Cardiovascular System Overview

Presenter

• Eric Strong, Clinical Associate Professor of Medicine at Stanford University

Lecture Objectives

• Functional overview of the cardiovascular system
• Identify major structures of the heart
• Understand the cardiac cycle: systole and diastole
• Describe different types of blood vessels
• Histological structure of the heart

Function of the Cardiovascular System

• Pumps blood throughout the body
• Delivers oxygen via blood
  • Deoxygenated blood -> lungs -> picks up oxygen
  • Oxygenated blood -> heart -> body
• Supports cellular respiration (ATP generation)
• Transports:
  • Oxygen, CO2, metabolic waste (bilirubin, lactate, urea)
  • Electrolytes, glucose, fatty acids
  • Hormones (insulin, cortisol)
  • Immune components (WBCs, antibodies, cytokines)

Heart Anatomy

• Structure

  • 4 chambers: right atrium, right ventricle, left atrium, left ventricle
  • Valves: tricuspid, pulmonary, mitral, aortic
  • Great vessels: superior/inferior vena cava, pulmonary arteries/veins, aorta
  • Septum: interatrial and interventricular

• Blood Flow Through Heart

  • Returns to heart: superior/inferior vena cava, coronary sinus
  • Flow: right atrium -> tricuspid valve -> right ventricle -> pulmonary valve -> pulmonary artery -> lungs -> pulmonary veins -> left atrium -> mitral valve -> left ventricle -> aortic valve -> aorta

• Valves

  • Function: ensure one-way blood flow
  • Types: atrioventricular (AV) and semilunar
  • Cusps: tricuspid, bicuspid (mitral)
  • Attached to chordae tendineae and papillary muscles

Conduction System

• Electrical Impulse Path

  • Originates: sinoatrial (SA) node
  • Travels through atria -> AV node -> His-Purkinje system -> ventricles

• Nodes

  • SA node: pacemaker, frequency controlled by autonomic nervous system
  • AV node: gatekeeper, delays signal to ventricles

Coronary Circulation

• Coronary Arteries
  • Right coronary artery (RCA)
  • Left main coronary artery -> bifurcates into:
    • Left anterior descending (LAD)
    • Left circumflex artery

Cardiac Cycle

• Phases
  • Atrial systole: atrial contraction, blood into ventricles
  • Ventricular systole: ventricles contract, blood out semilunar valves
  • Diastole: ventricles relax, AV valves open
• Heart Sounds
  • S1: closure of AV valves
  • S2: closure of semilunar valves

Blood Vessels

• Types
  • Arteries: thick-walled, elastic, handle high pressure
  • Arterioles: greatest resistance to flow
  • Capillaries: gas/nutrient/waste exchange
  • Veins: thin-walled, distensible, blood reservoir

Heart Histology

• Layers

  • Endocardium: inner lining, endothelial cells
  • Myocardium: cardiac muscle, cardiomyocytes
  • Pericardium: fibrous and serous layers

• Cardiomyocytes

  • Contractile units: sarcomeres (actin & myosin)
  • ATP and calcium-dependent
  • Connected by intercalated discs

Clinical Framework

• Heart Components

  • Valves: valvular heart disease, endocarditis
  • Myocardium: heart failure, myocarditis
  • Pericardium: pericardial effusions, pericarditis
  • Conduction System: arrhythmias
  • Coronary Arteries: coronary artery disease

• Blood Vessels

  • Arteries: peripheral artery disease
  • Veins: venous insufficiency
  • Capillaries: sepsis manifestations
  • Lymphatics: lymphedema

Conclusion

• Summary of cardiovascular components
• Pathological conditions mapping
• Next steps: deeper exploration of cardiovascular topics

• Action Items: Consider watching follow-up videos for deeper understanding on individual cardiovascular topics.