The structure of lungs and ventilation

Main parts of the human gas exhange system:

• Lungs
• Trachea
• Bronchi
• Bronchioles
• alveoli

Ventilation:

When the air pressure of the atmosphere is greater than the air pressure inside the lungs, air is forced into the alveoli, this is called inspiration. (Inhalation)

When the air pressure in the lungs is greater than the air pressure in the atmosphere, air is forced out of the lungs, this is called expiration (exhalation)

The pressure changes within the lungs are brought about by the movement of two sets of muscles: 

The diaphragm

The intercostal muscles- There are 2 sets of intercostal muscles:

The internal intercostal muscles, whose contraction leads to expiration 

The external intercostal muscles, whose contraction leads to inspiration

Inspiration:

• The…