Respiratory System

• Functions of the respiratory system


  • Conduction of gases to and from respiratory surfaces
  • Protection
  • Warm, humidify, filter
  • Sound production
  • Defense against airborne pathogens, allergens, and debris
  • Gas exchange
  • Regulation of blood volume, blood pressure, fluid levels, blood pH
• Zones of the respiratory system


  • Conductive zone
  • Respiratory zone
• Conductive zone


  • No gas exchange
  • Transports air
  • Warm, humidify, filters air
  • Sound production
• Respiratory zone


  • Defense
  • Gas exchange
  • Regulation of various blood properties
• Organs of the respiratory system


  • Nasal cavity
  • Nostril
  • Oral cavity
  • Pharynx
  • Larynx
  • Trachea
  • Right main bronchus
  • Left main bronchus
  • Right and left lung
• Types of gas exchange


  • External respiration (between lungs (alveoli) and bloodstream)
  • Internal respiration (between bloodstream and oxygen-starved tissue)
• Epithelia of the respiratory system


  • Pseudostratified ciliated columnar epithelia (PSCC) with goblet cells
  • Stratified squamous epithelia
  • Simple cuboidal epithelia
  • Simple squamous epithelia
• Pseudostratified ciliated columnar epithelia (PSCC)


  • Mucous cells that trap debris
  • Cilia move rhythmically, sweeping debris along surface
  • Humidifies and filters air
  • Part of the conductive zone (nasal cavity, trachea, bronchi)
• Stratified squamous epithelia


  • Shared regions of conductive zone with the digestive system
  • Protective tissue (vestibule, oro & laryngopharynx)
• Simple cuboidal epithelia


  • Most bronchioles - terminal bronchioles
• Simple squamous epithelia


  • All respiratory zone, point of gas exchange
• Regions of the respiratory system


  • Nose and nasal cavity
  • Pharynx - throat
  • Larynx
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
  • Lungs
• Nose and nasal cavity


  • Nasal cavity lined with PSCC
  • Nasal conchae, turbinate bones "swirl" air, throwing it against moist and sticky wall
  • Moisturizes and filters
  • Highly vascular to warm the incoming air
• Pharynx - throat


  • Muscular tube
  • Nasopharynx (hard palate - uvula, PSCC)
  • Oropharynx (fauces - hyoid bone, stratified squamous epithelium)
  • Laryngopharynx (hyoid bone - esophagus, stratified squamous epithelium)
  • Shared space with respiratory and digestive system
  • Soft palate seals at the back wall to close off oropharynx from nasal cavity
• Larynx


  • Voice box, made of cartilages and connective tissue bands (vocal cords)
  • Largest cartilage = thyroid cartilage, enlarges to form adams apple
  • Larynx closed off by epiglottis, little flap that acts as a lid in throat
  • Women & children have shorter and thinner cords, higher voice
  • Men have longer and thicker cords, deeper voice due to puberty enlargement
• Trachea


  • About 5 inches long, 1 inch wide, anterior in neck, posterior to heart
  • Carina (internal keel), highly sensitive with lots of nervous tissue
  • C shaped cartilage rings, opens in back, kept open by cartilage and trachealis muscle
  • Mucociliary transport
• Bronchi


  • Trachea splits into two branches, primary to secondary to third, gets smaller and starts to lose cartilage
  • Left bronchus is narrow and more horizontal, right bronchus is wider and vertical
  • Inhaled objects travel down this tube into the right lung
• Bronchioles


  • Small tubes, no cartilage, wrapped in smooth muscles, PSCC and simple cuboidal epithelia, lots of blood and nerve supply
  • Asthma affects these tubes, narrows them, causes swelling, increases mucus secretion, and smooth muscle contraction
• Alveoli


  • 300-500 million alveoli, majority of gas exchange, found in bundles with bronchiole, networked with capillaries and elastic fibers
  • Respiratory membrane where gases diffuse through
  • Three different types of cells: Type 1 (simple squamous for gas diffusion), Type 2 (surfactant production), alveolar macrophages (remove pathogens and debris)
• Lungs


  • Housed within pleural cavities, covered by pleural membrane that secretes pleural fluid, right lung has 3 lobes, left lung has 2 lobes, heart resides in part of it (cardiac notch), costal surface enclosed by thorax, lays on diaphragm
• Respiratory distress syndrome


