Where does deoxygenated blood enter the heart?
How does the deoxygenated blood reach the heart?
The circuit through the lungs where the deoxygenated blood is oxygenated before it enters the heart is called the ___ circulation.
How do fishes cope up with two chambered heart where oxygenated and deoxygenated blood mixes up unlike mammals which have four chambered heart for efficient flow of blood?