Carbon Monoxide Poisoning

Carbon Monoxide is a colorless and odorless gas that is less dense than in air. It is produced due to an incomplete combustion of carbon dioxide due to the lack of oxygen supply. Its common sources are: Faulty or old heating and cooking appliances, running/combusted engines, heme oxygenase 1 and 2, volcanoes, forest fires and rooms that are not properly ventilated. An exposure to carbon monoxide concentration of 800 ppm is risky and dangerous because this is where the body reacts by having convulsions and insensibility. The common symptoms to watch out for are: - Headache

- Dizziness - Disorientation

-Impairment of cerebral function

- Visual disturbances - Nausea - Seizures -Muscle Weakness / Cramps This could lead to coma, heart disease, and respiratory disease. If exposed to 12,800 ppm CO then the person affected can die within 3 minutes that is why immediate medical attention is needed. So, why and how do our internal system react to carbon monoxide? Heme is present in hemoglobin, myoglobin, and cytochrome oxidase. It is a tetrapyrrole ring system that is complexed with Iron (II) at the center. Iron (II) is octahedrally coordinated wherein nitrogen atoms take four out of the six ligands, leaving the rest to bind with the two electrons of oxygen but with the presence of carbon monoxide, it inhibits the binding of the oxygen to the Iron atom having an advantage of around 200 binding affinity compared to oxygen (O2).

Appling (2016), Biochemistry: concepts and connections, 233.

The binding of carbon monoxide with the heme prevents its transfer throughout the body causing hypoxia, affecting many body systems. It also causes the change in appearance of blood to a cherry-red color. Not only is the heme has higher binding affinity with carbon monoxide, cytochrome oxidase which is present in complex IV of Electron Transport Chain (ETC) also prefers carbon monoxide over oxygen which causes a leak in the ETC and prevents the reduction of O2 to water (H2O), and it also depletes the production of ATP.

Appling (2016), Biochemistry: concepts and connections

When ATP production in body depletes, it shuts down a lot of interconnecting pathways since it is the molecular currency which helps to transfer energy that is required to perform a task.

Treatment The binding of carbon monoxide to Iron (II) is fortunately reversible that is why it can easily be displaced by oxygen. This can be done through: Utilization of 100% Oxygen,use of hyperbaric chambers where the pressure of oxygen is greater than 1 atm,also along with this treatment an anti-oxidant should be administered to prevent the risk of oxidative stress that happens during reperfusion. References:

Akyol, S., Yuksel S., Pehlivan, S., Erdemli, H.K., Gulec, M.A. (2016). Possible role of antioxidants and nitric oxide inhibitors against carbon. Medical Hypotheses (92), 3-6.

Appling, D.R., Anthony-Cahill, S.J., Mathews, C.K. (2016). Biochemistry: concepts and connections (Global ed.). England: Pearson Education.

Goldstein, M. (2008). Carbon monoxide poisoning. Journal of Emergency Nursing , 6 (34), 538-542.

Liu, H., Zhang, Y., Ren, Y-B., Kang, J., Xing, J., Qui, Q-H., Gao, D-N., Ma, T., Liu, X-W., Liu, Z. (2015). Serum S100B level may be correlated with carbon monoxide poisoning. International Immunopharmacology (27), 69-75.

Struttmann, T., Scheerer, A., Prince, T.S., Goldstein, L.A. (1998). Unintentional carbon monoxide poisoning from an unlikely source. The Journal of the American Board of Family Practice. , 6 (11), 481-484.

Toy, E.C., Seifert, W.E., J.R., Strobel, H.W., Harms, K.D. (2008). Case Files Biochemistry. New York: Mc Graw Hill.

The images used in this infographics are not mine

So, If ever you start feeling dizzy when you're in an enclosed space such as cars and rooms, always open your windows and get fresh air immediately to prevent from worsening the situation.