Chronic Bronchitis Lecture Notes

Overview of Chronic Bronchitis

• Chronic bronchitis is characterized by hypersecretion in the airways.
• Excessive mucus production impedes efficient gas exchange in the lungs.
• Commonly caused by prolonged exposure to irritants like cigarette smoke or other pollutants.

Gas Exchange and Alveoli

• Alveoli: Site of gas exchange, oxygen moves from the alveoli to the bloodstream.
  • Oxygenated blood circulates to the body via the left side of the heart.
  • Deoxygenated blood returns to the heart to be reoxygenated by the lungs.
• In chronic bronchitis, mucus blocks alveoli and airways.
  • Thicker membranes obstruct the passage of oxygen into the blood.

Pulmonary Arterioles Response

• Pulmonary arterioles adjust to oxygen levels in the alveoli.
  • If oxygen is low, arterioles constrict, redirecting blood to better-oxygenated alveoli.
  • This is a normal response but problematic in chronic bronchitis where mucus fills all alveoli.

Consequences of Blocked Alveoli

• Pulmonary Hypertension: Occurs when all pulmonary arterioles constrict due to low perceived oxygen levels.
  • Blood backs up into the right side of the heart.
• Cor Pulmonale: Right side of the heart hypertrophies (muscle thickens) to overcome pulmonary hypertension.
  • Can lead to right-sided heart failure.

Systemic Effects

• Blood continues to back up into the systemic venous circulation causing venous hypertension.
• Edema: Fluid leaks from venous system into the body.
  • Causes individuals to be "blue bloaters":
    • Blue: Due to cyanosis from lack of oxygen.
    • Bloaters: Due to fluid retention and edema.

Key Terms

• Hypersecretion: Excessive secretion of mucus.
• Hypertrophy: Thickening of the heart muscle.
• Cor Pulmonale: Right-sided heart thickening due to pulmonary hypertension.
• Cyanosis: A bluish discoloration of the skin due to poor oxygenation.
• Edema: Swelling caused by fluid retention.