Exercise Science 9

Respiratory System Study Notes

Chapter Overview

  • Presenter: Nicole Mendola, MS, RCEP, C-EP, GEI, EIM III

  • Chapter Focus: Comprehensive understanding of the respiratory system, its anatomy, physiology, and physiological components for exercise monitoring.

Objectives

  • Understand the main components of the Respiratory System:

    • Anatomy

    • Physiology

  • Discuss physiological components used to monitor exercise.

Main Components of the Respiratory System

  • Overall Function:

    • Filtering air

    • Allowing for gas exchange

  • Key Structures:

    • Nose

    • Nasal cavity

    • Pharynx

    • Larynx

    • Trachea

    • Bronchial tree

    • Lungs

Anatomy of the Lungs

  • Location and Protection:

    • Inside the chest cavity, located above the diaphragm

    • Protected by ribs and pectoral muscles

  • Average Size of Adult Lung:

    • Weight: 1 kg

    • Volume: 4-6 L

Pleura

  • Structure:

    • Visceral Pleura: Inner layer that adheres to the lungs

    • Parietal Pleura: Outer layer lining the chest wall

  • Pleural Cavity: Space between visceral and parietal layers

  • Intercostal Muscles: Located in the chest wall, crucial for respiration

Distribution of Ventilation

  • The ventilation of the pulmonary system is divided into two major divisions:

    • Upper Respiratory Tract

    • Lower Respiratory Tract

Upper Respiratory Tract

  • Function: Conduction pathway for air into the lower respiratory tract

  • Components:

    • Nose

    • Sinuses

    • Pharynx

    • Nasopharynx

    • Oropharynx

    • Larynx

    • Vocal cords

  • Purification and Humidification:

    • Purifies and humidifies air before it reaches the alveoli (90%+ efficiency)

Lower Respiratory Tract

  • Location and Components:

    • Begins at the trachea, just below the larynx

    • Structures include:

    • Bronchi

    • Bronchioles

    • Alveoli

    • Decompositions of Airways:

    • 23 divisions of airways:

      • First 16: conducting airways

      • Last 7: respiratory airways ending in 300 million alveoli

Trachea

  • Anatomy:

    • Anterior to the esophagus

    • Base of the neck, extends 4-4.5 inches

    • Divides into right and left main bronchi

  • Structure Features:

    • Series of anterior horseshoe-shaped cartilaginous rings

    • Posterior longitudinal muscle bundle

Bronchial Tree Structure

  • Right Main Bronchus: Divides into three lobar bronchi (Upper, Middle, Lower)

  • Left Main Bronchus: Divides into two lobar bronchi (Upper, Lower)

  • Alveolar Sacs:

    • Shared by two or more alveoli

    • Alveoli Characteristics:

    • Cup-shaped pouches lined with type I and II epithelial cells

    • Surrounded by a thin elastic membrane for support

Gas Exchange

  • Mechanism: Takes place by passive diffusion across the respiratory membrane

  • Characteristics of the Respiratory Membrane:

    • Very thin wall (5 micrometers thick)

    • The combination of thin walls and large surface area promotes rapid diffusion of gases into and out of the blood

  • Blood Flow: Blood is drained into pulmonary venules and veins after gas exchange

Ventilatory Pump

  • Function: Provides mechanism for breathing consisting of:

    • Chest wall

    • Respiratory muscles

    • Pleural space

Chest Wall Anatomy

  • Muscles of Ventilation:

    • Primary intercostal muscles

  • Bones Involved:

    • Spine, ribs, sternum

Mechanism of Breathing

  • Inspiration:

    • Airflow into lungs due to activation of respiratory muscles, primarily the diaphragm

    • Creates more negative pressure in pleural space and lungs compared to atmosphere

    • Air enters until intrapulmonary gas pressure equals atmospheric pressure

  • Expiration:

    • Movement of air out of lungs involves relaxation of ventilatory muscles

    • Positive pressure generated by elastic recoil of lungs allows air to exit

Respiratory Muscles

  • Functions:

    • Only skeletal muscles essential to life

    • Diaphragm: Major muscle of inspiration, functioning as a piston

Control of Breathing

  • Type of Action: Breathing is primarily an involuntary action

  • Control Mechanism: Involves movements of respiratory muscles and diaphragm, along with changes in pressure

  • Pressure Dynamics:

    • At rest and during inspiration, pressure inside lungs is less than atmospheric pressure

    • Lower pressure inside the lungs during inhalation prevents fragile air sacs (alveoli) from collapsing

    • During exhalation, pressure differences reverse, allowing lungs to deflate and push air out

Distribution of Blood Flow

  • Pulmonary Arteries: Supply blood to lungs

    • Normal Mean Pressure: Approximately 15 mm Hg

  • Bronchial Arteries: Supply blood to bronchi and bronchioles

  • Gas Exchange: Occurs in walls of alveoli

Pulmonary Ventilation

  • Definition: Volume of air exchanged per minute

  • Average Male Rate: Approximately 6 L·min⁻¹

    • Can increase 15- to 25-fold during maximal exercise

  • Regulation: Primarily adjusted by the requirement for carbon dioxide removal

Ventilatory Changes due to Physical Conditioning

  • Adaptations:

    • Increases in larger lung volumes and diffusion capacity

    • Maximal ventilatory capacity may increase

    • Submaximal ventilation may decrease