Lecture Notes: Respiratory System Overview

Introduction

• Presentation focuses on the respiratory system, section 22 in the lab book.
• Main function: Gas exchange in the blood to transport to tissues.

Key Functions of the Respiratory System

• Pulmonary Ventilation: Movement of air in and out of lungs; breathing process.
• Air Filtration: Hairs and mucus in nasal cavity filter, moisten, and warm the air.
• External Respiration: Gas exchange between lungs and blood.
  • Oxygen enters blood, CO2 exits into alveoli.
• Internal Respiration: Gas exchange between blood and cells.
• Cellular Respiration: Oxygen used in cells for ATP production (glycolysis, Krebs cycle, electron transport chain).
• Sound Production: Communication is a crucial function.

Pleura and Pleural Cavity

• Pleurae: Serous membranes of the lungs.
  • Parietal Pleura: Lines inside body wall.
  • Visceral Pleura: Lines the lungs.
• Pleural Cavity: Space between pleura, filled with pleural fluid.
  • Allows sliding of lungs and body wall during breathing.

Pressure Mechanics in Breathing

• Intrapleural Pressure: Pressure in pleural cavity is less than intrapulmonary pressure.
• Intrapulmonary (Intraalveolar) Pressure: Air pressure within the lungs.
  • Greater than pleural cavity pressure, aiding lung expansion.

Boyle’s Law

• Equation: P1V1 = P2V2 (Pressure x Volume = constant)
  • Decreasing volume increases pressure and vice versa.
• Application in lungs:
  • Increase in lung volume decreases pressure, drawing air in.
  • Decrease in volume increases pressure, expelling air out.

Ventilation Types

• Negative Pressure Ventilation: Inhaling by increasing lung volume, reducing pressure.
• Positive Pressure Ventilation (e.g., ventilators): Forcing air into lungs.

Muscles Involved in Breathing

• Inspiration (Breathing in):
  • Active process involving diaphragm and external intercostals.
  • Accessory muscles engaged for deep breaths.
• Expiration (Breathing out):
  • Normally passive; relaxation of muscles.
  • Forced Expiration: Engages abdominal muscles and internal intercostals.

Closing Remarks

• Review additional materials including videos and photographs with annotations.
• Stay safe and good luck with studies.