Two Circulations in the Body | Circulatory system physiology | NCLEX-RN | Khan Academy

Summary

This educational video script explains the heart's dual circulation system: pulmonary and systemic. It illustrates the path of deoxygenated blood from the right ventricle through the pulmonary arteries to the lungs, where it picks up oxygen and returns to the left atrium via pulmonary veins. The systemic circulation is then detailed, showing oxygen-rich blood from the left ventricle traveling through the aorta to the body's tissues and organs before returning deoxygenated blood to the right atrium via the vena cava. Special attention is given to the unique roles of red blood cells, the heart's own blood supply via the coronary arteries, and the dual blood supply to the lungs from both systemic and pulmonary circulations.

Takeaways

• 💡 The heart can be thought of as a system of pumps and pipes, with the right and left atria and ventricles being key components.
• 🔍 The right side of the heart (right atrium and ventricle) is responsible for pulmonary circulation, sending deoxygenated blood to the lungs.
• 🚀 Blood from the right ventricle travels through the pulmonary trunk, then the pulmonary arteries, to the lungs where it picks up oxygen.
• 🔄 The pulmonary veins carry oxygenated blood from the lungs back to the left atrium, completing the pulmonary circulation loop.
• 🌐 The left side of the heart (left atrium and ventricle) is responsible for systemic circulation, distributing oxygenated blood to the rest of the body.
• 🚌 The aorta is the main vessel that carries oxygenated blood from the left ventricle out to the body's tissues and organs.
• 🔙 Blood that has delivered oxygen to the body returns via the superior and inferior vena cava to the right atrium, completing the systemic circulation.
• 🩸 Red blood cells (RBCs) are designed to carry oxygen without needing it themselves, as they lack mitochondria and a nucleus.
• 🫀 The heart muscle itself receives oxygenated blood from the systemic circulation via the coronary arteries, which branch off the aorta.
• 💨 The lungs receive oxygenated blood from both the pulmonary circulation (pulmonary arteries) and the systemic circulation (bronchial arteries), with some mixing occurring.
• 🔁 There is a complex interplay between the pulmonary and systemic circulations in the lungs, with most blood eventually entering the pulmonary veins.

Q & A

How is the heart described in the script?

The heart is described as a couple of pumps with pipes attached, where the pipes represent the blood vessels.

What is the first part of the heart's journey for blood after it leaves the right ventricle?

The first part of the journey is through a valve into the pulmonary trunk.

What are the pulmonary arteries and their function?

Pulmonary arteries are vessels that carry blood away from the heart towards the lungs.

How many pulmonary arteries are typically present, and what do they do?

There are usually two pulmonary arteries, left and right, which carry deoxygenated blood to the lungs.

What is the purpose of the pulmonary circulation?

The pulmonary circulation is the process where blood goes from the heart to the lungs and back to the heart to pick up oxygen.

How does the systemic circulation differ from the pulmonary circulation?

The systemic circulation involves blood traveling from the left ventricle to the body's tissues and organs and then returning to the right atrium.

What is the role of the aorta in the circulatory system?

The aorta is a large vessel that carries oxygenated blood from the left ventricle to the rest of the body.

What are the two major veins that bring blood back to the heart after systemic circulation?

The two major veins are the superior vena cava and the inferior vena cava.

How do red blood cells obtain oxygen, and do they use it themselves?

Red blood cells obtain oxygen in the lungs and carry it to the body's tissues. They do not use the oxygen themselves as they lack mitochondria.

Where does the heart get its oxygen from, and how?

The heart gets its oxygen from the systemic circulation through the coronary arteries, which are the first branches off the aorta.

How do the lungs get their oxygen, and is it different from the blood they send to the rest of the body?

The lungs receive oxygenated blood from the bronchial arteries, which are part of the systemic circulation, but they also mix this blood with deoxygenated blood from the pulmonary circulation before it is sent to the heart.