Pulmonary Blood Flow, Gas Exchange and Transport Flashcards
How is the bronchus supplied with blood?
Via bronchial arteries (nutritive)
What type of circulation supplies the bronchus?
Systemic Circulation
What tissues are supplied in the bronchus by the bronchial arteries?
- Smooth muscle - Nerves - Lung tissue
How are the lungs supplied with the vessels that exchange gas?
- Pulmonary arteries
Where do the pulmonary arteries originate from?
Right ventricle
What is the function of the pulmonary vein?
- Returning oxygenated blood to the heart
What is the systolic pressure of the pulmonary artery
25mmHg
What is the flow of the pulmonary artery?
High flow
How much blood goes through your lungs every minute?
5L
What is gas exchange said to travel down?
A partial pressure gradient?
What is the partial pressure of CO2 in venous circulation and the pulmonary artery?
46mmHg (6.2kPa)
What is the partial pressure of O2 in venous circulation and the pulmonary artery?
40mmHg (5.3kPa)
What does the partial pressure of gases in the venous blood give an indication into?
What is going on with gas exchange in the tissue
What is the partial pressure of CO2 in the arterial circulation and the pulmonary vein?
40mmHg (6.2kPa)
What is the partial pressure of O2 in the arterial circulation and the pulmonary vein?
100mmHg (13.3kPa)
What will the partial pressures of these gases in arterial circulation give an indication to?
What is going on with gas exchange in the lungs
What does PA stand for?
Alveolar pressure
What does Pa stand for?
Arterial blood pressure
What does Pṽ stand for?
Mixed venous blood pressure (pulmonary artery)
What 3 things is the rate of diffusion directly proportional to?
- Partial pressure across the membrane - Gas solubility - Surface area
What is rate of diffusion inversely proportional to?
Thickness of the membrane
What is the partial pressure GRADIENT of O2 in the alveoli to the vessels of deoxygenated blood?
60mmHg (100 in the alveoli, 40 in the blood)
How much O2 diffuses across the alveoli per minute?
250ml
What is the partial pressure GRADIENT of CO2 in the alveoli to the vessels of deoxygenated blood?
6mmHg (46 in the blood, 40 in the alveoli)
How much CO2 diffuses across the alveoli per minute?
200ml
Why is the rate of diffusion of CO2 not 10 times less than O2 if the partial pressure gradient is?
CO2 is more soluble in water
How does pulmonary oedema affect gas exchange?
- Fluid inbetween vessels and alveoli
- Since O2 doesn’t dissolve well in water it reduces the movement of O2
- Also increases distance between membranes so diffusion is reduced
How does emphysema reduce gas exchange?
Reduces surface area
How does fibrosis reduce gas exchange?
- Increases membrane thickness
- Reduces ventilation and compliance
How is pulmonary fibrosis confirmed?
Is radioopaque so shows up on chest X ray
How does emphysema increase surface area?
- Imagine the lungs are like a net and have loads of small holes
- If you tear the barrier between one of the holes you get 1 bigger hole
- This is what emphysema does to the lungs
What is ventilation?
Air getting to the alveoli (L/min)
What is perfusion?
Locol blood flow (L/min)
What is the relationship between ventilation and perfusion?
They are equal
Where in the lung are ventilation and perfusion both higher?
Bottom of the lung
Why are ventilation and perfusion higher in the bottom of the lung?
Gravity
Where in the lung are ventilation and perfusion the lowest?
Apex
Where does arterial pressure exceed alveolar pressure in the lungs?
Bottom of the lung
What is distribution of blood flow influenced by?
Hydrostatic pressure
What other reasons are there for pulmonary artery perfusion decreasing as you go up the lung?
Because the pressure is lower, it is MORE susceptible to gravity
Moving up the lung, at roughly what rib does alveolar pressure become equal to blood flow (ratio = 1)?
Rib 3
Above rib 3, which is higher out of alveolar pressure and Pa?
Alveolar