Cardiovascular System Overview

Presented by: Eric Strong, Clinical Associate Professor of Medicine at Stanford University

Main Objectives

• Describe the overall function of the cardiovascular system.
• Identify major anatomic structures of the heart, including coronary arteries and the conduction system.
• Describe the cardiac cycle with definitions of systole and diastole.
• List and describe different types of blood vessels.
• Explain histological structure of the heart.

Function of the Cardiovascular System

• Primary Function: To pump blood throughout the body.
  • Oxygen Delivery: Deoxygenated blood is pumped from the heart to the lungs where it picks up oxygen and returns to the heart to be pumped to the rest of the body.
  • Other Functions:
    • Transport waste (e.g., CO2, bilirubin, lactate, urea).
    • Carry electrolytes, glucose, fatty acids, hormones (e.g., insulin, cortisol).
    • Transport immune components (e.g., white blood cells, antibodies, cytokines).

Heart Anatomy

• Four Chambers: Right atrium, right ventricle, left atrium, and left ventricle.
• Valves: Tricuspid, pulmonary, mitral, and aortic valves.
• Great Vessels:
  • Superior and inferior vena cava.
  • Pulmonary arteries and veins.
  • Aorta (ascending, arch, descending thoracic, abdominal).
• Septums:
  • Interatrial septum (thin).
  • Interventricular septum (thick and muscular).

Heart Conduction System

• SA Node: Acts as the heart's pacemaker.
  • Controls heart rate through sympathetic and parasympathetic nervous systems.
• AV Node: Acts as gatekeeper, delaying signal to ventricles.
• His-Purkinje System: Rapidly delivers signal causing ventricular contraction.

Coronary Arteries

• Right Coronary Artery (RCA): Supplies right ventricle, SA and AV nodes.
• Left Main Coronary Artery: Splits into Left Anterior Descending (LAD) and Left Circumflex arteries.

Cardiac Cycle

• Systole: Ventricular contraction.
• Diastole: Ventricular relaxation (includes atrial systole).
• Heart Sounds: S1 (closure of AV valves), S2 (closure of semilunar valves).
• Diastole duration decreases more than systole as heart rate increases.

Blood Vessels

• Types:
  • Arteries > Arterioles > Capillaries > Venules > Veins.
  • Capillaries: Sites of gas exchange, extensive network.
• Lymphatics: Return interstitial fluid to bloodstream.

Heart Histology

• Endocardium: Contains endothelium and Purkinje fibers.
• Myocardium: Composed of cardiomyocytes (contractile units, high mitochondria density).
• Pericardium:
  • Fibrous and serous layers.
  • Potential space (pericardial space) contains lubricating fluid.

Functional Components & Pathology

• Heart Components: Valves, myocardium, pericardium, conduction system, coronary arteries.
• Vascular Components: Arteries, veins, capillaries, lymphatics.
• Pathologies can be mapped to these components.

Conclusion

• This framework can aid in diagnosing cardiovascular diseases.