Definition
Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed)
Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It is the product of the incomplete combustion of carbon-containing compounds, notably in internal-combustion engines. It consists of one carbon atom covalently bonded to one oxygen atom. It is a gas at room temperature. Carbon monoxide is a significantly toxic gas and is the most common type of fatal poisoning in many countries.Exposures can lead to significant toxicity of the central nervous system and heart. Following poisoning, long-term sequelae often occur. Carbon monoxide can also have severe effects on the fetus of a pregnant woman. Despite its serious toxicity, CO is extremely useful and underpins much modern technology, being a precursor to a myriad of useful - even life-saving - products. Carbon monoxide, though thought of as a pollutant today, has always been present in the atmosphere, chiefly as a product of volcanic activity. It occurs dissolved in molten volcanic rock at high pressures in the earth's mantle. Carbon monoxide contents of volcanic gases vary from less than 0.01% to as much as 2% depending on the volcano. It also occurs naturally in bushfires. Because natural sources of carbon monoxide are so variable from year to year, it is extremely difficult to accurately measure natural emissions of the gas. (wikipedia) [HMDB]
Description
Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. It is the product of the incomplete combustion of carbon-containing compounds, notably in internal-combustion engines. It consists of one carbon atom covalently bonded to one oxygen atom. It is a gas at room temperature. Carbon monoxide is a significantly toxic gas and is the most common type of fatal poisoning in many countries. Exposures can lead to significant toxicity of the central nervous system and heart. Carbon monoxide has a higher diffusion coefficient compared to oxygen and the only enzyme in the human body that produces carbon monoxide is heme oxygenase which is located in all cells and breaks down heme. Because it has a higher diffusion coefficient than oxygen the body easily gets rid of any CO made. When CO is not ventilated it binds to hemoglobin, which is the principal oxygen-carrying compound in blood; this produces a compound known as carboxyhemoglobin. The traditional belief is that carbon monoxide toxicity arises from the formation of carboxyhemoglobin, which decreases the oxygen-carrying capacity of the blood and inhibits the transport, delivery, and utilization of oxygen by the body. The affinity between hemoglobin and carbon monoxide is approximately 230 times stronger than the affinity between hemoglobin and oxygen so hemoglobin binds to carbon monoxide in preference to oxygen. Following poisoning, long-term sequelae often occur. Carbon monoxide can also have severe effects on the fetus of a pregnant woman. Despite its serious toxicity, CO is extremely useful and underpins much modern technology, being a precursor to a myriad of useful - even life-saving - products. Carbon monoxide, though thought of as a pollutant today, has always been present in the atmosphere, chiefly as a product of volcanic activity. It occurs dissolved in molten volcanic rock at high pressures in the earth's mantle. Carbon monoxide contents of volcanic gases vary from less than 0.01% to as much as 2% depending on the volcano. It also occurs naturally in bushfires. Because natural sources of carbon monoxide are so variable from year to year, it is extremely difficult to accurately measure natural emissions of the gas. (wikipedia).
Top Gene Interactions
Related Pathways
General Information
- Uses/Sources: Carbon monoxide is a major atmospheric pollutant in urban areas, chiefly from exhaust of internal combustion engines, but also from improper burning of various other fuels. (L960)
- Health Effects: Chronic exposure to low levels of carbon monoxide may cause persistent headaches, lightheadedness, depression, confusion, memory loss, and nausea and vomiting. (L961)
- Symptoms: Early symptoms of acute carbon monoxide poisoning are nonspecific and include headaches, nausea, and fatigue. Symptoms may progress to tachycardia and hypertension. The central nervous system is one of the organ systems most sensitive to poisoning and symptoms displayed include dizziness, ataxia, confusion, convulsions, unconsciousness, respiratory arrest, and even death. (L961)
- Treatment: Carbon monoxide poisoning is first treated by immediate removal from the source of exposure. High-flow or 100% oxygen should then be administered by a nonrebreather reservoir oxygen mask. Oxygen hastens the dissociation of carbon monoxide from hemoglobin, improving tissue oxygenation by reducing carbon monoxides biological half-life. Hyperbaric oxygen may also be used, as it increases carboxyhemoglobin dissociation to a greater extent than normal oxygen. (L961)
- Route of Exposure: Inhalation (L960)
Mechanism of Action
| Target Name | Mechanism of Action | References |
|---|---|---|
| Myoglobin | Carbon monoxide binds to myoglobin, impairing its ability to utilize oxygen. (L961) |
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Hemoglobin subunit beta Hemoglobin subunit alpha Hemoglobin subunit gamma-1 Hemoglobin subunit gamma-2 Hemoglobin subunit delta Hemoglobin subunit epsilon Hemoglobin subunit theta-1 Hemoglobin subunit zeta Hemoglobin subunit mu |
Carbon monoxide combines with hemoglobin to form carboxyhemoglobin (HbCO) in the blood. As carbon moxoxide has a higher affinity for hemoglobin than oxygen, this prevents the transport, delivery, and utilization of oxygen, causing anoxemia. (L961) |
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Cytochrome c oxidase subunit 1 Cytochrome c oxidase subunit 2 Cytochrome c oxidase subunit 3 Cytochrome c oxidase subunit 4 isoform 1, mitochondrial Cytochrome c oxidase subunit 5A, mitochondrial Cytochrome c oxidase subunit 5B, mitochondrial Cytochrome c oxidase subunit 6A1, mitochondrial Cytochrome c oxidase subunit 6A2, mitochondrial Cytochrome c oxidase subunit 6B1 Cytochrome c oxidase subunit 6C Cytochrome c oxidase subunit 7A1, mitochondrial Cytochrome c oxidase subunit 7A2, mitochondrial Cytochrome c oxidase subunit 7B, mitochondrial Cytochrome c oxidase subunit 7C, mitochondrial Cytochrome c oxidase subunit 8A, mitochondrial Cytochrome c oxidase subunit 6B2 Cytochrome c oxidase subunit 4 isoform 2, mitochondrial Cytochrome c oxidase subunit 7B2, mitochondrial Cytochrome c oxidase subunit 8C, mitochondrial Putative cytochrome c oxidase subunit 7A3, mitochondrial |
Carbon monoxide can bind to cytochrome c oxidase, though with a lesser affinity than oxygen. This interferes with aerobic metabolism and efficient ATP synthesis. As a result, cells switch to anaerobic metabolism, causing anoxia, lactic acidosis, and eventual cell death. (L961) |
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