CVS task 2

• Inferior Attachment of the Pericardium and Its Role in Lung Hyperinflation (e.g., COPD):

  • The pericardium attaches inferiorly to the central tendon of the diaphragm.
  • This attachment explains why, in conditions like COPD, where the lungs are hyperinflated, the diaphragm is flattened and pushed down. As a result, the heart appears long and thin on chest X-rays, rather than its usual broader shape.
• Histological Composition of the Fibrous Pericardium and Its Function

  • The fibrous pericardium consists of dense irregular connective tissue.
  • This structure provides:
  • Toughness and rigidity, preventing overdistension of the heart.
  • Anchorage to surrounding structures (sternum, diaphragm, and great vessels).
  • Protection by forming an external barrier against infection and trauma.
• Space Between Parietal and Visceral Layers of the Serous Pericardium

  • The space between the parietal and visceral layers is called the pericardial cavity.
  • It contains a small amount of pericardial fluid (~ 15 – 50 mL).
• Function of Pericardial Fluid

  • Lubrication: Reduces friction as the heart contracts and relaxes within the pericardial sac.
  • Shock Absorption: Helps cushion the heart against external forces.
• Effect of Pericarditis on Cardiac Function:

  • Pericarditis (inflammation of the pericardium) leads to increased fluid accumulation (pericardial effusion) or friction between pericardial layers.
  • Severe cases may cause cardiac tamponade, where excessive fluid compresses the heart, restricting its ability to fill with blood and pump effectively.
  • This resembles pleuritis/pleurisy in the lungs, where inflammation of the pleura causes friction rub and chest pain, especially during respiration.
• • The myocardium (cardiac muscle) is the thickest section of the heart wall and contains cardiomyocytes; the contractile cells or muscle fibres of the heart.
• • The innermost layer of the heart is the endothelium
  • Endothelium lining the cardiac chambers is continuous with the endothelium of all blood vessels in the body and is composed of squamous epithelial cells
  • The cardiac endothelium provides a friction free interface between the walls of the chambers and the blood contained within them and moving through them
  • This layer just like endothelial cells lining blood vessels also secretes prostacyclin, which repels platelets and prevents platelet adhesion to the walls of the cardiac chambers and vessels