Carbon dioxide molecules room transported in the blood from human body tissues to the lungs by one of three methods: dissolution directly into the blood, binding to hemoglobin, or carried as a bicarbonate ion. Numerous properties the carbon dioxide in the blood affect its transport. First, carbon dioxide is more soluble in blood than oxygen. Around 5 to 7 percent of every carbon dioxide is dissolved in the plasma. Second, carbon dioxide deserve to bind come plasma protein or can enter red blood cells and bind to hemoglobin. This kind transports about 10 percent that the carbon dioxide. When carbon dioxide binds to hemoglobin, a molecule referred to as carbaminohemoglobin is formed. Binding that carbon dioxide come hemoglobin is reversible. Therefore, when it get the lungs, the carbon dioxide can freely dissociate native the hemoglobin and be expelled indigenous the body.

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Third, the majority of carbon dioxide molecule (85 percent) are brought as component of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. Carbonic anhydrase (CA) within the red blood cells quickly converts the carbon dioxide into carbonic acid \left(\textH_2\textCO_3\right). Carbonic mountain is an unstable intermediate molecule that immediately dissociates right into bicarbonate ions \left(\textHCO^-_3\right) and hydrogen (H+) ions. Due to the fact that carbon dioxide is conveniently converted right into bicarbonate ions, this reaction enables for the continued uptake that carbon dioxide into the blood under its concentration gradient. It likewise results in the manufacturing of H+ions. If too much H+ is produced, it can transform blood pH. However, hemoglobin binding to the free H+ ions and also thus limits shifts in pH. The recently synthesized bicarbonate ion is transported the end of the red blood cell into the fluid component of the blood in exchange because that a chloride ion (Cl−); this is called the chloride shift. Once the blood get the lungs, the bicarbonate ion is transported ago into the red blood cell in exchange because that the chloride ion. The H+ ion dissociates from the hemoglobin and also binds come the bicarbonate ion. This to produce the carbonic mountain intermediate, which is converted ago into carbon dioxide through the enzymatic action of CA. The carbon dioxide created is expelled through the lungs during exhalation.

\textCO_2+\textH_2\textO\longleftrightarrow\underset\left(\textcarbonic acid\right)\textH_2\textCO_3\longleftrightarrow\underset\left(\textbicarbonate\right)\textHCO_3+\textH^+

The advantage of the bicarbonate buffer mechanism is that carbon dioxide is “soaked up” into the blood with little change to the pH of the system. This is important since it takes just a small change in the in its entirety pH the the human body for major injury or fatality to result. The presence of this bicarbonate buffer device also permits for civilization to travel and also live at high altitudes: when the partial push of oxygen and also carbon dioxide adjust at high altitudes, the bicarbonate buffer mechanism adjusts to control carbon dioxide while keeping the exactly pH in the body.

Carbon Monoxide Poisoning

While carbon dioxide have the right to readily associate and dissociate native hemoglobin, other molecules such together carbon monoxide (CO) cannot. Carbon monoxide has actually a higher affinity for hemoglobin 보다 oxygen. Therefore, as soon as carbon monoxide is present, it binding to hemoglobin preferentially end oxygen. As a result, oxygen cannot tie to hemoglobin, so very little oxygen is transported v the body (Figure 1).


Figure 1. As percent CO increases, the oxygen saturation of hemoglobin decreases.


Carbon monoxide is a colorless, odorless gas and also is therefore difficult to detect. It is produced by gas-powered vehicles and tools. Carbon monoxide can cause headaches, confusion, and nausea; long-term exposure deserve to cause mind damage or death. Administering 100 percent (pure) oxygen is the usual therapy for carbon monoxide poisoning. Management of pure oxygen accelerates the separation of carbon monoxide from hemoglobin.


In Summary: carry of Carbon Dioxide in the Blood

Carbon dioxide can be transported through the blood via 3 methods. It is dissolved directly in the blood, bound come plasma protein or hemoglobin, or converted into bicarbonate.

The majority of carbon dioxide is transported as part of the bicarbonate system. Carbon dioxide diffuses right into red blood cells. Inside, carbonic anhydrase converts carbon dioxide right into carbonic mountain \left(\textH_2\textCO_3\right), i m sorry is consequently hydrolyzed right into bicarbonate \left(\textHCO^-_3\right) and also H+. The H+ ion binding to hemoglobin in red blood cells, and bicarbonate is transported out of the red blood cells in exchange because that a chloride ion. This is referred to as the chloride shift.

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Bicarbonate leaves the red blood cells and enters the blood plasma. In the lungs, bicarbonate is transported ago into the red blood cell in exchange because that chloride. The H+ dissociates indigenous hemoglobin and combines through bicarbonate to kind carbonic acid with the help of carbonic anhydrase, which additional catalyzes the reaction to transform carbonic acid earlier into carbon dioxide and water. The carbon dioxide is climate expelled from the lungs.