Circulatory System Overview

Introduction

• The process of blood circulation begins in the heart.
• The cycle involves the heart, lungs, arteries, veins, and capillaries.

Blood Circulation Process

Step 1: Entry of Deoxygenated Blood

• Right Atrium: Blood low in oxygen (rich in CO2) enters the heart through the tricuspid valve into the right atrium.
• Right Ventricle: Blood flows from the right atrium to the right ventricle.

Step 2: Pulmonary Circulation

• Pulmonary Arteries: Blood is pumped from the right ventricle to the lungs via the pulmonary arteries.
• Gas Exchange: In the lungs, carbon dioxide is released, and oxygen is absorbed.

Step 3: Return to the Heart

• Pulmonary Veins: Oxygen-rich blood returns to the heart through the pulmonary veins.
• Left Atrium: Blood enters the left atrium.
• Left Ventricle: Blood is transferred from the left atrium to the left ventricle.

Step 4: Systemic Circulation

• Aorta: Blood is pumped from the left ventricle into the aorta.
• Arteries, Capillaries, and Veins: Blood travels through arteries, reaching capillaries where nutrients and waste are exchanged.
  • Arteries: Deliver oxygenated blood to body tissues.
  • Capillaries: Sites of exchange between blood and tissues.
  • Veins: Carry deoxygenated blood (rich in CO2) back towards the heart.
  • Vena Cava: Major veins (vena cava) bring blood back to the heart.

Summary

• The circulatory system is a continuous loop from the heart to the lungs, back to the heart, and throughout the body.
• The heart's pumping action is crucial for moving blood through this system.

Key Points

• Importance of oxygen and carbon dioxide exchange in the lungs.
• Role of heart valves in directing blood flow.
• The difference between oxygenated and deoxygenated blood in circulation.