Physio 3 priciples of gas exchange Flashcards
Pulmonary ventilation:
Resp rate* tidal volume
12*500= 6000ml
Alveolar air composition is different from atmospheric because:
1)Air is humidified in resp tract
2)oxygen constantly absorbed into blood from alveoli
3)CO2 diffuses into alveoli from blood
PO2 in alveoli is:
PO2 in Resp tract/ humid air:
PO2 in air is:
Low to high
100 mmHg
150mmHg
160mmHg
PCO2 in alveoli:
PCO2 in Humid air/ resp tract:
PCO2 in air:
high to low
40mmHg
0.3mmHg
0.3mmHg
Dalton’s law::
the summation of atm pressure is 79% Nitrogen and 21% oxygen
600mmHg
160mmHg
Gas diffusion motion:
-Kinetic motion is acheived when molecules collide into eachother and produce motion.
-Constant temp is needed.
Alveolar air is SLOWLY renewed why?
To prevent sudden concentration changes of gas in the blood.
note on alveolar PO2 and Alveolar ventilation:
Alveolar PO2 can only reach a max of 150mHg
alveolar ventilatilation is infinite
Alveolar ventilation affected by:
Rate of absorption
partial pressure to a limit
FICKS LAWWW
4 Factors affecting diffusion rate:
1)Thickness of membrane
2)Surface area of membrane
3)diffusion coefficient (chemical properties of particles)
4)Partial pressure
Thickness of respiratory membrane and what can affect it:
0.2 micrometres to 0.6 normally
But edema can increase that to 3-6mm
diffusion rate is inversely proportional to membrane thickness
Surface area of membrane and what affects it:
-Proportional i.e high SA high high diffusion.
-Emphysema, surgical removal of tumor and smoking can decrease alveoli SA.
Diffusion coefficients and their speed at dissolving:
-diffusion rate Inversely proportional.
-CO2 diffuses 20x faster than O2
-O2 diffuses faster than N2
Henry’s Law
-States that the difference in PCO2 between the two sides of alveolar-capillary membrane is 10 times smaller than PO2
solubility of gas is decreased if Liquid temperature rises
Partial pressure of gas in Alveoli>blood
Oxygen moves into blood
