Which statement is true about the mammalian heart?

Which statement is true about the mammalian heart?

• A. Mammals have four chambers.
• B. Mammals have three chambers.
• C. Mammals have two chambers.
• D. Mammals have five chambers.

Answer: (A)

A heart with two sides, each side containing an atrium and a ventricle, creates a complete separation between the blood that returns from the body and the blood that goes to the lungs. This arrangement supports double circulation, sending deoxygenated blood to the lungs to be oxygenated and then delivering oxygenated blood to the rest of the body. The two sides operate at different pressures, so the lungs aren’t exposed to the higher pressure needed to push blood to the body, while the body receives blood that has been kept distinct from the blood returning from the lungs. This clear separation and independent pumping on each side enable the high metabolic rate seen in mammals. Other vertebrates have systems with partial mixing or less complete separation, which isn’t as capable of supporting the demands of mammalian physiology. So, the statement that mammals have a fully divided heart is true.

A heart with two sides, each side containing an atrium and a ventricle, creates a complete separation between the blood that returns from the body and the blood that goes to the lungs. This arrangement supports double circulation, sending deoxygenated blood to the lungs to be oxygenated and then delivering oxygenated blood to the rest of the body. The two sides operate at different pressures, so the lungs aren’t exposed to the higher pressure needed to push blood to the body, while the body receives blood that has been kept distinct from the blood returning from the lungs. This clear separation and independent pumping on each side enable the high metabolic rate seen in mammals. Other vertebrates have systems with partial mixing or less complete separation, which isn’t as capable of supporting the demands of mammalian physiology. So, the statement that mammals have a fully divided heart is true.