Do both alveolar ventilation and compliance incline or decline with height from base of lung to the apex?
Decline
Bronchial circulation - what is it supplied by? where do these arise?
Nutritive
Supplied via bronchial arteries from systemic arteries
Pulmonary circulation - Describe the flow and pressure
Gas exchange
High flow and low pressure - only 25mmHg
What does A stand for?
Alveolar
What does a stand for?
arterial blood
What does v stand for?
mixed venous blood eg pulmonary artery
PACO2
Partial pressure of carbon dioxide in aveolar air
PaO2
Partial pressure of oxygen in arterial blood
What 3 things is the rate of diffusion across the membrane 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 oxygen or carbon dioxide more soluble in water?
Carbon dioxide
Emphysema and PO2
Destroys alveoli and reduces surface area
PO2 in alveoli is normal/low and blood is low
Fibrotic lung disease and PO2
Thick alveolar membrane so low rate of diffusion
Loss of lung compliance effects ventilation. Same values as emphysema
Pulmonary oedema and PO2
Fluid increases diffusion distance so PO2 in blood low
Asthma and PO2
Increased airway resistance and decreased ventilation so low PO2 in alveoli and blood
Ventilation
Air getting into the alveoli
Perfusion
Local blood flow
What are ventilation and perfusion measured in?
L/min
What is the distribution of blood flow in lungs influenced by? (2)
Blood pressure
Alveolar pressure
Is blood flow directly or inversely related to vascular resistance?
Inversely
Base of lung - arterial and alveolar pressure
Arterial is higher so vascular resistance is low
Apex of lung - arterial and alveolar pressure
Alveolar is higher so vascular resistance is high
Above what rib shows a serious mismatch in blood flow and ventilation? What is done about this?
Rib 3
Auto regulated at apex of lung to correct the ratio
If ventilation is greater that perfusion is the ratio greater or less than 1?
Greater
If perfusion is greater than ventilation is the ratio greater or less than 1?
Less
What happens if PCO2 is high and PO2 is low?
Blood does not get oxygenated and oxygenated blood from other areas is diluted
What happens to blood flow and where is it directed when tissue PO2 is low?
Underventilated alveoli arterioles constrict to direct blood flow to better ventilated areas
What does high PCO2 do the the bronchi?
Mild bronchodilation
Does constriction in response occur in only systemic vessels, pulmonary vessels or both?
Pulmonary only
Shunt
The passage of blood through areas of the lung that are poorly ventilated (ventilation<
Alveolar dead space
Alveoli that are ventilated but not perfused
Physiological dead space
Alveolar DS + Anatomical DS