Carbon Dioxide Transport

Front 1

List the forms in which CO2 is transported in the blood and the relative proportion of each form.

Back 1

1) Dissolved CO2 = 5%
2) Carbamino Compounds = 5%
3) Bicarbonate = 90%

Front 2

Describe the molecular process in which CO2 is acquired at the tissues and released in the lungs.

Back 2

A disproportionally large amount of CO2 leaves the lungs in the form of carbamino compounds. These form when CO2 binds to the amino groups of Hb. In the tissues that are of relatively low pH and high CO2, Hb loses its affinity for O2. CO2 tends to bind to Hb when it is deoxygenated (Haldane effect).

In the lungs, the reverse takes place as the high PO2 replaces the CO2 attached to Hb,

Front 3

Describe the curve for blood CO2 content.

Back 3

The plot of CO2 content versus PCO2 is linear within the physiologic range of PCO2 values.

Front 4

Understand why hyperventilation affects blood CO2 but not O2 content.

Back 4

The plot of CO2 content versus PCO2 is linear within the physiologic range of PCO2 values.

However, the plot of O2 content versus PO2 is sigmoidal. Thus, changes in PO2 will have lesser change on O2 content change.

Front 5

Understand how the body buffers against the pH shift caused by dissolved O2

Back 5

The buffering effect is made possible by Hb, which carries the CO2. The high PCO2 and low pH environment in the tissues causes O2 to be released, forming deoxyHb. Compared to oxyHb, deoxyHb is a weaker acid adn thus binds H+ with greater affinity. As H+ ions are bound, the H-H equation shifts to the right, enabling more CO2 to travel in the form of HCO3- in venous blood without a correspondingly large pH shift.