Hn 400 Test 4 Set 2

Front 1

unique among vitamins in that it is part vitamin, part hormone

Back 1

vitamin D

part hormone b/c we synthesize it and it acts like a hormone in our bodies

Front 2

two major dietary forms of vit D

Back 2

plants and yeast -- vit D2 (ergocalciferol)
animals -- vit D3

Front 3

in the presence of UV-B light, ________ is converted to vit D3

Back 3

7-dehydrocholesterol

Front 4

synthesized vit D will combine w/ _______ _______ ______ (____ ) to be transported to the liver

Back 4

vitamin D-binding protein (DBP)

ingested vit D is transported w/in chylomicrons

Front 5

circulating form of vit D

Back 5

25-hydroxy vit D (25-OH-D, calcidiol)

formed by liver enzyme 25-hydroxylase adding a hydroxyl group at the 25th carbon

Front 6

active form of vit D

Back 6

1,25 hydroxy vit D (1,25(OH)2 D) (calcitriol)

formed by having another hydroxyl group added to the circulating 25-hydroxy vit D by the enzyme 1alpha-hydroxylase in the kidney

Front 7

vit D synthesis peaks around what time of day?

Back 7

noon, increases all morning, declines rest of day

Front 8

the skin pigment melanin may require people with very dark skin color to get ___ to ____ times greater sunlight exposure than a light-skinned white person to synthesize the same amount of vit D3

Back 8

5-10

Front 9

a decrease in vit D3 synthesis coincides w/ aging b/c o a decrease in ________ concentrations in the skin

Back 9

7-dehydrocholesterol

Front 10

one natural good source of vit D is...

Back 10

fatty fish

Front 11

along with vit D, these two hormones are the other major regulators of blood calcium levels

Back 11

parathyroid hormone (PTH)

calcitonin

Front 12

in bone, calcium is found in _________ crystals on a collagen matrix

Back 12

hydroxyapatite

calcium and phosphorous are either deposited or liberated from hydroxyapatite in bone together to maintain blood calcium concentrations

Front 13

increases calcium absorption in the small intestine

also believed to help PTH increase bone resorption and decrease calcium excretion

Back 13

1,25 (OH)2 D

Front 14

increases bone resorption
decreases calcium, increases phosphorous excretion in urine
increases 1,25 (OH)2 D activation in the kidney

Back 14

PTH

released from parathyroid in response to low blood calcium concentrations

Front 15

decreases bone resorption, increase bone deposition
increases calcium and phosphorous excretion in urine
decreases 1,25 (OH)2 D activation in the kidney

Back 15

functions of calcitonin

released by thyroid in response to high blood calcium levels

Front 16

unique among the different vitamins b/c they have nuclear receptors

Back 16

vit D, along w/ vit A

Front 17

a hormone enters the nucleus and binds to the ________ ______ that has paired with (formed a dimer) the ________ ___ _______ (____ ) on the hormone response element (HRE) in the promoter of target genes

Back 17

hormone receptor

retinoid X receptor (RXR)

Front 18

1,25(OH)2D is considered to be the active form of vit D b/c this is the form that binds to the _____ __ _________ (___ )

Back 18

vitamin D receptor (VDR)

Front 19

vit D deficiency in infants and children

leads to decreased bone mineralization, causing bones to become weak

bones bow under pressure leading to characteristic bowed legs

Back 19

rickets

vit D deficiency

Front 20

besides bowed legs, this symptom of beaded ribs at the areas where cartilage meets bone on the rib cage is a characteristic symptom of rickets

Back 20

rachitic rosary

Front 21

vit D deficiency in adults, results in poor bone mineralization

bone becomes soft, resulting in bone pain and increased rate of fractures

Back 21

osteomalacia

Front 22

doesn't refer to preventing deficiency, rather that there are additional benefits at levels above what is needed to prevent deficiency

Back 22

insufficiency

Front 23

this toxicity (often from supplements but not from sunlight) results in hypercalcemia

becomes problematic b/c it can lead to calcification of soft tissues

Back 23

vit D toxicity

Front 24

most abundant mineral in the body

99% is found in the skeleton

Back 24

calcium

Front 25

calcium is taken up into the enterocyte via ______ _______ _______ ___ (____), which is a calcium channel found on the brush border

Back 25

transient receptor potential V6 (TRP)

Front 26

_______ is a calcium binding protein that facilitates uptake through the TRP channel, as well as transport across the enterocyte

