Question

Mary is sitting on a bench and reading a book. Suddenly, someone grabs her arm. Mary is startled. She finds that her muscles have tensed up. When Mary looks up, she sees her friend Denise, who surprised her. Mary feels relieved. She leaps up and hugs Denise. Explain how Mary's nervous system helped her carry out the described activities. Also explain whether her reactions were reflexive or voluntary.

Answer 1

This is the result of her sympathetic nervous system sending signals directly to the brain to provide an unconcious reflex action of moving away from a potential danger.

Answer 2

Mary's reactions were controlled by the sympathetic nervous system and were reflexive reactions.

Step-by-step explanation:

Also known as the orthosympathetic system or thoracolumbar system, the sympathetic nervous system prepares the body to handle stress or emergency situations. In this sense, at times when the brain perceives a danger (as Mary did when unexpectedly touched), the sympathetic nervous system comes into play.

During stress or emergency, the system will trigger a series of internal actions. Everything for the individual to respond to the situation in order to get rid of the uneasiness or danger. The system will for example:

• Increase heart rate;

• Release adrenaline;

• Increase blood pressure

• Contract and relax muscles.

There are still other physical changes at times when the sympathetic nervous system is triggered. These include:

• Dilated bronchial passages for greater oxygen retention;

• Pupil dilation to improve the sense of sight;

• Blood vessel contraction;

• Increased esophageal contraction;

• Perspiration.