Stress Physiology
Start with the big picture
The SAM axis provides a rapid response: sympathetic activation stimulates the adrenal medulla to release epinephrine and norepinephrine. The HPA axis acts more slowly, progressing from hypothalamic CRH to pituitary ACTH and adrenal cortisol. Together, catecholamines and cortisol affect cardiovascular function, airways, fuel availability, inflammation, and blood flow. Cortisol normally feeds back to restrain CRH and ACTH, while prolonged stress can disrupt regulation. The lesson also connects the phases of General Adaptation Syndrome with chronic stress effects, including metabolic, immune, cardiovascular, and memory changes. Concepts such as biomarkers, allostasis, allostatic load, and resilience provide ways to understand and assess the broader consequences of stress.
What you'll learn
- Distinguish the pathways and time courses of the SAM and HPA stress responses.
- Describe key cardiovascular, metabolic, and immune effects of catecholamines and cortisol.
- Explain cortisol feedback and how chronic stress may alter HPA regulation.
- Relate allostasis, allostatic load, and General Adaptation Syndrome to chronic stress.
- Identify stress biomarkers and describe how stress can affect memory.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
