What is the Pulmonary Circuit?

Hi, and welcome to this video on the pulmonary circuit.

Our body has two types of circulation to sustain life: pulmonary circulation and the systemic circulation. We’ll talk a little about both, but primarily focus on the functions of the pulmonary circulation.

Blood’s Journey

The primary function of the pulmonary circuit is to transport deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide.

Our circulation is quite a sophisticated set of highways and intersections that run through some major organs. One of those organs is the heart. The heart is our “pump”, which keeps the flow of traffic, our blood, moving in the right direction. Our lungs act as the gas station where gas exchange occurs and deoxygenated blood receives the oxygen it needs to then be returned back to our pump, the heart, and then eventually sent out to the rest of the body (the systemic circulation).

Think of the heart as having two sides, a right and a left. In each side, the heart has two chambers. On the right side of the heart, we have the right atrium and the right ventricle, and on the left side of the heart, we have the left atrium and the left ventricle. The right side of your heart is your pulmonary circuit pump, and the left side of your heart is your systemic circulatory pump.

We have a lot of blood vessels, or highways, some big and some small, traveling in different directions to transport blood to and from the heart.

Let’s focus on the smaller route first, the pulmonary circuit. There is a large blood vessel from the body called the superior vena cava. This large vessel is carrying blood to the pulmonary circuit to be oxygenated.

The blood enters the heart through the right atria, into the right ventricle where it then flows into the lungs for the gas exchange between the alveoli in the lungs and the pulmonary capillaries. That blood is now ready to return back to the heart through the left atria and left ventricle where it will be pumped out of the heart back into the systemic circulation via the aorta, another large blood vessel.

The heart actually functions in both the pulmonary and systemic circulation. These systems work in tandem with each other providing the body oxygen and nutrients we need for survival. If one system is affected by a tumor, blood clot, pneumonia, heart defect, or other condition, it will affect circulation in the other system as well.

So let’s review the differences between the Pulmonary Circuit and the Systemic Circuit.

• The circuit through which blood flows from the heart to the lungs and back is called the pulmonary circuit.
• The circuit through which blood flows from the heart to body tissues and back is called the systemic circuit.
• When compared with the systemic circuit, the pulmonary circuit is short – the lungs and group of pulmonary vessels also known as the “trunk” are about 6 inches apart.
• The arteries of the pulmonary circuit carry deoxygenated blood, whereas the arteries of the systemic circuit carry oxygenated blood.
• The right side of the heart is the pulmonary circuit pump, and the left side of the heart is the systemic circuit pump.
• The Pulmonary circuit receives blood from body tissues and circulates it through the lungs, whereas the systemic circuit receives blood from pulmonary veins and pumps to the aorta, which spreads the oxygenated blood throughout the body.
• The components of the pulmonary circuit are found mainly in the chest cavity, associated with lungs, whereas the components of the systemic circuit are found all over the body.

Thanks for watching, and happy studying!