Lecture 18

Question 1

What is the difference between stress and stress response?

Answer 1

Stress: physical or emotional situation that presents a threat to homeostasis
Stress response: predictable changes that the body organizes to deal with any situation it classifies as stressful

Question 2

How do the nervous and endocrine systems trigger the stress response?

Answer 2

Nervous: the forebrain processes information and categorizes some as stressful
Endocrine: limbic system directs the hypothalamus to activate the effector systems which will mediate the stress response

Question 3

What are the endocrine and physiological features of the alarm phase?

Answer 3

Endocrine: adrenal medulla releases epinephrine and norepinephrine
Physiological: SNS acts on visceral organs to support increased physical activity and alertness

Question 4

What are the endocrine and physiological features of the resistance/recovery phase?

Answer 4

• directs available nutrients and energy reserves to organs needed for short term survival
  Endocrine: CRH is released onto anterior pituitary, leads to cortisol production in adrenal cortex
  Physiological: protein catabolism, gluconeogenesis, lypolysis in adipocytes, diminished immune system functions, alterations to memory and cognition

Question 5

What is the consequence of manipulations of adrenergic (adrenaline, sympathetic activation) signalling for the stress response?

Answer 5

• increased heart rate
• increased ventilation
• decreased digestion
• glucose released from muscles and liver
• glucose is maintained in blood
• increased fat catabolism

Question 6

What is the consequence of manipulations of glucocorticoid signalling for the stress response?

Answer 6

• mobilization of energy reserves, conservation of glucose, increased blood glucose, conservation of salts and water
• suppressing immune system and reproductive system, cognitive functions altered

Question 7

What is chronic stress?

What are some symptoms of chronic stress?

Answer 7

• Cortisol levels remain elevated, not immediately life threatening
• depression, memory loss, sleep disturbances, susceptibility to infections, IBS, weight gain, thyroid imbalances, infertility, osteo

Question 8

How can hypercortisolaemia disrupt the HPA axis?

Answer 8

• prolonged exposure to glucocorticoids lead to reduction of synapses on hippocampus
• affects CRH secreting neurons, hippocampus usually inhibits CRH, but is no longer doing this

Question 9

Where does the stress response begin?

Answer 9

In the nervous system (neural circuits in the forebrain, especially limbic system)

Question 10

What are the two major hormonal pathways activated by the stress response?

Answer 10

Epinephrine: secreted from adrenal medulla; sympathetic activation
Cortisol: secreted from adrenal cortex; increases blood glucose levels

Question 11

What are the three phases of the stress response? (General adaption syndrome)

Answer 11

1. Alarm reaction (sympathetic stimulation)
2. Resistance (HPA axis)
3. Exhaustion

Question 12

Is stress homeostasis or allostasis?

Answer 12

Allostasis

Question 13

What hormones are involved in the exhaustion stage of the stress response?

Answer 13

Reduction in hippocampal neurons, and it can no longer inhibit CRH- secreting neurons in the hypothalamus and balance the amygdala