Vitamin A And Carotenoids

Question 1

What must happen for retinol to be incorporated into chylomicrons for transport

Answer 1

Retinol esterified

Question 2

Retinol is esterified by

Answer 2

Cellular retinol-binding protein (CRBP) II

Question 3

What carries vit A and carotenoids to liver?

What happens there?

Answer 3

–Chylomicrons carry to liver

–Additional metabolism in liver

Question 4

What is primary transport for retinol in the blood from the liver

Answer 4

Retinol binding protein complex with transthyretin

Question 5

What type of retinol can be stored in the liver

Answer 5

Esterified

Question 6

Where is esterified retinol stored in liver

Answer 6

•Stellate cells* & parenchymal cells

Question 7

2 proteins that transport vit A in the blood

Answer 7

• Retinol-binding protein (RBP)/Transthyretin (TTR)

* Albumin

Question 8

What form of vit A does albumin transport

Answer 8

Retinoic acid

Question 9

Carotenoids can be transported to other tissues by chilomicrons

T/F

Answer 9

T

Question 10

What transports carotenoids from liver

Answer 10

Lipoproteins

Question 11

Carotenoids transported as part of lipoproteins and percentages

Answer 11

• 50% α-, b-carotene and lycopene in LDL
• 25% in HDL
• 16% VLDL

Question 12

Carotenoids stored in

Answer 12

liver & adipose

Question 13

Retinoic acid is made in small amounts by

Answer 13

individual cells from retinal and works within individual cells

Question 14

What form of vit A is important for vision

Answer 14

11 cis-retinal (Rhodopsin)

Question 15

–All-trans retinoic acid and 9-cis retinoic acid is important for what 4 things

Answer 15

• Gene expression
• Cellular differentiation
• Growth and Reproduction
• Bone metabolism – Osteoblasts/clasts

Question 16

What types of cells do All-trans retinoic acid and 9-cis retinoic acid affect for cellular differentiation

Answer 16

Keratinocytes

Question 17

Growth and reproduction is assisted by what form of vit A

Answer 17

Retanoic acid

Question 18

In what 4 ways is retinoic acid important for cellular differentiation and growth

Answer 18

• Helps maintain normal structure and function of epithelial cells
• Directs differentiation of keratinocytes (immature skin cells) into epidermal cells through changes in gene expression
• Increases the synthesis of gap junction proteins (essential for cell to cell communication)
• Stimulate glycoprotein synthesis which can stimulate differentiation

Question 19

Excess Vit A interferes with absorption of?

Answer 19

Vit K absorption

Question 20

High b-carotene intake may decrease plasma

Answer 20

Vit E

Question 21

What 2 things influence Vit A status and transport

Answer 21

–Protein & zinc

Question 22

Iron metabolism interrelated with both

Answer 22

carotenoids and Vitamin A

Question 23

In what two ways is iron related to Vit A and carotenoids

Answer 23

• Required for conversion of b-carotene to Vit A

* Vitamin A deficiency may be associated with iron-deficiency anemia

Question 24

• 1 RAE = 1 μg retinol = 12 μg β-carotene = 24 μg α-carotene or β-cryptoxanthin
• In other words, 12 times the amount of β-carotene or 24 times the amount of α-carotene or β-cryptoxanthin is needed to get the same effects as 1 μg of retinol

Answer 24

Put on notecard

Question 25

Where does metabolism start for Carotenoids & retinoids

Answer 25

metabolized in enterocytes to some extent