Sympathetic nerve edings release non-adrenaline which leads to

Options

A. Increase in rate of heart beat
B. Decrease in speed of conduction of action potential through heart musculature
C. Decrease in cardiac output and stroke volume
D. Increase in stroke volume but decrease in cardiac output

Answer

To solve the question regarding the effects of noradrenaline released from sympathetic nerve endings, we can analyze the options provided step by step.

### Step-by-Step Solution:

1. **Understand the Role of Noradrenaline**:
- Noradrenaline (also known as norepinephrine) is a neurotransmitter released by sympathetic nerve endings. It plays a crucial role in the "fight or flight" response, which prepares the body for stressful situations.

2. **Analyze Each Option**:
- **Option 1: Increase in rate of heartbeat**:
- Noradrenaline stimulates the heart, leading to an increase in heart rate. This option is likely correct.
- **Option 2: Decrease in speed of conduction of action potential through heart musculature**:
- Noradrenaline actually increases the speed of conduction of action potentials in the heart. Therefore, this option is incorrect.
- **Option 3: Decrease in cardiac output and stroke volume**:
- Noradrenaline enhances cardiac output and stroke volume by increasing heart rate and the force of heart contractions. Thus, this option is also incorrect.
- **Option 4: Increase in stroke volume but decrease in cardiac output**:
- While noradrenaline does increase stroke volume, it does not decrease cardiac output; it typically increases it. Therefore, this option is incorrect.

3. **Conclusion**:
- Based on the analysis, the only correct statement is that noradrenaline leads to an increase in the rate of heartbeat.

### Final Answer:
- The correct answer is **Option 1: Increase in rate of heartbeat**.