Most reptiles have how many heart chambers?

Most reptiles have how many heart chambers?

• A. 3
• B. 4
• C. 2
• D. 5

Answer: (A)

Most reptiles have three heart chambers—two atria and one ventricle. Blood returns to the heart from the body and from the lungs into the two atria, then flows into a single ventricle that pumps blood to both the lungs and the rest of the body. The ventricle isn’t completely divided, and a muscular ridge helps reduce mixing of oxygen-rich and oxygen-poor blood, which is why the system is less separated than in birds and mammals. An important exception is crocodilians, which have a fully divided four-chambered heart, enabling complete separation of the pulmonary and systemic circuits.

Most reptiles have three heart chambers—two atria and one ventricle. Blood returns to the heart from the body and from the lungs into the two atria, then flows into a single ventricle that pumps blood to both the lungs and the rest of the body. The ventricle isn’t completely divided, and a muscular ridge helps reduce mixing of oxygen-rich and oxygen-poor blood, which is why the system is less separated than in birds and mammals. An important exception is crocodilians, which have a fully divided four-chambered heart, enabling complete separation of the pulmonary and systemic circuits.