Lecture Notes: Anatomy of the Heart

Introduction

• Focus on the basic anatomy of the heart.
• Heart location: Mediastinum, in the pericardial cavity of the thoracic cavity.

The Pericardium

• Definition: Serous membrane enclosing the heart.
• Structure: Two layers - Parietal (outer layer) and Visceral (inner layer, also called Epicardium).
• Function: Fluid-filled cavity provides lubrication, reducing friction as the heart beats.

Layers of the Heart Wall

1. Epicardium: Outermost layer, thin.
2. Myocardium: Middle layer, muscular, cardiac muscle.
3. Endocardium: Innermost layer, made of endothelial cells with connective tissue, smooth to avoid damage to red blood cells.

Anatomy of the Heart

• Four Chambers:
  • Atria: Two upper chambers, receiving blood.
  • Ventricles: Two lower chambers, pumping blood.
• Blood Flow:
  • Blood returns to the heart via inferior/superior vena cava.
  • Blood exits through the aorta.

Right Side of the Heart

• Function: Part of pulmonary circulation, sends deoxygenated blood to the lungs.
• Key Structures:
  • Receives blood from inferior/superior vena cava and coronary sinus.
  • Right Atrium: Blood enters here.
  • Tricuspid Valve: Opens to let blood into the right ventricle.
  • Right Ventricle: Pumps blood through the pulmonary valve to the pulmonary arteries.

Pulmonary Circulation

• Pulmonary Arteries: Carry deoxygenated blood to lungs.
• Pulmonary Veins: Return oxygenated blood to the heart.

Left Side of the Heart

• Function: Pumps oxygenated blood to the body.
• Key Structures:
  • Left Atrium: Receives oxygenated blood from pulmonary veins.
  • Bicuspid (Mitral) Valve: Opens to let blood into the left ventricle.
  • Left Ventricle: Larger, stronger muscle, pumps blood through the aortic valve into the aorta.

Heart Valves

• Types of Valves:
  • Atrioventricular Valves: Tricuspid and Bicuspid (Mitral) valves.
  • Semilunar Valves: Pulmonary and Aortic valves.
• Function: Open/close in response to pressure changes to maintain one-way blood flow.

Fibrous Skeleton of the Heart

• Structure: Connective tissue core, supports valves, prevents overstretching.
• Function: Electrical insulator, insertion point for cardiac muscles.

Circulation Pathways

• Systemic Circulation: Oxygenated blood to body tissues, returns deoxygenated blood to the heart.
• Pulmonary Circulation: Sends deoxygenated blood to lungs, returns oxygenated blood to the heart.
• Coronary Circulation: Supplies blood to the heart muscle itself.
  • Coronary Arteries: Branch from the aorta.
  • Coronary Veins: Drain into the right atrium via the coronary sinus.

Summary Questions

1. Describe the pericardium and its function.
2. What are the three layers of the heart wall made of?
3. Explain the flow of blood through the heart chambers and associated valves, arteries, and veins.
4. Describe how heart valves function to prevent backflow.
5. Outline pulmonary and systemic circulation.
6. Detail coronary circulation.

Next Steps

• The next video will cover cardiac muscle tissue and the conduction system.