BIO LEC RESPIRATORY

• Respiration


  The process of breathing that includes ventilation (movement of air into and out of the lungs) and the exchange of oxygen and carbon dioxide between the air in the lungs and the blood, the transport of oxygen and carbon dioxide in the blood, and the exchange of oxygen and carbon dioxide between the blood and the tissues

  
• Components of respiration


  • Ventilation (breathing)
  • Exchange of oxygen and carbon dioxide between the air in the lungs and the blood
  • Transport of oxygen and carbon dioxide in the blood
  • Exchange of oxygen and carbon dioxide between the blood and the tissues

  
• Chemoreceptors


  Receptors that detect changes in the chemical composition of the blood and stimulate the respiratory control center in the brain to regulate breathing
• Muscles used for


  • Inhalation
  • Forceful expiration
• Ventilation


  The movement of air into and out of the lungs
• Alveoli


  Small air sacs in the lungs where gas exchange occurs

  
• Asthma attack


  Contraction of terminal bronchioles leads to reduced air flow
• Respiratory membrane


  The thin membrane in the lungs where gas exchange between air and blood occurs, formed by the walls of the alveoli and capillaries

  
• Layers of the respiratory membrane

  • Thin layer of fluid from alveolus
  • Alveolar epithelium (simple squamous)
  • Basement membrane of alveolar epithelium
  • Thin interstitial space
  • Basement membrane of capillary endothelium
  • Capillary endothelium (simple squamous)

  
• Pleura


  The double-layered membrane around the lungs
• Parietal pleura


  The membrane that lines the thoracic cavity
• Visceral pleura


  The membrane that covers the lung's surface

  
• Pleural cavity


  The space around each lung
• Ventilation (breathing)


  The process of moving air in and out of the lungs
• Phases of ventilation


  • Inspiration (breathe in)
  • Expiration (breathe out)
  • Forceful expiration (uses internal intercostal muscles)
• When thoracic cavity volume increases

  Pressure decreases
• When thoracic cavity volume decreases


  Pressure increases
• Air flows


  From areas of high to low pressure
• Inspiration


  1. Diaphragm descends and rib cage expands

  2. Thoracic cavity volume increases, pressure decreases

  3. Atmospheric pressure is greater than alveolar pressure

  4. Air moves into alveoli (lungs)
• Expiration


  1. Diaphragm relaxes and rib cage recoils

  2. Thoracic cavity volume decreases, pressure increases

  3. Alveolar pressure is greater than atmospheric pressure

  4. Air moves out of lungs
• Forceful expiration


  Uses internal intercostal muscles
• Lung recoil


  • The tendency for an expanded lung to decrease in size
  • Occurs during quiet expiration
  • Due to elastic fibers and thin film of fluid lining alveoli
• Surfactant


  • A mixture of lipoproteins
  • Produced by secretory cells of the alveoli
  • A single fluid layer on the surface of thin fluid lining alveoli
  • Reduces surface tension
  • Keeps lungs from collapsing
• Pleural pressure


  • Pressure in the pleural cavity
  • Less than alveolar pressure
  • Keeps the alveoli from collapsing
• Factors that Influence Pulmonary Ventilation

  • Lung elasticity
  • Lung compliance
  • Respiratory passageway resistance

  
• Spirometer


  Device that measures pulmonary volumes

  
• Tidal volume (TV)


  Volume of air inspired and expired during quiet breathing
• Inspiratory reserve volume (IRV)


  Volume of air that can be inspired forcefully after a normal inspiration
• Expiratory reserve volume (ERV)


  Volume of air that can be expired forcefully after a normal expiration
• Residual volume (RV)


  Volume of air remaining in lungs after a maximal expiration (can't be measured with spirometer)

  
• Vital capacity (VC)


  Max. amount of air a person can expire after a max. inspiration
• Total lung capacity (TLC)

  VC + RV
• Factors that Influence Pulmonary Volumes

  • Gender
  • Age
  • Height
  • Weight
• Respiratory membrane


  • Where gas exchange between blood and air occurs
  • Primarily alveoli
  • Some in respiratory bronchioles and alveolar ducts

  
• Respiratory membrane does NOT occur in bronchioles, bronchi, trachea

  
• Respiratory membrane


  Influenced by thickness of membrane, total area of membrane, partial pressure of gases
• Increased thickness of respiratory membrane


  Decreases rate of diffusion
• Pulmonary edema


  Decreases diffusion
• Rate of gas exchange

  Is decreased
• O2 exchange is affected before CO2 because CO2 diffuse more easily than O2