Question

1) Give an illustrated account of the structure and function of the lung.

2) Describe how oxygen is taken up in the lung and delivered to the tissues.

3) Give an illustrated account of the structure and function of the gas exchange region of the lung.

Answer 1

QUESTION 1

Structure and Function of lung:

Structure:

• Lungs are the center of respiratory system and there are a pair of lungs located on either side of the chest or thorax, which are spongy, air-filled organs.
• The inhaled air is conducted into the lungs by the trachea or windpipe, through the tubular branches of lungs called 'bronchi'.
• The bronchi further divides into smaller microscopic branches called 'bronchioles'.
• The lung has five lobes. The right lung three lobes which are: superior, inferior and middle lobes whereas the left lung has two lobes which are: superior and inferior lobes.
• Due to the presence of heart, the left lung is slightly smaller than the right lung.

Function:

• The main function of lungs is the exchange of oxygen and carbon dioxide between the inhaled air and the blood.
• Lungs are responsible for the gaseous exchange called 'respiration'. During respiration, oxygen from incoming air enters the blood and carbon dioxide leaves the blood.
• Lungs are responsible for inhalation and exhalation of air called 'breathing'.

QUESTION 2

• The oxygen molecules are taken up by the lungs and are transported to the tissues of body by a specialized transport system which depends on the red blood cells or erythrocytes.
• Erythrocytes or red blood cells contains a metalloprotein called hemoglobin which helps in binding the oxygen molecules to the erythrocyte.
• 'Heme' in the hemoglobin contains iron which helps in binding the oxygen and due to the presence of iron-containing heme molecules in hemoglobin, each hemoglobin molecule can carry four oxygen molecules
• Due to the diffusion of oxygen across the respiratory membrane from the alveolus to capillary, diffusion of red blood cells also takes place and the oxygen taken up by the lungs is delivered to tissues by this way.

QUESTION 3

Structure and Function of gas exchange region of lung:

Structure:

• Exchange of gas or gas exchange takes place only in the lungs which are the largest organs of respiratory tract and the gaseous exchange takes place in the tiny air sacs of lungs called 'alveoli'.
• Gaseous exchange takes place between the air in alveoli and blood in the capillaries.
• Alveoli are the tiny balloon-shaped structures, which allows easy passage of oxygen and carbon dioxide between the air in it and the capillaries of blood (blood vessels).

Function:

• Alveoli are the important part of the respiratory system which functions to exchange oxygen and carbon dioxide to and from the bloodstream. These are arranged throughout the lungs in clusters.
• Alveoli gives a larger surface area to the lungs and they have moist and thin walls containing a lot of tiny blood vessels called 'capillaries', which helps oxygen to pass from the alveoli to the bloodstream.
• The capillaries of alveoli are connected to larger blood vessels called 'veins', which brings the oxygenated blood from the lungs to the heart.

Thank you!