISBN 978-0-323-16334-7.
  3. ^ "Kidney". Britannica. Retrieved 2022-05-09.
  4. ^ Peng, Zhenzhen; Sander, Veronika; Davidson, Alan J. (2017-01-01), Orlando, Giuseppe; Remuzzi, Giuseppe; Williams, David F. (eds.), "Chapter 71 - Nephron Repair in Mammals and Fish", Kidney Transplantation, Bioengineering and Regeneration, Academic Press, pp. 997–1003, ISBN 978-0-12-801734-0, retrieved 2022-05-09
  5. ^ Schulte, Kevin; Kunter, Uta; Moeller, Marcus J. (May 2015). "The evolution of blood pressure and the rise of mankind". Nephrology Dialysis Transplantation. 30 (5): 713–723. doi:10.1093/ndt/gfu275. PMID 25140012.
  6. ^ a b Kisia, S. M. (2016-04-19). Vertebrates: Structures and Functions. CRC Press. p. 434. ISBN 978-1-4398-4052-8.
  7. ^ a b c d e de Bakker, B. S.; van den Hoff, M. J. B.; Vize, P. D.; Oostra, R. J. (2019-07-01). "The Pronephros; a Fresh Perspective". Integrative and Comparative Biology. 59 (1): 29–47. doi:10.1093/icb/icz001. ISSN 1557-7023. PMID 30649320.
  8. ^ Dantzler, William H. (2016-07-05). Comparative Physiology of the Vertebrate Kidney. Springer. ISBN 978-1-4939-3734-9.
  9. ^ Kisia, S. M. (2016-04-19). Vertebrates: Structures and Functions. CRC Press. p. 436. ISBN 978-1-4398-4052-8.
  10. ^ Moffat, D. B. (1975-06-12). The Mammalian Kidney. CUP Archive. p. 13. ISBN 978-0-521-20599-3.
  11. ^ Keogh, Laura; Kilroy, David; Bhattacharjee, Sourav (Jan 2021). "The struggle to equilibrate outer and inner milieus: Renal evolution revisited". Annals of Anatomy. 233: 151610. doi:10.1016/j.aanat.2020.151610. ISSN 0940-9602. PMID 33065247. S2CID 223556080.
  12. ^ Schulte, Kevin; Kunter, Uta; Moeller, Marcus J. (May 2015). "The evolution of blood pressure and the rise of mankind". Nephrology, Dialysis, Transplantation. 30 (5): 713–723. doi:10.1093/ndt/gfu275. ISSN 1460-2385. PMID 25140012.
  13. ^ Ruppert, Edward E. (Aug 2015). "Evolutionary Origin of the Vertebrate Nephron". American Zoologist. 34 (4): 542–553. doi:10.1093/icb/34.4.542.
  14. ^ Edward E. Ruppert (1 August 2015). "Evolutionary Origin of the Vertebrate Nephron". American Zoologist. 34 (4): 542–553. doi:10.1093/ICB/34.4.542. ISSN 0003-1569. Wikidata Q126036840.
  15. ^ Desgrange, Audrey; Cereghini, Silvia (2015-09-11). "Nephron Patterning: Lessons from Xenopus, Zebrafish, and Mouse Studies". Cells. 4 (3): 483–499. doi:10.3390/cells4030483. ISSN 2073-4409. PMC 4588047. PMID 26378582.
  16. ^ Chan, Techuan; Asashima, Makoto (2006). "Growing kidney in the frog". Nephron Experimental Nephrology. 103 (3): e81–85. doi:10.1159/000092192. ISSN 1660-2129. PMID 16554664. S2CID 13912502.
  17. ^ Barrodia, Praveen; Patra, Chinmoy; Swain, Rajeeb K. (2018). "EF-hand domain containing 2 (Efhc2) is crucial for distal segmentation of pronephros in zebrafish". Cell & Bioscience. 8: 53. doi:10.1186/s13578-018-0253-z. ISSN 2045-3701. PMC 6192171. PMID 30349665.
  18. ^ a b Grunz, Horst (2013-03-09). The Vertebrate Organizer. Springer Science & Business Media. p. 240. ISBN 978-3-662-10416-3.
  19. ^ a b c "Nephron". Encyclopedia Britannica. Retrieved 2022-05-09.
  20. ^ Webster, Douglas; Webster, Molly (2013-10-22). Comparative Vertebrate Morphology. Academic Press. p. 494. ISBN 978-1-4832-7259-7.
  21. ^ Cite error: The named reference :16 was invoked but never defined (see the help page).
  22. ^ Khanna, D. R.; Yadav, P. R. (Dec 2005). Biology of Mammals. Discovery Publishing House. p. 294. ISBN 978-81-7141-934-0.{{cite book}}: CS1 maint: date and year (link)
  23. ^ Nishimura, Hiroko; Yang, Yimu (2013-12-01). "Aquaporins in avian kidneys: function and perspectives". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 305 (11): R1201–R1214. doi:10.1152/ajpregu.00177.2013. ISSN 0363-6119. PMID 24068044.
  24. ^ Rumballe, Bree; Georgas, Kylie; Wilkinson, Lorine; Little, Melissa (Jun 2010). "Molecular anatomy of the kidney: what have we learned from gene expression and functional genomics?". Pediatric Nephrology (Berlin, Germany). 25 (6): 1005–1016. doi:10.1007/s00467-009-1392-6. ISSN 0931-041X. PMC 3189493. PMID 20049614.
  25. ^ "Mesonephros". Britannica. 2017-07-06. Retrieved 2022-05-10.