What is the significance of having a double circulation in mammals?

The significance of double circulation in mammals primarily lies in its ability to enhance oxygen delivery to tissues and organs. In mammals, the circulatory system is divided into two distinct circuits: the pulmonary circuit, which transports deoxygenated blood to the lungs for oxygenation, and the systemic circuit, which delivers oxygenated blood to the rest of the body.

This separation allows for more efficient oxygen transport. Blood that has been oxygenated in the lungs does not mix with deoxygenated blood returning from the body, which ensures that tissues receive blood with a higher oxygen content. As a result, mammals can meet the high metabolic demands of their active lifestyles.

In contrast to options suggesting that double circulation results in mixing of blood or lowering heart pressure, double circulation actually maintains distinct paths for oxygenated and deoxygenated blood, facilitating optimal blood pressure conditions for efficient circulation. Additionally, limiting blood flow to the lungs contradicts the very purpose of double circulation, which is to ensure that enough blood flows to the lungs for effective gas exchange. Thus, the design of double circulation is crucial for maintaining the health and performance of mammalian organ systems.