Respiratory System Notes

Respiratory System Overview

  • Organs of Respiration
    • Right primary bronchus
    • Lungs
    • Pharynx
    • Nose
    • Nasal Cavity
    • Larynx
    • Trachea

Cellular Respiration

  • Key Points
    • End Products of Nutrient Breakdown:
    • Energy production from glucose, fatty acids
    • Organelle Responsible:
    • Mitochondria perform cellular respiration
    • Gas Exchange:
    • Oxygen (O2) is consumed
    • Carbon Dioxide (CO2) is produced

Ventilation

  • Definition: Movement of air in and out of lungs
  • Pressure Dynamics:
    • Inhalation: Pressure in lungs is lower than atmospheric pressure
    • Exhalation: Pressure in lungs is higher than atmospheric pressure
  • Types of Respiration:
    • External Respiration:
    • O2 and CO2 exchange between lungs and blood in pulmonary capillaries
    • Internal Respiration:
    • O2 and CO2 exchange between blood in systemic capillaries and systemic tissues
  • Transport: Oxygen and carbon dioxide transport in the blood

Respiratory System Zones

  • Conducting Zone:
    • Directs gases to the respiratory zone
    • Includes structures without gas exchange functions
  • Respiratory Zone:
    • Site of gas exchange
    • Structures include respiratory bronchioles, alveolar ducts, and alveoli

Respiratory Muscles

  • Major Muscles:
    • Diaphragm
    • Intercostal muscles
    • Abdominal muscles
    • Neck muscles (assist in respiration)

Conducting Zone Functions

  • Primary Function: Direct gases to the respiratory zone
  • Secondary Functions:
    • Remove foreign substances
    • Add heat and moisture to the inhaled air
  • Key Structures:
    • Nose, nasal cavity, paranasal sinuses
    • Pharynx, larynx, trachea
    • Bronchi, bronchioles, terminal bronchioles

Histology of Conducting Zone

  • Pseudostratified Columnar Epithelium:
    • Lines most of the conducting zone
    • Contains goblet cells (produce mucus) and cilia (help move mucus)
  • Superior Nasal Cavity:
    • Contains olfactory epithelium for smell

Nasal Cavity Features

  • Divided by nasal septum (perpendicular plate of ethmoid bone and vomer bone)
  • Conchae:
    • Increase surface area and prolong the air's time in the cavity
    • Aid in humidification, warming, and filtering the air

Paranasal Sinuses

  • Function:
    • Air-filled pockets that drain into nasal cavity
    • Produce mucus, humidify air, remove foreign substances, and provide voice resonance
    • Types: frontal, ethmoid, maxillary, sphenoid

Pharynx Regions

  • Oropharynx and Laryngopharynx:
    • Lined with stratified squamous epithelium due to their exposure to friction and abrasion
    • Differences from nasopharynx include location and function in both air and food transportation

Larynx

  • Structure:
    • Connects laryngopharynx to trachea, composed of 9 cartilages, membranes, ligaments, and muscles
  • Functions:
    • Routes air & food
    • Provides an open airway (glottis)
    • Facilitates voice production via vocal folds

Laryngeal Structure Functionality

  • Vocal Folds:
    • Elastic and vibrate to produce sound
  • Vestibular Folds:
    • Inelastic, protect vocal cords and assist in glottis closure

Trachea Structure

  • Histological Elements:
    • Pseudostratified columnar epithelium with mucus glands aids in trapping particles
    • Hyaline Cartilage:
    • Provides structural support, keeping trachea open

Bronchial Tree Structure

  • Changes Down the Tree:
    • Decrease in cartilage
    • Decrease in cilia & goblet cells
    • Increase in smooth muscle
    • Increase in surface area
    • Decrease in thickness of epithelium

Respiratory Zone

  • Site of External Respiration:
    • Comprising approximately 150 million alveoli per lung
    • Gaseous Exchange:
    • Gas exchange occurs in alveoli, respiratory bronchioles, alveolar ducts, and alveolar sacs
    • Epithelial Cells:
    • Alveoli lined with simple squamous epithelium for efficient gas exchange