EVERYDAY SCIENCE

Detailed explanation-1: -Most non-avian reptiles have a three-chambered heart, but have little mixing of the blood; they have double circulation. Mammals and birds have a four-chambered heart with no mixing of the blood and double circulation.

Detailed explanation-2: -In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation, and the other throughout the rest of the body and its organs including the brain (systemic circulation).

Detailed explanation-3: -Birds and mammals have atrial and ventricular septa, allowing separation between oxygenated and deoxygenated blood, and complete separation of the systemic and pulmonary circulations. The deoxygenated blood returns from the body to the right atrium through the large caval veins.

Detailed explanation-4: -Double circulation occurs in mammals, reptiles, birds etc, in which the blood passes through the heart twice before completing a full circuit of the body. Blood is pumped from the heart to the lungs and returns to the heart before being distributed to the other organs and tissues of the body.

Detailed explanation-5: -Mammal and Bird Hearts As mammals, we have four main parts to the heart, a left and a right atrium and a left and a right ventricle. This is called a four-chambered heart. Other mammals and birds all have four-chambered hearts.