Session 3 - Gas Exchange Flashcards
what layers must gases diffuse through in the alveoli to reach the lungs
- alveolar endothelial
- interstitum
- capillary endothelia
- plasma
- RBC membrane
why is the alveolar air and blood partial pressures the same
as the rate of diffusion is very fast
what does the rate of diffusion in the lungs depend on
- area available for exchange
- thickness of membrane
- solubility
- distance to travel
- partial pressure gradients
how does fibrosis affect gas exchange
it means theres are larger distance for gases to diffuse
in fibrotic lungs why might the partial pressure of carbon dioxide be normal but oxygen low
as carbon dioxide is more soluble so can pass through easier
why does pulmonary oedema affect the diffusion rate
the increase of fluid in the interstitum increases the distance for diffusion, slowing it down
how does emphysema affect gas exchange
the lack of alveolar walls means theres a smaller surface area for exchange
what is the normal pO2 in the alveoli
13.3 kPa
what is the normal pCO2 in the alveoli
5.3 kPa
what happens to the partial pressures of CO2 and O2 in hyperventilation
CO2 decreases
O2 increases
what is atmospheric pressure value
101 kPa
what happens to the blood nitrogen levels underwater
more nitrogen dissolves into the blood due to the increase in pressure
why must you resurface slowly after diving deep underwater
so that nitrogen dissolves out the blood slowly and no air bubbles are produced which could embolise
what happens to the oxygen levels in the blood underwater
they increase but not as much as it would with other gases as the haemoglobin would saturate first
what is the solubility coefficient
the amount of gas that dissolves in a litre of plasma at a given time
