Breath carbon dioxide

Metges, C, Kempe K. and Schmidt, H.-L. 1990 Dependence of the carbon-isotope contents of breath carbon dioxide, milk, serum and rumen fermentation products on the 8 Cvalue of food in dairy cows. British Journal ofNutritim 63 187-196. 

We also breathe carbon dioxide every day of our lives. Carbon dioxide is manufactured in the body during the process in which the body cells derive energy from the sugar-like substances known as carbohydrates. It is carried to the lungs in the blood and exhaled every time we breathe. Normally, it is totally harmless. In fact, it is only when the concentration of the carbon dioxide in the breathing air is such as to reduce the proportion of available oxygen that a problem arises. This can happen if, for example, you are in a sealed space where the carbon dioxide from your own body builds up in the atmosphere, or if, for some unknown reason,... 

Comparative Toxicokinetics. The toxicokinetic studies available in both humans and animals (dogs, rats, and guinea pigs) suggest that there may not be any major differences in the kinetics of this compound across certain species. Metabolites of 2-hexanone in the expired breath (carbon dioxide) of humans and rats exposed via the oral route and the presence of 2,5-hexanedione in the serum of humans exposed via inhalation, as well as in the blood and urine of orally exposed rats and the... 

Carbon dioxide (C02, melting point -56.6°C at 76 psi - 527 kPa, density 1.9769 gL at 0°C) is a colorless, odorless gas. Solid carbon dioxide sublimes at -79°C (critical pressure 1073 psi, 7397 kPa, critical temperature 31°C). High concentrations of the gas do cause stupefaction and suffocation because of the displacement of ample oxygen for breathing. Carbon dioxide is soluble in water (approximately 1 volume carbon dioxide in 1 volume water at 15°C), soluble in alcohol, and is rapidly absorbed by most alkaline solutions. 

The quantity of breathing gas consumed in deep dives is of both economical and logistical concern at depths of 300 m, a reasonably active diver requites ca 1.8 m (64 fT at STP) of breathing gas per minute. In closed-cycle breathing systems, of both the self-contained and umbiHcal types, the helium is recitculated after carbon dioxide is removed and the oxygen replenished (147). 

Anhydrous lithium hydroxide [1310-65-2], LiOH, is obtained by heating the monohydrate above 100°C. The salt melts at 462°C. Anhydrous lithium hydroxide is an extremely efficient absorbent for carbon dioxide (qv). The porous stmcture of the salt allows complete conversion to the carbonate with no efficiency loss in the absorption process. Thus LiOH has an important role in the removal of carbon dioxide from enclosed breathing areas such as on submarines or space vehicles. About 750 g of lithium hydroxide is required to absorb the carbon dioxide produced by an individual in a day. 

Because of the delay in decomposition of the peroxide, oxygen evolution follows carbon dioxide sorption. A catalyst is required to obtain total decomposition of the peroxides 2 wt % nickel sulfate often is used. The temperature of the bed is the controlling variable 204°C is required to produce the best decomposition rates (18). The reaction mechanism for sodium peroxide is the same as for lithium peroxide, ie, both carbon dioxide and moisture are required to generate oxygen. Sodium peroxide has been used extensively in breathing apparatus. 

Potassium Superoxide. Potassium, mbidium, and cesium form superoxides, MO2, upon oxidation by oxygen or air. Sodium yields the peroxide, Na202 lithium yields the oxide, Li20, when oxidized under comparable conditions. Potassium superoxide [12030-88-5] KO2 liberates oxygen in contact with moisture and carbon dioxide (qv). This important property enables KO2 to serve as an oxygen source in self-contained breathing equipment. 

Table 8.6 Effect of carbon dioxide exposure on breathing rates...

The chief source of such energy is the combustion of carbon compounds to C02. You know that man exhales more carbon dioxide than he inhales in the air he breathes. This extra carbon dioxide is one of the products of the oxidation processes by which food is oxidized and energy is liberated. 

L.6 Potassium superoxide, KC)2, is utilized in a closed-system breathing apparatus to remove carbon dioxide and water from exhaled air. The removal of water generates oxygen for breathing by the reaction 4 K02(s) + 2 H20(1) — 3 02(g) +... 

FIGURE 4.16 When carbon dioxide is passed over potassium superoxide (the yellow solid), it reacts to form colorless potassium carbonate (the white solid coating the walls of the tube) and oxygen gas. The reaction is used to remove carbon dioxide from the air in a closed-system breathing environment. 

The chemical engineering solution was to design a new material for the storage bag that was capable of "breathing"—of allowing carbon dioxide to diffuse out and oxygen to diffuse in. This prevents the drop in pH. Platelets stored in this new bag survive 10 days or more. 

Inhalation of carbon dioxide causes the breathing rate to increase (Table 7.6) 10% CO2 in air can only be endured for a few minutes at 25% death can result after a few hours exposure. 

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