Skildog Vitamins

Question 1

Biologically active form of Vitamin A

Answer 1

All-trans retinol

Question 2

Once Vitamin A is inside enterocytes, what 2 ways can it enter the blood?

Answer 2

Retinoic acid bound to albumin

Packaged in chylomicrons

Question 3

What cells are a reservoir for vitamin A storage?

Answer 3

Stellate cells in liver!

Question 4

What form of Vitamin A is functional in the eye?

Answer 4

Aldehyde form (cis-retinal) covalently linked to opsin

Question 5

What things does retinoic acid lead to when it acts as a transcriptional regulator?

Answer 5

Differentiation of goblet cells–mucus, prevents keratinization

Apopotosis of cancer cells

Maturation of dendritic cells

Recruitment of antibody-secreting cells to Small intestine

Question 6

What form of vitamin A acts as an antioxidant?

Answer 6

Carotenes (2 molecules of retinal)

Question 7

What does Relative Dose Response (RDR) tell you about the body’s Vitamin A status?

Answer 7

The higher the RDR, the more the body is relying on short term dietary Vita A rather than liver stores (>20 % indicates liver is not maintaining serum Vit. A)

Question 8

Vitamin E main function

Answer 8

Oxidative stress defense

Question 9

Vitamin E inhibits absorption of what other vitamin?

Answer 9

Vitamin K

Question 10

Saturated form of Vitamin E?

Answer 10

Tocopherols

Question 11

Main form of vitamin K in diet?

Answer 11

Phylloquinone

Question 12

What organ stores a lot of Vitamin K?

Answer 12

Lung

Question 13

Functions (2) of Vit. K?

Answer 13

Coagulation and carboxylation

Question 14

What enzyme inside cells is Vitamin K a cofactor for?

Answer 14

gamma-glutamyl carboxylase (for blood clotting proteins)

Question 15

What factors are dependent on Vitamin K dependent carboxylation?

Answer 15

IX
VII
X
Prothromin

Question 16

What fat soluble vitamin can be synthesized de novo from cholesterol?

Answer 16

Vit. D!

Question 17

Most important function of Vit. D?

Answer 17

maintain Ca++ homeostasis

Question 18

Dietary form of Vit. D?

Answer 18

Cholecalciferol

Question 19

Main form of VIt. D in blood?

Answer 19

25, hydroxycholecalciferol

*Not the most biologically active

Question 20

The active form of Vit. D is formed in the kidney in response to what hormone?

Answer 20

PTH

*PTH is produced in response to low calcium. When we have active Vit. D, we can absorb more calcium

Question 21

The activated VDR increases expression of what calcium transport proteins?

Answer 21

TRPV6-brush border
Calbindin-intracellularly brings Ca++ from lumenal to basal side

PMCA1b-Basolateral, requires ATP!