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3D week 2 - Hormones > physiology of the HPA axis (see notes!) > Flashcards

physiology of the HPA axis (see notes!) Flashcards

1
Q

what 2 hormones are released by the posterior pituitary gland

A
  1. anti-diuretic hormone (ADH)
  2. oxytocin
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2
Q

is the posterior pituitary gland an endocrine gland

A

no, not a true endocrine gland -> doesn’t produce its own hormones, it just stores and releases them

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3
Q

what kind of connection does the hypothalamus and posterior pit gland have

A

neural - the posterior pituitary is and extension of the hypothalamus and they communicate via nerves

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4
Q

what area of the hypothalamus is responsible for oxytocin release

A

paraventricular nuclues

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5
Q

what area of the hypothal is responsible for ADH release

A

supraoptic nucleus

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6
Q

what is the “neck” of the pituitary gland called

A

infundibulum

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7
Q

what kind of organ is the anterior pituitary gland

A

endocrine organ -> hypothal sends hormonal signals via the hypophyseal portal system to the pituitary gland

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8
Q

what 5 hormones does the hypothalamus release

A
  1. thyroid releasing hormone (TRH)
  2. prolactin releasing hormone (PRH)
  3. gonadotropin releasing hormone (GnRH)
  4. corticotropin releasing hormone (CRH)
  5. growth hormone releasing hormone (GHRH)
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9
Q

6 hormones released by the anterior pituitary gland

A
  1. Thyroid stimulating hormone (TSH)
  2. prolactin
  3. FSH
  4. LH
  5. adrenocorticotropin hormone (ACTH)
  6. growth hormone (GH)
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10
Q

HP-gonadal axis

A

GnRH -> LH -> ovaries/testes -> stimulates oestrogen/testosterone synthesis

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11
Q

HP-Thyroid axis

A

TRH -> TSH -> thyroid gland -> stimulate thyroxine synthesis

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12
Q

HP-adrenal axis

A

CRH -> ACTH -> adrenal cortex -> stimulates corticosteroid synthesis

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13
Q

what is the role of the HPA axis

A

to modulate stress responses leading to the release of cortisol

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14
Q

what kind of cells secrete CRH

A

small bodied neurones

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15
Q

what area of the hypothalamus is CRH secreted from

A

paraventricular nucleus

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16
Q

what is the short -ve feedback loop in the HPA axis

A

CRH-> anterior pit gland -> ACTH release -> ACTH inhibitsCRH release

17
Q

what cells are responsible for ACTH release

A

corticotrophs

18
Q

ACTH release cellular mechanism (draw out)

A

CRH binds to CRHR -> g protein coupled receptor causes ATP -> cAMP -> activates PKA -> PKA binds to Ca2+ receptors -> Ca2+ influx -> causes exocytosis of ACTH vesicles

19
Q

HPA axis long -ve feedback loop

A

CRH -> ant pituitary gland -> ACTH release -> adrenal glands -> cortisol synthesis -> cotrisol downregulates both CRH and ACTH release

20
Q

ACTH action on adrenal gland cells mechanism (intracellularly)

A

ACTH binds to melanocortin-2 receptor -> g coupled protein receptor causes ATP -> cAMP -> activates PKA -> increases activity of P450scc and increases enzyme synthesis

21
Q

when is cortisol secreted (2)

A
  1. throughout the day in a pulsitile manner
  2. in response to stress
22
Q

how does cortisol prepare the body for flight or flight response (2)

A
  1. provided adequate nutrients for ATP synthesis
  2. glucose sparing for the brain
23
Q

what are the 4 zones to the adrenal gland and what does each produce

A
  1. medulla -> adrenaline, NA
    cortex:
  2. zona Glomerulosa -> aldosterone (RAAS system)
  3. zona fasiculata -> glucocorticoids (e.g. cortisol), allows energy to be provided to vital tissues
  4. zona reticularis -> androstenedione -> androgens (sex hormones)
24
Q

how do hormones work (3)

A
  1. enters cell and binds to the receptor in the cytoplasm
  2. hormone-receptor complex enter nucleus
  3. acts as a transcription factor can causes transcription/inhibition of certain genes from the DNA
25
Q

why must glucose be spared for the brain in stress response

A

the brain will pretty much only metabolise glucose and so it must be reserved for the brain as other tissues can use other metabolites e.g. fatty acids

26
Q

what is the action of cortisol on adipose tissue, the liver and extra-hepatic tissue (e.g. skeletal muscle)

A
  1. adipose tissue - increased lipolysis => more free fatty acids in the blood that can be metabolised
  2. liver - gluconeogenesis and glycogenolysis => increased glucose in the blood
  3. extra-hepatic tissue - decreased protein synthesis, increased proteolysis => more free amino acids in the blood, these can be used for ATP release instead of glucose; increased fat oxidation (for ATP release); decreased glucose metabolism (more glucose for brain) -> i.e. shifting the metabolism of these tissues away from glucose
27
Q

what is the preferred metabolite for skeletal muscle in stress

3D week 2 - Hormones (8 decks)

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