Question

Describe the major processes of CO2 uptake by the blood in a systemic blood capillary

Answer 1

Carbon dioxide is uptaken into the systemic capillary mainly by 3 mechanism

1)CO2 dissolved in blood plasma(7%)

2)Transported as Bicarbonate(70%)

3)Trasnported in the RBC(20%)

CO2 dissolved in blood plasma

carbondioxide is not higly soluble in the blood, but a small amount of carbon dioxide are diffused in to the blood from the tissue are carried from the tissue to the lungs . in the lungs the idssolved carbon dioxide diffuse out of blood in to the alveoli

Transported as Bicarbonate(70%)

Most of the fraction of the carbon dioxide (70%) is transported as the bicarbonate ion . Carbon dioxid enter the RBC, in the RBC it combine with the water molecule to form carbonic acid (H2CO3). by the help of the enzyme carbonic anhydrase.it further split in to hydrogen ion and bicarbonate ion .

The bicarbonate ion is exchanged in to the blood circulation wuth the chloride ion (same charge). this is called chloride shift . The exchanged bicarbonate is carried into the pulmonary capillaries through the blood circulation.

Transported in the RBC(20%)

About 20% of the carbon dioxide is carried by the RBC.

carbon dioxide bind with the hemoglobin to form Carbaminohemoglobin. this form of hemoglobin is carried into the pulmonary capillaries. in the lungs the partial pressure of C02 is low and the partial pressure of the O2 is high , so that the carbaminohemoglobin split into hemoglobin and co2 . this co2 is diffused out of the cappilaries to the lungs.