Combining with hemoglobin

Ethylene is slightly more potent as an anesthetic than nitrous oxide, and the smell of ethylene causes choking. Diffusion through the alveolar membrane is sufficiendy rapid for equilibrium to be estabUshed between the alveolar and the pulmonary capillary blood with a single exposure. Ethylene is held both ia cells and ia plasma ia simple physical solution. The Hpoid stroma of the red blood cells absorb ethylene, but it does not combine with hemoglobin. The concentration ia the blood is 1.4 mg/mL when ethylene is used by itself for anesthesia. However, ia the 1990s it is not used as an anesthetic agent. 

The P02 of blood is the major factor determining the amount of oxygen chemically combined with hemoglobin, or the percent of hemoglobin saturation. The relationship between these two variables is illustrated graphically by the oxyhemoglobin dissociation curve (see Figure 17.6). This relationship is not... 

Asphalt Hydrocarbon material ranging in consistency from heavy liquid to a solid. Most common source is residue left after fractional distillation of crude oils used primarily for surfacing roads. Asphyxia Suffocation from lack of oxygen. Chemical asphyxia is produced by a substance, such as carbon monoxide, that combines with hemoglobin to reduce die blood s capacity to transport oxygen. Simple asphyxia is the result of exposure to a substance, such as carbon dioxide, that displaces oxygen. 

Carbon monoxide (CO), a colorless, odorless gas, is responsible for more than half of yearly deaths due to poisoning worldwide. CO has an approximately 250-fold greater affinity for hemoglobin than does oxygen. Consequently, relatively low levels of CO can have substantial and tragic effects. When CO combines with hemoglobin, the complex is referred to as carboxyhe-moglobin, or COHb. 

About 20% of the CO in the blood is carried in combination with hemoglobin as carbaminohemoglobrn, The balance of the combined carbon dioxide is carried as bicarbonate. A CO dissociation curve for blood can be prepared just as for oxygen, but the shape is not the same as for the latter. As the partial pressure of CO in the air increases, the amount in the blood increases the increase is practically linear in the higher ranges. Oxygen exerts a negative effect on the amount of CO which can be taken up by the blood. 

Carbon monoxide Motor vehicle emissions Burning fossil fuels Incomplete combustion Combines with hemoglobin to form carboxyhemoglobin, poisonous Asphyxia and death... 

Although much of the C02 in blood is transported as HCO, some combines with hemoglobin and acts as an allosteric effector (Chap. 9). C02 reacts with the unionized form of a-amino groups... 

For this reason, cyanide action has been described as internal asphyxia . Although some cyanide combines with hemoglobin to form a stable nonoxygenbearing compound, cyanhemoglobin, this substance is formed only slowly and in a small amount. Therefore, death is not due to cyanhemoglobin but to inhibition of tissue cell respiration. 

Cyanide reversibly binds the ferric iron associated with the cytochrome oxidase system, thereby inhibiting the mitochondrial respiratory chain. This results in an inability to adequately utilize oxygen and causes internal asphyxia . Cyanide combines with hemoglobin to form cyanhemoglobin, which does not transport oxygen. Cyanide also inhibits antioxidant enzymes such as catalase, superoxide di-smutase, and glutathione peroxidase. 

The occurrence of CO2 chemically combined with hemoglobin, as carbamino compounds. 

Haptoglobin—A group of 2-globulins in human serum, so called because of their ability to combine with hemoglobin, preventing loss in the urine levels are decreased in hemol5dic disorders and increased in inflammatory conditions or with tissue damage. 

Normally, hemoglobin molecules in the blood carry oxygen throughout the body, but when carbon monoxide is present, it combines with hemoglobin and prevents oxygen from doing so. As little as 0.001% CO in air can lead to headache, diTziness, and nausea. Concentrations of 0.1% can cause death. 

Carbon monoxide, CO, poisons the body by combining with hemoglobin some 250 times more tightly than Oj, thus hindering the transport of Oj to the body s tissues. In an environment of 0.1 percent 00 (within the lung), more than half the binding sites of hemoglobin become occupied with 00, and the victim dies within an hour. 

The normal transfer mechanism of oxygen in blood is different than in simple solutions (15,16). The quantity of oxygen carried in plasma at atmospheric pressure is very small, about 0.2 ml at STP/100 ml of plasma, expressed as a gas volume at standard conditions per solution volume. Whole blood, in contrast, can carry about 20 ml at STP/100 ml of blood. The larger load of oxygen is carried in chemical combinations with hemoglobin as expressed below ... 

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