L9. Calcium homeostasis, growth hormone and pineal gland

Question 1

4 roles of Ca2+

Answer 1

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

Question 2

what level of Ca2+ is rquired for muscle contraction?

Answer 2

increase in intracellular ca2+

Question 3

what does an increase in extracellular ca2+ cause?

Answer 3

decerase in neuromuscular contracility

Question 4

normal plasma ca2+ levels

Answer 4

9-10mg/dl

Question 5

where is 99% of ca2+ stored

Answer 5

bone

Question 6

3 hormones which control Ca2+ homeostais

Answer 6

PTH
Vit D
calcitonin

Question 7

where is PTH synthesised?

Answer 7

chief cells of PT glands

Question 8

describe steps of PTH synthesis

Answer 8

1. preproparathormone
2. proparathormone
3. PTH

Question 9

how is PTH removed?

Answer 9

liver & kidney

Question 10

half life of PTH

Answer 10

2-5mins

Question 11

what regulates PTH secretion

Answer 11

Ca2+

Question 12

what causes increased PTH secretion?

Answer 12

low plasma Ca2+

Question 13

what causes decreased PTH secretion?

Answer 13

high plasma Ca2+

Question 14

2 effects of chronic hypocalcaemia?

Answer 14

hyperplasia

hypertrophy of PT gland

Question 15

role of pTH

Answer 15

increase ECF Ca2+

Question 16

3 target organs of PTH

Answer 16

1. kidney
2. inetsine
3. bone

Question 17

effect of pTH on kidney

Answer 17

decreased ca exretion

increased phosphate excretion

Question 18

effect of PTH on intestinr

Answer 18

activates VitD3 to increase absorption of Ca and phos

Question 19

normal effecrt of PTH on bone

Answer 19

fast efflux of ca from bone fluid into plasma

Question 20

effect of PTH on bone during chronic hypocalcameia

Answer 20

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

Question 21

cause of PTH deficiency

Answer 21

operative procedure on thyroid/PT gland

Question 22

cause of PTH excess

Answer 22

tumour in PT gland

Question 23

effects of PTH deficiency

Answer 23

hypocalcaemia

Question 24

effects of PTH excess

Answer 24

hypercalcaemia + hypophosphataemia

Question 25

3 signs + sxs of hypocalcaemia

Answer 25

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

Question 26

sxs of hypercalcaemia on bone

Answer 26

extensive bone decalcification

Question 27

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

Answer 27

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

Question 28

sxs of hypercalcaeimai on kidney

Answer 28

increased risk of kidney stones

Question 29

treatment for hypocalcaemia

Answer 29

vit D and calcium supplements

Question 30

treatment for hypercalcaemia

Answer 30

surgical removal of tumour

Question 31

2 roles of Vit D

Answer 31

1. intestinal absorption of Ca2+ | 2. responsivenes of bone to PTH

Question 32

is vit D action fast or slow?

Answer 32

slow

Question 33

describe steps in activation of Vit D3

Answer 33

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

Question 34

Vit D deficiency effects on Ca2+ absoprtion

Answer 34

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

Question 35

vit D effects on children

Answer 35

rickets

Question 36

Vit d effects on adults

Answer 36

osteomalacia

Question 37

what is osteoporosis

Answer 37

reduction in bone mass - as bone resoption > bone formation

Question 38

function of calcitonin

Answer 38

reduce Ca2+

Question 39

how does calcitonin reduce Ca2+

Answer 39

inhibiting osteoclastic bone resorption - ca2+ is not released

Question 40

where is calcitonin synethsised

Answer 40

parafollicular/c cells of thyroid

Question 41

what increased calcitonin secretion

Answer 41

hypercalcaemia

Question 42

what decreases calcitonin secretion

Answer 42

hypocalcaemia

Question 43

therapeutic use of calcitonin

Answer 43

disorders of increased skeletal remodlling - paget's disease

Question 44

where is growth hormone secreted?

Answer 44

anterior pituitary

Question 45

where is calcitonin secreted from?

Answer 45

thyroid gland

Question 46

T/F: Growth hormone causes fat accumulation within adipocytes

Answer 46

false

Question 47

T/F: Growth hormone is glucose sparing.

Answer 47

true

Question 48

how do liver cells respond to growth factor?

Answer 48

release insulin-like-GF

Question 49

where in the skin is vitamin D synthesised?

Answer 49

epidermis

Question 50

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

Answer 50

true

Question 51

what gland secretes melatonin?

Answer 51

pineal

Question 52

what does melatonin secretion increase in response to?

Answer 52

darkness

Question 53

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?

Answer 53

parathyroid; PTH

Question 54

2 other names of growth hormone (GH)

Answer 54

somatotropic hormone/somatotropin

Question 55

where is GH sec from

Answer 55

ant pit

Question 56

2 normal growth spurts

Answer 56

post natal, puberty

Question 57

2 effects of GH

Answer 57

1. metabolic effect | 2. growth effect

Question 58

describe 2 metabolic effects of GH

Answer 58

1. increase FA levels | 2, increase BG levels by dec glucose uptake

Question 59

GH effect on soft tissues

Answer 59

hyperplasia, hypertrophy, protein synthesis

Question 60

what 2 components make up bone

Answer 60

bone cells + Ca phosphase crystsls in organic matrix

Question 61

what is part of the organic matrix of bone

Answer 61

collagen fibres + ground substance

Question 62

3 types of bone cells

Answer 62

osteoblasts, osteoclasts, osteocytes

Question 63

which bone cells are responsible for bone resorption

Answer 63

osteoclasts

Question 64

what affect does GH have on liver

Answer 64

release glucose and IGF-1

Question 65

which is the GH-inhibiting hormone

Answer 65

somatostatin

Question 66

2 drugs to treat excess GH

Answer 66

somatostain + bromocriptine

Question 67

precursor of melatonin

Answer 67

5-hydroxy tryptamine

Question 68

which enzyme converts 5-hydroxy tryptamine into melatonin

Answer 68

5-methoxytryptamine