SH

Chapter25:Fluids&electrolytespart3

Gas Exchange and Carbon Dioxide Dynamics

  • The process of exhaling is crucial for removing carbon dioxide (CO₂) from the body.

  • Thick respiratory membranes lead to lower oxygen (O₂) absorption and higher CO₂ levels in the bloodstream, often due to pulmonary fibrosis.

Effects of Pulmonary Fibrosis and Emphysema

  • Pulmonary fibrosis causes replacement of lung tissue with scar tissue, affecting both alveoli and elastic tissue.

  • In emphysema, the surface area for gas exchange is reduced due to ruptured alveoli, leading to similar gas exchange issues.

Blood Gas Levels in Lung Diseases

  • As lung disease progresses:

    • CO₂ levels increase in the blood.

    • O₂ levels decrease.

  • High levels of CO₂ lead to hypercapnia, influencing breathing more than low O₂ levels.

CO₂ and Blood Chemistry

  • CO₂ combines with water to form carbonic acid, which dissociates into hydrogen ions (H⁺) and bicarbonate (HCO₃⁻).

  • The reaction effort engages an equilibrium, balancing reactants and products.

Equilibrium Concept in Blood

  • A teeter-totter analogy explains the balance between CO₂/water and H⁺/bicarbonate:

    • If H⁺ levels drop, the equilibrium shifts to produce more H⁺.

    • The reaction moves from left (CO₂ + H₂O) to right (H⁺ + HCO₃⁻).

  • Excess CO₂ can be converted to stabilize low H⁺ conditions.