Pulmonary Blood Flow, Gas Exchange and Transport 1 Flashcards
What vessels supply the bronchial circulation?
Bronchial arteries
What circulatory system gives rise to the bronchial circulation?
Systemic
What is the function of the bronchial circulation?
Supplies airway smooth muscle, nerves and lung tissue with oxygen
Why is the Pulmonary circulation referred to as high flow, low pressure?
High flow - entire cardiac output 5L/min flows through it
Low pressure - only has systolic pressure of 25mmHg
What force influences a low pressure circulatory system?
Gravity
Expand on these abbreviations:
a
A
v
P
a - arterial
A - alveolar
v - venous
P - pressure
Therefore what does PaCO2 refer to?
Partial pressure of carbon dioxide in the arteries
What is the partial pressure of oxygen in the alveoli and arteries?
100mmHg or 13.3kPa
What is the partial pressure of carbon dioxide in the alveoli and arteries?
40mmHg or 5.3kPa
What is the partial pressure of venous oxygen?
40mmHg or 5.3kPa
What is the partial pressure of venous carbon dioxide
46mmHg or 5.6 kPa
What four factors effect the rate of gas exchange?
- Partial pressure gradient
- Gas solubility
- Surface area
- Membrane thickness
What partial pressure values reflects gas concentrations in the lungs?
Arterial partial pressures
What partial pressures values reflects gas concentrations in tissues?
Venous partial pressures
How does fibrotic alveolar membrane decrease the rate of gas exchange?
Thickened membrane
How does pulmonary oedema decrease rate of gas exchange?
Increased diffusion distance through fluid
How does asthma reduce gas exchange?
Constricted bronchi increase resistance to ventilation
What is ventilation?
Air getting to the alveoli
What is perfusion?
Local blood flow
What is the optimal condition for ventilation and perfusion?
They are equal
What two forces influence distribution of blood flow?
Hydrostatic blood pressure and alveolar pressure
What is blood flow in the lungs proportional to?
Vascular resistance
What trend does blood flow demonstrate in relation to height of the lung?
Decreases with height
Why is blood flow in the base of the lung high?
Arterial pressure > alveolar pressure
Therefore vascular resistance is low
A decrease in PAO2 in the alveoli causes what to occur?
Arterioles to those under-ventilated alveoli are constricted and blood is diverted to better ventilated ones
What does an increase in PACO2 do?
Causes mild bronchodilation
What response to hypoxia of the pulmonary system is unique?
Constriction due to hypoxia
What is shunting?
Refers to the physiological changes that occur in poorly ventilated areas of the lung (ventilation
What is alveolar dead space?
Refers to alveoli that are well ventilated but poorly perfused
