Exam - Calcium Flashcards

1
Q

what percentage of the body’s mineral mass does calcium represent

A

~40%

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2
Q

what percentage of the calcium in the body is contained by teeth and bone

A

99%

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3
Q

what is the remaining 1% used for

A

it is very important for signalling pathways

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4
Q

supplement label for calcium

A

helps prevent osteoporosis and develop strong bones

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5
Q

what is calcium predominantly obtained from

A

dairy products

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6
Q

how does calcium present in foods

A

as an insoluble salt

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7
Q

how does calcium become soluble

A

the stomach acid creates it - gets activated by HCl

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8
Q

what percentage of dietary calcium gets absorbed in the small intestine

A

25-30%

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9
Q

how does calcium get absorbed

A

saturable and carrier mediated active transport

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10
Q

what is calcium absorption mediated by

A

calcitriol

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11
Q

what is the secondary pathway for Ca2+ uptake

A

diffusion via paracellular route

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12
Q

percentages of the 3 ways calcium gets transported around the body

A

40% bound to albumin
10% found complexed with sulphate, phosphate etc
50% found in free ionized form

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13
Q

what do minerals make up in bone

A

hydroxyapatite (crystal like structure)

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14
Q

2 functions of calcium

A

bone
intra/extracellular

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15
Q

what is ionized calcium active and used for

A

blood clotting
skeletal muscle contraction
nerve potential
intracellular signalling pathways

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16
Q

what will happen if intra/extracellular levels of Ca2+ drop

A

bone will be sacrificed, otherwise death occurs

17
Q

how does calcium get used for blood clotting

A

formation of Gla residues on coagulation proteins

18
Q

how does calcium get used for skeletal muscle contraction

A

release of calcium stores

19
Q

how does calcium get used for nerve potential

A

acting through ion channels

20
Q

what factors decrease calcium absorption

A

caffeine
some fibres
magnesium and zinc

21
Q

what factors increase calcium absorption

A

pregnancy and lactation
PTH (Vit D)

22
Q

what does calcium deficiency profoundly affect

A

bone and muscle

23
Q

how does calcium deficiency affect bone

A

inadequate mineralization - rickets and osteomalacia

24
Q

how does calcium deficiency affect muscle

A

causes tetany - involuntary muscle contractions

25
Q

what is there evidence of calcium deficiency being associated with

A

hypertension
colon cancer

26
Q

what occurs with calcium toxicity

A

constipation
bloating/gas
hypercalcemia - kidney stones