1. Lectures on respiratory physiology Pulmonary Blood Flow

2. Pulmonary and systemic circulations

3. Alveoli with capillaries

4. Compression of capillaries

5. P ulmonary capillary has a very thin wall

6. Small pulmonary vein

7. Alveolar and extra-alveolar vessels

8. P in P out FLOW VASCULAR RESISTANCE = ELECTRICAL RESISTANCE = FLOW INPUT PRESSURE – OUTPUT PRESSURE CURRENT INPUT VOLTAGE – OUTPUT VOLTAGE Comparison of vascular and electrical resistance

9. Effects of increased pressures on vascular resistance

10. Recruitment and distension of capillaries

11. P ulmonary capillary has a very thin wall

12. Demonstration of recruitment

13. Demonstration of distension

14. Effect of lung volume on resistance

15. FICK PRINCIPLE Vo 2. vo 2 - C Ca o2o2 Vo 2. Q (. = Ca o2o2 vo 2 - C - ) Q. = Vo 2. Ca o2o2 vo 2 - C - Measurement of total pulmonary blood flow

16. Uneven distribution of blood flow

17. Effects of change of posture and exercise

18. Normal distribution in isolated lung

19. Effect of reducing pulmonary artery pressure

20. Effect of raising pulmonary venous pressure

21. Three zone model of distribution of blood flow

22. Compression of capillaries

23. Three zone model of distribution of blood flow

24. Model of a Starling resistor

25. Three zone model of distribution of blood flow

26. Non-gravitational causes of uneven blood flow Random variations in the resistance of blood vessels Some evidence that proximal regions of an acinus receive more blood flow than distal regions In some animals some regions of the lung have an intrinsically higher vascular resistance

27. Effect of breathing 10% oxygen

28. Effect of reducing the alveolar PO 2

29. Alveolar gas is very close to the wall of the artery

30. Low alveolar PO 2 causes vasoconstriction

31. Evolutionary pressure for hypoxic pulmonary vasoconstriction Pulmonary blood flow in the fetus is only about 15% of the cardiac output Most of the output of the right ventricle bypasses the lung through the ductus arteriosus The pulmonary vascular resistance is high because of hypoxic vasoconstriction in the very muscular pulmonary arteries Immediately after birth, and pulmonary blood flow must increase dramatically The great fall in pulmonary vascular resistance is due mainly to the release of hypoxic vasoconstriction In addition the ductus arteriosus gradually closes

32. Substances metabolized by the lung Biological activation: Angiotensin I is converted to the vasoconstrictor, angiotensin II via ACE Biological inactivation:. Examples include bradykinin, serotonin, prostaglandins E 1, E 2, and F 2 alpha. Norepinephrine is also partially inactivated Not affected: Examples include epinephrine, prostaglandins A 1 and A2, angiotensin II and vasopressin. Metabolized and released: Examples include the arachidonic acid metabolites - the leukotrienes, and prostaglandins. Secreted: Immunoglobulins, particularly IgA, in bronchial mucus.