Name: The Mechanics of Breathing
Uploaded: 2019-07-19
Duration: 1 min 56 s
Description: Out of the thousand things to worry about, have you ever wondered we never have to worry about our very much life-sustaining process - Breathing! Watch and l...

Question

Describe in detail the pathway of an oxygen molecule as it moves from the air outside your body into your blood and to a cell in a muscle in your arm. You could write your answer in words or use a flow diagram or perhaps a mixture of both.

Accepted Answer

The exchange of gases takes place inside the alveoli of lungs where the oxygen of the atmospheric air is exchanged with the carbon dioxide present in the deoxygenated blood of the lung capillaries. The gaseous exchange depends on the partial pressure of the gases.

In the alveoli of lungs, the partial pressure of oxygen is about 104 mm Hg while in the deoxygenated blood of lung capillaries it is about 40 mm Hg. Also, the partial pressure of carbon dioxide in the lung capillaries is about 45 mm Hg, while in the lung alveoli it is about 40 mm Hg. There exists a partial pressure gradient across these respiratory surfaces. Thus, the gases diffuse along their concentration gradient. i.e the oxygen enters the lung capillaries and the carbon dioxide diffuses into the alveoli.

In the tissues (muscle cell), the partial pressure of the CO2 (45 mm Hg) and that of O2 is 40 mm Hg. The PO₂ is less and PCO₂is more in the capillaries surrounding them. The oxy-haemoglobin in the tissue capillaries thus loses the O2 and combines with CO2 that diffuses out of the tissues to form carboxy-haemoglobin. It is then transported to the lung alveoli where it again releases the CO2 and forms oxy-haemoglobin. This process of gaseous exchange continues in the lungs and the body tissues. Given below is a diagram showing the exchange of gases across the respiratory surfaces:

Describe in detail the pathway of an oxygen molecule as it moves from the air outside your body into your blood and to a cell in a muscle in your arm. You could write your answer in words or use a flow diagram or perhaps a mixture of both.

Important Questions on Respiration and Gas Exchange

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