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Respiratory System (Transport of Respiratory Gases (Haldane Effect (the…

- - - - allows blood pH to maintain homeostasis and resist changes in pH
      - if H+ ion concentration in blood rises, it combines with HCO3 --> H2CO3 --> CO2 + H2O
      - HCO3- is the alkaline reserve, can increase pH of blood if it drops too low
  - - - decreasing blood pH and increasing P CO2 weakens Hb-O2 binding --> enhances oxygen unloading in metabolically active tissues
- - - - passive process, inspiratory muscles relax and lungs recoil, intrapulmonary pressure rises as air flows out of lungs
    - - Total Lung Capacity (TLC) - total amount of air lungs can contain, sum of all capacities
      - Vital Capacity (VC) -Total amount that can be inhaled and exhaled. Sum of IRV, TV and ERV
      - Inspiratory Capacity (IC)- total amount of air that can be inhaled. Sum of TV and IRV
      - Functional Residual Capacity (FRC)-amount of air remaining in lungs after a normal tidal volume breath
    - - Tidal Volume (TV) - normal breath inhale + exhale, "quiet breathing" - ~500 mL
      - Inspiratory Reserve Volume (IRV) - volume of air that can be inhaled after normal tidal breath inhale
      - Expiratory Reserve Volume (ERV) - volume of air that can be exhaled after a normal tidal breath exhale
      - Residual Volume (RV) - volume of air that remains in lungs at all times, can't exhale it, keeps alveoli open
    - - Intrapleural Pressure
        
        Pressure in the pleural cavity that fluctuates with breathing. Constantly about 4mmHg less than intrapulmonary pressure
        
        Adhesive forces between visceral and parietal pleurae creates a negative pressure, and a vacuum keeping the lungs inflated
      - Transpulmonary Pressure
        
        the difference between the intrapulmonary and intrapleural pressures. This difference keeps the lungs inflated, the greater the pressure the larger the lungs. Any condition causing this pressure to become the same as intrapulmonary pressure would cause lung collapse
      - Intrapulmonary Pressure
        
        Pressure within the alveoli. Fluctuates with breathing but always equalizes with atmospheric pressure
      - Boyle's Law explains the relationship between pressure and volume of a gas: At constant temperature, the pressure of a gas is inversely related to its volume. P1V1=P2V2
    - - diaphragm and external intercostals contract increasing thoracic cavity size and decreasing pressure, and air flows into lungs until interpulmonary pressure is equal to Patm
    - - VRG - Ventral Respiratory Group
        
        generates rhythm of breathing --> eupnea = normal respiratory rate ~12-15 breaths/min; integrative system
        
        ventral portion of medulla
      - DRG - Dorsal Respiratory Group
        
        dorsal portion of medulla
        
        integrates input from peripheral stretch and chemoreceptors, sends info to VRG neurons, modifies rhythms made by VRG
      - Pontine
        
        dorsal portion of pons
        
        neurons influence and modify VRG activity, smooth out transition between inspiration and expiration (respiratory pattern)
- - - - controlled by local autoregulatory mechanisms that continuously respond to local conditions
      - Low PO2 due to inadequate ventilation and blood takes away O2 faster than it can be replaced. Arterioled will constrict
      - When PCO2 is low, bronchioles constrict to promote flushing of blood through pulmonary capillaries
      - High PO2 dilates arterioles
      - Chemoreceptors - respond to chemical fluctuations in arterial blood - levels of CO2, O2, and H+
        
        Central chemoreceptors - throughout brain stem, including ventrolateral medulla
        
        Peripheral chemoreceptors - aortic arch and carotid arteries
- - - - Henry's Law: when a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure.
      - Dalton's Law of Partial Pressures: total pressure exerted by a mixture of gases is directly proportional to the percentage of a particular gas in the mixture