Describe how atmospheric and alveolar air differ in composition, and explain these differences.
Describe how atmospheric and alveolar air differ in composition, and explain these differences.
In human respiratory system, the oxygen is inhaled from atmosphere and carbon dioxide is released. The primary function of respiratory system is performing gaseous exchange that mainly takes place due to difference in partial pressure of gases in alveoli and atmosphere. The partial pressure can be defined as the pressure of individual gas in a mixture of gases.
|
Atmospheric air |
Alveolar air |
|
The partial pressure of nitrogen is 597mmHg. |
The partial pressure of nitrogen is 569mmHg. |
|
The partial pressure of oxygen is high and is about 159mmHg. |
The partial pressure of oxygen is low and is about 104 mmHg. |
|
The partial pressure of carbon dioxide is low and is equal to 0.3mmHg. |
The partial pressure of carbon dioxide is high and is equal to 40mmHg. |
|
The water vapours content is low. |
The water vapours content is high. |
The difference in the concentration and partial pressure of these gases allows the exchange of gases between alveoli and the atmosphere during each breath. The oxygen is easily diffuse and absorbed in the pulmonary blood from the alveolar air due to the difference in partial pressure of oxygen in alveolar air and blood. The carbon dioxide is easily diffused from blood and alveoli due to its high partial pressure in blood than in alveoli. The water vapors humidify the dry atmospheric air that is entering the respiratory passage.
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