Back 26

calbindin

Front 27

__________ pumps calcium out of the enterocyte and into circulation and magnesium into the enterocyte

Back 27

Ca2+-Mg2+ ATPase

Front 28

increased _______ synthesis in the kidney leads to increased binding to the vit D receptor, leading to increased calbindin syntehsis that increases calcium uptake and absorption

Back 28

1,25(OH)2D

Front 29

_______, which is found in high levels in spinach, rhubarb, sweet potatoes, and dried beans is the most potent inhibitor of calcium absorption

Back 29

oxalate

Front 30

_____ _____ is one of the compounds that makes up kidney stones

should not be surprising therefore that formation of this compound leads calcium absorption to be inhibited

Back 30

calcium oxalate

Front 31

another inhibitor of calcium absorption that is found in whole grains and legumes

Back 31

phytate

Front 32

2 most common forms of calcium found in supplements

Back 32

calcium carbonate

calcium citrate

Front 33

an intracellular signaling molecule

tightly controlled w/in cells, stored w/in organelles

involved in:
neurotransmitter release
muscle contration
hormone release
blood clotting
enzyme regulation

Back 33

calcium

Front 34

in muscle cells, calcium is released to bind to the protein ______, changes its shape, and removes the ______ blockade of actin active sites so that contraction can occur

Back 34

troponin

tropomyosin

Front 35

how calcium stimulates the release of insulin

Back 35

opening of voltage-gated Ca channels stimulates insulin granules to fuse with beta cell membrane to release insulin

Front 36

calcium binds to the activated ____ proteins that is important in the blood clotting cascade

Back 36

Gla

Front 37

involuntary muscle contraction that can occur during hypocalcemia

Back 37

tetany

Front 38

bone mass is normal, but the matrix to mineral ratio is increased, meaning there is less mineral in bone

Back 38

osteomalacia

Front 39

bone mass is decreased, but the matrix to mineral ratio is not altered from normal bone

intermediate condition b/t normal and osteoporosis

Back 39

osteopenia

t-score from -1 to -2.5 (normal greater than -1)

Front 40

bone mass is further decreased from osteopenia, but the matrix to mineral ratio is not altered from normal bone

Back 40

osteoporosis

t-score of less than -2.5 (normal greater than -1)

Front 41

this procedure accurately measures bone mineral density using a smal amount of radiation

Back 41

dual energy X-ray absorptiometry (DEXA)

Front 42

animal products are rich sources of phosphate

plant products contain phosphorous, but some is in phytic acid (phytate)

the bioavailability of phosphorous from phytate is poor b/c we lack the enzyme ____

Back 42

phytase

Front 43

______ _____ is used to acidify colas

soft drink consumption may be correlated with decreased bone mineral densities

Back 43

phosphoric acid

Front 44

deficiency is rare, but can hinder both bone and teeth development
other symptoms include anorexia, weakness and bone pain

toxicity is also rare, resulting in low blood Ca concentrations and tetany

Back 44

phosphorous

Front 45

used to activate and deactivate a number of proteins
common component of phospholipids
structural role in DNA
used in bonds in the major energy currency of our bodies
found within structure of secondary messengers cAMP and IP3

Back 45

phosphorous non-bone functions

Front 46

nonessential mineral
isn't widely found in the food supply
majority of what we consume comes from water

absorption is near 100% --> rapidly excreted in urine

Back 46

fluoride

Front 47

excessive intake of fluoride can cause ...

Back 47

nausea
vomiting
diarrhea
convulsions

Front 48

chronic fluoride toxicity results in irreversible condition known as ______ characterized by the mottling and pitting of teeth

Back 48

fluorosis

Front 49

primary form of vit K in the diet

good sources include green leafy vegetables, broccoli, brussels sprouts, and asparagus

Back 49

phylloquinone

Front 50

bacteria in the colon synthesize about 10% of the vit K we absorb each day as ________

Back 50

menaquinone

Front 51

synthetic form of vit K

Back 51

menadione

Front 52

vit K is absorbed like other _____ ______ subtances, w/ about 80% of phylloquinone and menaquinone estimated to be incorporated into chylomicrons and stored primarily in the liver

Back 52

fat-soluble

Front 53

vit K is metabolized and primarily excreted in ____ and ultimately the _____, w/ less being excreted in urine

Back 53

bile

feces

Front 54

cofactor for carboxylation reactions that add a to the amino acid ____ _____ (____) in certain proteins

Back 54

glutamic acid (glutamate)

Front 55

enzyme gamma-glutamyl carboxylase uses vit K as a cofactor to convert glutamic acid to ____ ________ _____ (___)

Back 55

gamma-carboxyglutamic acid (Gla)

Front 56

one place where ____ proteins are important is in blood clotting, which occurs through a cascade of events

Back 56

Gla

Front 57

after being used as a cofactor or a reaction by ____ ______ ______, vit K forms vit K epoxide, a form that needs to be converted back to vit K to serve as a cofactor again

Back 57

gamma-glutamyl carboxylase

Front 58

warfarin (coumadin) and dicumarol are a couple of blood thinning drugs that inhibit the regeneration of...

