Editing Respiratory system (section)

==Amphibians==
{{Main |Amphibian#Respiratory system}}
Both the lungs and the [[Frog#Morphology and physiology|skin]] serve as respiratory organs in [[amphibians]]. The ventilation of the lungs in amphibians relies on [[positive pressure ventilation]]. Muscles lower the floor of the oral cavity, enlarging it and drawing in air through the nostrils into the [[oral cavity]]. With the nostrils and mouth closed, the floor of the oral cavity is then pushed up, which forces air down the trachea into the lungs. The skin of these animals is highly vascularized and moist, with moisture maintained via secretion of [[mucus]] from specialised cells, and is involved in [[cutaneous respiration]]. While the lungs are of primary organs for gas exchange between the blood and the environmental air (when out of the water), the skin's unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water.<ref>{{cite journal
 | last = Gottlieb
 | first = G
 |author2=Jackson DC
  | title = Importance of pulmonary ventilation in respiratory control in the bullfrog
 | journal = Am J Physiol
 | volume = 230
 | pages = 608–13
 | year = 1976
 | pmid = 4976
 | issue = 3
 | doi=10.1152/ajplegacy.1976.230.3.608| doi-access = 
 }}</ref>
Some amphibians have gills, either in the early stages of their development (e.g. [[tadpole]]s of [[frogs]]), while others retain them into adulthood (e.g. some [[salamanders]]).<ref name=campbell />