Lecture 23: Fat-Soluble Vitamins

Question 1

Which two fat soluble vitamins are synthesized endogenously?

Answer 1

Vit D/K

Question 2

Which two fat soluble vitamins are metabolized?

Answer 2

D/A

Question 3

Provitamin A is a part of ___ family while Vit A is a part of ___ family

Answer 3

Carotenoids; Retinoids

Question 4

B-carotene can convert to ___, which can convert to ___ , which can produce ____

Answer 4

retinal <—-> retinol
retinoic acid
11-cis retinal

Question 5

What form of Vit A treats psoriasis and promyelocytic leukemia?

Answer 5

Trans retinoic acid

Question 6

Which form of Vit A treats severe acne?

Answer 6

13-cis retinoic acid

Question 7

What Vit A can you get from animal tissue vs. plants?

Answer 7

animal: retinyl esters; retinol
plants: b-carotene

Question 8

Retinyl esters are broken down into ___ and ___ in the intestinal lumen

Answer 8

Fatty acids and retinol

Question 9

In the intestine cells, retinol is re-esterified and incorporated into _____, which can be transported to liver/adipse

Answer 9

chylomicrons

Question 10

How is Vit A stored? Where is it stored?

Answer 10

Retinyl Esters
-liver
-adipose

Question 11

The liver can store 8-6 mths of Vit A with the help of a retinol binding protein known as _____

Answer 11

Transthyretin

Question 12

Rhodopsin is typically bound to inactive 11 cis-retinol and opsin. When light strike, __ breaks down and actives ___ and ___

Answer 12

rhodopsin ; trans-retinal and cGMP

Question 13

Conformational change in opsin generated nerve ___

Answer 13

impulse

Question 14

All trans retinal can be use to make more _____

Answer 14

11-cis retinal

Question 15

In target tissues, retinol is oxidized to ______

Answer 15

retinoic acid

Question 16

What complex can active/inhibit genes?

Answer 16

Retinoic acid-receptor complex

Question 17

What form of Vit A functions in gene regulation?

Answer 17

All-trans retinoic acid

Question 18

If epithelial cells have a good supply of retinal, it is converted to retinoic acid and no ___ is made

Answer 18

Keratin

Question 19

____ _____ suppresses synthesis of keratin by binding to nuclear receptor

Answer 19

Retinoic Acid

Question 20

Why do epidermal epithelial cells usually undergo terminal keritinization?

Answer 20

Not vascularized, no retinal, therefore: no retinoic synthesis

Question 21

______ cells secrete mucus to keep moist. They do not usually keratinize.

Answer 21

Internal Epithelial Cells

Question 22

How does Vit A decrease cancer risk?

Answer 22

Acts as an anti-oxidant substance

Question 23

Hypervitaminosis of Vit A?
Hypovitaminosis of Vit A?

Answer 23

Hypervitaminosis: Teratogen

Hypovitaminosis: Severe xeropthalmia

Question 24

Mild hypovitaminosis of Vit A

Answer 24

-night blindness
-anemia
-follicular hyperkeratosis

Question 25

What 4 populations require additional Vit A?

Answer 25

1) premature infants 2) people w/ fat malabsorption/deficiency/pancreatic insufficiency 3) hepatobil tree disease 4) intestinal mucosa dysfunction

Question 26

How can ergocalciferol (Vit D2) can be obtained?

Answer 26

Dairy

Question 27

How can cholecalciferol (Vit D3) be generated?

Answer 27

UV light converted 7-dehydrocholesterol to Vit D3

Question 28

For Vit D3 to be converted to its active form two processes must occur, one in the ___ and the other in the ___.

Answer 28

Liver; kidney

Question 29

CYP2R1 in the liver creates ____ CYP27B1 produces ____, active form of Vit D, which inhibits further Vit D3 production

Answer 29

25-OH-cholecalciferol 1,25-diOH-cholecalciferol

Question 30

Ergosterol + UV = ?

Answer 30

Ergocalciferol

Question 31

How does Vitamin D/PTH inhibit calcium excretion from kidney?

Answer 31

Stimulates calcium reabsorption

Question 32

Under what two conditions do you require more Vit D?

Answer 32

1) Fat malabsorption disorder 2) Use of corticosteroids/anticonvulsants

Question 33

Hyper vs. Hypovitaminosis of Vit D?

Answer 33

Hypervitaminosis: growth retardation, calcify soft tissues, permanent kidney damage Hypovitaminosis: rickets; osteomalacia

Question 34

What happens when serum calcium levels are low?

Answer 34

Increase PTH, calcitrol, more calcium is reabsorbed from bone, more renal absorption of calcium, more calcium absorbed from intestine

Question 35

Three functions of 1,25-dihydroxycholecalciferol (calcitrol)?

Answer 35

1) Induces synthesis of calbindin 2) Works with PTH to ensure bone reabsorption 3) Works with PTH to inhibit calcium excretion from kidney

Question 36

In the intestine, Vit D induces synthesis of ___, which absorbs dietary calcium

Answer 36

calbindin

Question 37

What fat-soluble vitamin has no toxicity associated with excess of it?

Answer 37

Vit K

Question 38

Under what two conditions would a patient require more Vit K than usual?

Answer 38

1) Broad spectrum abx's 2) Counteract OD of coumadin

Question 39

Why do newborns often get prophylactic dose of Vit K?

Answer 39

They have sterile GI and low liver stores of Vit K. Also, breast milk is low in Vit K

Question 40

Hypovitaminosis of Vit K?

Answer 40

Hemorrhage

Question 41

What can pre-dispose a patient to hypovitaminosis of Vit K?

Answer 41

1) Total parentral nutrition 2) Liver Dysfunction 3) Maladaption Syndrome

Question 42

Role of Vit K?

Answer 42

Co-factor in gamma-carboxylation of glutamine residues in: -Coag factors -Bone proteins

Question 43

Phylloquinone = Vit

Answer 43

K

Question 44

While various forms of vit E are absorbed, which is the only one to be retained?

Answer 44

alpha-tocopherol

Question 45

Main function of Vit E?

Answer 45

Anti-oxidant

Question 46

Increase fragility of RBC membrane is associated with hypovitaminosis of what fat-soluble vitamin

Answer 46

Vit E

Question 47

Epithelial cells will not make ___ as long as they are supplied with retinal to make retinoic acid

Answer 47

keratin

Question 48

Three functions of Vit A?

Answer 48

Vision Gene regulation Anti-oxidant

Question 49

______ is a component of the visual pigment rhodopsin

Answer 49

11 cis-retinal

Question 50

Cholecalciferol is converted to the active form by two hydroxylations - the first is in the ____ while the second is in the ____

Answer 50

Liver; kidney (yields active form of vit D: 1,25 diOH cholecalciferol)