PULMONARY CIRCULATION
General Goal: To describe the role of the pulmonary circulation in
gas exchange and to describe in turn the influence of the respiratory
system on the pulmonary circulation.
Specific Objectives: The student should:
1. be able to list several functions of the lung in addition to gas
exchange.
2. be able to give typical values for pressures in the pulmonary
artery, pulmonary capillaries and pulmonary veins and know typical
pulmonary blood flow values.
3. be able to calculate pulmonary vascular resistance from pressure
and flow values, and know resistance is influenced by intravascular
pressure, lung volume, and hypoxia.
4. be able to calculate either oxygen consumption or pulmonary blood
flow from the Fick Equation given appropriate missing values.
5. know how blood flow distribution changes from apex to base.
6. understand the conditions determining Zone 1, Zone 2 and Zone 3
lung, and know what pressure gradient determines flow in each case.
7. be able to list the three principle causes of right to left shunt,
know how shunt affects arterial oxygenation, and how it can be
calculated clinically.
Resources
Lecture: Dr. Baer
Reading:
West, JB. Respiratory Physiology-The Essentials (4th Ed.) Williams
& Wilkins. Chapter 4.
Guyton, AC. Medical Physiology (7th Ed.). Chapter 24.
INTRODUCTION
a Anatomy
i Lung is only organ to receive entire cardiac output.
ii Extra-alveolar vessels vs. alveolar vessels. Pulmonary artery
branches run parallel to airways to the level of the
terminal bronchioles where they break off to form the
capillaries in the alveolar walls.
iii Sheet flow. Pulmonary capillaries are so dense within the
alveolar walls that flow can be thought of as
capillary lumen interrupted by occasional supporting
walls....