Homestasis and Stress

Question 1

Homeostasis is______

Answer 1

feature of a system ( human body) that regulates a specific parameter to maintain stable condition

Question 2

Homeostasis is ___________ regulated.

Answer 2

highly

Question 3

Allostasis is________

Answer 3

mechanisms that let an organism maintain long-term stability and viability by coordinating body-wide (brain controlled) responses via overriding homeostatic setpoints to meet predicted needs

Question 4

4 keys points of Allostasis

Answer 4

1. achieves long term stability through change
2. a series of coordinated changes in multiple systems
3. override homeostatic mechanisms
4. is preemptive and predictive ( zebra being chase by a lion)

Question 5

Allostatic state

Answer 5

a period when there is an override of homeostatic setpoints

Question 6

Allostatic load

Answer 6

short term burden caused by allostatic states

Question 7

Allostatic overlaod

Answer 7

long term, maladpative allostatic load that causes damage to system

Question 8

A stressor is__________

Answer 8

a positive or negative experiences that changes homestasis

Question 9

What is a stress response?

Answer 9

a response to changes in allostatic or homeostatic balance

or

response to stressor

Question 10

What is stress?

Answer 10

anything that changes the allostatic or homeostatic balance of a living organism

Question 11

Sella Turcica

Answer 11

Where pituitary gland is encased

Question 12

What is the purpose of releasing hormones/factors released by hypothalamus

Answer 12

Releasing hormones tell pituitary to release hormones found in pituitary into blood

Question 13

2 types of neurons found in the paraventricular nucleus (PVN) of hypothalamus

Answer 13

1. medial parvocellular ( parvo=small) neurons -secrete releasing factors into smaller, special circurlation via media eminence
2. magnocellular ( magno=large) neurons -secrete oxycotin and vasopressin directly into general circulation

Question 14

HPA axis and stress hormone release

Answer 14

1. medial parvocellular neurons make and secrete CRH/F
2. CRH/F is released in capillary bed called median eminence and carried down to anterior pituitary via superior hypophyseal artery ( a special portal circulation)
3. CRH/F binds to CRH/F receptors on corticotrophs, cell type found in anterior pituitary
4. Corticotroph are activated/stimulated by CRH/F to release ACTH in general blood circulation
5. ACTH travels in blood to effector organ, adrenal cortex
6. ACTH binds on receptor in adrenal cortex and stimulates release of cortisol

Question 15

Hormones released by Posterior Pituitary

Answer 15

1. ADH/vasopressin

2. Oxytocin

Question 16

Adenohypopsis

Answer 16

the anterior pituitary
adeno=gland
a lot of blood vessels

Question 17

Neurohypopsis

Answer 17

posterior pituitary
neuro=neurons
contain alot of neuronal axons

Question 18

Cortisol/corticorsterone

Answer 18

main stress hormone in humans/rodents

hormones differ by one hydroxyl group

Question 19

biosynthesis of steroid hormones

Answer 19

precursor of all steroids is cholesterol

aldosterone, progesterone, testoterone, estrogen, cortisol

Question 20

How is stress response terminated

Answer 20

1. removal of stressor

2. Negative feedback along the Hypothalamus, Pituitary, Effector Organ Axis

Question 21

What evidence shows that hippocampus is invovlved in stress response?

Answer 21

There is a dense concentration of cortisol/corticosterone receptors in the hippocampus

Question 22

3 types of effects caused by stress response

Answer 22

1. CRFergic central effects ( hypothalamus)
2. Glucocorticoid peripheral effects ( increase GC receptors)
3. SNS mediated peripheral effects

Question 23

Effect of Stress on Reproduction

Answer 23

A CRFergic central effect

Stress inhibits reproduction

Question 24

Effect of stress on SNS

Answer 24

A SNS peripheral effect

Stress activates SNS system

Question 25

Effect of stress on GC control

Answer 25

A GC peripheral effect stress increase stress hormone release and results in 1. Increase metabolism ( protein production) 2. Decreased immune response (immuno-suppression)

Question 26

Mechanism of glucocorticoid effect during stress response

Answer 26

1. Cortisol can freely enter cell vis passing through cell membrane 2. Cortisol binds to glucocorticoid receptor inside cell 3. Glucocorticoid receptors are normally held in cytsol of cell by chaperone proteins like heat shock protein so the receptors can’t enter into nucleus of cell 4. Glucocorticoid displaces the chaperone protein and enters into nucleus as a glucocorticoid-glucocorticoid receptor complex 5. G-GC complex binds to glucocorticoid responsive element in nucleus and this recruits transcription factors 6. Transcription factors are start transcription of genes with glucose responsive elements; mRNA is translated to protein 7. Newly produced protein increases cellular function

Question 27

Rate of change and Stress Response

Answer 27

Stress response occurs at molecular, cellular, and behavioral levels slow change-protein synthesis faster change-SNS

Question 28

Effect of cortisol on neuron activity

Answer 28

hippocampal neurons fire more frequency

Question 29

Brain structures that inhibit stress response

Answer 29

Hippocampus | Pre-frontal cortex

Question 30

Brain structures that increase stress response

Answer 30

Amygdala

Question 31

What happens to key brain structures during chronic stress?

Answer 31

Amygdala hypertrophies and then atrophies Hippocampus and prefrontal cortex atrophy

Question 32

Net effect of Hypothalamus-Pituitary-Adrenal Cortex Axis in Chronic Stress Brain remodeling?

Answer 32

Stress response is lengthened because negative feedback mechanism are decreased and pro-stress mechanism are increased

Question 33

Hippocampus activity and stress response

Answer 33

Acute stress: Hippocampus is healthy and decreases effects of stress Chronic stress: hippocampus is damaged and there is an increase in negative effects of prolonged stress response

Question 34

Stress and Learning/memory

Answer 34

Acute stress: increase stress, increase learning and memory chronic stress: increase stress, decrease learning and memory

Question 35

Why is stress an vital physiological feature?

Answer 35

Acute Stress and stress response has evoluntionary benefit; stress hormones help us survive stressful situations!

Question 36

Describe the epigenetic nature of early life stress on organism

Answer 36

Stress during early development has negative long-lasting effects on brain and behavior Stress is not only mediated by genetic effects but also environment

Question 37

What did low/high grooming rodent study reveal about epigenetic affects of stress

Answer 37

rats who had low stress/high groom enviroment had more demethlyaltion of the promoter NR3C1, the glucocorticoid receptor responsible for increased glucocorticoid receptor expression ( a good thing!) than rats that had high stress/low groom environment