JAMB - Biology (2018 - No. 51)
Blood circulation in a mammal is said to be double because
It passes twice through the heart in a complete circuit
It moves in both arteries and veins
It circulates in both the hands and other organs
The heart contains auricles and ventricles
설명
Double circulation is the type of circulatory system that occurs in mammals, 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. The heart is divided into two separate compartments to prevent oxygenated blood returning from the lungs from mixing with deoxygenated blood from the other parts of the body.
its passes through the hear twice