Editing Frog (section)

===Respiration and circulation===
Like other amphibians, [[oxygen]] can pass through their highly permeable skins. This unique feature allows them to remain in places without access to the air, respiring through their skins. Ribs are generally absent, so the lungs are filled by [[buccal pumping]] and a frog deprived of its lungs can maintain its body functions without them.<ref name=Observer/> The fully aquatic [[Bornean flat-headed frog]] (''Barbourula kalimantanensis'') is the first frog known to lack lungs entirely.<ref>{{cite web |url=http://amphibiaweb.org/cgi-bin/amphib_query?where-genus=Barbourula&where-species=kalimantanensis |title=''Barbourula kalimantanensis'' |author=Boisvert, Adam |date=October 23, 2007 |work=AmphibiaWeb |publisher=University of California, Berkeley |access-date=July 9, 2012}}</ref>

Frogs have three-chambered [[heart]]s, a feature they share with [[lizard]]s. Oxygenated blood from the lungs and de-oxygenated blood from the [[Respiration (physiology)|respiring]] tissues enter the heart through separate [[atrium (anatomy)|atria]]. When these chambers contract, the two blood streams pass into a common [[Ventricle (heart)|ventricle]] before being pumped via a spiral valve to the appropriate vessel, the [[aorta]] for oxygenated blood and [[pulmonary artery]] for deoxygenated blood.<ref name=Kimball>{{cite web |url=http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AnimalHearts.html |title=Animal Circulatory Systems: Three Chambers: The Frog and Lizard |author=Kimball, John |year=2010 |work=Kimball's Biology Pages |access-date=July 9, 2012 |archive-url= https://web.archive.org/web/20160511032359/http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AnimalHearts.html |archive-date= May 11, 2016}}</ref>

Some species of frog have adaptations that allow them to survive in oxygen deficient water. The [[Titicaca water frog]] (''Telmatobius culeus'') is one such species and has  wrinkly skin that increases its surface area to enhance gas exchange. It normally makes no use of its rudimentary lungs but will sometimes raise and lower its body rhythmically while on the lake bed to increase the flow of water around it.<ref>{{cite web |url=http://amphibiaweb.org/cgi-bin/amphib_query?where-genus=Telmatobius&where-species=culeus |title=''Telmatobius culeus'' |author=Lee, Deborah |date=April 23, 2010 |work=AmphibiaWeb |publisher=University of California, Berkeley |access-date=July 9, 2012}}</ref>

[[File:Frog anatomy tags.PNG|thumb|right|alt=Dissected frog|Anatomical model of a dissected frog: 1&nbsp;Right&nbsp;atrium, 2&nbsp;Lungs, 3&nbsp;Aorta, 4&nbsp;Egg mass, 5&nbsp;Colon, 6&nbsp;Left&nbsp;atrium, 7&nbsp;Ventricle, 8&nbsp;Stomach, 9&nbsp;Liver, 10&nbsp;Gallbladder, 11&nbsp;Small&nbsp;intestine, 12&nbsp;Cloaca]]