Lung function Flashcards
How many generations of airways do we have?
23
From which generation does gas exchange happen?
From the 17th generation
What is the role of the conducting zone is the airways (generation 0 to 16)?
Transfer of gases to and from the alveoli
Warming and humidifying inspired air
Filtration and removal of foreign material
This zone essentially prepared air for gas exchange
What is gas movement driven by?
It is driven by diffusion from the partial pressure differences. IT IS PASSIVE!
What law can you use to find the rate of diffusion?
Fick’s Law
How do gas molecules move in the conducting zone versus the respiratory zones?
In the conduction zones air is moving by bulk flow (all the molecule move in one direction)
In the respiratory zones all the gas molecules move by diffusion (Oxygen and CO2 can move in different directions)
Where is the best ventilation and perfusion in the lungs when someone is sitting? How does this change when someone is lying down?
Best as the base of the lung due to the effects of gravity that pulls blood and air down.
When lying down the spread is much more evenly distributed across the lungs.
When would the ventilation: perfusion ratio be 0? When would the ratio be infinity?
When there is no ventilation of the lungs (no blood coming into contact with alveolar air)
It would be infinity when ventilated air is not coming into contact with blood (e.g. in the conduction zones of the lung or alveoli that are not being perfused)
What is the Bohr shift?
This is when increasing CO2, H+ conc (e.g. lactic acid from exercise), temeprature all cause the haemoglobin-O2 dissociation curve to shift to the right which decreases haemoglobins affinity for oxygen at lower partial pressures as more oxygen is released into cells for metabolic reactions.
How is CO2 carried in the blood?
Can form carbamino compounds on Hb and can diffuse in the plasma as carbonic acid/ carbonate ions.
(As H+ ions are formed in bicarbonate compounds, H+ ions are produced which results in changes in pH)
What are problems with hyperventilation?
This decreases the CO2 concentration in arterial blood which decreases the pH.
O2 conc is not affected much as most haemoglobin is already bound to oxygen so it just means more oxygen dissolves in the blood
This can happen:
at altitude
under stress
during acute asthma attacks
What are problems with hypoventilation?
Decrease in O2 consumption and increase in CO2 in the blood which means ventilation is not meeting metabolic needs of the body.
