Partial Pressure & Diffusion Flashcards
What is Dalton’s Law?
total pressure of the gases = the sum of the partial pressures of the individual gases
What is the pressure at sea level?
101 kPa = 1 atmosphere
What percentage of air is oxygen?
21%
Why is alveolar pressure of oxygen less than in the conducting airways?
New air and old air mix as only 450ml of air is inhaled at rest (tidal volume) and some of this is in anatomical dead space
What is the p02 and pCO2 in the alveoli?
p02 = 13.3kPa and pC02 = 5.3kPa
How do you calculate the amount of gas dissolved?
partial pressure (kPa) x solubility coefficient of gas
Which oxygen in the blood contributes to partial pressure?
The oxygen dissolved in the plasma
What percentage of oxygen is bound to haemoglobin?
98-99%
Which 3 factors affect diffusion rate?
Surface area, thickness and diffusion coefficient
Which 2 factors contribute to the diffusion coefficient?
Solubility and molecular weight of the gas
What is the difference in diffusion between oxygen and carbon dioxide?
Carbon dioxide diffuses 20 times faster than oxygen
What happens to the partial pressures during hypoventilation?
pC02 goes up and pO2 goes down
