Respiratory Physiology 3 Flashcards
What is the anatomical dead space volume?
About 150ml occupied by the conducting airways
What is meant by pulmonary ventilation?
Total air movement into/out of lungs (is insignificant in functional terms) L/min
What is meant by alveolar ventilation?
Fresh air moving to alveoli and that is therefore available for gas exchange (functionally significant.) L/min
What does Dalton’s law state?
It states that the total pressure of a gas mixture is the sum of the pressures of the individual gases.
What happens to the partial pressure of oxygen and carbon dioxide during hyper ventilation?
Partial pressure of oxygen rises to ~120mmHg and carbon dioxide falls to ~20mmHg
What happens to partial pressure of gases during hypo ventilation?
Partial pressure of oxygen falls to 30mmHg and carbon dioxide rises to 100mmHg
How does alveolar ventilation across the lung?
It declines with height from base to apex.
Is depth or rate of breathing more influential in determining alveolar ventilation?
Depth of breathing because of the effect of anatomical dead space.
What is the bronchial circulation?
Supplied via the bronchial arteries arising from the systemic circulation to supply lung tissues themselves. 2% of left heart output
What factors determine the rate of diffusion between alveoli and blood?
The rate of diffusion across the membrane is:
-directly proportional to the partial pressure gradient.
-directly proportional to gas solubility
-directly proportional to the available surface area
-inversely proportional to the thickness of the membrane
-most rapid over short distances.
How does emphysema affect gas exchange?
Destruction of alveoli reduces surface area for gas exchange.
How does fibrosis affect lung disease?
The alveolar membranes are thickened reducing gas exchange.
How does pulmonary oedema affect gas exchange?
There is an increased distance between alveolus and blood vessel decreasing gas exchange.
