Gas Exchange Flashcards
In what direction do gases move?
Down partial pressure gradients
What factors effect the diffusion of a gas?
Pressure diff
Solubility of the gas
Surface area
Distance the molecules must dissolve
Molecular weight of the gas
Temp of the fluid
How much faster does CO2 diffuse than O2?
20 times
What compensates for the different diffusions coefficients of O2 and CO2?
Difference in partial pressure
Larger pressure diff = compensates for slower diff of O2
What gives such a large surface area in the lungs?
Many alveoli
Tight network of capillaries surrounding = large diffusional surface area
What barrier do gases have to cross to diffuse in the lung?
Epithelial cell of alveolus
Tissue fluid
Endothelial cell of capillary
Plasma
Red cell membrane
What happens to the blood-gas barrier during inhalation?
Distance decreases as lung expands = fast/efficient diffusion
How does the proportion of gases change down the respiratory tract?
Inhaled = high O2, low water, low CO2
Alveolar = lowered O2, higher water, higher CO2
What is the partial pressures in venous blood?
pCO2 = 6.1
PO2 = 5.3
What are the partial pressures in arterial blood?
PCO2 = 5.1
PO2 = 13.3
How can the thickness of the lung membrane be affected?
Fibrosis
Oedema
How can the surface area of the lung be affected?
Removal of the lung
Emphysema
How can the diffusion coefficient of a gas been affected?
This should never change
