1. Cardiovascular System: This includes the heart and blood vessels (arteries, veins, and capillaries). The heart pumps blood throughout the body, delivering oxygen and nutrients and removing waste products.

2. Respiratory System: This includes the lungs and airways (nose, trachea, bronchi, and bronchioles). The lungs are responsible for taking in oxygen and releasing carbon dioxide.

These two systems work together to deliver oxygen to the body's cells and remove carbon dioxide. The cardiovascular system transports the oxygen and carbon dioxide, while the respiratory system is responsible for the actual exchange of these gases.