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endocrine control 2 Flashcards

1
Q

corticotropin releasing hormones

A

act on anterior pituitary to release adrenocorticotropic hormone
adrenocorticotropic hormone acts on the adrenal cortex mineralocorticoids (aldosterone) glucocorticoids (cortisol) androgens

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2
Q

cholesterol

A

has a large side chain preventing it from being transported into the mitochrondria

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3
Q

how to get cholesterol into the mitochdondria

A

cholesterol dose chain cleavage enzymes

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4
Q

cholesterol once into the mitcochodnira

A

pregnenolone

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5
Q

pregnenolone converted into

A

any steroids

depends on assembly of different enzymes available in the cell

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6
Q

2 main steps of steroidoegensi

A
  1. cholesterol changing to pregneolone

2. pregnenolone changing too all other steroids

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7
Q

cholesterol side chain cleavage

A

P450scc = cholesterol side chain cleavage (rate limiting step) enzyme
transported by AtAR = sterodssogenic acute regulatory protein - transports cholesterol into the mitochondria once the side chain has been cleaved off

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8
Q

changing pregnenlolone into other steroids

A

2 types of enzymes involved

  1. cytochrome P450s (CYPs) - redox changes
  2. hydroxysteroid dehydrogenase HSDs = interconversons
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9
Q

how to make testosterone

A

17bHSD turns androstendone to testosterone

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10
Q

hot to make progesterone

A

Sb-HSD turns pregnenolone not progesterone

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11
Q

adrenal cortex produces

A

androstenedione, cortisol and aldosterone

androstenedione - requires CYP17a1 and 3b-HSD
cortisol - requires CYP21 and CYP11b1
aldosterone - requires CYP11b2 (aldosterone synthase)

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12
Q

testes produced

A

testosterone - 17b-HSD to convert androstenedione to testosterone

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13
Q

ova produce

A

progesterone - 3b-HSD converts pregnenolone into progesterone
oestrogen - requires CYP19a1 converts testosterone into oestradiol

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14
Q

StAR

A

steroidogenic acute regulatory protein
stimulates steroid production (rate limiting transport step)
found in all tissues that can produce steroids
transports cholesterol molecules into the mitochondria
regulated by cAMP

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15
Q

P450scc

A

cholesterol side chain cleavage
rate limiting catalytic step
regulated by cAMP

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16
Q

receptors for trophic hormones

A

activate cyclic AMP to activate StAR and P450scc

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17
Q

corticosteroids

A

mineralocorticoids - cortex hormones regulating minerals
glucocorticoids - cortex hormones that regulate glucose
sex hormones

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18
Q

what produces corticosteroids

A

adrenal glands - adrenal cortex (outer)

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19
Q

zona fasciculata produces

A

cortisol

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20
Q

zona glomerulosa

A

produces aldosterone because it has aldosterone synthase

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21
Q

zona reticularis produces

A

androstenedione

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22
Q

mineralocorticoids

A

produced by the zone glomerulosa of the adrenal cortex

secretion is mediated by primary angiotensin 2, and increase in local potassium

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23
Q

dominant for of mineralocorticoids

A

aldosterone (although some others also have mineralocorticoid function)

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24
Q

mineralocorticoids binds

A

MC - mineralocorticoids receptor in the cytoplasm
expressed in kidney, distal colon, sweat glands
activates signal transduction via gene transcription and heat shock proteins

