In a study, researchers exposed undergraduates to a stressful public speaking task while collecting saliva samples every 15 minutes. They observed elevations in adrenocorticotropic hormone (ACTH) followed by sharp increases in salivary cortisol that peaked about 20 minutes after the speech. Heart rate and blood pressure also rose during the speech. Participants in a quiet reading control condition showed no such increases.
The pattern of ACTH followed by cortisol most directly reflects the activity of which system?
- A
The somatic motor system
- B
The sympathetic ganglia of the spinal cord only
- C
The parasympathetic nervous system
- Dcheck_circle
The hypothalamic-pituitary-adrenal (HPA) axis
Explanation
The HPA axis describes the cascade in which the hypothalamus releases CRH, prompting the pituitary to release ACTH, which signals the adrenal cortex to release cortisol. This is the slower endocrine arm of the stress response.