How many double circulations are normally completed by the human heart in one minute

Options

A. Eight
B. Sixteen
C. Thirty six
D. Seventy two

Answer

To determine how many double circulations are normally completed by the human heart in one minute, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Double Circulation**:
- The human circulatory system is classified as a double circulatory system. This means that blood travels through two separate circuits: the pulmonary circulation and the systemic circulation.

2. **Define Pulmonary and Systemic Circulation**:
- **Pulmonary Circulation**: This is the pathway where deoxygenated blood is transported from the heart to the lungs. In the lungs, the blood gets oxygenated and returns to the heart.
- **Systemic Circulation**: This is the pathway where oxygenated blood is transported from the heart to the rest of the body, delivering oxygen and nutrients to various organs and tissues.

3. **Identify the Heartbeat Rate**:
- In a normal, healthy individual, the human heart beats approximately 72 times per minute.

4. **Calculate Double Circulations**:
- Since each heartbeat corresponds to one complete cycle of both pulmonary and systemic circulation, the number of double circulations in one minute is equal to the number of heartbeats per minute.
- Therefore, if the heart beats 72 times in one minute, it completes 72 double circulations.

5. **Select the Correct Option**:
- Given the options (8, 16, 36, 72), the correct answer is 72.

### Final Answer:
The human heart normally completes **72 double circulations** in one minute.

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