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• Functions of the respiratory system

  • Respiration
  • Blood pH regulation
  • Sound production
  • Olfaction
  • Protection

  
• Respiration


  1. Ventilation - movement of air in and out of lungs

  2. External respiration - gaseous exchange between lungs and blood

  3. Respiratory gas transport - through blood to the whole body

  4. Internal respiration - gaseous exchange between blood and tissues
• Physical process of inhalation and exhalation
• Air that we breathe in passes through long respiratory passage until it reaches alveoli (last holding point of air in body)
• Once air reaches alveoli, external respiration occurs
• Alveoli are covered extensively by blood capillaries which carries deoxygenated blood collected from various parts of body
• Gaseous exchange takes place between air in alveoli and gases in blood
• Oxygen moves from alveoli into blood, carbon dioxide moves from blood into alveoli
• Once oxygen moves from alveoli into blood, transported to tissues and at tissues, carbon dioxide is collected and brought to the lungs. this way, gases are transported in blood
• At tissue level when the blood reaches tissue, internal respiration occurs. oxygen is offloaded from blood into tissues and carbon dioxide is picked up from tissues and moved into blood
• pH


  How acidic or alkaline a medium is on scale of 0-14 (acidic-alkaline)
• Any change in blood pH has impact on body physiology/function
• If have increase in level of CO2, will make blood more acidic so it needs to be removed from our system/blood to maintain the pH
• Sound production


  As air passes through vocal cords located in larynx region of respiratory tract, sound is produced and by changing tension of vocal folds, sound can be more defined in pitch
• When forcefully exhale air, can increase loudness of sound
• Can manipulate sound by working on vocal folds
• Olfaction


  Specialised cells in nasal cavity that is sensitive to smell so we can get idea of surroundings
• Protection


  Provided with hair, cilia, mucus, lymphoid tissue and structures likewise which prevent entry of harmful substances in our body
• Divisions of respiratory system

  • Nasal cavity
  • Larynx
  • Bronchi
  • Lungs

  
• Structural classification


  • Upper respiratory tract - nose, nasal cavity, pharynx
  • Lower respiratory tract - larynx, trachea, bronchi, bronchioles & alveoli of the lungs

  
• Functional classification


  • Conducting zone - from nose to terminal bronchioles
  • Respiratory zone - respiratory bronchioles, alveolar duct & alveoli
• Respiratory tract - continuous tube that runs from nares to alveoli

  
• Anatomical dead space


  No gaseous exchange happening, just a dead space for passage of air
• Where gaseous exchange takes place
• Air gets cleansed, humidified
• Nasal cavity


  • Nares
  • Vestibule
  • Septum
  • Floor of nasal cavity

  
• Nasal cavity


  • Hard palate
  • Soft palate
  • Uvula

  
• Nasal cavity


  • Superior conchae
  • Middle conchae
  • Inferior conchae
• Nasal cavity


  • Superior meatuses
  • Middle meatuses
  • Inferior meatuses
• Nasal cavity is made of bone and cartilage (hyaline) and covered by skin

  
• Nasal cavity opens to inside through nostrils
• Vestibule is the beginning part of nasal cavity

  
• Vestibule has coarse hair and sweat and sebaceous glands
• When we breathe in air it will go through these elevations (conchae) and depressions (meatuses) which creates turbulence in air
• Opening of paranasal sinuses and tear ducts
• Functions of nasal cavity


  • Passageway for air
  • Hair - filter coarse particles from the inspired air
  • Mucus - traps dust, bacteria and other debris from the inspired air, humidifies air
  • Cilia - create gentle current by beating moving contaminated mucus towards throat to be swallowed
  • Lysozyme - kills bacteria
  • Rich capillary network - maintain temperature of inhaled and exhaled air
  • Conchae & meatuses - increase mucosal surface, create turbulence facilitating above functions
  • Olfaction - olfactory epithelium containing olfactory receptors
  • Sinuses, nasal cavity - resonating chambers, lighten skull
• Throat


  Common passage for food and air
• Regions of throat


  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Nasopharynx is posterior to nasal cavity, from choana to uvula, contains Eustachian tube opening and pharyngeal tonsils

  
• Oropharynx is posterior to oral cavity, from uvula to epiglottis/hyoid bone, contains common passage for air & food, palatine & lingual tonsils