Endocrinology of Stress

Question 1

Eustress

Answer 1

normal physiologic workings of the living organism

Question 2

Pathogenic stress or distress

Answer 2

when homestasis threatened or perceived to be so in setting of overwhelming or sustained external and internal stressors

Question 3

What are the two components of the stress system?

Answer 3

Central and peripheral

Question 4

Describe the central component of the stress system

Answer 4

Hypothalamus and brain steam

CRH and ADH secreting neurons of the hypothalamus

Noradrenergic cell groups in medulla and pons

Question 5

Peripheral components

Answer 5

Peripheral limbs of HPA axis

Efferent sympathetic-adrenal medullary system

Components of the parasympathetic system

Question 6

What are the two overall axis for Hypothalamus - pituitary - adrenal axis?

Answer 6

Hypothalamus (CRH + AVP) –> Anterior pituitary –> ACTH –> Adrenal cortex –> Cortisol

Hypothalamus –> sympathetic nervous system –> Adrenal Medulla

Question 7

What are the three stress hormones?

Answer 7

Corticotropin releasing hormone

Adrenocorticotropic hormone

Glucocorticoids

Question 7

Describe the release of CRH

Answer 7

Increased pulsatile release early in morning = increased primary amplitude of ACTH and cortisol secretion

Question 8

Name some other hormones changes during stress

Answer 8

Oxytocin increase
glucagon increase
epinephrine increase
Angiotensin increase

Insulin decrease

Question 8

What are the receptors for CRH?

Answer 8

CRHR1 and CRHR2

Question 8

What is the primary regulator of the HPA?

Answer 8

CRH

Question 9

What functions does the ANS control in regards to stress?

Answer 9

Cardiovascular, respiratory, GI, renal and endocrine

Question 9

What are the effects of cortisol on growth?

Answer 9

Increased HPA axis = decreased GH

Prolonged cortisol presence = supression of growth hormone

Cortisol induced inhibition of IGF-1

CRH increases somatostatin

Chronic stress = supressed growth

In Cushing’s syndrome: delayed growth and shorter overall height

Question 10

Describe the relationship between stress and thyroid hormone.

Answer 10

Stressed induced cortisol = decreased levels of TSH and inhibition of T3 and T4 formation

Due to increased CRH-induced somatostatin and cortisol

Question 11

Describe the effect of stress on reproduction

Answer 11

Inhibited by ALL aspects if HPA axis

Decreased GnRH secretion = increased resistance od gonadal tissue

Ovarian and testicular steroidogenesis inhibited

Question 12

What can happen in cases of chronic stress?

Answer 12

all functions of immune system is decreased

there can be a slight shift towards adaptive = potentially detrimental changes

Question 13

What can happen in cases of acute stress?

Answer 13

Shift towards innate immune response

Question 14

What is the impact of cortisol on immune system?

Answer 14

Anti-inflammatory and immunosupressive effect

Question 15

Describe the overall effect of cortsiol in metabolism

Answer 15

Direct catabolic effects

Question 16

Outline general effects of stress on metabolism.

Answer 16

Direct catabolic effects

Glucocorticoids antagonise the metabolic actions of GH and sex steroids

Chronic stress= increased gluconeogenesis, increased visceral adiposity, decreased bone and muscle mass, decreased osteoblastic activity and insulin resistance. -

Question 17

What are the three reactions in General Adaption Syndrome?

Answer 17

Alarm reaction (shock stage

Stage of resistance (counter shock)

Stage of exhaustion

Question 18

Describe the actions and effects of the Alaram reaction stage of General adaptive syndrome.

Answer 18

Generalised stimulation of the sympathetic nervous system = release of catecholamines

Increased sympathetic-adrenal action = increased HR, constriction of blood vessels to viscera and skin, blood supply to heart and muscles, BP and glycogenolysis

decreased digestive and reproductive system.

Question 19

What occurs in the stage of resistance (2nd stage of GAS)

Answer 19

Body adapts to stress (system changes to reduce stress effects)

Question 20

What hormone acts in the stage of resistance (2nd stage of GAS) and what effect does it have?

Answer 20

Cortisol

lipolysis, gluconeogenesis, protein catabolism, increased blood vessel sensitive and decreased inflammation.

Question 21

What occurs in the 3rd stage of General Adaptive

Answer 21

Resources are depleted

Signs of ‘wear and tear’ show

Decreased body energy and immunity

Decreased stress tolerance –> mental and physical exahustion and illness

Question 22

What health disorders can result from chronic activation of the stress system?

Answer 22

Disease of cardiovascular, GI, immune and neurological systems

Depression, chronic alcoholism, drug abuse, eating disorders, accidents and suicide.

Question 22

what can prolonged activation of the HPA result in?

Answer 22

Stress induced health disorders

Question 23

What is allostasis?

Answer 23

Ability to achieve stability through change

Biological mechanisms protects from internal and external stress to maintain internal homeostasis

Question 24

What is Allostatic loading?

Answer 24

Long term effect of the physiological response to stress

Metabolic wear and tear at cellular level

Question 25

What are the associated mechanisms of Allostatic loading?

Answer 25

Frequent stress/ multiple stressors

Prolonged exposure to stress and consequent lack of adaptation

Inability to shut of allostatic responses –> delayed shut down once stressor terminated

Inadequate response