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IHN BIOCHEMISTRY FINAL > FINAL: vitamin D > Flashcards

FINAL: vitamin D Flashcards

1
Q

vit D is __ soluble

A

vit D is fat soluble

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2
Q

how is vit D carried in blood

A

by vit D binding protein

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3
Q

vit D is not really a __ but a __

A

vit D is not really a vitamin but a steroid

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4
Q

D3 =

A

animal sources
supplements
cholecalciferol

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5
Q

D2 =

A

prescription
ergocalciferol
plant form

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6
Q

__ and __ are biologically inactive

A

D2 and D3 are biologically inactive

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7
Q

D2 and D3 transformation steps

A
  1. liver: D3+D2 –> 25(OH)D
  2. kidney: 25(OH)D –> 1,25(OH2)D
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8
Q

vit D from diet/UVB is turned to __ by __ in __

A

vit D from diet/UVB is turned to 25(OH)D by CYP2R1 in liver

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9
Q

25(OH)D has 3 fates

A
  1. local conversion to 24, 25 (OH)2D
  2. kidney conversion to 1,25(OH)2D, then local to 1,24,25 (OH)2D
  3. extra-renal conversion to 1,25(OH)2D then to targets
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10
Q

local conversion is upregulated by

A

1,25(OH)2D
Caclium
FGF23
PO43-

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11
Q

kidney conversion enzyme

A

CYP27B1

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12
Q

kidney conversion from 25OHD to 1,25(OH2)D regulation

A

upregulated by PTH
downregulated by Calcium, FGF23, PO43-

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13
Q

after extra-renal conversion 1,25(OH)2D is bound to __

A

after extra-renal conversion 1,25(OH)2D is bound to DBP and albumin

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14
Q

DBP and albumin bound 1,25(OH)2D target tissues

A

gut
kidney
bone
immune cells
muscle
pancreas

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15
Q

vit D deficiency in kids

A

rickets
demineralized bones bow as child’s weight increases

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16
Q

vit D deficiency in adults

A

osteomalacia

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17
Q

__ can prevent rickets and osteomalacia

A

400 IU vit D supp daily can prevent rickets and osteomalacia

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18
Q

vit D as a trxn factor

A
  1. 1,25 (OH)2 vit D3 binds, VDR acts as trxn factor
  2. heterodimer with RXR (retinoic X receptor)
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19
Q

VDR mediates most __ actions

A

VDR mediates most 1,25 (OH)2D actions

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20
Q

where is VDR found

A

many tissues, including cancer cells

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21
Q

using __, VDR turns 25OHD3 to __ which enables cell __

A

using 1 alpha hydroxylase, VDR turns 25OHD3 to 1,25(OH)2D3 which enables cell proliferation and differentiation

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22
Q

25(OH)D is bound by (2)

A

albumin
vit D binding protein (DBP)

23
Q

free 25(OH)D is aka

A

bioavailable

24
Q

__ may help understand why total 25(OH)D levels show variability for disease outcomes btwn individuals

A

free 25(OH)D may help understand why total 25(OH)D levels show variability for disease outcomes btwn individuals

25
RDA for vit D increases with
age pregnancy/lactation
26
vit D increases (4)
Ca2+ absorption osteoclast activity immune function renal 1,25(OH)D synthesis
27
1,25(OH)2D3 plays a role in (5)
1. muscle and skeletal development 2. renin-angiotensin regulation 3. neuronal development 4. inhibits cell cycle 5. increases insulin secretion
28
US intake of vit D __ doesn't matter highest = lowest = are most ppl deficient?
US intake of vit D **latitude** doesn't matter highest = **summer** lowest = **spring** are most ppl deficient? **NO**
29
high __ diet affects lowers serum levels
high **fat** diet lowers serum levels
30
__ ppl respond better to supplementation
**deficienct (lower baseline vit D)** ppl respond better to supplementation
31
do we consume a lot of vit D?
no, sunlight helps us though
32
3 main sources of vit D
1. sunlight (carinogen issue) 2. endogenous production (after sun or diet) 3. diet (minor, so we fortify milk)
33
dietary vit D sources
1. fatty fish and oil 2. mushrooms (more sunlight = better) 3. fortified foods
34
what foods are fortified with vit D
milk (not cheese or yogurt) cereal bread OJ
35
vit D toxicity caused by (2)
1. Ca2+ serum build-up 2. manufacturing errors with supplements or fortification
36
vit D toxicity symptoms
drowsiness vomiting peptic ulcers increased BP tachycardia kidney issues
37
VITAL study looked at
vit D supp and cancer and CVD disease prevention
38
VITAL study effect
no effect supp don't help elderly people in high doses
39
VITAL high dose = __ rxn time
VITAL high dose = **decreased** rxn time
40
VITAL vit D supp may help __ by __ relevant in preventing __
VITAL vit D supp may help **cognitive decline** by **increasing neuron development and helping beta-amyloid clearance** relevant in preventing **dementia**
41
vit D is a risk factor for __
vit D is a risk factor for **mobility after hip fracture**
42
vit D deficiency increases __ and __
vit D deficiency increases **autoimmunity** and **infection**
43
vit D receptor is located in __, so it may affect __ function
vit D receptor is located in **pancreas**, so it may affect **beta-cell** function
44
who is at special risk for vit D deficiency
African Americans pregnant and lactating older ppl with risk of falling or fracture obese (low vit D = increased body weight)
45
is the primary function of vitamin D to support bone health?
NO
46
are most ppl vit D deficient?
NO
47
do we get enough vit D in diet?
no, supp help
48
should we just supp with a ton of vit D
no bc it could be toxic
49
__ min sun exposure __x per week is enough
**10-20** min sun exposure **2-3x** per week is enough
50
what percent of ppl are vit D deficient?
33%
51
excess sun exposure makes us make large amounts of __ will this become toxic?
excess sun exposure makes us make large amounts of **D3** will this become toxic? **prob not bc it is further metabolized**
52
3 inactive forms of vit D
lumisterol tachysterol suprasterol I and II
53
summer has __ vit D production __ and __ decrease amount of vit D produced in skin
summer has **high** vit D production **sunscreen** and **clothing** decrease amount of vit D produced in skin
54
ability to produce vit D in skin varies with (2)
1. pigmentation (melanin = decreased UVB to skin) 2. age = decreased with older age

IHN BIOCHEMISTRY FINAL (15 decks)

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