Blood Supply, Gas Exchange, Ventilation and Perfusion Flashcards
What is bronchial circulation?
Supplies oxygenated blood to airway smooth muscle, nerves and lungs
What is pulmonary circulation?
Carries entire cardiac output from the right ventricle
Supplies dense capillary network surrounding alveoli and returns oxygenated blood to the left atrium
It is a high flow, low pressure system
What is the rate of diffusion directly proportional to?
Partial pressure gradient
Gas solubility
Available surface area
What is the rate of diffusion inversely proportional to?
Thickness of the membrane
Is the partial pressure gradient steeper for carbon dioxide or oxygen?
Oxygen
Why are the rates of diffusion of carbon dioxide and oxygen a lot closer together than the expected values?
Carbon dioxide is much more soluble than oxygen
What is ventilation?
Air getting to the alveoli (L/min)
What is perfusion?
Local blood flow (L/min)
What is distribution of blood flow in lungs influenced by?
Hydrostatic and alveolar pressure
How is it regulated when ventilation
PCO2 increases and PO2 decreases
Alveoli constrict their arterioles diverting blood to better ventilated alveoli
Increased PCO2 also cause mild bronchodilation
How is it regulated when ventilation > blood flow
Increased PAO2 causes pulmonary vasodilation
Decreased PACO2 cause bronchial constriction
Response increases perfusion and to a lesser extent decreases ventilation
What is shunt?
Movement of blood from the right side of the heart to the left side without being oxygenated
What is alveolar dead space?
Regions of the lung that have ventilation but not perfusion
What is physiologic dead space?
Alveolar dead space + anatomical dead space
