Stimulation from sympathetic nervous system to heart causes decrease in

Options

A. Cardiac output
B. Duration of cardiac cycle
C. Stroke volume
D. Heart rate

Answer

To solve the question regarding the effects of sympathetic nervous system stimulation on the heart, we will analyze the options provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding the Sympathetic Nervous System**: The sympathetic nervous system is part of the autonomic nervous system and is responsible for the body's 'fight or flight' response. It generally prepares the body for action by increasing heart rate, contractility, and blood flow to muscles.

2. **Effects on Heart Rate**: Stimulation from the sympathetic nervous system typically leads to an increase in heart rate. Therefore, the heart rate does not decrease.

3. **Effects on Stroke Volume**: The sympathetic nervous system increases the force of heart contractions, which can lead to an increase in stroke volume (the amount of blood pumped by the heart with each beat). Thus, stroke volume does not decrease.

4. **Effects on Cardiac Output**: Cardiac output is the product of heart rate and stroke volume. Since both heart rate and stroke volume increase due to sympathetic stimulation, cardiac output also increases, not decreases.

5. **Effects on Duration of Cardiac Cycle**: The cardiac cycle duration is the time it takes for one complete heartbeat (systole and diastole). When the heart rate increases, the duration of the cardiac cycle decreases because the heart beats more frequently. Therefore, the duration of the cardiac cycle decreases.

6. **Conclusion**: Based on the analysis, the correct answer to the question "Stimulation from sympathetic nervous system to heart causes decrease in" is the **duration of the cardiac cycle**.

### Final Answer:
The stimulation from the sympathetic nervous system to the heart causes a decrease in the **duration of the cardiac cycle**.

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