Respiratory System

• Respiratory system


  The system responsible for breathing and gas exchange in the body
• Respiratory passages


  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs

  
• Nose


  • External nose
  • Nasal cavity

  
• Nares/Nostril


  External opening of the nose
• Choanae


  Opening into the pharynx
• Nasal cavity


  Extends from the nares to the choanae

  
• Conchae


  • Prominent bony ridges that increase the surface area of the nasal cavity and cause air to churn, so that it can be cleansed, humidified, and warmed

  
• Pharynx


  Common passageway for both the respiratory and the digestive systems
• Pharynx


  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Nasopharynx


  The superior part of the pharynx, posterior to the choanae and superior to the soft palate, lined with pseudostratified ciliated columnar epithelium
• Oropharynx


  Extends from the uvula to the epiglottis, lined with stratified squamous epithelium
• Laryngopharynx


  Passes posterior to the larynx and extends from the tip of the epiglottis, lined with stratified squamous epithelium and ciliated columnar epithelium
• Tonsils


  Located near the opening between the mouth and the oropharynx, including the pharyngeal tonsil, tubal tonsils, palatine tonsil, and lingual tonsils

  
• Larynx


  A passageway for air between the pharynx and the trachea, also known as the "voice box"
• Larynx


  • Maintains an open airway
  • Protects the air during swallowing
  • Produces the voice
• Larynx cartilages


  • Thyroid cartilage
  • Cricoid cartilage
  • Epiglottis
• Epiglottis


  Differs from the other cartilages in that it consists of elastic cartilage rather than hyaline cartilage, protects the airway during swallowing
• Vocal cords


  The primary source of voice production, air moving past them causes them to vibrate and produce sound
• Trachea


  The "windpipe" that allows air to flow into the lungs, a membranous tube attached to the larynx
• Trachea


  • Connective tissue with muscle reinforced with 16 to 20 C-shaped pieces of hyaline cartilage
  • Lined with pseudostratified columnar epithelium containing cilia and goblet cells
• Constant irritation and inflammation of the respiratory passages

  Stimulates the cough reflex, resulting in "smoker's cough"
• Constant, long-term irritation of the trachea by cigarette smoke

  Can cause the tracheal epithelium to change to stratified squamous epithelium
• Bronchi and bronchioles


  • As the air passageways become smaller, the structure of the walls changes with decreasing cartilage and increasing smooth muscle
• Smooth muscle in bronchi and bronchioles

  Can change the diameter of the air passageways, causing dilation during exercise and contraction in asthma
• Types of epithelium in the respiratory system

  • Pseudostratified ciliated columnar epithelium (trachea and bronchi)
  • Ciliated simple columnar epithelium (bronchioles)
  • Ciliated cuboidal epithelium (terminal bronchioles)
  • Cuboidal epithelium (respiratory bronchioles)
  • Simple squamous epithelium (alveolar ducts and alveoli)

  
• Respiratory membrane


  Where gas exchange between the air and blood takes place, formed mainly by the walls of the alveoli and the surrounding capillaries
• Respiratory membrane


  • Thin to facilitate the diffusion of gases
  • Consists of 6 layers: fluid lining, alveolar epithelium, basement membrane, interstitial space, capillary basement membrane, capillary endothelium
• Ventilation/Breathing


  The process of moving air into and out of the lungs, with two phases: inspiration/inhalation and expiration/exhalation
• Respiratory volumes and capacities

  • Tidal volume
  • Inspiratory reserve volume
  • Expiratory reserve volume
  • Residual volume
  • Functional residual capacity
  • Inspiratory capacity
  • Vital capacity
  • Total lung capacity

  
• Thickness of the respiratory membrane

  Increases during respiratory diseases like pulmonary edema, decreasing the rate of gas exchange
• Oxygen exchange is affected before CO2 exchange because O2 diffuses through the respiratory membrane about 20 times less easily than does CO2