Vitamin A

Question 1

Which Vitamins are Fat Soluble

Answer 1

Vitamin A, D, E, K

Question 2

How are fat soluble vitamins absorbed in the body?

Answer 2

by Passive Diffusion

Question 3

How are Fat Soluble vitamins transported in the body

Answer 3

in lipoproteins

Question 4

Which type of vitamin is significantly lost during cooking? Fat soluble or water soluble?

Answer 4

Water Soluble is lost during cooking, Fat soluble is not

Question 5

Which type of vitamins are able to be stored? Fat Soluble or Water Soluble?

Answer 5

Fat soluble are stored, water soluble are not (Very little)

Question 6

What is the precursor to bile?

Answer 6

Cholesterol

Question 7

What is the function of bile

Answer 7

Emulsifies fats (breaks large fatty droplets down into smaller ones)

Question 8

Where is Bile stored?

Answer 8

in the Gall Bladder

Question 9

what stimulates release of bile from the gall bladder?

Answer 9

CCK (cholecystokinin)

Question 10

What is the entry from the gal bladder to the small intestine called that bile travels through

Answer 10

Spinchter of Oddi

Question 11

How do you know something is a bile acid?

Answer 11

it contains the word cholate

Question 12

Which type of Vitamin A is responsible for vision

Answer 12

Retinal

Question 13

Which type of Vitamin A is responsible for Reproduction and Growth

Answer 13

Retinol

Question 14

Which type of Vitamin A is responsible for Cell Differentiation

Answer 14

Retinoic Acid

Question 15

What is Preformed Vit A

Answer 15

Vitamin A that came from an Animal Source

- Retinol Esters

Question 16

What is Proformed Vitamin A

Answer 16

Vitamin A that came from a Plant source

- Carotenoids

Question 17

T or F we only use carotenoids (Proformed Vit A) when we don’t get enough Preformed

Answer 17

T

Question 18

In Food, Retinol Esters (Preformed) are bound to a fatty acid and a protein and carotenoids (Proformed) are bound to a fatty acid. When we digest them the protein and then fatty acid must be removed. What removes the fatty acid? What removes he Protein?

Answer 18

Proteases remove the Protein

Lipases remove the fatty acid

Question 19

after the protein and the fatty acid have been removed from retinol esters and carotenoids the free retinol and carotenoids are incorporated into ______?

Answer 19

Micelles

Question 20

How and where is Vitamin A Absorbed into the body

Answer 20

By passive diffusion in the Duodenum and Jejunum

Question 21

What are the steps of Vit A Absorption

Answer 21

1) Free Retinol, fatty acids and Carotenoids are absorbed in a micelle into an enterocyte of the SI
2) Once in the enterocyte retinol is bound to CRBP (cellular retinol binding protein)
3) the fatty acids are reesterified (reattached) to retinol by LRAT (lecithin retinol acyltransferase) reforming a Retinol ester
4) Retinol esters and carotenoids are packed into chylomicrons and sent into the lymph

Question 22

If are Retinol intake is low what happens during absorption to carotenoids?

Answer 22

1) carotenoids will be turned into 2 retinals which are………… A) Either reduced to retinol and packed into chylomicrons
OR
B) Oxidized to retinoic acid and sent to the liver bound to albumin

Question 23

If retinol intake is adequate what happens during absorption to carotenoids?

Answer 23

carotenoids are incorporated into chylomicrons

Question 24

where is vitamin A stored. In what form is it stored?

Answer 24

50-80% in the liver as Retinol Ester

Question 25

patients with low _______ cannot metabolize retinol out of the liver

Answer 25

Protein

Question 26

how does vitamin A circulate in the blood

Answer 26

bound to thyroxine

Question 27

Which type of Vitamin A is important for vision?

Answer 27

Retinal

Question 28

How do we get Rhodopsin?

Answer 28

Retinol --> Retol + Opsin = Rhodopsin

Question 29

What is Rhodopsin important for

Answer 29

vision in dim light, highly concentrated in rods of retina

Question 30

How can a deficiency in Vitamin A effect vision

Answer 30

Decreased Vit A = Decreased Rhodopsin = Nigh Blindness

Question 31

Which type of Vitamin A is important for Cellular Differentiation (immature cell transformed into a specific mature cell type)

Answer 31

Retinoic Acid

Question 32

What is an example of a cell type that is affected by Vitamin A to differentiate?

Answer 32

Keratinocytes under the influence of Vit A will differentiate into Mature Epidermal Cells (Keratinizing cells will turn into mucus secreting cells in the eye, mouth, lungs, kidneys and reproductive tract)

Question 33

How will a Vitamin A deficiency effect cell differentiation? What effect will this have on the body?

Answer 33

A decrease in Vitamin A will cause less keratinizing cell to differentiate into mucus producing cells (Result is less mucus producing cells in respiratory, gastrointestinal and urinary tracts) = Hyperkeratinization

Question 34

Which type of Vitamin A is important for Reproduction and Growth

Answer 34

Retinoic Acid

Question 35

How does retinoic Acid effect gene expression?

Answer 35

- Retinoic acid inteacts with DNA in the nucleus stimulating production of enzymes and growth factors

Question 36

T or F retinoic Acid functions in Reproduction, Immune System, growth and Gene Expression

Answer 36

T

Question 37

What is the function o Carotenoids

Answer 37

An Antioxidant

Question 38

How many grams of fat are required for digestion of fat soluble vitamins

Answer 38

5-10g

Question 39

what is the RDA for Vitamin A

Answer 39

``` Men = 900RAE Women = 700 RAE ```

Question 40

What are some good sources of Vit A

Answer 40

Preformed - liver, fish, dairy, eggs | Proformed - Carrots, Sweet Potato, Cantelope, Tomatoes

Question 41

What is the name for Vitamin A Deficiency? What is the primary cause? secondary cause?

Answer 41

Hypovitaminosis A - inadequate Intake of Vitamin A (Primary) - Fatty Malabsorption (Secondary)

Question 42

what are some symptoms of Vitamin A deficiency

Answer 42

``` Night Blindness Xeropthalmia ( dry eye from inadequate mucus production) Bitots Spots Permanent Blindness Impaired Reproduction Skin Problems Depressed Immune System ```

Question 43

Who is at risk for Vitamin A Deficiency

Answer 43

Children in Developing Countries | Patients with Fatty Malabsorption

Question 44

Steatorrhea (excessive fat in stools) is a symptom of Vitamin A deficiency? T or F

Answer 44

T

Question 45

What is Vitamin A Toxicity Called?

Answer 45

Hypervitaminosis A

Question 46

What is the difference between Chronic and Acute Hypervitaminosis A

Answer 46

Acute - single dose of >200,000 RAE = nausea, vomiting, headache, double vision and dizziness Chronic - Dry lips, dry itchy skin, alopecia, bone fractures, liver damage

Question 47

can Vit A toxicity cause birth defects in pregnant women? (Teratogenic)

Answer 47

Yes

Question 48

are the carotenoid form of vitamin a toxic?

Answer 48

no tolerable upper limit set | - can cause yellow/orange skin