EX 30 Pre-Lab Lecture (2)

Anatomy of the Heart

• Description: The heart is a cone-shaped organ, approximately the size of a fist, situated in the mediastinum between the lungs.

  • Shape: It resembles an inverted triangle with a defined base and apex.

Learning Objectives

• Location of the Heart: Understand where the heart is located within the thoracic cavity.

• Covering and Lining Tissues: Identify the tissues that cover and line the heart.

• Anatomical Areas: Name and locate major anatomical areas and features of the heart along with their functions.

• Valves: Explain the operation of atrioventricular and semilunar valves.

• Oxygenation Distinction: Distinguish between vessels carrying oxygen-rich blood and those carrying CO2-rich blood.

• Heart as Double Pump: Understand the concept of the heart as a double pump and compare pulmonary vs systemic circuits.

• Blood Pathway: Trace the pathway of blood through the heart, including functional supply and related vessels.

• Histology of Cardiac Muscle: Describe cardiac muscle histology, emphasizing intercalated discs and the spiral arrangement of cells.

Structure and Location of the Heart

• Mediastinum: Heart located between lungs in the mediastinum region.

• Apical Impulse: Located near the midsternal line, approximately at the level of the 2nd rib to diaphragm.

Pericardial Sac

• Layers:

  • Visceral Pericardium: Innermost layer directly covering the heart.

  • Parietal Pericardium: Outer fibrous layer that encloses the heart.

  • Pericardial Cavity: Space between the visceral and parietal layers, containing fluid.

Heart Wall Structure

• Epicardium: The outer layer of the heart wall.

• Myocardium: The middle layer, primarily composed of cardiac muscle cells.

• Endocardium: The inner lining of the heart chambers.

• Supporting Structures: Include fibrous pericardium and coronary vessels.

Heart Chambers and Valves

• Chambers:

  • Atria: Upper chambers that receive blood.

  • Ventricles: Lower chambers that pump blood out.

  • Septum: Divides right and left heart into interatrial and interventricular sections.

• Valves:

  • Atrioventricular Valves: Tricuspid (Right) and Bicuspid/Mitral (Left).

  • Semilunar Valves: Pulmonary (Right) and Aortic (Left).

Blood Flow Through the Heart

• Pathway:

  1. From Body to Heart:

     • Blood returns via the Superior and Inferior Vena Cava to the Right Atrium.

     • Passes through Tricuspid Valve to Right Ventricle.

     • Moves through the Pulmonary Valve into Pulmonary Trunk to lungs.

  2. From Lungs to Body:

     • Oxygenated blood returns through Pulmonary Veins to Left Atrium.

     • Passes through Bicuspid Valve to Left Ventricle.

     • Blood is pumped through Aortic Valve into Aorta, distributing to the body.

Major Blood Vessels of the Heart

• Arteries:

  • Right Ventricle to Pulmonary Trunk.

  • Left Ventricle to Aorta.

• Veins:

  • Right Atrium collects blood from the Coronary Sinus, SVC, and IVC.

  • Left Atrium receives blood from Pulmonary Veins.

Microscopic Anatomy of Cardiac Muscle

• Structure: Cardiac muscle is striated, containing intercalated discs for communication between cells.

• Arrangement: Cells are bundled into spirals or figure-8 shapes to facilitate efficient contraction.

Activities for Learning

• Using Heart Model: Identifying anatomical structures and understanding cardiac circulation.

• Dissection: Analyzing a sheep heart to compare with human anatomy.

• Identifying Structures:

  • External: Pericardial sac, chambers, coronary vessels, etc.

  • Internal: Valves, coronary artery openings, and muscle features.

Structures to Identify in Dissection

• External Structures:

  • Auricles, Pulmonary arteries/trunk, Aorta, and other major features.

• Internal Structures:

  • Valves (Aortic, Pulmonary, Tricuspid, Mitral), coronary arteries, and papillary muscles.