Chapter 8: Problem 7

Why is the pressure in the pulmonary circulation lower than in the systemic circulation?

Short Answer

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Answer: The pressure in the pulmonary circulation is lower than in the systemic circulation due to the differences in vascular resistance between the two systems. The systemic circulation encounters higher resistance primarily due to longer blood vessels, smaller vessel diameters, and greater branching. Additionally, the heart must pump with more force in the systemic circulation, resulting in higher pressure.

Step by step solution

Understand Pulmonary and Systemic Circulation

Pulmonary circulation refers to the circulation of blood between the heart and the lungs. It is responsible for carrying deoxygenated blood from the right side of the heart to the lungs for oxygenation and then returning the oxygenated blood to the left side of the heart. Systemic circulation, on the other hand, refers to the circulation of blood between the heart and the rest of the body. It carries oxygenated blood from the left side of the heart to the various organs and tissues of the body for oxygen utilization and then returns deoxygenated blood back to the right side of the heart.

Pressure Difference in Circulatory Systems

The main reason for the difference in pressure between the pulmonary and systemic circulations is the difference in the resistance they encounter. Resistance is mainly determined by the length of the blood vessels, their diameter, and the viscosity of the blood.

Understand Vascular Resistance

Systemic circulation has a higher vascular resistance compared to pulmonary circulation due to the following reasons: 1. The systemic circulation has longer blood vessels than the pulmonary circulation. This greater distance increases the resistance in the systemic circulation. 2. Blood vessels in the systemic circulation constrict or dilate depending on the body's demands and are smaller in diameter than those in the pulmonary circulation. A smaller diameter creates higher resistance. 3. Systemic circulation involves multiple small branches of blood vessels to reach different organs and tissues, which adds more resistance.

Role of the Heart

The heart pumps blood into both circulatory systems. However, it must pump with more force in the systemic circulation to overcome the higher resistance. Therefore, the pressure generated by the heart in the systemic circulation is higher than in the pulmonary circulation.

Conclusion

The pressure in the pulmonary circulation is lower than in the systemic circulation due to the differences in vascular resistance between the two systems. The systemic circulation encounters higher resistance primarily due to longer blood vessels, smaller vessel diameters, and greater branching. The heart must also pump with more force in the systemic circulation, resulting in higher pressure.

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Why is the pressure in the pulmonary circulation lower than in the systemic circulation?

Short Answer

Step by step solution

Understand Pulmonary and Systemic Circulation

Pressure Difference in Circulatory Systems

Understand Vascular Resistance

Role of the Heart

Conclusion

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