Describe the main way carbon dioxide is transported in the blood.

Question

what happens to bicarbonate ions in the lungs?

Answer 1

BICARBONATE IONS (HCO3- )

The majority of carbon dioxide is transported in this way.      Carbon dioxide enters red blood cells in the tissue capillaries where it combines with water to form carbonic acid (H2CO3). This reaction is catalysed by the enzyme carbonic anhydrase (C.A.), which is found in the red blood cells. Carbonic acid then dissociates to form bicarbonate ions (HCO3- ) and hydrogen ions (H+).

             C.A.            

    CO2 + H20 H2CO3 HCO3- + H+

This reaction also occurs outside the red blood cells, in the plasma, but is much slower due to the lack of carbonic anhydrase.The hydrogen ions, formed from the dissociated carbonic acid, combine with the haemoglobin in the red blood cell.

Bicarbonate ions react with hydrogen ions to form carbon dioxide and water and are exhaled

-Other forms of carbon dioxide (carbaminohemoglobin and carbon dioxide dissolved in the plasma) are converted to carbon dioxide gas and exhaled

-Oxygen bonds with hemoglobin forming oxyhemoglobin

-Reduced hemoglobin releases the hydrogen ions it is carrying forming hemoglobin

The following chemical reactions occurs

a. Oxygen

Hemoglobin bonds with oxygen according to the following reaction:



           Hb                +        O2    ----->      HbO2            

Hemoglobin       +     oxygen            oxyhemoglobin