Cardiology+

Learning Outcomes

  • Anatomy of the Heart: Describe heart structure, vascular supply, pericardium, and blood flow tracing (major vessels, chambers, and valves).

  • Action Potential in Cardiac Muscle: Explain cardiac action potential, calcium ions' role in contraction, and the heart's conducting system. Identify ECG-related electrical events.

  • Cardiac Cycle Events: Describe atrial and ventricular systole/diastole phases and correlate heart sounds with events in the cycle.

  • Cardiac Output Factors: Define cardiac output (CO), influence of heart rate and stroke volume, and adjustments during varied physical activity levels.

Introduction to the Heart

  • The Cardiovascular System includes:

    • Heart: Pumps blood; approximately 100,000 beats/day.

    • Blood: Circulates nutrients and oxygen.

    • Blood Vessels: Arteries, veins, and capillaries facilitate blood flow.

Anatomy of the Heart

Blood Circuits

  • Pulmonary Circuit: Blood movement to/from lung gas exchange surfaces.

  • Systemic Circuit: Blood movement to/from the body.

Structure and Function

  • Chambers of the Heart (four total):

    • Right Atrium: Receives systemic circuit blood.

    • Right Ventricle: Pumps blood into the pulmonary circuit.

    • Left Atrium: Receives pulmonary circuit blood.

    • Left Ventricle: Pumps blood into the systemic circuit.

Physical Structure

  • Location:

    • Positioned in the mediastinum between the pleural cavities, apex pointing inferiorly.

    • Surrounded by the pericardium (outer fibrous and inner serous layers).

Pericardium

  • Pericardium: Structure surrounding the heart composed of two layers:

    • Outer Fibrous Layer: Provides structural support.

    • Inner Serous Layer: Contains parietal and visceral layers, with fluid-filled pericardial cavity.

Cardiac Anatomy Overview

Vascular Connections

  • Great Vessels: Connection points for major arteries/veins at the base of the heart.

Surface Landmarks

  • Atria: Thin-walled with auricles for expansion; Sulci are grooves marking boundaries of chambers and contain fat and blood vessels.

Functional Anatomy

  • Valves:

    • Atrioventricular (AV) Valves: Tricuspid and mitral valves prevent backflow from ventricles to atria during contraction.

    • Semilunar Valves: Pulmonary and aortic valves prevent backflow during relaxation.

Coronary Circulation

  • Coronary arteries: Supply blood to heart muscle.

  • Coronary veins: Return deoxygenated blood from the heart muscle.

  • Coronary artery disease (CAD): Blockages in coronary circulation lead to decreased oxygen supply and can cause heart damage.

Cardiac Cycle

Phases of the Cardiac Cycle

  • Systole and Diastole: Phases of contraction and relaxation in heart chambers.

  • Heart Sounds: Detected using a stethoscope (S1 for AV valve closure, S2 for semilunar valve closure).

Cardiac Output

  • Cardiac Output (CO): Amount of blood pumped by the left ventricle in one minute, calculated as CO = HR x SV (Heart Rate x Stroke Volume).

  • Influencing Factors:

    • Heart Rate: Changed by autonomic innervation and hormones.

    • Stroke Volume: Influenced by end-diastolic volume (EDV), end-systolic volume (ESV), and the strength of cardiac contractions.

Impact of Activity Levels

  • Adjustments to Physical Activity: Changes in heart rate and stroke volume ensure adequate blood flow during different levels of physical exertion.

Summary

  • The heart operates as a complex organ composed of distinct chambers and valves, which facilitates the circulation of blood throughout the body, supported by the coronary system and regulated by electrical impulses and various physiological processes.