What is meant by double circulation? What is its significance?

Explanation

### Step-by-Step Solution:

1. **Definition of Double Circulation**:
- Double circulation refers to the process in which blood flows through two distinct circuits in the body: the systemic circulation and the pulmonary circulation. This means that blood passes through the heart twice during one complete cycle.

2. **Components of Double Circulation**:
- **Systemic Circulation**: This circuit carries oxygenated blood from the heart to the body tissues and returns deoxygenated blood back to the heart.
- **Pathway**: Heart → Tissues (Oxygenated) → Heart (Deoxygenated).
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