Name: Discovery of Gases and Respiration
Uploaded: 2019-07-19
Duration: 6 min 24 s
Description: We all know we breathe in oxygen and breathe out carbon dioxide. But how was this discovered? Watch this experiment to learn more about it in detail.

Question

Describe with the help of a diagram how the exchange of gases (oxygen and carbon dioxide) takes place between alveoli and blood capillaries.

Accepted Answer

The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via passive diffusion. It is of two types: External respiration and Internal respiration.
External respiration:
Also known as pulmonary gas exchange is the diffusion of O₂ from the air in the alveoli of the lungs to blood in pulmonary capillaries and the diffusion of CO₂ in the opposite.
In alveoli, pO₂ is 104 mm Hg and pCO₂is 40 mm Hg. In deoxygenated blood, pO₂ is 40mm Hg: which is less than the partial pressure of oxygen in alveoli. Due to this, it enters the blood in the alveoli.
In deoxygenated blood, pCO₂ is 45 mm Hg: which is more than the partial pressure of CO₂ in alveoli. Due to this, carbon dioxide exits from tissue cells and enters the alveoli.

Internal respiration:
The exchange of gases in the body tissues is called internal respiration it occurs between arterial blood and extracellular fluid. It takes place by diffusion and is also called tissue respiration.
Once blood reaches the tissues, the partial pressure of oxygen in oxygenated blood is 95 mm Hg which is more than the partial pressure of oxygen in deoxygenated blood (40mm Hg). Hence, oxygen from the blood enters the tissues.
At the tissue level, the partial pressure of carbon dioxide in deoxygenated blood is more than that in oxygenated blood. Hence, carbon dioxide exits from the tissues.

Below is the diagram showing the exchange of oxygen and carbon dioxide between alveoli and blood capillaries.

Describe with the help of a diagram how the exchange of gases (oxygen and carbon dioxide) takes place between alveoli and blood capillaries.

Important Questions on Breathing and Respiration

Learn and Prepare for any exam you want !