Transport of Carbon Dioxide in the Blood
When the process of cell respiration is completed, tissues produce carbon dioxide as an end product. After that, carbon dioxide from the cells disperses into blood and interchange with the oxygen present in blood under normal resting conditions. About 3.7 ml of carbon dioxide reaches 100 ml of blood. It is carried by both plasma and hemoglobin of blood.
Blood transport carbon dioxide in three ways:
Transport of Carbon Dioxide in the Blood as Carbonic Acid
Around 7% of carbon dioxide (CO2) travels in the blood dissolved directly in blood plasma. This dissolved CO2 contributes about 0.3 milliliters (ml) per deciliter (dL) of blood. The amount of dissolved CO2 also affects the blood’s CO2 tension, which reflects the pressure exerted by CO2.
CO2 + H2O——————–> H2CO3
This reaction mostly takes place in red blood cells (RBCs) because it is catalyzed by a zinc-activated enzyme, carbonic anhydrase, and that is stimulated by low PO2 at the cellular level.
Also Read: Full Form of RBC
Transport of Carbon Dioxide in the Blood as Bicarbonates of Sodium and Potassium
Around 70% of carbon dioxide is carried in the blood as bicarbonate ions (HCO3-). Inside red blood cells (RBCs), carbonic acid (H2CO3) forms from CO2 and water. This carbonic acid quickly breaks down into bicarbonate ions and hydrogen (H+) ions. Most bicarbonate ions then leave the RBCs and enter the blood plasma, while chloride ions (Cl–) move from the plasma into the RBCs in exchange. This maintains electrical neutrality within the cells.
This swapping of bicarbonate and chloride ions is called the chloride shift or Hamburger shift. A protein in RBCs called the bicarbonate-chloride carrier facilitates this exchange, allowing the ions to move in opposite directions.
H2CO3 ———————> H+ + HCO3–
K. Hb ————————> K+ + Hb–
(In RBC) K+ + HCO3- ————-> KHCO3
(In plasma) Na+ + HCO3 ————> NaHCO3
Transport of Carbon Dioxide in the Blood as Carbaminohaemoglobin
About 23% of CO2 is transferred as carbaminohaemoglobin which is made by a reversible combo of CO2 with amino groups (globin part) of hemoglobin. Its emergence is leaned by high PCO2 and low PO2 at the level of body tissues.
Hb– + H+ ————> H -Hb (Haemoglobin acidic)
H. Hb + CO2 ————–> CO2 . H Jb (Carbaminohaemoglobin)
Reversible compounds are bicarbonates, carbonic acid, and Carbaminohaemoglobin and which are formed in the presence of low PO2 ad low acidic hemoglobin at a cellular level. Such compounds detached at the lung level, where high PO2 prefers dissociation of carbonic acid and acidic oxyhemoglobin by carbonic anhydrase enzyme. Now, carbon dioxide becomes free to be interchanged with oxygen during external respiration.
Transport of Carbon Dioxide in the Blood
Transport of carbon dioxide in the blood occurs by three main methods: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions. Respiration is a biological process that involves the activity of interchanging oxygen and carbon dioxide through a liquid medium to use the oxygen for the oxidation of glucose inside the mitochondria.
In this article, we will cover how carbon dioxide is transported in the blood.
Table of Content
- Mechanism of Transport of Gases
- Transport of Carbon Dioxide in the Blood
- Transport of Carbon Dioxide in the Blood as Carbonic Acid
- Transport of Carbon Dioxide in the Blood as Bicarbonates of Sodium and Potassium
- Transport of Carbon Dioxide in the Blood as Carbaminohaemoglobin
- Conclusion – Transport of Carbon Dioxide in the Blood
- FAQs on Transport of Carbon Dioxide in the Blood