Respiratory System

• Only externally visible part of the respiratory system - Nose
• external nares (nostrils) 
• Internal nares (choanae)
• interior of the nose consists of a nasal cavity divided by a nasal septum 
• Nasopharynx - behind nasal cavity 

  Oropharynx - behind mouth 

  Laryngopharynx - behind the larynx 
• Pharynx - throat
• Larynx - voice box
• Epiglottis 

  • Routes air and food into proper channels
• Thyroid Cartilage 

  • Largest hyaline cartilage 
  • (Adam’s apple) 
• Glottis 

  • Opening between vocal chords
• Vocal chords - vocal folds
• Trachea - windpipe
• Trachea  

  • Walls are reinforced with C-shaped hyaline cartilage 
  • Starts at cricoid cartilage (C6)
  • Ends at level of sternal angle 
• Tracheal Bifurcation 

  • Trachea bifurcates into Left and Right Bronchi 
  • CARINA 
  • Level of bifurcation corresponds to T4
• Primary Bronchi 

  • Right bronchus is wider, shorter, and straighter than left
• Bronchioles 

  •  Smallest  branches of bronchi 
  • Terminal bronchioles end in alveoli 
• Respiratory Zone 

  • Site of gas exchange Structures: 
  • respiratory bronchiole  
  • alveolar duct 
  • alveoli
• Alveoli

  • Sac-like structure where gas exchange takes place within the respiratory membrane
• Lungs 

  • Apex is near the clavicle (superior portion) 
  • Base rests on the diaphragm (inferior portion) 
• Coverings of the Lungs 

  1. Visceral pleura
  2. Parietal pleura 
• (Coverings of the Lungs)

  Pleural fluid - fills the area between layers of pleura to allow gliding
• Mediastinum 

  • Anatomic region located between the lungs
• Pulmonary ventilation - moving air in and out of the lungs
• External respiration - gas exchange between pulmonary blood and alveoli
• Internal respiration - gas exchange between blood and tissue cells in systemic capillaries. 
• Respiratory gas transport - transport of oxygen and carbon dioxide via the bloodstream
• Mechanics of Breathing (Pulmonary Ventilation) 

  2 phases 

  1. Inspiration - flow of air into lung

  Expiration - air leaving lung
• Diaphragm 

  • Dome shaped muscle 
  • Main muscle for breathing 
• Eupnea → normal respiratory rate

  • 12-20 cycles per minute 

  Hyperpnea/Tachypnea → increased respiratory rate often due to extra oxygen needs 

  Bradypnea → decreased RR 
• Carbon dioxide levels

  • The main regulatory chemical for respiration 
  • Acts directly on the medulla oblongata
• Frenulum - line sa ilalim ng dila
• Philtrum - dented part under of nose
• Orthopnea - cessation of breathing when lying or standing