Lecture Notes: Anatomy and Physiology of Respiration

Part 1: Anatomy of Respiration

Vocabulary and Definitions

Structural Areas

• Pleura: Double-layered membrane surrounding the lungs that reduces friction.
• Lobes: Sections of the lungs (Right lung: 3 lobes, Left lung: 2 lobes).
• Upper Respiratory Tract: Consists of the nose, nasal cavity, pharynx, and larynx.
• Lower Respiratory Tract: Includes the trachea, bronchi, bronchioles, and alveoli.

Muscles

• Diaphragm: Dome-shaped muscle under the lungs; contracts during inhalation.
• External Intercostals: Muscles between the ribs that expand the chest during breathing.

Pathway Structures

• Nostrils: External openings for air intake.
• Nasal Cavity: Warms, moistens, and filters air.
• Oral Cavity: Secondary entrance for air.
• Pharynx: Throat; common pathway for air and food.
  • Nasopharynx: Upper section behind nasal cavity.
  • Oropharynx: Middle section behind oral cavity.
  • Laryngopharynx: Lower section leading to the larynx.
  • Epiglottis: Flap that prevents food from entering the airway.
  • Larynx: Voice box; contains vocal cords.
  • Trachea: Windpipe; conducts air to bronchi.
  • Pseudostratified Epithelium: Ciliated cells lining airways for cleaning.
  • Cilia: Hair-like structures that move mucus and debris.
  • Mucus: Traps particles and pathogens.

Airway Branching

• Left and Right (Primary) Bronchi: First branches off the trachea into each lung.
• Secondary Bronchi: Branches to each lobe of the lung.
• Tertiary Bronchi: Further division within the lobes.
• Bronchioles: Smaller air passages without cartilage.
• Terminal Bronchiole: Last part before alveoli.
• Alveolar Duct: Leads from bronchioles to alveoli.
• Alveoli: Air sacs where gas exchange occurs.

Learning Target: Compare Upper vs. Lower Respiratory Tracts

T-Chart Example

• Upper Respiratory Tract

  • Nose, Nasal Cavity, Pharynx, Larynx
  • Filters, warms, and moistens air
  • Involved in smell and vocalization
  • Contains tonsils and epiglottis

• Lower Respiratory Tract

  • Trachea, Bronchi, Bronchioles, Alveoli
  • Conducts air to lungs, gas exchange
  • Includes respiratory membrane
  • Includes alveolar sacs for gas exchange

Part 2: Physiology of Respiration

Vocabulary and Definitions

Processes

• Pulmonary Ventilation: Movement of air into/out of lungs (breathing).
• Respiratory Gas Transport: Transport of O₂ and CO₂ via bloodstream.
• Inspiration: Breathing in; diaphragm contracts, volume increases.
• Expiration: Breathing out; diaphragm relaxes, volume decreases.
• Internal Respiration: Gas exchange between blood and body tissues.
• External Respiration: Gas exchange between alveoli and blood.

Volumes & Capacities

• Tidal Volume (TV): Air moved in/out during normal breathing (~500 mL).
• Inspiratory Reserve Volume (IRV): Extra air inhaled after normal breath (~3100 mL).
• Expiratory Reserve Volume (ERV): Extra air exhaled after normal breath (~1200 mL).
• Residual Volume (RV): Air remaining after full exhalation (~1200 mL).
• Vital Capacity (VC): Total air that can be exhaled after max inhalation (TV + IRV + ERV).
• Total Lung Capacity (TLC): VC + RV (~6000 mL in adults).

Learning Target: Trajectory of an Oxygen Molecule

Pathway of Oxygen

1. Enters through Nostrils/Nasal Cavity → filtered, warmed, humidified.
2. Passes through Pharynx → Larynx → Trachea.
3. Travels down Primary Bronchi → Secondary → Tertiary Bronchi.
4. Enters Bronchioles → Terminal Bronchioles → Alveolar Ducts → Alveoli.
5. Gas Exchange at alveoli → O₂ enters pulmonary capillaries.
6. O₂ binds to hemoglobin in red blood cells.
7. Blood transports O₂ via arteries → Body Tissues for Internal Respiration.

Lung Capacity in Action (Example)

• If taking 12 breaths per minute with a Tidal Volume of 500 mL:
  • 12 x 500 mL = 6000 mL or 6 Liters per minute
  • During exercise, TV and breathing rate increase dramatically (up to ~100 L/min in elite athletes!)