Back 58

vit K from vit K epoxide

results in a reduction in the amount of Gla in blood clotting proteins and thus, the clotting response

Front 59

vit K deficiency is rare, but can occur in these situations

Back 59

in newborn infants
after prolonged antibiotic treatment (may kill GI flora)

high intake of vit E can also interfere w/ vit K's functions

leads to increased risk of bleeding or hemorrage

Front 60

3 forms of vit A

Back 60

retinoids

retinol (alcohol form)
retinal (aldehyde form)
retinoic acid (carboxylic acid form)

retinal and retinol are interchangeable

only retinal can be converted to retinoic acid, and this step is irreversible

Front 61

two primary dietary sources of vit A

Back 61

retinyl esters (animal products) -- preformed vit A

provitamin A carotenoids (plants) -- provitamin A not currently a form of vit A

Front 62

40 carbon compounds that are found throughout nature

animals do not produce them -- all are originally produced by plants or microorganisms

Back 62

carotenoids

Front 63

beta-carotene
alpha-carotene
beta-cryptoxanthin
lutein
zeaxanthin
lycopene

Back 63

6 main carotenoids found in diet and the body

Front 64

provitamin A carotenoids are those that can be cleaved to form _______, while the nonprovitamin A carotenoids cannot

Back 64

retinal

Front 65

to help account for the fact that retinol can be made from carotenoids, the DRI committee made ______ _____ ______ (___) that take into account the bioavailibility and bioconversion of the provitamin A carotenoids

Back 65

retinol activity equivalents (RAE)

1 ug RAE
= 1 ug of retinol
= 2 ug of supplemental beta-carotene
= 12 ug of dietary beta-carotene
= 24 ug of alpha-carotene or beta-cryptoxanthin

Front 66

provitamin A carotenoids are taken up into enterocytes, where some are cleaved to _____ that is converted to ______

provitamin A carotenoid absorption is normally much lower than preformed vitamin A

Back 66

retinal

retinol

Front 67

retinol in the enterocyte is esterified, forming retinyl esters and packaged into ________

Back 67

chylomicrons (CM)

Front 68

after going through the lymph system chylomicrons reach circulation, where triglycerides are cleaved off of the chylomicrons, forming ______ ______

Back 68

chylomicrons remnants (CM Rem)

Front 69

chylomicron remnants are taken up by __________, where the retinyl esters are deesterified forming retinol

Back 69

hepatocytes

liver is the major storage site of vit A

Front 70

for storage, the retinol will be transported to ___ _____ and converted back to retinyl esters, the storage form of vit A

Back 70

stellate cells

liver

Front 71

if vit A is to be released into circulation, retinol will combine w/ retinol binding protein (RBP) to be released into circulation.

retinol + RBP are then bound to _________ ((___), a larger protein w/o which it is believed that retinol + RBP could be filtered out by the kidney

Back 71

transthyretin (TTR)

Front 72

like vit D, vit A has a nuclear receptor

actually it has 2... which are

Back 72

retinoic acid receptors (RARs) --- ligand -> all-trans-retinoic acid

retinoid X receptors (RXRs) --- ligand --> 9-cis retinoic acid

Front 73

RAR and RXR are paired or dimerized on ____ ______ _____ _____ (______) in the promoterr region of target genes

Back 73

retinoic acid response elelment (RARE)

Front 74

active form of vit A

Back 74

all-trans retinoic acid

Front 75

in rods, __________ combines with the protein opsin to form rhodopsin

Back 75

11-cis retinal

Front 76

when light strikes ______, it is converted to opsin plus all-trans retinal and causes a message to be sent to your brain

