Pulmonary System Function and Composition

Pulmonary System Function

• Provides gas exchange: intake of oxygen (O2) for delivery to body cells and removal of carbon dioxide (CO2) produced by cells.
• Regulates blood pH.
• Contains receptors for smell, filters inhaled air, produces vocal sounds (phonation), and excretes small amounts of water and heat.

Respiratory System Composition

• Structural Components:
  • Upper respiratory system: nose, nasal cavity, pharynx, associated structures
  • Lower respiratory system: larynx, trachea, bronchi, lungs
• Functional Components:
  • Conducting Zone: Filters, warms, and moistens air; conducts it into the lungs. Includes: nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
  • Respiratory Zone: Where gas exchange occurs; main sites of gas exchange between air and blood. Includes: respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

Respiration: Gas Exchange Process

• Three Steps:
  • Pulmonary Ventilation: Inhalation and exhalation of air; exchange of air between atmosphere and lung alveoli.
  • External (Pulmonary) Respiration: Exchange of gases between alveoli and pulmonary capillaries across the respiratory membrane. Blood gains O2 and loses CO2.
  • Internal (Tissue) Respiration: Exchange of gases between blood in systemic capillaries and tissue cells. Blood loses O2 and gains CO2.
• Cellular Respiration: Metabolic reactions within cells that consume O2 and produce CO2 during ATP production.

Goals of Respiration

• Provide oxygen to tissues and remove carbon dioxide.
• Four Major Functions:
  • Pulmonary ventilation (breathing)
  • Diffusion of oxygen and carbon dioxide between alveoli and blood
  • Transport of oxygen and carbon dioxide in blood and body fluids
  • Regulation of ventilation and other aspects of respiration