Cardiovascular System Study Notes

Anatomy of the Heart

Major Structures of the Heart

  • Brachiocephalic Truck
  • Superior Vena Cava
  • Right Pulmonary Artery
  • Ascending Aorta
  • Pulmonary Trunk
  • Right Pulmonary Veins
  • Left Common Carotid Artery
  • Left Subclavian Artery
  • Aortic Arch
  • Ligamentum Arteriosum
  • Left Pulmonary Artery
  • Left Pulmonary Veins
  • Right Atrium
  • Right Coronary Artery (located in coronary sulcus)
  • Anterior Cardiac Vein
  • Right Ventricle
  • Right Marginal Artery
  • Small Cardiac Vein
  • Auricle of Left Atrium
  • Circumflex Artery
  • Left Coronary Artery (located in coronary sulcus)
  • Left Ventricle
  • Inferior Vena Cava
  • Great Cardiac Vein
  • Anterior Interventricular Artery (located in anterior interventricular sulcus)
  • Apex of the Heart

Views of the Heart

(b) Anterior View
  • Aorta
  • Left Pulmonary Artery
  • Left Pulmonary Veins
  • Auricle of Left Atrium
  • Left Atrium
  • Great Cardiac Vein
  • Posterior Vein of Left Ventricle
  • Left Ventricle
  • Apex
  • Superior Vena Cava
  • Right Pulmonary Artery
  • Right Pulmonary Veins
  • Right Atrium
  • Inferior Vena Cava
  • Coronary Sinus
  • Right Coronary Artery (located in coronary sulcus)
  • Posterior Interventricular Artery (in posterior interventricular sulcus)
  • Middle Cardiac Vein
  • Right Ventricle
(d) Posterior Surface View
  • Superior Vena Cava
  • Right Atrium
  • Right Pulmonary Artery
  • Pulmonary Trunk
  • Right Pulmonary Veins
  • Fossa Ovalis
  • Pectinate Muscles
  • Tricuspid Valve
  • Right Ventricle
  • Chordae Tendineae
  • Trabeculae Carneae
  • Inferior Vena Cava
  • Aorta
  • Left Pulmonary Artery
  • Left Atrium
  • Left Pulmonary Veins
  • Mitral (Bicuspid) Valve
  • Aortic Valve
  • Pulmonary Valve
  • Left Ventricle
  • Papillary Muscle
  • Interventricular Septum
  • Epicardium
  • Myocardium
  • Endocardium
(e) Frontal Section
  • Superior Vena Cava
  • Right Atrium

Electrical Conduction System of the Heart

Sequence of Electrical Excitation

  1. Sinoatrial (SA) Node (Pacemaker)
    • Generates impulses vital for initiating heartbeats.
  2. Internodal Pathway
    • Conducts impulses from the SA node to the Atrioventricular (AV) node.
  3. Atrioventricular (AV) Node
    • Impulses pause for 0.1 seconds to allow the atria to contract completely before the ventricles are activated.
  4. Atrioventricular Bundle
    • Connects the atria to the ventricles, allowing the electrical impulse to travel through the heart.
  5. Bundle Branches
    • Conduct impulses through the interventricular septum, directing the electrical signals down towards the ventricles.
  6. Purkinje Fibers
    • Depolarize the contractile cells of both ventricles, leading to coordinated contraction.

Electrical Activity on ECG

  • P Wave: Represents atrial depolarization, initiated by the SA node.
  • QRS Complex: Represents ventricular depolarization, occurring after the atrial depolarization has completed and the impulse is delayed at the AV node. Atrial repolarization occurs simultaneously.
  • T Wave: Represents ventricular repolarization, which begins at the apex of the heart.
  • Intervals and Segments on ECG:
    • P-Q Interval: Time taken for atrial depolarization to ventricular depolarization.
    • S-T Segment: Time during which the ventricles are depolarized.
    • Q-T Interval: Time from the start of the QRS complex to the end of the T wave, showing the length of time for ventricular depolarization and repolarization.

Blood Flow Through the Heart

Pathway of Blood Flow

  1. Blood returns from the superior and inferior vena cavae to the Right Atrium.

    • Receives blood from:
      • Superior vena cava
      • Inferior vena cava
      • Coronary sinus
    • Sends blood to:
      • Right Ventricle
    • Valves involved:
      • Right Atrioventricular Valve (Tricuspid Valve)

  2. From the Right Ventricle, blood flows through:

    • Pulmonary Semilunar Valve to the Pulmonary Trunk.
    • Blood enters the pulmonary circuit of vessels for gas exchange in the lungs.

  3. Oxygen-rich blood returns from the Pulmonary Veins to the Left Atrium.

    • Sends blood to:
      • Left Ventricle
    • Valves involved:
      • Left Atrioventricular Valve (Mitral Valve)

  4. From the Left Ventricle, blood flows through:

    • Aortic Semilunar Valve into the Aorta.
    • Blood enters systemic circuit of vessels for nutrient delivery to peripheral tissues and organs.