Understanding Systemic and Pulmonary Circulation

Our heart and blood vessels work together to keep us healthy. There are two important parts of this system: systemic circulation and pulmonary circulation. They are quite different from each other in how they are built and how they work.

1. How the Blood Vessels are Built

• Systemic Circulation:

  • This system includes arteries, veins, and tiny blood vessels called capillaries.
  • It carries oxygen-rich blood from the left side of the heart to all parts of the body.
  • One of the main arteries is the aorta, which is about 2.5 cm wide.
  • Veins, on the other hand, are a bit wider but have thinner walls. They usually measure about 1-2 cm in width.

• Pulmonary Circulation:

  • This part moves oxygen-poor blood from the right side of the heart to the lungs and then back to the left side of the heart.
  • The pulmonary arteries, which carry the blood without oxygen, are shorter and smaller, usually about 1-2 cm wide.
  • Pulmonary veins bring the oxygen-rich blood back to the heart, and are generally 1-1.5 cm wide.

2. How Blood Moves and Pressure Levels

• Systemic Circulation:

  • The blood pressure here is much higher, about 120/80 mmHg in healthy adults.
  • Blood moves pretty fast in systemic arteries, at about 40 cm per second.

• Pulmonary Circulation:

  • The pressure is lower in this system, around 25/10 mmHg.
  • Blood flows slower here as well, moving at about 15 cm per second.

3. How the Blood Vessels Work

• Systemic Vessels:

  • These have strong muscles in their walls, which help them control blood flow by tightening or relaxing.

• Pulmonary Vessels:

  • These vessels have less muscle and don’t control blood flow as tightly. They focus more on helping our body take in oxygen and get rid of carbon dioxide.

In summary, systemic and pulmonary circulation are very different but both play a crucial role in keeping our bodies working well. They handle oxygen and blood flow in unique ways to help us stay healthy.