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Endocrinology & Reproduction > HPA axis and stress > Flashcards

HPA axis and stress Flashcards

1
Q

HPA axis

A

hypothalamic-pituitary-adrenal axis

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2
Q

examples of experimental stressors

A

toxic injection, trauma, infection, cold environment, swimming to exhaustion

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3
Q

examples of experimental responses to stress

A

adrenal hyperplasia, atrophy of immune system organs, peptic ulcers

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4
Q

what do stressors increase

A

secretion of glucocorticoid

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5
Q

when is secretion of glucocorticoid increased

A

in response to stressors

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6
Q

what is the stress hormone

A

cortisol

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7
Q

what is cortisol

A

glucocorticoid steroid hormone

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8
Q

physiological stress

A

any event that elecits increased secretion of the glucocorticoid steroid hormone cortisol

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9
Q

GAS

A

general adaptation syndrom

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10
Q

3 parts of GAS

A

alarm - fight or flight, short term adrenaline
resistance to stress - chronic cortisol levels x 10
exhaustion - immune suppresion, illness or death

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11
Q

how many adrenal glands

A

2, left and right

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12
Q

what is a plastic organ & example

A

can get bigger and smaller. If one adrenal gland is removed, the other will increase in size to compensate

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13
Q

where are steroid hormones made

A

the cortex of the adrenal glands

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14
Q

how many zones does the adrenal cortex have

A

3

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15
Q

zona glomerulosa makes

A

aldosterone

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16
Q

zona fasciculata & reticularis make

A

cortisol & androgens

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17
Q

medulla makes

A

adrenaline and noradrenaline

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18
Q

what is the outer zone of adrenal called

A

cortex

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19
Q

what is the inner zone of the adrenal called

A

medulla

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20
Q

what part of the adrenal has the slow response

A

outer cells; where steroid hormones are made

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21
Q

what part of the adrenal has the immediate response

A

the medulla; where adrenaline is released

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22
Q

describe steroid hormones

A

lipid like becuase they’re maed from cholesterol

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23
Q

what are steroid hormones made from

A

cholesterol

made from lipid droplets in the outermembrane of the mitochondria

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24
Q

specifically where are steroid hormones amde

A

outermembrane of the mitochondria

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25
what do sterois hormone make cells have lots of
mitochondira, lipid droplets and SER
26
what happens to steroids once made
they diffuse out of cell into blood circualtion. they are not stored
27
steroid release is
slow
28
what is the meduall made up of
modified nerve cells
29
what happens to adrenaline once made
stored in vesicles
30
how does adrenaline enter circulation
stored in secretory vesicles then released rapidly by exocytosis
31
half life of adrenaline
3-4 minutes
32
what is adrenaline synthesised from
tyrosine AA
33
where are steroid hormone receptors found
intracellular, becsuse steroids can diffuse plasma membrane
34
how do steroid hormone receptors work
``` bind to hormone translocate to nucleus bind to specific DNA sequence influce gene expression = relatiely long term effects ```
35
example of transmembrane receptor
catecholamine
36
where is catecholamine receptor found
transmembrane
37
where does hormone bind to catecholamine receptor
will bind in the extracellular domain of this transmembrane receptor because cant cross plasma membrane
38
how does catecholamine receptor work
receptor transmits signal to intracellular domain via GTP binding prodtein this activates 2nd messenger e.g cyclic AMP, DAG Ca2+ = rapid reversible response, short term effects
39
examples of 2nd messenegers
cyclic AMP, DAG, Ca 2+
40
Endocrine response to stress
fight or flight = noradrenaline and adrenaline as a short term rapid response
41
short term response to stress
adrenaline / noradrenaline
42
what does increased noradrenaline and adrenaline do to the body
