ï»¿ Describe the mechanism of exchange of gases. from Biology Breathing and Exchange of Gases Class 11 Assam Board

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Describe the mechanism of exchange of gases.

Exchange of gases : The gases are exchanged in alveoli of lungs and cells of the body. The exchange of gases in alveoli occurs between blood and alveolar air.

The alveolar air has pO2Â 104 mm and pO2Â of blood is 40 mm of Hg. Thus, oxygen from alveolar air diffuses into blood till pO2 of the bloodÂ becomes 95 mm.

The pCO2Â of alveolar air is 40 mm and of blood is 45 mm. Thus, CO2Â from blood diffuses into alveolar air.Â

Exchange of gases in cells : The blood which is in contact with cells have pO2Â 95 mm and pCO2Â 40 mm while cells of the tissues have pO2Â 40 mm and pCO2Â 45 mm. Thus, oxygen from blood diffuses into the cells and CO2Â from cells diffuses into blood till PCO2Â becomes 46 mm of Hg and PO2Â becomes 40 mm. Now the blood is carried by veins to heart, then to lungs by pulmonary arch. In lungs it is purified.

Diagrammatic representation of exchanges of gases at the alveolus and the body tissues with blood and transport of oxygen and carbon dioxide

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Name the cavity having lungs.

Thoracic cavity.
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70% of carbondioxide is transported as ?

Bicarbonate
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What is the partial pressure of oxygen in Â oxygenated blood ?

95 mm Hg
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By what amount the solubility of carbondioxide is more than the solubility of oxygen?

20 - 25 times
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Oxygen is carried by haemoglobin as?

Oxyhaemoglobin.
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