In consideration with the nervous system in humans Which of the following actions are stimulated by the sympathetic neural system ?

Options

A. heartbeat
B. secretion of digestive juices
C. secretion of saliva
D. All of the above

Explanation

To determine which actions are stimulated by the sympathetic neural system in humans, we can follow these steps:

### Step-by-Step Solution:

1. **Understand 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 prepares the body to respond to stressful situations.

2. **Identify Key Functions of the Sympathetic Nervous System**:
- The sympathetic system increases heart rate and cardiac output.
- It also increases blood pressure and enhances the force of heart contractions.
- It inhibits non-essential functions such as digestion and salivation.

3. **Analyze the Options Given**:
- Option 1: **Increase in heart rate** - This is a function of the sympathetic nervous system.
- Option 2: **Secretion of gastric juices** - This is primarily stimulated by the parasympathetic nervous system, not the sympathetic.
- Option 3: **Secretion of saliva** - Similar to gastric juices, this is inhibited by the sympathetic nervous system.

4. **Determine the Correct Answer**:
- Based on the analysis, the only action that is stimulated by the sympathetic nervous system is the increase in heart rate. Therefore, option 1 is the correct answer.

### Final Answer:
The action stimulated by the sympathetic neural system is **the increase in heart rate**.