Crash Course Video

The two systems connect in a couple ways. First they work together by inhaling and exhaling. The heart pumps blood through the pulmonary artery into the lungs where gas exchange happens and deoxy blood turns into oxy blood. Then returns back to the heart from the pulmonary vein and to the body. A gas exchange happens in the respiratory system and releases CO2 from the body and brings in O2 hence inhaling. I learned that some animals which don't have lungs still take in oxygen through a process of simple diffusion where air goes through pores or wet membranes.