- increases glycogenolysis in liver and muscle - increases lipolysis in fat - increases Cardiac output - diverts blood flow from viscera to skeletal muscle - increases ventialation to increase VO2
43
resistance to stress
occurs with chronically elevated cortisol leels
44
what regulates levels of cortisol
anterior pituiatry
45
what regulates the anterior pituiatry
hypothalamus
46
what does the HPA axis regulate
endorcrine and neurocrine system
47
how does the HPA axis work
- neurones in the hypothalamus send axons to the medien eminence - CRH is released at the medien eminence and enters blood with ease - CRH controls the release of ACTH from the anterior pituiatry - ACTH is relreased and enters venous drainage to be transported to adrenals
48
where is CRH released from
medien eminence
49
how does CRH enter blood stream
with ease at the medien eminence becuase there is no BBB
50
what does CRH control
the release of ACTH from the anterior pituitary
51
where is ACTH released
anterior pituitary
52
where does ATCH go
from anterior piuitary, enters venous drainage to travel in blood to the adrenals
53
which has a long jourrney and which has a short journey - CRH - ACTH
``` CRH = SHORT ACTH = LONG ```
54
HPA axis regulates the endorcrine and autonomic system by
negative feedback
55
when does cortisol peak
in the morning to prepare you for th day
56
what does a peak in cortisol do
increases vasucular tone BP increases awareness CNS mobilises fuel sotres and energy
57
wha disturbs cortisol peak
disturbance of circadian rhythm
58
what happens to cortisol secretion in response to stress
will peak in the fight or flight response then return to normal
59
chronic stress
cortisol levels remain high after morning peak
60
what is the effect of cortisol release in reponse to stress
- has catabolic effects and opposes the effects of insulin maintains enzyme expression - enhances CV reactivity to catecholamines - inhibits inflammatory and immune response - inhibits non-essential function
61
how does cortisol have catabolic effects
it maintains the expression of metabolic enzymes
62
symptom of continued protein synthesis in chronic stress
muscle wastage and bone weakening
63
symptom of continued hepatic gluconeogenesis inchronic stress
bruising
64
how does chronic stress affect diabetics
alters their insulin requirements bc cortisol opposes the effects of insulin
65
what does enhances CV reactivity to catecholamines mean
adrenaline and noradrenaline will cause vasoconstriction to increase BP
66
what effect does high cortisol have on the heart
hypertension leading to stroke or heart disease
67
what does low crotisol do to the heart
hypotension
68
what are the metabolic processes stimulated by cortisol
- stimulates protein breakdown - stimulates hepatic gluconeogenosis - stimulates lipolysis
69
how does cortisol inhibit inflammatory and immune response
- inhibits TG and LT production - inflammatory cytokines stimulate ACTH and hence cortisol secretion in a negative feedback loop to down regualte inflammatory response
70
how does cortisol inhibit non-essesntial function & what
reproduction and growth reduces bone density, skin thickness and muscle mass becuase of catabolic processes growth retardation reduced fertility & wound healing
71
disease of cortisol deficiency
Addison's disease
72
how is cortisol deficieny caused in Addison's
adrenal cortex is damaged by TB or by autoimmune destruction in over 80%
73
adrenal insufficiency causes
- hypotension, hypoglycemia, hyperpigmentaton, tiredness, weakness, anorexia, vomitting, depression
74
what does addisons often get misdiagnosed as and why
chronic fatigue becuase Addisons is a progressive disease
75
Addisonian crisis
inabilty to respond to stress | fatal if untreated
76
treatment of Addison's
oral sterid replacement therapies
77
pathology of addisons
- no negative feedback from cortisol - continued CRH secrtetion - continued ACTH secretio - very high plasma ACTH
78
what does high plasma ACTH cause
hyperpigmentation | ACTH in high levels will act on melanocytes to generate melanin
79
what normally acts on melanocytes to generate melanine
alpha MSH
80
why can ACTH act on melanocytes
there is a alpha MSH sequence in ACTH which also triggers MCR
81
cushing's syndrome
inapproprite secretion of cotisol when not stressed
82
what causes cushing's syndrom
- adrenal cortex tumours causing increased cortisol secretion - pituitary adenomas causing increased ACTH secretion (70%)
83
most common form of endocrine cancer
pituitary adenoma causin excess ACTH = cushings
84
net effects of cushings are similar to
chronic stress
85
net effects of cushings
- increase catabolic effects - increased vasoconstriction - suppressed immune response
86
bone catabolism, hirsuitism (hair growth), skin thinning and bruising, muscle wastage and buffalo hump are signs of
cushing's syndrome. Excess cortisol

Endocrinology & Reproduction (15 decks)

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