Tubulus renalis colligens

Tubulus renalis colligens vel brevius tubulus collector in anatomia renum est pars tubularis quae urinam e plurium nephronum tubulis contortis distalibus colligit atque per partem medullae sale maxime saturatam usque ad calycem renalem ducit. Tubi collectores apud mammalia maximi momenti sunt ad aquam sive in organismo retinendam sive ex organismo emittendam, ita ut volumen aquae in toto organismo sibi constans maneat. Nam illi tubi qui urinam dilutam (100 mOsm apud homines) recipiunt sine vasopressino impermeabiles sunt. Econtra si cellulae tubuli lumen cingentes vasopressinum (antidiureticum hormon) ligant aquaporinas (hoc est canales aquae permeabiles) membranae suae inserunt^[1]. Tum aqua sponte sua per osmosim, ut a liquore dilutiore ad liquorem saturatum (nam medulla renalis infima sale et urea saturata est), e tubulo collectore exit et in sanguinem remeat.^[2] Osmolaritas urinae humanae usque ad 1200 mOsm condensari potestː tum aquà quam plurimà servatà substantiae inutiles per urinam parum dilutam excerni possunt. Ita per vasopressinum mammalia homoeostasem aquae moderantur. Rodentia quaedam in desertis aridis viventia (exempli gratia Dipodomys ordii) urinam usque ad 5500 mOsm saturare valent; ne bibere quidem eis necessarium estː aqua metabolica aut in victu reperto utuntur.

Non tantum vasopressino respondent cellulae tubuli colligentis sed etiam aliis hormontibus ut aldosteroni^[3] qui iontum Na⁺ ex urina recuperationem stimulat aut auriculari natriuretico factori qui contrarium efficit et iontum Na⁺ ex urina recuperationem inhibet (natriureticus = natrium in urina, auricularis quia ille factor e cellulis auriculi sive atrii cordis emittitur cum pressio sanguinis crescit). Aliae substantiae e sanguine in urinam per easdem cellulas tubuli collectoris excernuntur ut ionta K⁺ (aldosterone instigante) vel H⁺ (ad sanguinis ceterorumque humorum corporalium aciditatem moderandam^[4]).

Notae

↑ Stefan Kreida, Susanna Törnroth-Horsefield, "Structural insights into aquaporin selectivity and regulation", Current Opinion in Structural Biology, 2015(Augustus)ː 126-134.
↑ Nielsen S., Chou C. L., Marples D., Christensen E. I., Kishore B. K., Knepper M. A. (Feb 1995). "Vasopressin increases water permeability of kidney collecting duct by inducing translocation of aquaporin-CD water channels to plasma membrane". Proceedings of the National Academy of Sciences of the United States of America 92 (4): 1013-7 doi:10.1073/pnas.92.4.1013.
↑ Olga Komarynets, Alexandra Chassot, Eva Bernabeu, Jan Czogalla, Isabelle Roth, Nicolas Liaudet, François Prodon, Johannes Loffing, Eric Feraille. 2019. "Aldosterone controls primary cilium length and cell size in renal collecting duct principal cells", The FASEB Journal.
↑ Carolyn Yucha, "Renal regulation of acid-base balance", Nephrol Nurs J, 2004: 201-8.

Fontes

Sherwood, Klandorf, Yancey, Animal physiologyː from Genes to Organisms, 2013ː cap. 12 et 13.
Elaine N. Marieb et Katja Koehn, Anatomie et physiologie humaines (undecima editio), Pearson, 2019 cap. 25 et 26.

Nexus externi

Osmoregulation apud Aquaportail (Francogallice)

[1] Stefan Kreida, Susanna Törnroth-Horsefield, "Structural insights into aquaporin selectivity and regulation", Current Opinion in Structural Biology, 2015(Augustus)ː 126-134.

[2] Nielsen S., Chou C. L., Marples D., Christensen E. I., Kishore B. K., Knepper M. A. (Feb 1995). "Vasopressin increases water permeability of kidney collecting duct by inducing translocation of aquaporin-CD water channels to plasma membrane". Proceedings of the National Academy of Sciences of the United States of America 92 (4): 1013-7 doi:10.1073/pnas.92.4.1013.

[3] Olga Komarynets, Alexandra Chassot, Eva Bernabeu, Jan Czogalla, Isabelle Roth, Nicolas Liaudet, François Prodon, Johannes Loffing, Eric Feraille. 2019. "Aldosterone controls primary cilium length and cell size in renal collecting duct principal cells", The FASEB Journal.

[4] Carolyn Yucha, "Renal regulation of acid-base balance", Nephrol Nurs J, 2004: 201-8.

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