1. “Uptake in the lungs
2. Carrying capacity of blood
3. Global delivery from lungs to tissue
4. Cellular use of oxygen” (Treacher & …show more content…
Diffusion across this pressure gradient is so effective that the capillary blood is fully oxygenated by the time it has passed through 1/3rd of the alveolar capillary network (Grossman & Porth, 2014). Ficks law of diffusion describes the relationship between factors that influence diffusion rates. It can be used to look at diffusion between the alveoli and this pulmonary capillary network. These factors include the partial pressure difference of gas (p1-p2), the thickness (T) and surface area (SA) of the membrane and the diffusion coefficient (D). It can be summarized in this equation where the Vgas =(SA x D(p1-p2)) ÷ T (Grossman & Porth, …show more content…
There are different 2 types of shunting, absolute and relative. An absolute shunt is when the blood from the right side of the heart never comes into contact with any alveoli, and does not partake in gas exchange (Des, J. T. R., & Burton, G. G, 2001, p.32). This can happen in a normal healthy person and usually accounts for 3% of cardiac output. This becomes not normal is in the case of alveolar collapse and consolidation when oxygen therapy is relatively ineffective. A relative shunt is where the blood is passing the alveoli but due to hypoventilation, V/Q mismatch or diminished diffusion they are not oxygenated properly. This can also happen with increased cardiac output, where there is not enough time for diffusion to take place (Des, J. T. R., & Burton, G. G, 2001,