Respiratory System

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Respiratory System
2012-10-01 21:57:22

Structure, function
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  1. Pleura cavity
    Visceral pleura
    Parietal pleura
    Function (3)
    • Pleura cavity = btwn visceral and parietal pleurae
    • Visceral pleura = inner lung lining
    • Parietal pleura = outer lung lining, lines the thoracic wall and sperior aspect of the diaphragm
    • Functions:
    • a) reduce friction
    • b) create pressure gradient
    • c) compartmentalization (preventing spread of infection)
  2. Upper resp system
    - 3 parts
    - function (2)
    • nose
    • nasal cavity
    • pharynx
    • function: a) filter and b) humidify incoming air
  3. Lower resp system
    - 5 parts
    • larynx
    • trachea
    • bronchi
    • bronchioles
    • alveoli
  4. Tracheobronchial epithelium
    • smooth muscles in walls of airway increase gradually and control conductance of airaways
    • conductance: the ability to allow flow; inverse of resistance
    • tracheobronchial tree: a system of tubes conveying air to the respiratory system; has 24 orders of braches; ends in alveoli where gas xchange occurs
    • cartilage rings support the trachea and smaller airways to bronchioles, preventing collapse
    • elevator effect: cilia pushes mucus and forieng particles up airway
    • functions: a) warms, b) humidifies, c) filters
  5. Respiratory membrane cells
    1) type I alveolar cells
    2) type II alveolar cells
    3) alveolar macrophages (dust cells)
    4) capillary endtothelium
    • type I alveolar cells: simple squamous epithelium
    • type II alveolar cells: cuboidal cells; produce surfactant
    • alveolar macrophages or dust cells: patrol epithelium; engulf foreign particles
    • capillary endothelium
  6. Compliance
    - definition
    - factors (3)
    Surfactant (produced from what cell type?)
    • compliance: how easily lungs can be inflated
    • factors:
    • a) elastin (stretch) and collagen fibers (resist stretch)
    • b) water content
    • c) surface tension (* increase ST = increase compliance)
    • - Surface tension in alveoli reflects the attraction of H2O molecules via H-bond. Surfactant interrupts the H-bond thus reduce suraface tension - such reduction in surface tension makes it easier to inflate the alveoli
    • - Surfactant is produced from type II alveolar cells
    • - inflation pressure stimulates release of surfactant from type II cells
  7. What (3) factors affect alveolar-capillary diffusion? (mvt of O2 and CO2)
    • 1) permeability (thickness)
    • 2) surface area
    • 3) concentration gradient for the gas (obstruction can lead to stale air, limiting [gradient])
  8. Lung ventilation
    - definition
    - (2) factors
    • lung ventilation: the act of driving air in and out of the lungs
    • factors:
    • a) action of respiratory (intercoastal) muscles - chest compliance (affecting volume)
    • b) lung compliance (how easiliy lungs can be inflated; alveoli to change size)
  9. Respiratory muscles (5)
    - principle resp muscles
    - accessory muscles of inhalation
    - accessory muscles of exhalation
    • principle respĀ  muscle: (1) diaphram (and external intercoastal muscles)
    • accessory musclles of inhalation: (2) scalene, (3) sternocleidomastoid
    • accessory muscle on exhalation: (4) internal intercoastal (pulls chest space = smaller, (5) abdominal muscles (3 of them; forces diaphragm upwards; diaphragm bounces back b/c its passive)
  10. tidal volume*
    • air inhaled or exhaled in oen quiet breath
    • (hard to measure) (~0.5L)
  11. inspiratory reserve volume
    air in excess of tidal inspiration that can be inhaled with max effort (~3L)
  12. expiratory reserve volume
    • air in excess of tidal expiration that can be exhaled with max effort
    • (minus residue volume)
  13. residual volume
    air remaining in lungs after max expiration, keeps alveoli inflated
  14. vital capacity
    • amount of air that can be exhaled with max effort after max inspiration; assess strength of thoracic muscles and pulmonary function (during exercise)
    • max inhalation to max expiration (minus residual volume)
  15. inspiratory capacity
    • max amount of air that can be inhaled after a normal tidal expiration
    • max inhalation to tidal expiration
  16. functional residual capacity
    • amount of air in lungs after a normal tidal expiration
    • tidal expiration to residual volume
  17. total lung capacity
    max amount of air lungs can contain (~5-6L)
  18. forced expiratory volume (FEV)*
    • % of vital capacity exhaled/time
    • health adult 75 to 85% in 1 sec
    • (vital capacity, max exhaled after max inspiration)
  19. minute respiratory volume (MRV)
    • TV x resp rate (at rest)
    • e.g. 500mL x 12 breaths/min = 6L/min or 6000mL/min
    • max 125-170L/min
  20. partial pressure
    Pa02 or PO2 normal value
    Normal O2 saturation
    • partial pressure: pressure of just O2 gas/all gases OR pressure of a gas in a gas mixutre is similar to concentration fo that gas in that gas mixture
    • Pa02 or PO2 normal value: >80 mm Hg
    • Normal O2 saturation: 95-97%
  21. Normal partial pressure PaCO2
    When you exhale you remove CO2 from your blood and also (increase/decrease) the amount of carbonic acid, (raising/lowering) your blood pH
    • Normal partial pressure PaCO2: 35-45 mm Hg
    • When you exhale you remove CO2 from your blood and also decrease the amount of carbonic acid,
    • raising your blood pH (basic)
  22. Two types of chemoreceptors

    central chemoreceptors
    peripheral chemoreceptors
    • central chemoreceptors: measure PCO2 and pH in cerebrospinal fluid; increase resp when PCO2 increases or pH decreases
    • peripheral chemoreceptors:
    • a) measures PO2 in arterial blood;
    • b) increases resp when PO2 <60 mm Hg;
    • c) more sensitive than central chemorecept. (starts faster)
    • d) not as powerful
    • Both can adapt to stimulus and become less sensitive with prolonged exposure