corticosteroids and steroid receptors - 1 Flashcards
(107 cards)
1
Q
what are the two major classes of corticosteroids
A
glucocorticoids and mineralocorticoids
2
Q
which is the main endogenous glucocorticoid
A
cortisol
3
Q
what are 2 main functions for glucocorticoids
A
metabolism
anti-inflammatory
4
Q
which is the main endogenous mineralocorticoid
A
aldosterone
5
Q
what are 2 main functions for aldosterone
A
water and electrolyte balane
6
Q
what controls the secretion of cortisol
A
hypothalamic-pituitary-adrenal HPA axis
7
Q
what is a diurnal rhythm
A
a pattern of activity based upon a 24-hour cycle, in which there are regular light and dark periods
8
Q
when does cortisol peak in humans
why
A
early morning (diurnal rhythm)
9
Q
what are 2 main stimulus for cortisol secretion
A
physical and psychological stressors
10
Q
what are 4 physical stressors for cortisol secretion
A
heat
cold
injuries
infections
11
Q
what are 3 psychological stressors for cortisol secretion
A
money
work
relationships
12
Q
what kind of feedback does cortisol do on the hypothalamus
A
negative
13
Q
what kind of feedback does cortisol do on the pituitary gland
A
negative
14
Q
where is cortisol released from
A
adrenal cortex
15
Q
what causes cortisol release from the adrenal cortex
A
ACTH activation
16
Q
where is ACTH release
A
anterior pituitary
17
Q
what negatively inhibits the anterior pituitary from releasing ACTH
A
cortisol
18
Q
what are the factors released by the hypothamaus that causes ACTH release from the ant pit
A
CRH and AVP
19
Q
what is CRH and AVP
A
the factors released by the hypothamaus that causes ACTH release from the ant pit
20
Q
does CRH or AVP play a bigger role in the stress response
A
CRH
21
Q
what 2 things cause the release of ACTH from the ant pit (and where do they come from)
A
CRH AVP from the hypothalamus
22
Q
where is the site of synthesis of cortisol (specific)
A
zona fasciculate of adrenal cortex
23
Q
what is the starting substance of cortisol
A
cholesterol
24
Q
what G protein does ACTH act through
A
Gs (adenylate cyclase)
25
what is the rate limiting step of cortisol synthesis
conversion of cholesterol to pregnenolone
26
how is cortisol relased from the adrenal cortex
diffusion across plasma
27
why can cortisol just diffuse out of the adrenal cortex
because its highly lipid soluble (made from cholesterol)
28
what 2 things can plasma cortisol bind to
albumin and corticosteroid-binding globulin (CBG)
29
what does CBG stand for
corticosteroid-binding globulin
30
what does corticosteroid-binding globulin do
binds only to natural cortisosteroids
31
what does albumin do
binds to both natural and synthetic cortisol
32
what 2 things cause an increase in CBG (corticosteroid-binding globulin) levels
estrogen
| hyperthyroiddism
33
what 2 things cause a decrease in CBG (corticosteroid-binding globulin) levels
hypothyroidism
| protein deficiency
34
what happens with cortisol with high estrogen levels and why
less plasma cortisol because more is bound by CBG
35
what happens with cortisol with hyperthyroidism and why
less plasma cortisol because more is bound by CBG
36
what happens with cortisol with hypothyroidism and why
more plasma cortisol because less is bound by CBG
37
what happens with cortisol with protein deficiency and why
more plasma cortisol because less is bound by CBG
38
what binds to both natural and synthetic cortisol
albumin
39
what binds to only natural cortisol
CBG (corticosteroid-binding globulin)
40
what is the overall effect of glucocorticoids on sugar levels
increase sugar levels in blood so that theres adequate supply of glucose to the brain
41
what do glucocorticoids do to glucose uptake in skeletal muscle
decreases
42
what do glucocorticoids do to glucose use in skeletal muscle
decrease
43
what do glucocorticoids do to gluconeogenesis
increase
44
what do glucocorticoids do to insulin
increases secretion
45
why do glucocorticoids increase insulin secretion
because there is a rise in plasma glucose
46
what do glucocorticoids do to protein breakdown
increase
47
what do glucocorticoids do to protein synthesis
decrease
48
where does glucocorticoids have a catabolic effect
lymphoid, connective tissue, muscle, skin and bone
49
what do glucocorticoids do to lipolysis
increase
50
what do glucocorticoids do to lipogenesis and why
increase due to insulin secretion
51
what does insulin do to lipogenesis
increase
52
what is the overall effect of glucocorticoids on fat
increases fat deposition
53
if cortisol causes lipolysis, why does fat deposition occur
cortisol causes lipolysis
but insulin causes lipogenesis
so in this case lipogenesis wins
54
what do glucocorticoids do to # of immune cells
decreases
55
what do glucocorticoids do to macrophage functions
inhibits
56
what do glucocorticoids do to fibroblast functinos
decreases
57
what do glucocorticoids do to cytokine production and actions
decrease
58
what do glucocorticoids do to IgG production
decrease
59
what do glucocorticoids do to blood vessels