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25
aldosterone action in kidney
binds MC receptor to stimulate activity and expression of sodium channels and Na/K ATPase increases blood pressure and blood volume
26
glucocorticoids
produce in the zona vessiculata of the adrenal cortex | regulated by ACTH (corticotrophin releasing hormone)
27
dominent form of glucocorticoids
cortisol
28
glucocorticoids bind
GR - glucocorticoid receptor ubiquitous - in almost every cell a receptor transcription factor to activate gene transcription also represses the function of NK-kappaB and AP-1
29
what do glucocorticoids do
helps the body deal with stressful situations - trauma, surgery, exercise, anxiety, depression, crowding, fasting, hypoglycaemia, fever, infection regulated cardiovascular, metabolic and immune system function keeps blood glucose high breaks down protein for fuel source
30
in large quantitiess of glucocorticoids
depresses immune and inflammatory response | also redirects circulating lymphocytes to lymphoid/peripheral tissues
31
glucocorticoids on CHO metabolism
elevates blood glucose - stimulate gluconeogenesis (mobilises AAs, increase conversion enzymes) decrease cellular glucose uptake (mostly by muscle and adipose tissue)
32
glucocorticoids on lipid metabolism
elevates blood fat mobilises FAs from adipose tissue also stimulates beta oxidation for energy
33
glucocorticoids on protein metabolism
elevates blood [protein, AA] | mobilises AA from non hepatic tissues - enhances liver protein synthesis
34
anti inflammatory processes of glucocorticoids
inhibits cytokine release block early stage inflammatory inception increases healing of inflammation surpasses cellular immune response, stabilises lysosomes, reduces vessel permeability
35
ACTH
adrenocorticotrophic hormone acts on adrenal cortex ACTH stimulate secretion af adrenal glucocorticoids binds cell surface melanocortin type 2 receptors MC2R
36
ACTH binds melanocortin type 2 receptors
activate cAMP
37
MC2R most abundant in
zona fasciculata
38
ACTH regulates
steroid hormone secretion stimulates lipoprotein uptake into cortical cells (increase cholesterol) plus mitochondria ox-phos genes (steroid synthesis requires lottos energy) activates StAR and P450scc stimulates transcription of the steroidogenic enzyme genes
39
ACTH
produced from POMC pre-pro-opiomelanocortin concurrently produces endorphin, lipotrophin and melanocyte stimulating hormone b-endorphin binds opiate receptor y-lipotropin stimulates lipolysis a/b/y-MSH stimulates melanocytes and can darken skin
40
stimulation of ACTH release
CRH and ADH (hypothalamus) stress hypoglycaemia
41
circadian pattern of release
highest levels early AM | sleep-wake cycle
42
short term stress response
adrenaline and noradrenaline increase blood glucose, increase blood pressure, increase breathing rate, increase metabolic rate, change in blood flow patterns
43
long-term stress response
mineralocorticoids sodium ions and water by kidneys increase blood volume and blood pressure glucocorticoids conversion of proteins and fats to glucose and immune system suppressed
44
Addisons disease
adrenal insufficiency not enough cortisol or aldosterone low blood pressure low blood glucose patients lack cortisol so there is no negative feedback fro ACTH overproduction of ACTH skin colour darkens (overproduction of melanocyte stimulating hormone)
45
Cushing's syndrome
too much cortisol may be because of too much CRH (hypothalamus tumour) or too much ACTH (anterior pituitary tumour) rapid weight gain central obesity hypertension, muscle wasting, poor wound healing hypercholesterolaemia, diabetes melllitus
46
sex hormones synthesised in
synthesised in the zona reticularis DHEA (dehydroepiandrosterone) and androstenedione converted in peripheral tissues to testosterone, oestrogen
47
testosterone is secreted by
leydig cells in the testis in response to LH
48
DHT
testosterone is converted to dihydrotestosterone by 5-alpha reductase which is only present in some target cells amplifies action of testosterone in some target tissues DHT-R complexes required for development of male external genitalia
49
testosterone feedback control
systemic testosterone powerfully inhibits GnRH and LH secretion
50
sertoli barrier
blood testes barrier sertoli cells create locally high concentration of testosterone keeping it trapped in the testes to drive sperm production concentrated testosterone without negative feedback
51
IV testosterone
does not arise testes androgen level | exerts negative feedback and stops production of testosterone
52
oestrogen potency
beta-oestradiol>oestrone>oestriol
53
oestrogen produced by
granulosa cells (also corpus luteum) require aromatase activity regulated by LH and FSH (via cAMP)
54
progesterone
``` corpus luteum (tiny amount from follicular theca cells) regulated by LH (via cAMP) ```
55
2 cells producing oestrogen
theca cells and granuloma cells
56
oestrogen from granuloma cells
release oestrogen but can't make them from scratch themselves - must be supplied with androgens which may come from the adrenal cortex or from nearly theca cells
57
granuloma cells are responsive to
LH and FSH
58
process of making oestrogens
cholesterol - pregnenolone - progesterone - androgens - oestrogen's
59
FSH catalises in the production of oestrogen
catalyses production of aromatase which converted androgens to oestrogen
60
theca cells are responsive to
LH
61
LH catalyses
cholesterol > pregnenolone
62
effects of oestrogen
- facilitate growth of ovarian follicles and uterine tube motility cyclical changes in endometrium increases blood flow and smooth muscle contractility of uterus oestrogen-dominatedd uterus is more sensitive to oxytocin increases breast duct growth
63
effects of progesterone
uterus - progestational changes in endometrium, cervix and vagina antioestrogenic effects - prevents uterine contraction breast - stimulates lobule and alveoli development, supports lactation brain- stimulates thermogenesis and respiration

physiology 2 (21 decks)

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