Respiratory System studying

• Respiratory System


  Part of the body responsible for gas exchange and breathing
• Main organs of the respiratory system


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


  • Only externally visible part of the respiratory system
  • Air enters through external nostrils (nares)
  • Interior consists of nasal cavity divided by nasal septum
• Nasal Cavity


  • Olfactory receptors located in mucosa on superior surface
  • Lined with respiratory mucosa that moistens air, traps foreign particles
  • Lateral walls have projections called conchae that increase surface area and air turbulence
  • Separated from oral cavity by palate
• Paranasal Sinuses


  • Cavities within bones surrounding nasal cavity
  • Lighten the skull
  • Act as resonance chambers for speech
  • Produce mucus that drains into nasal cavity
• Pharynx (Throat)


  • Muscular passage from nasal cavity to larynx
  • Three regions: nasopharynx, oropharynx, laryngopharynx
  • Contains tonsils: pharyngeal, palatine, lingual
• Larynx (Voice Box)


  • Routes air and food into proper channels
  • Plays a role in speech
  • Made of cartilages and epiglottis
  • Vocal folds (true vocal cords) vibrate to create sound
• Trachea (Windpipe)


  • Four-inch-long tube connecting larynx with bronchi
  • Walls reinforced with C-shaped hyaline cartilage
  • Lined with ciliated mucosa that beat continuously to expel mucus and debris
• Main (Primary) Bronchi


  • Formed by division of the trachea
  • Right bronchus is wider, shorter, and straighter than left
  • Bronchi subdivide into smaller and smaller branches
• Lungs


  • Occupy most of the thoracic cavity
  • Heart occupies central mediastinum
  • Apex near clavicle, base rests on diaphragm
  • Left lung has 2 lobes, right lung has 3 lobes
• Coverings of the Lungs


  • Serosa covers outer surface
  • Pulmonary (visceral) pleura covers lung surface
  • Parietal pleura lines thoracic cavity walls
  • Pleural fluid allows gliding between layers
• Bronchial (Respiratory) Tree Divisions


  • Primary bronchi
  • Secondary bronchi
  • Tertiary bronchi
  • Bronchioles
  • Terminal bronchioles
• Respiratory Zone


  • Structures: respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli
  • Site of gas exchange is alveoli only
• Respiratory Membrane (Air-Blood Barrier)


  • Thin squamous epithelial layer lines alveolar walls
  • Pulmonary capillaries cover external surfaces of alveoli
  • Air on one side, blood on the other
• Gas Exchange


  1. Oxygen enters the blood

  2. Carbon dioxide enters the alveoli

  3. Alveolar macrophages provide protection

  4. Surfactant coats alveolar surfaces
• Four Events of Respiration


  • Pulmonary ventilation (breathing)
  • External respiration (gas exchange between blood and alveoli)
  • Oxygen loading into blood
  • Carbon dioxide unloading from blood
• Mechanics of Breathing (Pulmonary Ventilation)


  1. Inspiration (inhalation): diaphragm and intercostal muscles contract, thoracic cavity size increases, air pulled into lungs

  2. Expiration (exhalation): largely passive, lung elasticity pushes air out
• Pressure Differences in Thoracic Cavity


  Normal intrapleural pressure is always negative, keeps lungs from collapsing
• Respiratory Volumes


  Tidal volume (TV): normal breathing moves about 500 mL of air
• Respiratory Sounds


  • Bronchial sounds: air rushing through trachea and bronchi
  • Vesicular breathing sounds: air filling alveoli
• Respiration


  • Pulmonary ventilation (breathing)
  • External respiration (gas exchange between blood and outside environment)
  • Respiratory gas transport (via blood)
  • Internal respiration (gas exchange between blood and tissue)
• Hyperventilation


  Increased CO2 in blood (acidosis), breathing becomes deeper and more rapid to blow off CO2 and restore normal pH
• Hypoventilation


  Blood becomes alkaline (alkalosis), extremely slow or shallow breathing allows CO2 to accumulate in blood
• Lung Cancer


  • Accounts for 1/3 of cancer deaths in US
  • Associated with smoking
  • 3 common types: squamous cell, adenocarcinoma, small cell
• Sudden Infant Death Syndrome (SIDS)


  • Apparently healthy infant stops breathing and dies during sleep
  • Some cases due to neural respiratory control center issues
  • Some due to heart rhythm abnormalities
  • Genetic component
• Asthma


  • Chronic inflamed hypersensitive bronchiole passages
  • Response to irritants with dyspnea, coughing, wheezing
• Aging Effects


  • Elasticity of lungs decreases
  • Vital capacity decreases
  • Blood oxygen levels decrease
  • Stimulating effects of CO2 decrease
  • Elderly often hypoxic and have sleep apnea
  • More risks of respiratory tract infection