Pulmonary Blood Flow, Gas Exchange and Transport Flashcards
Bronchial circulation
Nutritive - supplied via bronchial arteries arising from systemic circulation to supply O2 to airway smooth muscle, nerves and lung tissue
Pulmonary circulation
Gas exchange - L & R pulmonary arteries originating from right ventricle. Carries entire cardiac output. Supplies dense capillary network and returns oxygenated blood to the left atrium via the pulmonary vein
Shunt
Passage of blood through areas of the lung that are poorly ventilated
Alveolar dead space
Alveoli that are ventilated but not perfused
Anatomical dead space
Conducting airways that do not participate in gas exchange
Physiological dead space
Alveolar dead space + anatomical dead space
Pulmonary circulation sytem
High flow, low pressure - same volume of blood flowing to the lungs as to entire body
Miscellaneous
CO2 much more soluble than oxygen so passes through membrane more easily
Capillary always directly adjacent to type 1 alveolar cell - reduces distance for gas to diffuse
Lung disease and gas exchange
Mainly has an effect on diffusion, except for asthma where there is a low PO2 in general
Perfusion
Local blood flow
Ventilation/perfusion relationship
Ideally compliment each other
Blood flow in lungs
Inversely proportional to vascular resistance and declines with height across the lung
Blood flow at base of lungs
Blood flow is high as arterial pressure (Pa) exceeds alveolar pressure (PA) and vascular resistance is therefore low
Volume of O2 dissolved/L of plasma
3ml
Haemoglobin
Increases O2 carrying capacity to 200ml/L
1.34ml O2 bound to each gram of haemoglobin
