Structure of human gas exchange system

Structure:

Nasal cavity -

• Act as the main passageway for the airflow entering the lungs
• The nasal cavity also filters the incoming air, regulates temperature and humidifies the nasal passage to aid the filtering function.

Trachea -

• Flexible airway that is supported by rings of cartilage
• The cartilage prevents the trachea collapsing as the air pressure inside falls when breathing in
• The tracheal walls are made up of muscle lined with ciliated epithelium and goblet cells which produce mucus

Pleural cavity -

• Filled with fluid
• Acts as lubricant and allows lungs to move effectively

Bronchi -

• Plural of bronchus
• Two divisions of the trachea each leading to the lungs
• Similar structure to the trachea
• Also produce mucus to trap dirt particles
• Have cilia that move the dirt-laden mucus towards the throat
• The larger bronchi are supported by cartilage, although the amount of cartilage is reduced as the bronchi gets smaller

Ribcage -

• Bony box
• Supports and protects the lungs
• Can be moved by the muscles between them

Intercostal muscles -

• Internal: Contraction leads to expiration
• External: Contraction leads to inspiration

Diaphragm -

• The diaphragm is the primary muscle used in the process of inspiration, or inhalation.
• It is a dome-shaped sheet of muscle that is inserted into the lower ribs.
• Lying at the base of the thorax (chest), it separates the…