Stress activates the _. a. HPA axis, which reacts more quickly than the other b. HPA axis, which becomes increasingly important with prolonged stressors c. autonomic nervous system, which secretes the hormone ACTH d. autonomic nervous system, which secretes the hormone cortisol
The correct answer and explanation is:
Correct Answer: b. HPA axis, which becomes increasingly important with prolonged stressors
The hypothalamic-pituitary-adrenal (HPA) axis is one of the central stress response systems in the body. It is particularly important in regulating the response to prolonged or chronic stressors. When a person experiences a stressor, the hypothalamus in the brain releases corticotropin-releasing hormone (CRH). This hormone stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH), which then acts on the adrenal cortex to stimulate the release of cortisol, a key stress hormone.
Cortisol helps the body cope with stress by mobilizing energy stores, reducing inflammation, and assisting in maintaining homeostasis. While cortisol is vital for short-term survival, sustained high levels due to chronic stress can have negative effects on the immune system, digestion, mood, and overall health.
In contrast, the autonomic nervous system (ANS), particularly the sympathetic division, is responsible for the immediate or acute stress response, often known as the “fight-or-flight” response. This system reacts quickly by releasing neurotransmitters like norepinephrine and epinephrine to prepare the body for immediate physical action. These effects are rapid but short-lived compared to the hormonal influence of the HPA axis.
Therefore, while the autonomic nervous system plays an initial role in acute stress situations, the HPA axis becomes more dominant during prolonged stress. This axis manages long-term adjustments by maintaining elevated cortisol levels to support energy production and bodily functions under continuous strain. Understanding this distinction is important in fields such as psychology, medicine, and neuroscience, where stress responses impact mental and physical health outcomes.