3.1 Gas Exchange Flashcards
What is ‘dry air’?
Mixture of O2 and N2 with variable amounts of water depending on the humidity
What is ‘tracheal air’?
Fully saturated with water as it passes along moist airways. O2 and N2 are slightly diluted
What factors relating to the gas does diffusion speed relate to?
Weight of the gas- lighter gas diffuses quicker
Solubility of the gas- more soluble will diffuse quicker
What diffuses quicker O2 or CO2?
CO2 by about 20x
How are the alveoli adapted to aid diffusion?
Very large surface area
Thin diffusion pathway
Why does O2 diffuse into the capillaries?
Moves down a pO2 gradient
When O2 enters the blood, how is it transported?
Combines with haemoglobin to travel in the blood.
How is CO2 moved in the blood?
CO2 reacts with water to become carbonic acid. The H+ ions are buffered by haemoglobin. The HCO3- travel in the plasma.
How does fibrosis alter diffusion?
Makes the alveolar membrane thicker so increases the diffusion pathway
How does emphysema alter diffusion?
Destroys alveoli so surface area is lost
How does pulmonary oedema alter diffusion?
Fluid in interstitial space causes diffusion to slow down
What is the alveolar ventilation rate?
The amount of air that reaches the alveoli
What is the ideal ventilation- perfusion ratio? (V/Q ratio)
1
What is ‘dead space’?
Air that enters first will leave first so does not reach the alveoli and is therefore wasted.
