This question looks at oxygen transport from air to alveolar space blood

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This question looks at oxygen transport from air to alveolar space blood. Model this system as a fluid layer on the alveolar surface separated from blood by lung Lungs fluid layer (well mixed) matrix tissue. The lung matrix is a 20-um thick, [~ scar tissue (dark)

 

‘ ‘ healthy tissue (light) planar structure separating the two well-stirred blood (well mixed regions of the fluid layer and blood. The fluid pe ood (well mixed) layer is in equilibrium with the alveolar space; this captures the transition from gas to liquid, simplifying the model.

 

Under standard conditions, we'll assume the following partial pressures of O2, which correspond to

 

concentrations of dissolved gas (through Henry’s Law, nothing new here).

TPs tied [TOT assole gas

useful numbers: | M = | mole/L = 1 x 10° mole/m?*; solubility of O2 = 1.4 x 10° M/mmHg

A patient comes to the clinic, reporting difficulty in maintaining strenuous activity. A scan of the lung structure reveals that a quarter of the total surface of the lung has been affected by injury.

In the injured areas, the upper half of the healthy tissue (10 um) has been replaced by scar tissue; while the uninjured areas consist of a 20-um thick layer of healthy tissue, the injured areas consist of a 10-ym thick layer of scar tissue on top of a 10-ym thick layer of healthy tissue. Oxygen interacts differently with healthy and scare tissue, as indicated in this table:

a 0

 

4.1) Per square meter, what is the rate of oxygen transport by diffusion across a healthy lung, that

has not been replaced with diseased tissue? Assume diffusion across this tissue is a 1-

dimensional system, with oxygen going from fluid layer to blood; ignore any edge effects

where the healthy tissue interfaces with injured tissue. Use the standard conditions indicated

above, and express in terms of mol/s. (5 pts)

 

4.2) Per square meter, what is the rate of oxygen transport by diffusion across the injured tissue?

These are the areas consisting of layers of heathy and scar tissue. Assume diffusion in this

tissue is a 1-dimensional system, as described for healthy tissue. Use the conditions indicated

above, and express in terms of mol/s. (5 pts)

 

4.3) Now come back to the situation presented by the patient. Compared to lungs composed of only

healthy matrix, how much does the presence of injured tissue replacing a quarter of the lung

area reduce oxygen transport? Diffusion is still considered 1-dimensional, ignoring any effects

of the interface between healthy and injured tissue. Consider the standard conditions indicated

above, and express in terms of percent decrease. (10 pts)

 

4.4) In this final part, assume that Po2 in blood can be different than 40 mmHg. To achieve the same

oxygen transport of healthy matrix alone (results of 4a above), but in the situation where

injured tissue covers a quarter of the total area, what would be the Poz of blood? (5 pts