Fat Soluble Vitamins

Question 1

fat-soluble vitamins are A,D,E,K
stored in:

Answer 1

liver and/or fatty deposits
D synthesized by skin and K by intestinal flora
A and D extensively metabolized
E and K are not metabolized

Question 2

Vitamin A
belong to retinoids family
provitamins A belongs to family called?
most abundant dietary carotenoid is?
beta-carotene cleaved and forms?

Answer 2

carotenoids
beta-carotene
2 retinal

Question 3

6 microgram of beta-carotenes gives

Answer 3

1 retinol equivalent

Question 4

11 cis retinal helps us

Answer 4

see in the dark

Question 5

Diet of vitamin A mostly as ?
plant food as ?

Answer 5

-retinyl esters
-beta-carotene
retinyl esters are hydrolyzed in the intestinal lumen to free fatty acids and retinol

Question 6

liver stores 6-12 month stupply of vitamin A with retinol binding protein bound to

Answer 6

transthyretin
they could be lost in urine through kidney and by binding to more proteins it wont be excreted

Question 7

Vitamin A functions in 3 main areas

Answer 7

vision
gene regulation
antioxidant

Question 8

Vision
rhodopsin contains

Answer 8

11 cis retinal with opsin
when light strikes the rhodopsin breaks down and signals send through cyclic GMP and brain interprets signal for vision in the dark

Question 9

Gene regulation
all-trans retinoic acid binds protein which then binds

Answer 9

DNA during steroid hormone signaling and results in either activation or suppress genes

Question 10

cells with lots of Vitamin A

Answer 10

epithelial cells:
gastrointestinal
genitourinary
respiratory

Question 11

epithelial cells with not synthesize ___ as long as they are supplied with retinal to make retinoic acid

Answer 11

keratin

Question 12

retinoic acid ___ synthesis of keratin

Answer 12

suppress

Question 13

epidermal epithelial cells normally undergo terminal keratinization bc

Answer 13

they are not vascularized and therefore have no supply of retinal for retinoic acid synthesis

Question 14

Anti-oxidant:
Vitamin A and carotenoids function as anti-oxidants

Answer 14

an optimal level of vit A may reduce risk of cancer but care should be taken bc excess vitamin A is toxic

Question 15

Hypovitaminosis vitamin A
severe xerophthalmia

Answer 15

progressive keratinization of the cornea of eye which can lead to blindness

Question 16

Mild hypovitaminosis vitamin A

Answer 16

night blindness, follicular hyperkeratosis, anemia

Question 17

Special needs for vitamin A include

Answer 17

premature infants have low liver reserve
individuals with fat malabsoprtion syndromes or pancreatic insufficiency
hepatobilitary tree disease
intestinal mucosa dysfunction

Question 18

Overconsumption of vitamin A
hypervitaminosis

Answer 18

tertogenic causes birth defects
(accutane)

Question 19

Vitamin D

Answer 19

we can synthesize it ourselves as long as exposed to sunlight

Question 20

Cholecalciferol is converted to the active form by two hydroxylations

Answer 20

first hydroxylation occurs in liver catalyzed by CYP2R1 and yields 25-OH-cholecalciferol
second rxn occurs in kidney (cat. by CYP27B1) and yields active form of vitamin D 1,25 diOH cholecalciferol

Question 21

calcium needed for vitamin D absorption

Answer 21

vitamin D binds to receptor binds DNA and synthesizes calbindin

Question 22

decrease serum calcium results in

Answer 22

increase parathyroid hormone and thus increase calcitrol in kidney
keeps calcium levels up

Question 23

bone resorption

Answer 23

removes calcium from bone in order to maintain blood calcium levels

Question 24

vitamin D and PTH inhibit calcium excretion by the kidney by

Answer 24

stimulating calcium reabsorption

Question 25

functions of 1,25 dihydroxycholecalciferol

Answer 25

1) induce syn of protein required for calcium absorption
2) act synergistically with parathyroid hormone to promote bone resorption
3) acts synergistically with PTH to inhibit calcium excretion in kidney by stimulating calcium reabsorption
CALCIUM HOMEOSTASIS

Question 26

Hypovitaminosis of Vitamin D
def in children causes ___
def in adults causes ___

Answer 26

rickets
osteomalacia
special needs: in fat malabsorption syndromes
during the use of corticosteroids and anti-convulsants

Question 27

Excess of vitamin D can be deleterious

Answer 27

can cause permanent kidney damage, growth retardation, calcification of soft tissues

Question 28

Vitamin E

Answer 28

tocopherol
tootrienol
various forms of vitamin E absorbed
only alpha tocopherol is retained

Question 29

Vitamin E
hepatic alpha tocopherol transfer protein only holds onto

Answer 29

alpha tocopherol

Question 30

Utilization and FUnction of VItamin E
main function

Answer 30

antioxidant

Question 31

Vitamin E Hypovitaminosis

Answer 31

increased fragility of RBC membranes due to oxidant stress

Question 32

Vitamin K

Answer 32

cofactor in gamma-carboxylation of glutamate residues in certain proteins that include precoagulation factors and bone proteins

Question 33

Vitamin K hypovitaminosis

Answer 33

uncommon but may cause hemorrhage
predisposing conditions:
total parenteral nutrition
malabsorption syndrome
liver dysfunction

Question 34

newborns have low liver stores and a sterile GI tract

Answer 34

breast milk low in vitamin K
give newborns prophylactic dose of vitamin K

Question 35

Vitamin K special needs

Answer 35

counteract overdoses of oral coumarin anticoagulatns
broad spectrum antibiotic therapy
no toxicity from excess