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regulatory physiology and pharmacology > Calcium homeostasis > Flashcards

Calcium homeostasis Flashcards

1
Q

when calcium is ionised it is inactive/active ?
when calcium is protein bound it is inactive/active ?

A

active
inactive

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2
Q

what is calcium bound to in bone

A

phosphates

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3
Q

what are the 3 hormones involved in calcium homeostasis

A

1,25-dihydroxyvitamin D
parathyroid hormone
calcitonin

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4
Q

where is parathyroid hormone produced

A

chief cells of parathyroid gland

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5
Q

parathyroid hormone responds to hyper/hypocalcaemia?

A

hypocalcaemia

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6
Q

what the pathway that involves the CaSR

A

calcium binds to CaSR activating PLC
PLC converts PIP2 into DAG + IP3
IP3 triggers release of Ca from SR/ER

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7
Q

what type of receptors are located on osteoblasts

A

PTH receptors

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8
Q

what is PTH responsible for

A

increasing extracellular Ca

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9
Q

how does PTH work on bone

A

stimulates cytokines that recruit osteoblasts that then induce osteoclasts

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10
Q

why are osteoclasts important in terms of Ca

A

help break down hydroxyapitie crystals

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11
Q

effect of PTH on small instestine

A

activates synthesis of 1,25-dihydroxyviamin D

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12
Q

effect of PTH on kidneys

A

increases Ca reabsorption by increasing activity of Ca pumps and channels
and increases phosphate excretion

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13
Q

where is 1,25-dihydroxyvitamin D (calcitriol) produced

A

kidneys

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14
Q

why are osteoclasts good for increasing Ca conc in blood

A

they break down bone to release phosphate and Ca into blood

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15
Q

what does 1,25-dihydroxyvitamin D do in the small intestine

A

diffuses into enterocytes where it binds to vitamin D receptors and increases gene expression
increases calcium absorption in small intestine

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16
Q

what are negative feedback of second hydroxylation

A

decrease in FGF23 and 1,25-dihydroxyvitamin D

17
Q

1,25-dihydroxyvitamin D role in kidney

A

increases expression of Na-Pi cotransporters
improves PTH mediated Ca reabsorption

18
Q

1,25-dihydroxyvitamin D role in bone

A

increases number of osteoclasts

19
Q

where is calcitonin produced

A

clear cells of thyroid glands

20
Q

calcitonin responds to

A

hypercalaemia

21
Q

calcitonins role in bone

A

reduces rate of bone turnover and release of Ca from bone

22
Q

calcitonins role in kidneys

A

increase Ca excretion

23
Q

what do glucocorticoids regulate

A

bone density and intestinal Ca absorption

24
Q

parathyroid related proteins

A

mimics actions of PTH

25
Q

name the most studied phosphatonin

A

FGF23

26
Q

FGF23 stimulates

A

phosphate loss in urine

27
Q

How does FGF23 affect calcitriol (active vitamin D) production?

A

FGF23 decreases calcitriol production by inhibiting the enzyme 1α-hydroxylase in the kidneys

28
Q

what does FGF23 prevent

A

hyperphosphatemia

29
Q

what is hypocalcaemia

A

low plasma Ca

30
Q

signs and symptoms of hypocalcaemia

A

pins and needles
muscle spasms
paralysis
convulsions

31
Q

what happens to voltage gated Na channels when Ca is low

A

open at resting membrane potential

32
Q

what is hypercalcaemia

A

high plasma Ca

33
Q

signs and symptoms of hypercalcaemia

A

bones stones grones and psychiatric overtones

34
Q

what is hypoparathyroidism

A

lack of PTH

35
Q

signs and symptoms of hypoparathyroidism

A

hypocalcaemia
hyperphosphataemia
muscle spasms

36
Q

what is hyperparathyroidism

A

excess of PTH

37
Q

What can cause hyperparathyroidism

A

tumors
chronic kidney disease
calcium malabsorption

38
Q

signs and symptoms of hyperparathyroidism

A

hypertension
consitpation
weakness
hypercalcaemia
confusion

39
Q

severe vitamin D deficiency can cause

A

osteomalacia
rickets

regulatory physiology and pharmacology (20 decks)

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