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 rise in heart rate and blood pressure during the speech is most directly attributable to:
- A
Parasympathetic activation slowing heart rate
- B
Decreased thyroid hormone secretion
- C
Cerebellar regulation of cardiac muscle
- Dcheck_circle
Sympathetic nervous system activation releasing epinephrine
Explanation
The fight-or-flight response is mediated by the sympathetic nervous system, which signals the adrenal medulla to release epinephrine (adrenaline), increasing heart rate, blood pressure, and respiration. The parasympathetic system does the opposite.