محاضرة الاولى

• Respiratory system


  • Conducting portion
  • Respiratory portion

  
• Conducting portion of respiratory system


  • Intrapulmonary bronchi
  • Bronchioles
  • Terminal bronchioles

  
• Respiratory portion of respiratory system


  • Respiratory bronchioles
  • Alveolar ducts
  • Alveoli

  
• Airways - conducting portion

  • Bronchi (extra pulmonary)
  • Trachea
  • Larynx
  • Pharynx (naso - oro - laringo-)
  • Nasal cavity/mouth - paranasal sinuses

  
• Function of respiratory system

  • To provide O2
  • To eliminate CO2 from cells
  • Breathing/ventilation (in - out - lung)
  • External respiration (CO2-O2 exchange - in blood) - respiratory portion - lung
  • Transport of gases - to cells
  • Internal respiration (CO2-O2 exchange- in the vicinity of cells)
• Nasal cavity


  • Walls - borders
  • Openings: Nares/nostrils - anterior, Choanae - posterior

  
• Portions of nasal cavity

  • Anterior portion - vestibule: vibrissae - skin - sebaceous + sweat glands
  • Posterior aspect - nasal fossae: resp. ep. - conchae (sup, mid, inf), olfactory region, area of arterial plexuses and venous sinuses - bleeding

  
• Epithelium types in nasal cavity

  • Keratinized stratified squamous epithelium
  • Non Keratinized stratified squamous epithelium
  • Pseudostratified ciliated columnar epithelium with goblet cells
  • Olfactory Epithelium

  
• Components of nasal cavity

  • Lamina Propria
  • Mucous Glands
  • Serous Glands
  • Venous Sinuses
  • Mucoperiosteum or Mucoperichondrium

  
• Secretions of nasal mucosa

  • Bactericides
  • Lysozymes
• Olfactory region


  • Roof-nasal cavity, superior aspect-nasal septum, conchae superior
  • Olfactory epithelium - yellow
  • Olfactory cells- bipolar neuron: dendrite end - olfactory vesicle - olfactory cilia - odor receptor
  • Sustentacular cells, basal cells
  • Lamina propria: Bowman's gland - serous, Capillary plexus

  
• Pharynx (naso-oro-laringo)


  • Mucosa: Respiratory epithelium, Stratified squamous epithelium
  • Lamina propria - loose-dense irreguler CT, Vascularized, Seromucous gland, Lymphoid tissue - posterior: pharyngeal tonsil
  • Skeletal muscle-epimysium

  
• Larynx - voice box

  • Additional function: Phonation, Prevent food/drinks - respiratory system
  • Tube: cartilage (hyaline, elastic) - ligaments - skeletal muscles (intrinsic-extrinsic)
  • Epiglottis - elastic cartilage: Stratified squamous non keratinized epithelium, Pseudostratified (respiratory epithelium)
  • Vestibular fold - false vocal cord (superior)
  • Vocal fold - true vocal cord (inferior) - stratified squamous: Vocalis muscle, vocal ligament - regular dense elastic CT
• Trachea-extrapulmonary bronchus


  • Mucosa: Respiratory epithelium - pseudostratified ciliated columnar epithelium: goblet, cilated columnar, basal, brush, serous, DNES cells, Lamina propria - loose fibroelastic-mucous, seromucous gl-lymphoid tissue, Elastic lamina
  • Submucosa-dense irreg. fibroelastic CT, mucous-seromucous gl- lymphoid tissue
  • Adventitia - fibroelastic CT - C ring hyaline cartilage (p cartilaginea) - fibrous CT - smooth muscle (p. membranacea)

  
• Intrapulmonary bronchus


  • Mucosa -folded app: Respiratory epithelium, Lamina propria - fibroelastic-seromucous gl-lymphoid nodules, Smooth muscles-spiral
  • Submucosa-seromucous gl-lymphoid nodules
  • Adventitia - plates of cartilage (hyaline)

  
• Bronchioles


  • Mucosa: Pseudostratified columnar epithelium-goblet cells - ciliated simple columnar - ciliated cuboidal (with Clara cells)
  • Lamina propria: No glands, Elastic fibers
  • Smooth muscles - helical loose meshwork - surrounded by fibroelastic CT

  
• Terminal bronchioles


  • Ciliated simple cuboidal epithelium with Clara cells
  • Lamina propria - fibroelastic CT
  • Smooth muscle cells
  • Adventitia-elastic fibers

  
• Respiratory bronchioles


  • Similar - terminal br.
  • Wall - alveoli - gas exchange

  
• Alveolar duct


  • Wall ≈ alveoli
  • Ends into alveolar sac

  
• Alveolar sac


  • Cluster of alveoli
  • Open - common space - atrium
• Alveolus


  • Small air sac - gas exchange
  • Between alveoli - interalveolar septum - alveolar pores
  • Connective tissue: elastic, reticular (coll III) - lymphoid tissue, Macrophages, fibroblast, myofibroblast, mast cells
  • Continuous capillary bed (from pulmonary artery - vein)
  • Type I pneumocytes/alveolar cells - squamous alveolar cells) - tight junction - basal lamina - very thin region - permeable to gasses
  • Type II pneumocytes/alveolar cells - great alveolar cell - septal cells - surfactant - surface tension- ≠ collapse

  
• Alveolar macrophages


  • Monocytes
  • Migrate - through pneumocytes I - lumen alveolus - phagocytose surfactant, particulate matter (dust, bacteria) - dust cells - bronchy - cilia- swallowed/ expectorated
  • Migrate back - connective tissue - interpulmonary septum - lymph vessel

  
• Blood gas barrier


  • Gas exchange - thinnest region - interalveolar septum: alveolar lumen - blood
  • Surfactant
  • Pneumocyte I - thin region
  • Fused basal laminae
  • Endothelial cell - continuous capillary

  
• Defense mechanisms of respiratory system

  • Vibrissae - filter large particles
  • Mucus - trap smaller particles
  • Cough reflex - expectoration
  • Alveolar macrophages - phagocytose
  • Lymphoid tissue - specific immune response