Factors Influencing Pulmonary Ventilation

on 12.1.08 with 0 comments

  1. Respiratory Passageway Resistance
    1. upper respiratory passageways - relatively large, very little resistance to airflow (unless obstruction such as from food lodging or cancer)
    2. lower respiratory passageways - from medium-sized bronchioles on down, can alter diameter based on autonomic stimulation
      • a. parasympathetic - causes bronchioconstriction
      • b. sympathetic - inhibits bronchioconstriction
        • epinephrine - used to treat life-threatening bronchioconstriction such as during asthma and anaphylactic shock (carried by people susceptible to sudden constriction)
  2. Lung Compliance & Elasticity
    1. Lung Compliance - the ease with which lungs can be expanded by muscle contraction of thorax
      • fibrosis - decreases compliance
      • blocked bronchi - decreases compliance
      • surface tension - alveoli difficult to expand
      • thorax inflexibility - decreases compliance
    2. Lung Elasticity - the ease with which lungs can contract to their normal resting size (exhalation)
      • emphysema - decreases elasticity
    3. Alveolar Surface Tension - liquid on surface of alveoli causes them to collapse to smallest size
      • surfactant - lipoproteins that reduces surface tension on alveoli, allowing them to expand more easily
      • infant respiratory distress syndrome - premature babies that do not yet produce enough surfactant; must be ventilated for respiration

Category: Physiology Notes



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