3.2 Responding to Acute and Chronic Stress

Question 1

What is stress? What are stressors?

Answer 1

Stress: physiological and psychological response to a perceived threat

Stressor: stimulus that triggers stress in an organism

Question 2

Draw a map of the physiological response to stress, and compare to 3.2

Answer 2

https://myuni.adelaide.edu.au/courses/94387/pages/3-dot-2-responding-to-acute-and-chronic-stress?module_item_id=3305619

Question 3

How does the vascular connection between the adrenal medulla and cortex allow for adrenaline production?

Answer 3

• Cortisol from zona fasciculata bathes the medulla
• This stimulates the PNMT enzyme, which converts noradrenaline to adrenaline by adding a methyl group

Question 4

Which enzyme is often implicated in Congenital Adrenal Hyperplasia? Why?

Answer 4

• 21 hydroxylase
• When deficient, less mineralocorticoids/glucocorticoids, so more androgens
• Can lead to features of CAH

Question 5

What are the three stages of Selye’s proposed General Adaptation Syndrome? Describe them. How may these phases present?

Answer 5

1: Alarm -> this is the acute stress response (hormonal and neural)

2: Resistance -> the acute stress response is downregulated (cortisol decreases etc.) but the body remains vigilant. This may show as irritability, fatigue, or inability to concentrate.

3: Exhaustion -> the resources being used during the resistance phase are depleted. May present as extreme fatigue or depression.

(These ARE the components of GAS)

Question 6

What are some limitations of General Adaptation Syndrome?

Answer 6

• Tests were only conducted on animals
• Focuses on physiological response; does not factor in psychological differences
• The “non-specific” nature proposed by Selye has since been disproven

Question 7

How have our ideas about stress changed since Selye’s GAS?

Answer 7

• We now view stress as having a certain element of specificity
• Instead of “any demand”; it’s a conscious or unconsciously perceived threat to homeostasis

Question 8

What are the effects of chronic stress on memory, cognition, and learning? Why?

Answer 8

Decreased; the brain is sensitive to stress hormones such as glucocorticoids, and chronic exposure to these hormones can negatively affect memory, cognition, and overall brain function.

Question 9

What are the effects of chronic stress on immune system? How might this be?

Answer 9

• Weakened immune system
• Among other things, could be due to increased activity of HPA axis (cortisol is an immunosuppressant, after all)

Question 10

What are the effects of chronic stress on cardiovascular system?

Answer 10

• Increased BP, HR, and contractility
• Sustained increase in sympathetic activity can cause cardiac remodelling (e.g. AF), and increased risk of atherosclerosis/thrombosis

Question 11

What are the 2 main effects of chronic stress on gastrointestinal system? Explain them.

Answer 11

1. Increased appetite. Increased metabolism of fat/carbs causes hunger
2. Increased susceptibility to inflammatory disease, decreased absorption, decreased function of the system as a whole