Stress and Stress Diseases

Question 1

What is the stress response?

Answer 1

Neuroendocrine control systems that mediate physical, emotional, and behavioral reactions to stressors.

Question 2

Negative feedback

Answer 2

Neuroendocrine control system facilitates a change in the body, then stops or activates a pathway with an opposite effect when adequate response occurs

This maintains homeostasis!

Question 3

How is regulation of blood glucose an example of negative feedback?

Answer 3

1. Increase in blood glucose
2. Beta cells in pancreas release insulin
3. Insulin binds receptors on cells and increases the availability of glucose transporters
4. Blood glucose levels fall
5. Insulin secretion is inhibited
6. Glucagon is released from alpha cells of hte pancreas and stimulates release of glycogen stores from the liver
7. Blood glucose rises

Question 4

Positive feedback

Answer 4

Cycle where initiating stimulus produces more of the same response

CREATES INSTABILITY

Question 5

What is an example of positive feedback?

Answer 5

Oxytocin in birthing

Question 6

What is the HPA axis and why is it important?

Answer 6

Hypothalamic-pituitary-adrenal axis

Endocrine control of stress response occurs as a hormonal cascade from the paraventricular nucleus of the hypothalamus, anterior lobe of the pituitary, to the adrenal gland ending in cortisol secretion.

Question 7

In what way can stress be beneficial?

Answer 7

It can be a stimulus for emotional growth and development

BUT positive stressors (like having a baby) can have a similar physical effect of negative stressors

Question 8

What are conditioning factors?

Answer 8

Internal (genetic predisposition, age, gender) and external (diet, social support, environment) influencers on a person’s ability to adapt to stress through physiological response.

Question 9

Allostasis

Answer 9

Interactive physiological changes in the neuroendocrine, autonomic, and immune systems that occur in response to instability; or

the body’s attempt to maintain stability by reacting to stressful stimuli

Question 10

Allostatic load

Answer 10

Accumulation of allostatic changes (immune suppression, sympathetic NS, and renin-angiotensin-aldosterone system)

Question 11

Function of the cerebral cortex

Answer 11

Mental capacities - vigilance, cognition, focused attention in stress response

Question 12

Function of limbic system in stress response

Answer 12

Emotions (fear, anger, excitement)

Question 13

Function of thalamus in stress response

Answer 13

relay center - receives, sorts, and distributes sensory information

Question 14

Function of hypothalamus in stress response

Answer 14

Coordinates responses of the endocrine and autonomic nervous system (releases CRF and stimulates locus ceruleus)

Question 15

Function of reticular activating system (RAS)

Answer 15

Modulates mental alertness, ANS activity, and skeletal muscle tone through reflex circuits

Question 16

What is the locus ceruleus?

Answer 16

Part of the brain stem with lots of neurons that produce NT norepinephrine (integrating site for ANS response to stress) when it receives sensory info from different parts of the brain. Responsible for increased attention and alertness, thought to improve memory during stress.

Question 17

What does the adrenal medulla secrete in the stress response?

Answer 17

Norephinephrine and epinephrine

Question 18

What is the body’s physiological response to epinephrine and norepinephrine release?

Answer 18

• decrease in insulin release and increase in glucagon release (increased gluconeogenesis, lipolysis, proteolysis)
• increased cardiac contractions, vascular smooth muscle contractions, and heart rate
  -relaxation of bronchial smooth muscle

Question 19

What hormone does the hypothalamus release in the stress response?

Answer 19

Corticotropin-releasing factor (CRF)

Question 20

What effect does Corticotropin-releasing factor (CRF) have on the body?

Answer 20

• stimulates ACTH release from the pituitary gland
• increased activity of neurons in locus ceruleus

Question 21

What hormone does the anterior pituitary gland release during the stress response?

Answer 21

Adrenocorticotropic hormone (ACTH)

Question 22

what affect does ACTH have on the body?

Answer 22

-stimulates synthesis and release of cortisol after release into circulation and binding to the adrenal gland receptors

Question 23

What hormone does the adrenal cortex produce in the stress response?

Answer 23

Glucocorticoid hormones (CORTISOL)
- this is a steroid hormone

Question 24

How does cortisol affect the body?

Answer 24

• enhances the action of epinephrine and glucagon
• inhibits release or action of reproductive hormones and TSH
• decreases the number of immune cells and inflammatory mediators

IN SUM: regulates metabolic, immune, cardio, and behavioral responses to stress and maintains homeostasis through negative feedback. allows us to survive stressors and allows our bodies to come back to homeostasis after stressor subsides.

Question 25

Where are mineralocorticoid hormones released? (ex. aldosterone)
What do they do?

Answer 25

The adrenal cortex

Increases sodium absorption by the kidney

Question 26

How is the renin-angiotensin-aldosterone system (RAAS) involved in the stress response?

Answer 26

-aldosterone release increases sodium and water retention (peeing is not a priority when stressed)
-angiotensin II enhances CRF release in the hypothalamus, ACTH release from the pituitary, vasopressin release from the posterior pituitary, and norepinephrine from the locus ceruleus

Question 27

What part of the stress response results in pupil dilation, sweaty hands and feet, dry mouth, reduced activity of GI, and increased heart and respiratory rate?

Answer 27

The sympathetic nervous system (ANS), which is enhanced by epinephrine and norepinephrine hormonal release from the adrenal medulla

Question 28

How is antidiuretic hormone involved in the stress response? Where is it released from?

Answer 28

It is released from the posterior pituitary
It is a vasopressin- it increases water retention by the kidneys and vasoconstriction of blood vessels (fluid retention = more fluid in BVs = more pressure on walls of BVs = High BPH)
-more active in hypotensive stress or stress due to fluid volume loss (again, an attempt at homeostasis!)

Question 29

What do cytokines do?

Answer 29

They are chemical messengers that are involved in inflammatory and stress response. Released by monocytes and lymphocytes, which can cross the BBB. Involved in activating tissue repair and increasing WBCs,

Question 30

How does physiologic reserve contribute to our ability to adapt to stress?

Answer 30

Body systems have a large safety margin and can increase their level of function as a form of adaptation (ex: hypertrophy of kidney after nephrectomy)

our cells produce/carry more substances than is needed

Question 31

What are the stages of Selye’s general adaptation syndrome?

Answer 31

1. Alarm stage: activation of SNS and HPA axis
2. Resistance stage: body selects more effective defenses
3. Exhaustion stage: physiologic resources are depleted and signs of systemic damage appear

Question 32

What pathophysiology explains PTSD as a chronic stress disorder?

Answer 32

Results from the exaggerated stress response and failure of the neuroendocrine system to maintain homeostasis.

Recent research shows increases SNS activity, but low levels of cortisol and inhibition of negative feedback of cortisol.

Increased reactivity of the amygdala and hippocampus and decreased activity of the anterior cingulate and orbitofrontal areas (area involved in fear response