carboxyhemoglobin: Definition from Answers.com

Carboxyhemoglobin (British English: Carboxyhaemoglobin) (COHb) is a stable complex of carbon monoxide and hemoglobin that forms in red blood cells when carbon monoxide is inhaled, and hinders delivery of oxygen to the body. Tobacco smoking (through carbon monoxide inhalation) raises the blood levels of COHb.

In large quantities, the effect of COHb is death - known medically as carboxyhemoglobinemia^[1] or carbon monoxide poisoning.^[2] However in smaller quantities COHb leads to oxygen deprivation of the body causing tiredness, dizziness and unconsciousness.

Hemoglobin binds to carbon monoxide preferentially compared to oxygen (approx 240:1)^[3], so effectively, COHb will not release the carbon monoxide, and therefore hemoglobin will not be available to transport oxygen from the lungs to the rest of the body. Humans should survive with very small amounts of COHb in their blood with very little or no observable effects.

COHb has a half-life in the blood of 4 to 6 hours, but this can be reduced to 40 minutes with administration of 100% oxygen. COHb increases risk of blood clot. It is thought that through this mechanism smoking increases the risk of having an ischemic stroke.

Pregnant smokers may give birth to babies of a lower birth mass as fetal hemoglobin takes up carbon monoxide more readily than in an adult, therefore the fetus of a smoker will suffer from mild hypoxia potentially retarding its development.

References

^ López-Herce J, Borrego R, Bustinza A, Carrillo A (September 2005). "Elevated carboxyhemoglobin associated with sodium nitroprusside treatment". Intensive Care Med 31 (9): 1235–8. doi:10.1007/s00134-005-2718-x. PMID 16041521. http://dx.doi.org/10.1007/s00134-005-2718-x.
^ Roth D, Hubmann N, Havel C, Herkner H, Schreiber W, Laggner A (July 2009). "Victim of Carbon Monoxide Poisoning Identified by Carbon Monoxide Oximetry". J Emerg Med. doi:10.1016/j.jemermed.2009.05.017. PMID 19615844. http://linkinghub.elsevier.com/retrieve/pii/S0736-4679(09)00407-7.
^ West JB: Respiratory Physiology -the essentials, 5th Ed. Williams & Williams, 1995, p. 76

External links

MeSH Carboxyhemoglobin

This article about an organic compound is a stub. You can help Wikipedia by expanding it.

Proteins: hemeproteins

Globins

Hemoglobin

Subunits	Alpha locus on 16: α (HBA1, HBA2) · ζ (HBZ) · θ (HBQ1) · μ (HBM) Beta locus on 11: β (HBB) · δ (HBD) · γ (HBG1, HBG2) · ε (HBE1)

Tetramers	stages of development: HbA (α₂β₂) · HbA2 (α₂δ₂) · HbF/Fetal (α₂γ₂) · HbE Gower 2 (α₂ε₂) · HbE Gower 1 (ζ₂ε₂) pathology: HbH (β₄) · HbS (α₂β^S₂) · HbC (α₂β^C₂) · HbE (α₂β^E₂)

Compounds	Carboxyhemoglobin · Carbaminohemoglobin · Oxyhemoglobin/Deoxyhemoglobin · Sulfhemoglobin

Other human	Glycosylated hemoglobin · Methemoglobin

Nonhuman	Chlorocruorin · Erythrocruorin

Other

human: Myoglobin (Metmyoglobin) · Neuroglobin · Cytoglobin
plant: Leghemoglobin

Other

Cytochrome (Cytochrome b, Cytochrome P450) · Hemocyanin · Methemalbumin

References

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Donate to Wikimedia

		Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more
		Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Read more
		Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more
		Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Carboxyhemoglobin". Read more

	carboxy– (prefix)
	carbonmonoxyhemoglobin (biochemistry)
	Carbon Monoxide Poisoning: Diagnosis