Why breathing in frog is called positive pressure breathing?

Breathing in frogs is called positive pressure breathing because they actively push air into their lungs using the floor of their mouth. When a frog closes its nostrils and lowers its mouth, it creates a pressure difference that forces air into the lungs. This method contrasts with negative pressure breathing, which is used by mammals, where the diaphragm creates a vacuum to draw air in. In essence, frogs rely on this positive pressure mechanism to ensure efficient gas exchange.