USA Biology Olympiad (USABO) Practice Exam

Why is the sympathetic nervous system vital during a predator-prey encounter?

1. It promotes relaxation and calm

2. It manages digestion processes

3. It initiates the fight-or-flight response

4. It regulates sleep patterns

The correct answer is: It initiates the fight-or-flight response

The sympathetic nervous system plays a crucial role in the fight-or-flight response, which is vital during predator-prey encounters. When an organism senses danger, such as the presence of a predator, the sympathetic nervous system activates various physiological changes that prepare the body to either confront the threat (fight) or escape from it (flight). These changes include an increase in heart rate and blood pressure, dilation of airways to enhance oxygen intake, and the diversion of blood flow away from non-essential functions, such as digestion, towards the muscles to prepare for rapid movement. Additionally, the release of stress hormones like adrenaline further amplifies these responses, enhancing alertness and physical ability. In contrast, other options relate to functions that are not as critical during immediate threats. The promotion of relaxation and calm, as well as the management of digestion processes, are primarily associated with the parasympathetic nervous system, which dominates during restful states. Similarly, the regulation of sleep patterns falls outside the scope of acute responses to threats, emphasizing the specialized role of the sympathetic nervous system in high-stress situations where survival is at stake.