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Flashcards in Review of Endocrine Deck (28)
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1

what Is insulin released from?

pancreatic B cells

2

what stimulates the release of insulin?

-Raised blood glucose (direct effect on β cells)
- Raised blood amino acids (arginine)
- Parasympathetic (vagal) nerve activity
- Raised blood CCK, gastrin, incretins (feedforward)

3

what inhibits the release of insulin?

-Low blood glucose
-Sympathetic nerve activity (e.g. exercise)
- Raised blood cortisol (to maintain blood glucose)

4

what are the actions of insulin?

-Stimulates glucose uptake into muscle & fat (GLUT4)
- Promotes glycogen synthesis in liver
- Stimulates amino acid incorporation into protein (muscle)
- Promotes lipogenesis, inhibits lipolysis
- Hormone of the fed state - anabolic

5

what is glucagon released from?

pancreatic Alpha cells

6

what stimulates the release of glucagon?

- Decreased blood glucose (direct effect on α cells)
- Amino acids (raises blood glucose after protein meal)
- Decreased blood fatty acids
- Sympathetic nerve activity (e.g.exercise)
- Cortisol (to aid raising blood glucose)

7

what inhibits the release of glucagon?

- Raised blood glucose
- Raised blood fatty acids
- Insulin

8

what are the actions of glucagon?

- Increases liver glycogenolysis (blood glucose rises)
- Inhibits liver glycogen synthesis
- Promotes lipolysis in liver & adipose tissue
- Promotes liver gluconeogenesis
- Hormone of the unfed state - catabolic

9

what are glucocorticoids released from?

Adrenal cortex (zona fasciculata)

10

what stimulates the release of glucocorticoids?

-Circadian (ACTH bursts, most frequent in morning)
- Stress (via hypothalamic CRH and ant.pit. ACTH)
- Low plasma cortisol - long & short loop feedback

11

what inhibits the release of glucocorticoids?

-Depression of ACTH in evening
- High plasma cortisol - long & short loop feedback
- Low stress

12

what are the actions of glucocorticoids?

-Raises blood glucose
- Promotes liver glycogenolysis and gluconeogenesis
- Promotes protein breakdown
- Promotes lipolysis
- Permissive action on vascular adrenoceptors
- Essential for resisting stress

13

what releases adrenaline (epinephrine)?

Chromaffin cells of adrenal medulla

14

what stimulates the release of adrenaline?

Sympathetic nerve stimulation (“fight or flight”)

15

what inhibits the release of adrenaline?

Inhibition of sympathetic nerve stimulation

16

what are the actions of adrenaline?

-Promotes liver and muscle glycogenolysis
- Promotes lipolysis (raises blood FFAs)
- Raises metabolic rate
- Chronotropic & inotropic effects on heart (β1)
- Dilates coronary & skeletal muscle arterioles (β2)

17

what releases the growth hormone?

anterior pituitary gland

18

what stimulates the release of the growth hormone?

-Deep sleep – release greatest at night (GRH surges)
-Deficiency in energy substrates (exercise, fasting)
-Increased AAs in blood (e.g. arginine, leucine)

19

what inhibits the release of the growth hormone?

-Plentiful metabolic substrates (glucose, FFAs)
-Cortisol (to offset GH effect on protein anabolism?)
- Hypothyroidism (permissive action of T3)
- REM sleep

20

what are the actions of the growth hormone?

-Promotes growth via IGFs (bone & lean body mass)
- Promotes AA uptake & net protein synthesis
- Increases blood glucose (raises output from liver & has “anti-insulin” effect on muscle)
- Promotes lipolysis (raises blood FFAs)

21

what releases thyroid hormones?

thyroid glands

22

what stimulates the release of thyroid hormones?

-Plasma levels usually steady – negative feedback control of TSH
-Prolonged exposure to cold in infants – TRH release

23

what inhibits the release from thyroid hormones?

-Plasma levels usually steady – negative feedback control of TSH
- Prolonged exposure to heat

24

what are the actions of thyroid hormones?

-Set Basal Metabolic Rate
- Increased levels raise metabolic rate
- Promote protein & fat catabolism
- Raise body temperature – “ calorigenic action”
- Essential for normal development of CNS in foetus
- Permissive effect on growth hormone
-Permissive effect on β adrenoceptors – increase number & affinity to catecholamines

25

what releases parathyroid hormone?

Chief cells of parathyroid glands

26

what stimulates the release of parathyroid hormone?

Falling plasma calcium concentration (hypocalcaemia)

27

what inhibits the release of parathyroid hormone?

Rising plasma calcium concentration (hypercalcaemia)

28

what are the actions of parathyroid hormone?

-Mobilization of calcium from bone
- Increased calcium reabsorption by kidneys
- Decreased phosphate reabsorption by kidneys
- Stimulates kidney to complete conversion of Vit D to calcitriol