A person entering an empty room suddenly fins a snake right in front on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system

Options

A. Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse
B. Hypothalamus activates the parasympa-thetic division of brain
C. Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal cortex
D. Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal medulla

Answer

### Step-by-Step Solution:

1. **Understanding the Scenario**: A person suddenly encounters a snake, which is a stressful and potentially dangerous situation. This triggers a rapid response in the body.

2. **Neuro-Hormonal Response**: In such situations, the body activates the neuro-hormonal control system. The adrenal medulla, which is part of the adrenal glands, plays a crucial role in this response.

3. **Hormonal Secretion**: The adrenal medulla releases two key hormones: epinephrine (also known as adrenaline) and norepinephrine (noradrenaline). These hormones are critical for the body's immediate response to stress.

4. **Activation of the Sympathetic Nervous System**: The release of epinephrine and norepinephrine activates the sympathetic nervous system. This system is responsible for the "fight or flight" response, which prepares the body to either confront or flee from the threat.

5. **Effects of the Hormones**: The activation of the sympathetic nervous system leads to several physiological changes:
- Increased heart rate and strength of heart contractions.
- Heightened alertness and readiness to respond to the threat.
- Dilation of air passages to improve oxygen intake.
- Redistribution of blood flow to essential muscles.

6. **Analyzing the Options**: The question provides multiple options regarding what happens in the neuro-hormonal control system:
- **Option 1**: Incorrect, as neurotransmitter activity is not the primary focus here.
- **Option 2**: Incorrect, as the hypothalamus does not activate the parasympathetic division in this scenario.
- **Option 3**: Incorrect, as it misattributes the source of epinephrine and norepinephrine to the adrenal cortex instead of the adrenal medulla.
- **Option 4**: Correct, as it accurately states that the sympathetic nervous system is activated and that epinephrine and norepinephrine are released from the adrenal medulla.

7. **Conclusion**: The correct answer is that the sympathetic nervous system is activated, releasing epinephrine and norepinephrine from the adrenal medulla.