Describe double circulation in human beings and why is it necessary?

Double circulation means blood passes through the heart twice during one complete circulation in the human body. It includes pulmonary circulation and systemic circulation. This ensures that oxygen-rich and oxygen-poor blood never mix.

Types of circulation

• Pulmonary circulation: Blood moves from the right ventricle to the lungs to absorb oxygen and release carbon dioxide, then returns to the left atrium.
• Systemic circulation: Blood moves from the left ventricle through the body, delivering oxygen to tissues, and returns deoxygenated blood to the right atrium.

Importance

• Keeps oxygenated and deoxygenated blood separate for efficiency.
• Maintains high pressure in systemic circulation for faster nutrient delivery.
• Ensures full oxygenation of body tissues and removal of carbon dioxide.