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2=Endocrinology > L9. Calcium homeostasis, growth hormone and pineal gland > Flashcards

L9. Calcium homeostasis, growth hormone and pineal gland Flashcards

1
Q

4 roles of Ca2+

A

• Excitation-contraction coupling
Excitation-secretion coupling
Excitability of nerves and muscle •
Clotting of blood (haemostasis)

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2
Q

what level of Ca2+ is rquired for muscle contraction?

A

increase in intracellular ca2+

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3
Q

what does an increase in extracellular ca2+ cause?

A

decerase in neuromuscular contracility

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4
Q

normal plasma ca2+ levels

A

9-10mg/dl

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5
Q

where is 99% of ca2+ stored

A

bone

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6
Q

3 hormones which control Ca2+ homeostais

A

PTH
Vit D
calcitonin

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7
Q

where is PTH synthesised?

A

chief cells of PT glands

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8
Q

describe steps of PTH synthesis

A
  1. preproparathormone
  2. proparathormone
  3. PTH
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9
Q

how is PTH removed?

A

liver & kidney

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10
Q

half life of PTH

A

2-5mins

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11
Q

what regulates PTH secretion

A

Ca2+

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12
Q

what causes increased PTH secretion?

A

low plasma Ca2+

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13
Q

what causes decreased PTH secretion?

A

high plasma Ca2+

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14
Q

2 effects of chronic hypocalcaemia?

A

hyperplasia

hypertrophy of PT gland

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15
Q

role of pTH

A

increase ECF Ca2+

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16
Q

3 target organs of PTH

A
  1. kidney
  2. inetsine
  3. bone
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17
Q

effect of pTH on kidney

A

decreased ca exretion

increased phosphate excretion

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18
Q

effect of PTH on intestinr

A

activates VitD3 to increase absorption of Ca and phos

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19
Q

normal effecrt of PTH on bone

A

fast efflux of ca from bone fluid into plasma

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20
Q

effect of PTH on bone during chronic hypocalcameia

A

dissolution of bone to allow slow tranfer of Ca2+ into plasma

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21
Q

cause of PTH deficiency

A

operative procedure on thyroid/PT gland

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22
Q

cause of PTH excess

A

tumour in PT gland

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23
Q

effects of PTH deficiency

A

hypocalcaemia

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24
Q

effects of PTH excess

A

hypercalcaemia + hypophosphataemia

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25
Q

3 signs + sxs of hypocalcaemia

A
  1. tetany of hands and feet
  2. removal of glands = death due to asphyxiation due to tetany of resp muscle
  3. seizures due to excitiablity in brain
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26
Q

sxs of hypercalcaemia on bone

A

extensive bone decalcification

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27
Q

sxs of hypercalcaemia is reduced neuromuscular excitiability. what 6 sxs does this lead to?

A
  1. muscle weakness
  2. decreased mentation
  3. poor memory
  4. constipation, abdo pain graons
  5. peptic ulcer
  6. depressed relaxation of heart during diastole
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28
Q

sxs of hypercalcaeimai on kidney

A

increased risk of kidney stones

29
Q

treatment for hypocalcaemia

A

vit D and calcium supplements

30
Q

treatment for hypercalcaemia

A

surgical removal of tumour

31
Q

2 roles of Vit D

A
  1. intestinal absorption of Ca2+

2. responsivenes of bone to PTH

32
Q

is vit D action fast or slow?

A

slow

33
Q

describe steps in activation of Vit D3

A
  1. Vit D3
  2. 25-hydroxy Vit D3 (liver)
  3. 1,25-dihydroxy Vid D3 (kidney) via PTH
34
Q

Vit D deficiency effects on Ca2+ absoprtion

A

reduced - causes PTH to maintain Ca2+ levels ; demineralisation of bone

35
Q

vit D effects on children

A

rickets

36
Q

Vit d effects on adults

A

osteomalacia

37
Q

what is osteoporosis

A

reduction in bone mass - as bone resoption > bone formation

38
Q

function of calcitonin

A

reduce Ca2+

39
Q

how does calcitonin reduce Ca2+

A

inhibiting osteoclastic bone resorption - ca2+ is not released

40
Q

where is calcitonin synethsised

A

parafollicular/c cells of thyroid

41
Q

what increased calcitonin secretion

A

hypercalcaemia

42
Q

what decreases calcitonin secretion

A

hypocalcaemia

43
Q

therapeutic use of calcitonin

A

disorders of increased skeletal remodlling - paget’s disease

44
Q

where is growth hormone secreted?

A

anterior pituitary

45
Q

where is calcitonin secreted from?

A

thyroid gland

46
Q

T/F: Growth hormone causes fat accumulation within adipocytes

A

false

47
Q

T/F: Growth hormone is glucose sparing.

A

true

48
Q

how do liver cells respond to growth factor?

A

release insulin-like-GF

49
Q

where in the skin is vitamin D synthesised?

A

epidermis

50
Q

T/F: Vitamin D exhibits property similar to a steroid hormone.

A

true

51
Q

what gland secretes melatonin?

A

pineal

52
Q

what does melatonin secretion increase in response to?

A

darkness

53
Q

Before the discovery of these glands, thyroid surgery often led to a rapid drop in blood calcium levels, which triggered muscle contractions and cardiac arrhythmias. What glands are these and which hormone is lacking?

A

parathyroid; PTH

54
Q

2 other names of growth hormone (GH)

A

somatotropic hormone/somatotropin

55
Q

where is GH sec from

A

ant pit

56
Q

2 normal growth spurts

A

post natal, puberty

57
Q

2 effects of GH

A
  1. metabolic effect

2. growth effect

58
Q

describe 2 metabolic effects of GH

A
  1. increase FA levels

2, increase BG levels by dec glucose uptake

59
Q

GH effect on soft tissues

A

hyperplasia, hypertrophy, protein synthesis

60
Q

what 2 components make up bone

A

bone cells + Ca phosphase crystsls in organic matrix

61
Q

what is part of the organic matrix of bone

A

collagen fibres + ground substance

62
Q

3 types of bone cells

A

osteoblasts, osteoclasts, osteocytes

63
Q

which bone cells are responsible for bone resorption

A

osteoclasts

64
Q

what affect does GH have on liver

A

release glucose and IGF-1

65
Q

which is the GH-inhibiting hormone

A

somatostatin

66
Q

2 drugs to treat excess GH

A

somatostain + bromocriptine

67
Q

precursor of melatonin

A

5-hydroxy tryptamine

68
Q

which enzyme converts 5-hydroxy tryptamine into melatonin

A

5-methoxytryptamine

2=Endocrinology (8 decks)

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