  Hyaline membrane disease, premature infants have immature lungs with no surfactant production, lungs collapse with each breath, ⅓ of all infant deaths due to RDS, in adults it is usually due to diseased lungs
• Emphysema


  Progressive disease, alveolar walls are destroyed, capillaries narrowed and constricted, reduced surface area for gas exchange, elastic fibers breakdown, exhaling takes energy, 100% of smokers over 40 years have it
• Mechanics of quiet breathing


  1. Inspiration muscles (diaphragm, dorsal intercostals) contract, thoracic cavity volume increases, pressure drops, lung volume increases, air rushes in

  2. Expiration is a passive process
• Smoking


  Lowers respiratory efficiency due to nicotine constricting terminal bronchioles, carbon monoxide binding to hemoglobin reducing oxygen carrying capacity, irritants causing increased mucus production, swelling of tissue lining respiratory tubes, reduction in function and destruction of cilia, long term use leads to breakdown of elastic fibers and collapse of bronchioles, causing emphysema
• Functions of the respiratory system


  • Conduction of gases to and from respiratory surfaces
  • Protection
  • Warm, humidify, filter
  • Sound production
  • Defense against airborne pathogens, allergens, and debris
  • Gas exchange
  • Regulation of blood volume, blood pressure, fluid levels, blood pH
• Zones of the respiratory system


  • Conductive zone
  • Respiratory zone
• Conductive zone


  • No gas exchange
  • Transports air
  • Warm, humidify, filters air
  • Sound production
• Respiratory zone


  • Defense
  • Gas exchange
  • Regulation of various blood properties
• Organs of the respiratory system


  • Nasal cavity
  • Nostril
  • Oral cavity
  • Pharynx
  • Larynx
  • Trachea
  • Right main bronchus
  • Left main bronchus
  • Right and left lung
• Types of gas exchange


  • External respiration (between lungs (alveoli) and bloodstream)
  • Internal respiration (between bloodstream and oxygen-starved tissue)
• Epithelia of the respiratory system


  • Pseudostratified ciliated columnar epithelia (PSCC) with goblet cells
  • Stratified squamous epithelia
  • Simple cuboidal epithelia
  • Simple squamous epithelia
• Pseudostratified ciliated columnar epithelia (PSCC)


  • Mucous cells that trap debris
  • Cilia move rhythmically, sweeping debris along surface
  • Humidifies and filters air
  • Part of the conductive zone (nasal cavity, trachea, bronchi)
• Stratified squamous epithelia


  • Shared regions of conductive zone with the digestive system
  • Protective tissue (vestibule, oro & laryngopharynx)
• Simple cuboidal epithelia


  • Most bronchioles - terminal bronchioles
• Simple squamous epithelia


  • All respiratory zone
  • Point of gas exchange
• Regions of the respiratory system


  • Nose and nasal cavity
  • Pharynx - throat
  • Larynx
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
  • Lungs
• Nose and nasal cavity


  • Nasal cavity lined with PSCC
  • Nasal conchae
  • Turbinate bones "swirl" air, throwing it against moist and sticky wall
  • Moisturizes and filters
  • Highly vascular to warm the incoming air
• Pharynx - throat


  • Muscular tube
  • Nasopharynx (hard palate - uvula, PSCC)
  • Oropharynx (fauces - hyoid bone, stratified squamous epithelium)
  • Laryngopharynx (hyoid bone - esophagus, stratified squamous epithelium)
  • Shared space with respiratory and digestive system
  • Soft palate seals at the back wall to close off oropharynx from nasal cavity
• Larynx


  • Voice box
  • Made of cartilages and connective tissue bands (vocal cords)
  • Largest cartilage = thyroid cartilage
  • Cartilage enlarges to form adams apple
  • Larynx closed off by epiglottis (little flap that acts as a lid in throat, keeps food or other things from going into the respiratory system)
  • Women & children have shorter and thinner cords, higher voice
  • Men have longer and thicker cords, deeper voice due to dramatic enlargement of larynx at puberty
• Trachea


  • About 5 inches long, 1 inch wide
  • Anterior in neck, posterior to heart
  • Carina (internal keel), highly sensitive with lots of nervous tissue
  • C shaped cartilage rings open in back, kept open by cartilage
  • Trachealis muscle in the back constricts during coughing, allows swallowing in esophagus
  • Uses mucociliary transport like bronchi