decrease in vasodilation
60
what do glucocorticoids do to histamine release from mast cells and basophils
decrease
61
what do glucocorticoids do to CRH and ACTH secretion
inhibition via negative feedback
62
what does ACTH do to adrenal cortex
maintenance, including making sure theres no atrophy
63
what do glucocorticoids do to adrenal cortex
how
causes atrophy
| reduce ACTH levels so a decrease in size of adrenal cortex
64
what do glucocorticoids do to blood vessel size
vasoconstriction
65
what do glucocorticoids do to BP
increase
66
what do glucocorticoids do to vascular responsiveness (and to what)
increased responsiveness to angiotensin2 NA A
67
what do glucocorticoids do to Ca++
negative Ca++ balance
- decreased Ca++ uptake via GI
- increased kidney Ca++ excretion
68
what do glucocorticoids do to musculoskeletal system
decreased osteoblast activities, increased osteoclast activities
69
what do glucocorticoids do to behaviour initially
insomnia, euphoria
70
what do glucocorticoids do to subsequently (not initially)
depression
71
what is excessive cortisol linked to
major depressive disorders
72
what are 5 symptoms of decreased cortisol levels
- muscle weakness
- fatigue
- weight loss
- hypotension
- fasting hypoglycemia
73
what are 3 symptoms of decreased aldosterone levels
dehydration
hyponatremia
hyperkalemia
74
what can cause acute adrenocortical insufficiency
abrubt withdrawal of exogenous glucocorticoid after prolonged therapy
75
how long can adrenocortical insufficiency from exogenous glucocorticoid recovery take
several months
76
what is addisons disease
chronic adrenocortical insufficiency
77
what can cause addisons disease
autoimmune, infection, cancer, congenital unresponsiveness to ACTH
78
why does fasting hypoglycemia happen with adrenocortical insufficiency
cortisol usually stops sugar uptake into cells, so with less cortisol, there will be low plasma sugar
79
what causes congenital adrenal hyperplasia
lack of 21β-hydroxylase
80
what happens in congenital adrenal hyperplasia (what is affected)
- reduction in cortisol and aldosterone synthesis
- increased ACTH (less -ve feedback)
- increased androgens and estrogen
81
what happens to cortisol with congenital adrenal hyperplasia
levels reduce
82
what happens to aldosterone with congenital adrenal hyperplasia
less synthesis
83
what happens to ACTH with congenital adrenal hyperplasia and why
more because less negative feedback
84
what happens to androgen with congenital adrenal hyperplasia + why
increase because more androstenedione
85
what happens to estrogen with congenital adrenal hyperplasia + why
increase because more androstenedione
86
which pathway is favorted with 21β-hydroxylase defect and why
sex steroid pathway because 21β-hydroxylase works mostly in the mineralocorticoid and glucocorticoid pathways
87
what metabolite becomes excess with 21β-hydroxylase defect
androstenedione
88
what is the main thing that 21β-hydroxylase metabolizes
progesterone
89
what characterises cushings disease
high plasma level of cortisol
90
what causes cushings disease (3)
pituitary adenoma (tumor)
nodular hyperplasia of adrenal gland
ectopic production of ACTH by other tumor (not in pit)
91
what is required after surgical removal in cushings disease
glucocorticoid replacement
92
in cushings disease, what would an adrenal or pituitary gland tumor release
adrenal-cortisol
| Pituitary-ACTH
93
what is the diagnostic test called for cushings disease
dexamethasone suppression test
94
how do you do the dexamethasone suppression test
administer dexamethasone at night, measure plasma cortisol level
95
what would indicate a cortisol producing tumor with the dexamethasone suppression test
high cortisol and low ACTH
96
what is dexamethasone
a synthetic cortisol
97
what would indicate a ACTH producing tumor with the dexamethasone suppression test
high cortisol and high ACTH
98
what would high cortisol and low ACTH mean with a dexamethasone suppression test
cortisol producing tumor
99
what would high cortisol and high ACTH mean with a dexamethasone suppression test
ACTH producing tumor
100
where are 2 places that an ACTH producing tumor could be
in pituitary or lungs
101
where is 1 place that a CORTISOL producing tumor could be
in adrenal glands
102
why would there be high cortisol and low ACTH with a dexamethasone suppression test in a CORTISOL producing tumor
because adrenal tumor makes cortisol so theres negative feedback so low ACTH
103
what are 2 clinical uses for glucocorticoids
diagnostic test (cushings disease ) or lung maturation
104
what does cortisol do to lungs
regulates lung maturation in fetus
105
why can cortisol be used therapeutically for lungs (and for who)
immature lung development in fetuses because cortisol regulates lung maturation in fetus
106
what can cause immature lung development in fetuses
low maternal cortisol or early birth
107
what can cortisol administration do to infants with resp issues
reduce incidence of respiratory distress
