1 / 9

Pulmonary Circulation Characteristics

Pulmonary Circulation Characteristics. Low Resistance /Pressure The specific structure(s) primarily responsible for the majority of control of resistance in the resting state is controversial.

john
Télécharger la présentation

Pulmonary Circulation Characteristics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pulmonary CirculationCharacteristics • Low Resistance /Pressure • The specific structure(s) primarily responsible for the majority of control of resistance in the resting state is controversial. • Resistance more evenly distributed, but majority of resistance is normally on the arterial side (upstream) of the the capillaries. • Thin-walled arterial system (relatively little smooth muscle) • Anatomical considerations • Vessels are surrounded by bags of gas and flexible interstitial fluid-filled regions • No true arterioles?? • Alveolar and extra-alveolar vessels respond to conditions differently

  2. Neural/Humoral: all the same players as in the periphery (but less effective) and a few with more specific actions Serotonin: Arterial side vasoconstriction Histamine: Venular side vaso(veno)constriction ***venous side can become dominant resistance Intravascular Pressure R 1/P recruitment (primary) distension Pulmonary Circulation Influences on resistance

  3. 300 200 Increasing Arterial Pressure (cmH2O/L•min-1) Pulmonary Vascular Resistance 100 Increasing Venous Pressure 0 10 20 30 40 Arterial or Venous Pressure (cm H2O) Perfusion

  4. Pulmonary Circulation Influences on resistance • Neural/Humoral:all the same players as in the periphery (but less effective) and a few with more specific actions • Serotonin: Aretrial side vasoconstriction • Histamine Venular side vaso(veno)constriction • Intravascular Pressure R 1/P • recruitment (primary) • Distension ***Thus, cardiac output is considered to be the primary determinant of pulmonary vascular resistance • Lung volume

  5. 120 100 Vascular Resistance (cmH2O/L•min-1) 80 60 200 50 100 150 Lung Volume (ml)

  6. Pulmonary Circulation Influences on resistance • Lung volume • Low Volume: extra-alveolar vessels are smaller, capillaries more open • High Volume: extra-alveolar vessels are pulled open; capillaries become defromed by stretch (more oval; higher resistance) * Lung volume effects on extra-alveolar vessels is lost with positive pressure ventilation. • PO2: Local Control Decreased PAO2 causes vasoconstriction. Advantage: blood is shunted away from poorly ventilated alveoli. • Surrounding Pressure • Alveolar • Interstitial (<0)

  7. The Starling Resistor Concept Pulmonary Circulation

  8. Zone 1 PA>Pa>Pv Zone 2 Pa>PA>Pv Distance Zone 3 Pa>Pv>PA Blood Flow Pulmonary Circulation Arterial (Pa) Alveolar (PA) Venous (Pv)

  9. Pulmonary Artery Pulmonary Circulation 60 Pulmonary Arterial 50 Catheter Tracing 40 mmHg 30 20 10 0 Left Atrial Pressure Tracing Pulmonary Capillaries Left Atrium Pulmonary Vein

More Related