Which adrenal hormone accelerates heart beat under normal conditions ?

Explanation

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks which adrenal hormone accelerates the heartbeat under normal conditions.

2. **Understand the Role of Adrenal Hormones**: The adrenal glands secrete several hormones, but the two most relevant to heart rate are adrenaline (also known as epinephrine) and noradrenaline (also known as norepinephrine).

3. **Function of Adrenaline**: Adrenaline is known to increase heart rate and cardiac output. It prepares the body for 'fight or flight' responses, which includes accelerating the heartbeat.

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