Kaplan Nursing Entrance Practice Exam

How many chambers do birds and mammals have in their hearts?

1. Two

2. Three

3. Four

4. Five

The correct answer is: Four

Birds and mammals both have four chambers in their hearts, which is a key feature that distinguishes them from many other types of animals. The four chambers include two atria and two ventricles. This structure allows for a more efficient separation of oxygenated and deoxygenated blood, enabling a higher metabolic rate and supporting active lifestyles. In birds, the four-chambered heart helps in sustaining the high energy demands required for flight. Similarly, in mammals, the structure supports various metabolic processes, allowing for efficient oxygen delivery to tissues and organs. This adaptation is crucial for maintaining the warm-blooded nature of these animals, which is essential for survival in diverse environments. The presence of four chambers enables complete separation of pulmonary and systemic circulation, enhancing overall efficiency in energy utilization and oxygen transport.