Name: Mycoplasma pneumoniae
Uploaded: 2019-07-19
Duration: 4 min 47 s
Description: Shockingly a single disease can have more than 30 different causes! Many germs, such as bacteria, viruses and fungi can cause pneumonia. Explore one such pat...

Question

How do gases (O₂ and CO₂) are transported in the blood.

Accepted Answer

The exchange of gases in the lungs is called external respiration. 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.

The exchange of gases in the tissues and blood capillaries is called internal respiration. In the tissues, the partial pressure of the CO2 (45 mm Hg) is more and that of O2 (40 mm Hg) is less than in the capillaries surrounding them. The oxy-haemoglobin 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:

How do gases (O₂ and CO₂) are transported in the blood.

Important Questions on Breathing and Exchange of Gases

Learn and Prepare for any exam you want !

How do gases (O2 and CO2) are transported in the blood.

Important Questions on Breathing and Exchange of Gases

Learn and Prepare for any exam you want !

How do gases (O₂ and CO₂) are transported in the blood.