The Respiratory System Overview

Overview of Respiration

• Respiration has three main functions: taking in oxygen, excreting carbon dioxide, and regulating blood composition.

Inspiration and Expiration

• Inspiration is an active process that expands the lungs inside the thorax, caused by muscle contraction.
• Expiration is a passive process that reduces lung volume, caused by muscle relaxation.
• Lungs are elastic and depend on the thoracic walls for support.
• If air enters the space between the thoracic wall and lungs, one or both lungs will collapse.

The Respiratory Center

• The respiratory center stimulates respiration when carbon dioxide levels are too high.
• When carbon dioxide levels fall too low, the respiratory center slows down respiration.

The Trachea and Airways

• Air is inhaled through the nose and mouth, then passes through the pharynx and larynx to the trachea.
• The trachea is a muscular tube that divides into two primary bronchi at its lower end.

Gas Exchange

• The alveoli and capillaries are responsible for exchanging oxygen and carbon dioxide.

Coughing Mechanism

• Coughing is a forced expiratory effort that removes large amounts of mucus and foreign materials from the airways.
• Dust and other foreign materials are inhaled with every breath, and excess mucus is removed by coughing.