How do amphibian lungs differ from mammal lungs?

Amphibian lungs differ significantly from those of mammals in both their physical structure and their method of inflation.

Structural Differences

Unlike the complex, spongy lungs found in mammals, amphibian lungs are simple, saclike structures. They lack the intricate internal architecture that characterizes mammalian lungs, which are designed to maximize surface area for gas exchange.12

Inflation Mechanism

The process of moving air into the lungs also differs fundamentally:
* Amphibians: They utilize a buccal pumping mechanism (a mouth-throat pump). To inhale, an amphibian depresses the floor of its mouth to draw air in through the nostrils. It then closes the nostrils and elevates the floor of the mouth, creating positive pressure that forces air into the lungs.12
* Mammals: In contrast, mammals typically use negative pressure, where the contraction of the diaphragm and chest muscles expands the thoracic cavity to draw air into the lungs.

Furthermore, while mammals rely almost exclusively on their lungs for respiration, amphibians often supplement lung function with cutaneous respiration, absorbing oxygen and eliminating carbon dioxide directly through their thin, moist skin.12