Video Transcript
The diagram provided shows a simplified view of the different circulatory pathways in
the human body. Which color line represents the pulmonary circulatory system?
Let’s review the circulatory system in humans in order to answer this question
correctly. You might remember that the circulatory system has two major circuits: the systemic
circuit and the pulmonary circuit. Let’s review each circuit and its function so that we can answer our question.
Let’s start with the systemic circulatory system. Here, the word “systemic” refers to processes that involve the entire body. All body cells require oxygen in order to function, and they receive this oxygen from
the circulatory system. You might have already learned that red blood cells carry oxygen to body tissues. Blood is also responsible for transporting carbon dioxide and waste products away
from these tissues. In order to continue oxygenating body cells, the carbon dioxide that is transported
by the blood away from the tissues must be replaced with oxygen. This process, called oxygenation, occurs in the lungs.
The deoxygenated blood from the body, or the systemic system, is transported back to
the heart. The heart pumps this deoxygenated blood to the lungs, where it is oxygenated. In the lungs, oxygen diffuses from the air sacs, called alveoli, into the blood. The carbon dioxide diffuses out of the blood and into the lungs to be exhaled from
the body. The circulatory system that transports blood between the heart and the lungs is
called the pulmonary circulatory system. Here, the word “pulmonary” refers to the lungs. The oxygen-rich blood is then returned to the heart, ready to be pumped through the
systemic circulatory system again.
So, in summary, the systemic circulatory system transports oxygenated blood from the
heart to the body and deoxygenated blood back to the heart. The pulmonary circulatory system transports deoxygenated blood from the heart to the
lungs, where it is oxygenated. It then returns the oxygenated blood to the heart so it can be pumped around the
systemic circulation, delivering oxygen to cells as it travels.
The question asks us to identify which color line represents the pulmonary
circulatory system. We have just learned that the pulmonary circuit involves the lungs. So the line that represents the pulmonary circulatory system is green.
