18. CO2 transport Flashcards Preview

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Flashcards in 18. CO2 transport Deck (16):

CO2 transport from tissue to lungs in how many and which form ( and proportions)

3 forms
1. HCO3 - (90%)
2. Carbaminohemoglobin ( HbCO2) (5%)
3. Dissolved CO2 (5%)


Carbaminohemoglobin ( HbCO2) - structure

CO2 bound ti Hb at N - terminus (NOT HEME)


CO2 bindinf on hemoglobin favors .... form of hemoglobin

taut (O2 unloaded)


CO2 transportation - what is happening in the lungs

oxygenation of Hb promotes Dissociation of H+ . This shift equilibrium ( CO 2+, H2O - H2O2 - H+ + HCO3- ) toward CO2 formation. Therefore, CO2 is released from RBCs ( Haldane effect


CO2 transportation - what is happening in the peripheral tissues

increased H+ tissue metabolism shifts curve to right , unloading O2 ( Bohr effect)


RBC - membrane antiporter

CL -/ HCO3-


Bohr effect vs Haldone effect according to location

Bohr effect --> peripheral tissue
Haldane effect --> lungs


Haldane effect

oxygenation of the blood causes CO2 releasing from RBCs


• In which forms is carbon dioxide transported from the tissues to the lungs? What is the percentage of each form?

90% as bicarbonate (HCO3-), 5% bound to hemoglobin as carbaminohemoglobin (HbCO2), 5% dissolved CO2


• What enzyme catalyzes the conversion of carbon dioxide and water into carbonic acid?

Carbonic anhydrase


• Within a red blood cell, the carbonic acid formed from the combination of carbon dioxide and water dissociates into what two compounds?

Hydrogen and bicarbonate ions


What is the fate of the bicarbonate that results from the deprotonation of carbonic acid within a red blood cell?

It gets exchanged out of the red blood cell for a chloride molecule that enters the red blood cell


• In the lungs, the oxygenation of hemoglobin promotes what?

The dissociation of a proton from hemoglobin and therefore a decrease in pH, which favors formation of carbon dioxide from bicarbonate


• Name the effect in which oxygenation of hemoglobin in the lungs promotes H+ dissociation, causing CO2 release from RBCs.

The Haldane effect


• A woman has lactic acidosis. How will this pH reduction in the peripheral tissues relative to the lungs shift the oxygen dissociation curve?

It will shift it to the right, favoring dissociation of oxygen from hemoglobin


• In peripheral tissue, the right shift of the oxygen dissociation curve causes oxygen unloading. What is this effect called?

The Bohr effect