Registered Practical Nurse (RPN) Practice Test

What is the body's first line of defense against stressors?

1. Hypothalamus response

2. Endocrine system response

3. ANS (Autonomic Nervous System)

4. Immune system response

The correct answer is: ANS (Autonomic Nervous System)

The body's first line of defense against stressors is primarily mediated by the autonomic nervous system (ANS). When a stressor is perceived, the ANS initiates an immediate response through its sympathetic division, preparing the body for a "fight or flight" reaction. This response includes an increase in heart rate, blood pressure, and adrenaline release, all of which are crucial for quick action and heightened alertness in the face of stress. The ANS regulates involuntary physiological functions, allowing the body to respond rapidly to various stimuli without the need for conscious thought. This quick reaction helps protect the organism from potential threats before the other systems, such as the endocrine or immune systems, can engage. While other systems play crucial roles in stress response, none act as swiftly or as directly as the ANS does in the initial stages of responding to stressors.