• The respiratory tract extends from the nose to the alveoli and includes not only the air-conducting passages also but the blood supply

  • The primary purpose of the respiratory system is gas exchange.

  • The respiratory system is divided into two parts: the upper respiratory tract and the lower respiratory tract.

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The Upper Respiratory Tract

  • The nose
  • Pharynx
  • Adenoids
  • Tonsils
  • Epiglottis
  • Larynx
  • Trachea.

The lower respiratory tract

  • Bronchi
  • Bronchioles
  • Alveolar ducts
  • Alveoli
  • With the exception of the right and left main-stem bronchi, all lower airway structures are contained within the lungs.

Physiology of Respiration

Ventilation: ventilation involves inspiration (movement of air into the lungs) and expiration (movement of air out of the lungs).

Contraction of the diaphragm and intercostal muscle - Increases chest dimensions, thereby decreasing intrathoracic pressure - Gas flows from an area of higher pressure (atmospheric) to one of lower pressure (intrathoracic)