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Human Heart

by Yaswanth•

The human heart is a muscular organ that pumps blood throughout the body. It is roughly the size of a fist and is located in the chest, slightly to the left of the midline. The heart is divided into four chambers and works as a dual pump, sending oxygen-rich blood to the body and oxygen-poor blood to the lungs.

Anatomy of the Human Heart

1. Chambers of the Heart

The heart has four chambers:

  • Right Atrium – Receives oxygen-poor blood from the body through the superior and inferior vena cava.
  • Right Ventricle – Pumps oxygen-poor blood to the lungs via the pulmonary artery.
  • Left Atrium – Receives oxygen-rich blood from the lungs through the pulmonary veins.
  • Left Ventricle – Pumps oxygen-rich blood to the body through the aorta.

2. Valves of the Heart

To ensure unidirectional blood flow, the heart has four valves:

  • Tricuspid Valve – Between the right atrium and right ventricle.
  • Pulmonary Valve – Between the right ventricle and pulmonary artery.
  • Mitral (Bicuspid) Valve – Between the left atrium and left ventricle.
  • Aortic Valve – Between the left ventricle and aorta.

3. Major Blood Vessels

  • Superior and Inferior Vena Cava – Carry oxygen-poor blood from the body to the right atrium.
  • Pulmonary Arteries – Carry oxygen-poor blood from the right ventricle to the lungs.
  • Pulmonary Veins – Carry oxygen-rich blood from the lungs to the left atrium.
  • Aorta – The largest artery, carrying oxygen-rich blood from the left ventricle to the body.

4. Layers of the Heart Wall

  • Endocardium – The inner lining of the heart.
  • Myocardium – The thick muscular layer responsible for contractions.
  • Epicardium – The outermost protective layer.

5. Blood Circulation in the Heart

  • Pulmonary Circulation – Blood moves from the right side of the heart to the lungs for oxygenation and back to the left side.
  • Systemic Circulation – Oxygen-rich blood is pumped from the left side to the entire body and returns oxygen-poor blood to the right side.

6. Electrical Conduction System

The heart’s rhythmic contractions are controlled by electrical signals:

  • Sinoatrial (SA) Node – The natural pacemaker of the heart, located in the right atrium.
  • Atrioventricular (AV) Node – Delays the impulse before sending it to the ventricles.
  • Bundle of His & Purkinje Fibers – Help distribute the electrical impulse to ensure coordinated contraction.