2. INTRODUCTION
Respiration, as the term is generally used, includes two processes:
• External respiration
• Internal respiration
External respiration
• The absorption of Oxygen and removal of Carbon dioxide from the body as a
whole
Internal respiration,
• The utilization of Oxygen and production of CO2 by cells and the gaseous
exchanges between the cells and their fluid medium
Dr S B Phiri
3. Functions of the Respiratory System
Primary function of the lungs is gas exchange
Host defence
It is metabolic organ that synthesizes and metabolizes different
compounds
Functions as a barrier between the world outside and inside the body
Dr S B Phiri
4. Non Respiratory Functions of the System
Route for water loss and heat elimination
Enhances venous return (Cardiovascular Physiology)
Helps maintain normal acid-base balance (Respiratory and Renal Physiology)
Enables speech, singing, and other vocalizations
Defends against inhaled foreign matter
Removes, modifies, activates, or inactivates various materials passing
through the pulmonary circulation
Nose serves as the organ of smell
Dr S B Phiri
5. FUNCTIONAL ANATOMY OF RESPIRATOY SYSTEM
Nose/mouth: filters, warms, humidify inhaled air
Mucus traps bacteria & foreign debris
Cilia sweep mucus toward throat (Mucociliary
escalator) digested by stomach
Pharynx: throat (passage for food/air)
Tonsils: clusters of lymphatic tissue
Larynx: contains vocal cords
Epiglottis: covers larynx when liquids/food swallowed
Trachea: windpipe; lined with cartilage (C-
shaped)
Bronchi: branches into the lungs
Bronchioles: smaller branches
Lungs Alveoli: air sacs for gas exchange
Dr S B Phiri
