Part 8/10:
Reptiles: Have a heart with three chambers (except crocodilians, which have four). Blood from the heart flows to lungs and tissues in a mix, sometimes allowing for blood mixing, which can affect oxygen delivery efficiency.
Birds and Mammals: Feature a four-chambered heart with complete separation of oxygenated and deoxygenated blood, allowing for high metabolic rates and efficient oxygen delivery. The systemic and pulmonary blood flows are connected in series, ensuring oxygen-rich blood is delivered swiftly to tissues.