How do gases (O 2 and CO 2 ) are transported in the blood.

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:

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All in one ISC BIOLOGY Class 11>Chapter 20 - Breathing and Exchange of Gases>Chapter Practice

Kavita Thareja and Dushyant Prajapati Solutions for Chapter: Breathing and Exchange of Gases, Exercise 1: Chapter Practice

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Kavita Thareja Biology Solutions for Exercise - Kavita Thareja and Dushyant Prajapati Solutions for Chapter: Breathing and Exchange of Gases, Exercise 1: Chapter Practice

Attempt the practice questions on Chapter 20: Breathing and Exchange of Gases, Exercise 1: Chapter Practice with hints and solutions to strengthen your understanding. All in one ISC BIOLOGY Class 11 solutions are prepared by Experienced Embibe Experts.