Lecture Notes on the Heart

Introduction

• Discuss the location of the heart and its protection.
• Explore the four chambers of the heart and its internal structure.
• Examine the blood vessels attached to the heart.
• Understand how the heart functions as two pumps in one.
• Discuss the flow of blood through the heart.
• Talk about heart valves and the electrical system of the heart.
• Introduction to electrocardiogram, contraction, and relaxation (systole and diastole).

Location and Protection of the Heart

• Positioned in the chest between vertebral column (posterior) and sternum (anterior).
• Laterally protected by the lungs; diaphragm below separates thoracic and abdominal cavities.
• Apex touches the chest wall; base is superior and posterior.
• Heart is suspended by great vessels (arteries and veins).

Serous Membrane System

• Protects heart and abdominal organs.
• Heart is enclosed in a serous membrane (visceral layer on the organ, parietal layer on the cavity wall).
• Contains serous fluid to reduce friction.

Anatomy of the Heart

Heart Valves

• Atrio-Ventricular (AV) Valves: Prevent backflow from ventricles to atria.
  • Right AV Valve: Tricuspid (3 cusps)
  • Left AV Valve: Mitral/Bicuspid (2 cusps)
• Semilunar Valves: Prevent backflow from arteries to ventricles.
  • Pulmonary Valve (right side)
  • Aortic Valve (left side)

Heart Chambers

• Atria: Upper chambers (right and left) receive blood.
• Ventricles: Lower chambers (right and left) pump blood out.
• Septum divides right and left sides of the heart.

Blood Flow Through the Heart

• Pulmonary Circuit: Heart to lungs (pulmonary arteries).
• Systemic Circuit: Heart to body (aorta).
• Blood enters right atrium (deoxygenated), goes to right ventricle, to lungs via pulmonary trunk.
• Oxygenated blood returns to left atrium, to left ventricle, pumped through aorta.

Coronary Circulation

• Coronary Arteries: Supply blood to heart muscle.
  • Right Coronary Artery (RCA)
  • Left Coronary Artery (LCA)
• Coronary Sinus: Veins drain blood back to right atrium.

Heart's Electrical System

• Sinoatrial (SA) Node: Initiates heartbeat, located in right atrium.
• Atrioventricular (AV) Node: Conducts impulse to ventricles.
• Bundle of His & Purkinje Fibers: Conduct impulses through ventricles for contraction.

Electrocardiogram (ECG)

• P Wave: Atrial depolarization.
• QRS Complex: Ventricular depolarization.
• T Wave: Ventricular repolarization.

Cardiac Cycle

• Systole: Heart contraction, blood ejection.
• Diastole: Heart relaxation, blood filling.
• Cardiac sounds: "Lub" (AV valves closing) and "Dub" (semilunar valves closing).

Calculating Cardiac Output

• Stroke Volume: Amount of blood pumped per beat (~70 mL at rest).
• Heart Rate: Beats per minute (~70 at rest).
• Cardiac Output: Stroke volume x heart rate.
  • At rest: ~5 liters/min.
  • Max exertion: ~25 liters/min.

This summary captures the comprehensive coverage of the heart's anatomy, function, and associated systems discussed in the lecture.