Physiology Final

• Internal respiration


  Cellular respiration that occurs in the mitochondria to generate ATP by oxidative phosphorylation, and then the production of carbon dioxide
• External respiration


  The exchanges of oxygen and carbon dioxide between the atmosphere and the tissues of the body (involved both the respiratory and cardiovascular systems)
• External respiration


  Air moves between the atmosphere and the lungs where carbon dioxide and oxygen are then transported in the blood and then are exchanged between systemic tissues and the blood
• Lungs


  • Bring oxygen into body and send carbon dioxide out
• Airways (bronchi)


  • Branched tubes of the respiratory tract, located between the trachea and the bronchioles of the lungs. They conduct air to each lung.
• Diaphragm


  • Creates a vacuum effect that pulls air into the lungs when contracting and pushed air out of lungs when relaxing
• Voice box (larynx)


  • Initial passageway of the respiratory tract, which contains the vocal cords. Protects lower respiratory tract from aspirating food into the trachea while breathing.
• Throat (pharynx)


  • A passageway leading from the mouth to the esophagus or larynx that serves as a common passageway for food and air
• Nose and mouth (upper airways)

  • Air passages in the head and neck
• Respiratory membrane


  A barrier between blood and air consisting of capillary endothelial cells and their basement membranes and alveolar epithelial cells and their basement membranes
• Respiratory membrane


  Bronchioles branch into respiratory bronchioles
• Alveoli


  • Clusters called alveolar sacs at the ends of alveolar ducts
  • Associated with alveolar ducts and respiratory bronchioles
• Alveoli


  • Dense capillary network surrounding
• Alveolar wall


  • Contains type 1 cells (make up the structure wall)
  • Contains type 2 cells (secrete surfactant)
  • Contains macrophages
• Describe the anatomy of alveoli

  1. Alveoli are balloon-shaped structures located at the end of the respiratory tree

  2. Expand during inhalation, taking in oxygen

  3. Shrink during exhalation, expelling carbon dioxide
• Type 1 alveolar cells

  Epithelial cells lining alveoli
• Type 2 alveolar cells


  Cells that line alveoli and secrete surfactant
• Alveolar macrophages


  Engulf foreign particles and pathogens inhaled into the lungs
• Describe the mechanics of breathing

  Air flow into and out of the lungs is driven by pressure gradients that the muscles of respiration create by changing the volume of the lungs
• Boyle's Law


  • For a given quantity of gas (air) in an airtight container, the pressure is inversely related to the volume of the container
  • As volume of container increases, pressure decreases
  • As volume of the container decreases, pressure increases
• External intercostal muscles


  • Contraction causes the ribs to pivot upward and outward, expanding the chest wall
  • Mostly used in inspiration
• Diaphragm


  • Contraction causes it to flatten and move downward (inspiration)
  • Relaxes during expiration
• Internal intercostal muscles


  • Contract for active expiration only
• Toi


  1. Causes chest cavity and lungs to contract

  2. Causes ribs and sternum to depress
• ABDOMINAL MUSCLES


  Contract for active expiration only
• ATMOSPHERIC PRESSURE (Patm)


  Pressure of the outside air
• At sea level


  760mm Hg or 1 atmosphere
• INTRA-ALVEOLAR PRESSURE (Pat)


  Pressure exerted by the air within the alveoli
• At rest it is equal to atmospheric pressure thus it is 0mm Hg
• When atmospheric pressure exceeds intra-alveolar press (intra-alveolar pressure is negative)

  Inspiration occurs
• When intra-alveolar pressure exceeds atmospheric pressure (intra-alveolar pressure is positive)


  Expiration occurs
• INTRAPLEURAL PRESSURE (P)


  Pressure of the fluid inside the pleural space
• At rest it is -4mm Hg
• It is always negative during normal breathing and is always less than intra-alveolar pressure because opposing forces exerted by the chest wall and the lungs
• TRANSPULMONARY PRESSURE


  The difference between the intrapleural pressure and the intra-alveolar pressure, which represents the distending pressure acting on the lungs
• Indicates the distending force across the lungs
• An increase in transpulmonary pressure


  Creates a larger distending pressure across the lungs (expansion of the lungs)
• LUNG COMPLIANCE


  The ease with which lungs can be stretched
• Larger lung compliance makes it easier to inspire
• Lung compliance


  • Depends on the elasticity of the lungs and on the surface tension of the fluid fibers in the connective tissue
  • More elastic less compliant
  • Greater tension = less compliant