Overview of Heart Function:

• Oxygenated blood is pumped from the left side of the heart, delivering oxygen and nutrients to tissues.
• Blood returns to the right side of the heart, which pumps it through the pulmonary circuit for reoxygenation.
• The cycle repeats continuously.

Heart Structures and Layers:

• Great vessels: Entry and exit points for blood to and from the heart.

Heart Wall Layers:

1. Endocardium: Innermost layer, composed of simple squamous epithelial tissue, lines all four heart valves.
2. Myocardium: Middle layer; cardiac muscle with trabeculae carneae (rough, muscular pattern).
3. Epicardium (visceral layer): Outer layer of simple squamous epithelium; secretes serous fluid into the pericardial cavity to lubricate and prevent friction.
4. Pericardial cavity: Space between the visceral and parietal layers containing serous fluid.
5. Fibrous pericardium: Outermost dense connective tissue layer, inelastic and fibrous, providing protection and anchoring the heart.

Mediastinum:

• The region within the thoracic cavity that contains:
  • The heart.
  • The esophagus.
  • The trachea.

Heart Valves:

• Atrioventricular (AV) valves: Control blood flow between atria and ventricles:
  • Mitral (bicuspid) valve: Left side.
  • Tricuspid valve: Right side.
• Semilunar valves: Control outflow from ventricles:
  • Aortic valve: Left ventricle to aorta.
  • Pulmonary valve: Right ventricle to pulmonary artery.

Septum:

• Thick myocardial layer separating the right and left ventricles, lined with endocardium.

The Cardiac Cycle:

• Describes the sequence of electrical and mechanical events during a heartbeat.

Includes atrial systole, ventricular systole, and relaxation phases (diastole).

Summary:

This review consolidates foundational anatomy and physiology of the heart, covering its layered structure, valvular functions, and the systemic and pulmonary circuits. Understanding these components is essential for grasping how various diseases impact cardiac function.