Respiratory: Gas Exchange Flashcards Preview

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Flashcards in Respiratory: Gas Exchange Deck (6)
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1
Q

What are the factors affecting diffusion of a gas?

A
  • the pressure difference across the barrier
  • the solubility of the gas in solution
  • the surface area of the barrier
  • the diffusion distance
2
Q

What is more soluble, CO2 or O2?

A

CO2 is 20x more soluble so the partial pressure gradient is smaller. This is because oxygen is small and therefore fast so CO2 is more soluble. In a diseased lung oxygen gas exchange is therefore more impaired.

3
Q

What are the layers making up the diffusion barrier?

A
RBC membrane 
Capillary endothelium 
Capillary basement membrane 
Epithelial cell of alveolus 
Fluid and surfactant layer
4
Q

What factors affect diffusion resistance?

A

The nature of the barrier - permeability, thickness

The nature of the gas

5
Q

What are the different ways that CO2 is transported in the blood?

A

5% dissolved
5% as carboxyhaemoglobin on proteins
90% as bicarbonate ions

6
Q

What happens once CO2 enters a RBC?

A

CO2 enters RBCs as a waste product then reacts with water to form carbonic acid.
Carbonic acid dissociates into bicarbonate ions and hydrogen ions.
Bicarbonate ions enter plasma, h+ buffered by Hb in the RBC

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