Did you know that frogs and most reptiles (not crocodiles) have 3 chambered hearts?! That’s 2 atria and 1 ventricle. How does it work??
Muscular ridges (one of which is an incomplete interventricular septum) create a separation that directs blood to either lungs or systemic circulation. Amazingly and despite popular belief, there is little mixing of oxygenated and deoxygenated blood.
This feature allows reptiles to shunt blood away from pulmonary circulation when there is no oxygen available (eg. while they are under water) and their bodies can continue to function with low oxygen concentration. This cardiovascular and respiratory physiology is something that needs to be taken into account when anaesthetising and recovering reptiles, and one of the many reasons why their anaesthetics are different compared to creatures with 4 chambered hearts!
