Systemic vs Pulmonary Circulation FAQ
Rahul's Noteblog
Notes on Pulmonology
Systemic vs Pulmonary Circulation FAQ
List some of the differences between the pulmonary circulation and the systemic circulation of the adult:
Pulmonary circulation:
• Blood destined for the lungs.
• Deoxygenated blood.
• Right side of the heart.
• Walls are generally thinner.
• Blood flowing from r. ventricle ->lungs -> l. atrium.
• Called “low resistance, high compliance”. Resistance is low because blood is not going through tissue, and compliance is high because these structures can be stretched.
Systemic circulation:
• Blood coming out of the lungs, destined for the body.
• Oxygenated blood.
• Blood flowing from l. ventricle -> r. atrium.
• Walls are generally thicker.
• Arteries.
What volume of blood is accommodated in the pulmonary circulation? How does this compare with the systemic circulation?
Volume of blood in the systemic circulation – about 60% - is higher than that in pulmonary circulation. This is because systemic veins and venules contain the highest percentage of blood, serving as blood reservoirs.
What is the blood pressure in the aorta? How does this compare with the pulmonary artery?
BP in the aorta is 120 mm Hg / 80 mm Hg, and normal pulmonary-artery pressure is about 14 mm Hg at rest.
Outline the Starling forces in the pulmonary capillaries:
Also known as Starling’s Law of Capillaries:
Starling defined four variables for capillary circulation, namely, BHP, IFOP, BCOP and IFHP.
BHP: Blood hydrostatic pressure is the pressure by which fluid flows toward the outside of capillaries. Remember, fluids don’t want to “move”, so when blood is flowing through capillaries, fluid tends to move outward into the interstitial space. BHP ~ 35 mm Hg.
IFOP: Interstitial fluid osmotic pressure is the pressure by which interstitial space (with the help of interstitial proteins, ions, etc.) pulls out fluid from the capillaries. Because there are not many proteins, ions, etc. in interstitial space, IFOP ~ 1 mm Hg.
IFHP: Interstitial fluid hydrostatic pressure is the pressure by which fluid flows toward the inside of capillaries. However, since interstitial fluid is already at rest, interstitial fluid doesn’t want to move out into capillaries, thus, IFHP ~ 0 mm Hg.
BCOP: Blood colloid osmotic pressure is the pressure that causes interstitial fluid to be pulled into the capillaries due to osmotic pressure created by proteins in the blood. BCOP ~ 26 mm Hg.
Net filtration pressure = (BHP + IFOP) – (BCOP + IFHP)
Additional Reading:
Basic Pulmonology
1. Lung Mechanics
2. Alveolar-Blood Gas Exchange
3. Gas Transport and Regulation of Respiration
4. Four Causes of Hypoxemia
5. Control of Respiration
6. Systemic vs Pulmonary Circulation FAQ
7. Principles of Gas Exchange in Lungs
8. Hypoxia, Hypoxemia & Hemoglobin-Oxygen Saturation Curve
9. FAQ on Mechanics of Breathing
10. FAQ on Control of Breathing
11. Criteria for Transudate Pleural Effusion
12. Light's Criteria for Exudate Pleural Effusion
13. Notes on Lung Sounds
14. Patient with Acute Respiratory Distress Syndrome (ARDS)
15. Management of Acute Deep Venous Thrombosis
16. Notes on Asthma Treatment
Pulmonology Videos
1. Video of Pulmonology Examination in a Clinical Setting
Related Topics
1. Histology of the Respiratory System
2. Upper and Lower Respiratory Disorders
3. Pulmonary Examination for Internal Medicine
Medical Images
Useful Medical Images & Diagrams (link opens in a new window)
Random Pages:
Please Do Not Reproduce This Page
This page is written by Rahul Gladwin. Please do not duplicate the contents of this page in whole or part, in any form, without prior written permission.