Back 76

rhodopsin

Front 77

stem cell ---> specialized cells differentiation

growth and develpment
reproduction
immune function

Back 77

functions of vit A aside from vision

Front 78

most common early symptom of vit A deficiency

Back 78

night blindness due to insufficient production of rhodopsin

Front 79

further changes to the eye that occur due to lack of vit A

Back 79

xerophthalmia

Front 80

in this condition caused by vit A deficiency, cell overproduce the protein keratin, causing the skin to become rough and irritated

Back 80

hyperkeratosis

Front 81

blurred vision, liver abnormalities, skin disorders, joint pain, easier bone fractures, teratogenic (causing birth defects)

Back 81

vit A toxicity

Front 82

vit A toxicity cannot be developed from consuming too much beta-carotene or other provitamin A carotenoids. Instead a nontoxic condition known as __________ occurs where the accumulation of the carotenoid in the fat below the skin causes the skin to look orange

Back 82

carotenodermia

Front 83

2 major dietary forms of iron

Back 83

heme iron - only in foods of animal origin - found in hemoglobin and myoglobin

non-heme iron

40% iron in fish, meat, poultry is heme-iron

Front 84

two forms of non-heme iron

Back 84

ferric (Fe3+, oxidized)
ferrous (Fe2+, reduced)

Front 85

estimated that ____% of heme iron and ____% of non-heme iron are absorbed

it is estimated that 85-90% o the iron we consume is non-heme iron

Back 85

25%
17%

Front 86

transporter for non-heme iron

Back 86

divalent mineral transporter 1 (DMT1)

transports Fe2+ into the enterocyte

Front 87

transporter for heme iron

Back 87

heme carrier protein 1 (HCP-1)

after being taken up, heme is metabolized to Fe2+

Front 88

to reach circulation, Fe2+ is transported through _______ into circulation

Back 88

ferroportin

only reduced non-heme iron is taken up

Front 89

in addition to vitamin C, another enhancer of non-heme iron is _____ _____ _____

Back 89

meat protein factor (MPF)

Front 90

inhibitors of non-heme iron absorption typically ______, or bind iron, thus preventing its absorption

Back 90

chelate

phytates, which inhibit calcium absorption, also chelates non-heme iron, decreasing its absorption

other compounds that inhibit absorption are:
polyphenols (coffee, tea)
oxalate (spinach, rhubarb, sweet potatoes, dried beans)

calcium is also believed to inhibit iron uptake

Front 91

the major iron transport protein (transports iron through blood)

Back 91

transferrin

Fe3+ is the only form of iron that binds to transferrin

Front 92

2 copper-containing proteins that catalyze the oxidation of Fe2+

Back 92

ceruloplamsin and hephaestin

Front 93

primary iron storage protein

Back 93

ferritin

at higher concentrations, more iron is stored in hemosiderin

Front 94

three functional iron subcompartments

Back 94

hemoglobin
myoglobin
iron-containing enzymes

Front 95

iron stores consist of...

Back 95

ferritin
hemosiderin

Front 96

unique among minerals in that our body has limited excretion ability

Back 96

iron

Front 97

absorption is controlled by the hormone ______. the liver has an iron sensor that will signal or release of ________ which leads to the degradation of ferroportin, thus iron is not allowed to be transported into circulation

Back 97

hepcidin

Front 98

when iron stores are almost completely exhausted

Back 98

iron depletion --> progressed from early negative iron balance

Front 99

stores are completely exhausted and circulating and functional iron are also depleted in this condition

Back 99

iron deficiency

Front 100

the circulating and functional iron levels are further depleated from iron deficiency in this condition

Back 100

iron anemia

Front 101

a measure of the proportion of blood that is RBCs, determined after centrifugation

Back 101

hematocrit

most common measure of iron status along with hemoglobin concentrations

Front 102

in the hematocrit, the RBCs end up in the bottom of the tube and can be quantified by measuring the ____ ___ ____ relative to whole blood volume

Back 102

packed cell volume (PCV)

Front 103

best measure for deficiency or anemia in iron is either percent ______ _______ saturation or plasma iron

Back 103

serum transferrin

Front 104

the most common deficiency worldwide

Back 104

iron deficiency

Front 105

iron deficiency results in a mycrocytic (small cell), hypochromic (low color ) anemia, that is a result of decreased _____ production

Back 105

hemoglobin

Front 106

why runners need more iron

Back 106

foot strike hemolysis

Front 107

genetic condition in which there is a mutation in a protein in the enterocyte that prevents them from decreasing intestinal iron absorption

since the body doesn't have a mechanism for excreting iron, it accumulates in tissues ultimately resulting in organ failure

Back 107

hemochromatosis