Fat Soluble Vitamins - A Flashcards by Jane Kareem

Hippocrates at about 500 B.C. cured night

blindness with…

…his prescription of ox liver in honey, now known to contain high Vitamin A content.

How well did you know this?

Not at all

Perfectly

Vitamin A in animal food a.

animals

Pre-formed, such as Retinol

How well did you know this?

Not at all

Perfectly

Vitamin A in plant food

Pro-formed such as carotenoids (the only

source for vegans)

How well did you know this?

Not at all

Perfectly

Structure of Vitamin A

It contains a single 6-membered ring to which is attached an 11-carbon side chain.

How well did you know this?

Not at all

Perfectly

Forms of retinol

Retinol (alcohol form of vitamin A)
Retinal (vitamin A aldehyde):
Retinoic acid (acid form of vitamin A):
Produced by retinal oxidation.

How well did you know this?

Not at all

Perfectly

Retinal is obtained by…

…oxidation of retinol.

How well did you know this?

Not at all

Perfectly

Which forms of retinol are interconvertible?

Retinal and retinol

How well did you know this?

Not at all

Perfectly

Retinoic acid is produced by…

…oxidation of retinal

How well did you know this?

Not at all

Perfectly

Beta-Carotene is referred to as…

provitamin A

How well did you know this?

Not at all

Perfectly

What do pre-formed and pro-formed vitamins mean?

Pre-formed: Ready for activity

Pro-formed: Has to be converted first

How well did you know this?

Not at all

Perfectly

Beta-Carotene: Pre-formed or pro-formed?

Pro-formed

How well did you know this?

Not at all

Perfectly

Journey of beta-carotene in the body

It is sourced from plant foods and is cleaved in the intestine to produce two molecules of retinal, which is then reduced to retinol by retinaldehyde reductase in the intestines

How well did you know this?

Not at all

Perfectly

Compare retinol to beta-carotene

It possesses only about one-sixth vitamin A activity when compared to retinol.

How well did you know this?

Not at all

Perfectly

Plant sources of Vitamin A

Potatoes, Carrots, Dark green leafy vegetables, Palm oil, Pink Grapefruit, Fruits, Spinach

How well did you know this?

Not at all

Perfectly

Animal sources of Vitamin A

Chicken liver, Cod liver oil, Fish oil, Eggs, Fish, Shellfish
Butter/Margarine/Cheese, Milk

How well did you know this?

Not at all

Perfectly

Recommended daily intake of Vitamin A in Men

750 μg

How well did you know this?

Not at all

Perfectly

Recommended daily intake of Vitamin A in Women

600 μg

How well did you know this?

Not at all

Perfectly

Recommended daily intake of Vitamin A in Women during pregnancy and lactation

950 μg

How well did you know this?

Not at all

Perfectly

Recommended daily intake of Vitamin A in infants

350 μg

How well did you know this?

Not at all

Perfectly

Recommended daily intake of Vitamin A in children

600 μg

How well did you know this?

Not at all

Perfectly

Physiological functions of Vitamin A

Vision
Growth
Reproduction
Resistance to infectious disease
Epithelial cell integrity
Bone remodeling

How well did you know this?

Not at all

Perfectly

Role of Vitamin A in vision

Retinal is an important structural component of

rhodopsin, the light sensitive pigment within the rod and cone cells of the retina.

How well did you know this?

Not at all

Perfectly

Difference between rod and cone cells of the eye

Rods are involved in dim light
vision while cones are responsible for
bright light & colour vision

Role of Vitamin A in epithelial cell integrity

For proper differentiation and maintenance.
Lack of vitamin A leads keratinized and scaly skin because mucus secretion of secreting epithelial cells is
suppressed

Role of Vitamin A in reproduction

It is required for: - spermatogenesis in males - normal reproductive cycle in female - retinol and RA for embryonic development,

Which Vitamin A form has been found to regulate gene expression for growth hormone?

Retinoic Acid

Role of Vitamin A in bone remodelling

Normal functioning of osteoblasts and osteoclasts

Role of Vitamin A in immunity

It decreases the frequency and severity of infectious disease, e.g. measles

Role of Vitamin A in haematopoiesis

``` - RA plays a central role in the development and differentiation of leukocytes - Stem cell differentiation - Mobilization of iron from storage sites to the developing red blood cell for haemoglobin production. ```

Which Vitamin A form may be required for differentiation of stem cells into red blood cells?

Retinoids

Most susceptible population to Vitamin A deficiency

- Preschool children with decreased intake - Poor persons - Older adults - Alcoholism - Liver disease - Fat malabsorption

How does liver disease lead to Vitamin A deficiency?

It limits storage

Ocular Vitamin A symptoms

- Night blindness - Conjunctival xerosis - Bitot’s spot - Corneal xerosis - Keratomalacia

Extra-ocular Vitamin A symptoms

- Retarded growth - Skin disorders - Adverse effects on reproduction - Effect on bone

Night blindness or inability to see in dim light caused by Vitamin A deficiency is as a result of...

...inadequate pigment in the retina

Symptoms of eyes with conjunctival xerosis

The conjunctiva becomes: - dry - lustreless - non-wettable - thickened - wrinkled - pigmented

Bitot's spots refer to...

...built up keratin located superficially in the conjunctiva. They are raised, silvery white, oval, irregular or triangular patch of keratinized epithelium.

What happens in corneal xerosis?

The cornea appears dull with granular pebbly dryness, not wettable and eventually opaque. Severe cases may lead to corneal ulceration, which may heal to leave scar that affects vision.

Keratomalacia refers to...

- Softening and necrosis of the cornea associated with vitamin A deficiency - Softening, drying and ulceration of the cornea - Circular, sharply demarcated steep margins

How does Vitamin A deficiency affect the skin?

Phrynoderma; dry, keratinized scaly skin.

Deficiency symptoms of Vitamin A in the reproductive system

Atrophy of germinal epithelium

Deficiency symptoms of Vitamin A in the respiratory tract

Squamous metaplasia of respiratory | mucosa & ciliary damage

Deficiency symptoms of Vitamin A in the gastrointestinal system

Reccurent diarrhea

Deficiency symptoms of Vitamin A in growth

Retardation occurs

Therapeutic uses of Vitamin A include...

- Treatment of dry eye - Deficiency prophylaxis - Use of retinoic acid preparations in treatment of psoriasis, acne and several other skin diseases, because of its role in epithelial cell differentiation and integrity

Vitamin A toxicity is referred to as...

Hypervitaminosis A

Acute toxicity symptoms of Hypervitaminosis A

- Headache & dizziness - Nausea - Vomiting - Abdominal pain - Pseudotumour cerebri (bulging anterior fontanel)

Chronic toxicity symptoms of Hypervitaminosis A

- Anorexia - Pruritis - Sparse hair - Benig n intracranialhypertension - Hepatosplenomegaly

How does paraffin use affect Vitamin A in the body

Regular use of paraffin may cause deficiency because it carries Vitamin A away with it from the body.

Which other fat soluble vitamin enhances the storage and functions of Vitamin A?

Vitamin E

One drug that interferes with Vitamin A absorption?

Neomycin. Long term oral neomycin causes steatorrhea and interferes with Vitamin A absorption.

How does zinc deficiency affect Vitamin A?

- Reduction of retinol-binding protein synthesis - Decreased activity of the enzyme that releases retinol from its storage form, retinyl palmitate, in the liver -zinc is required by the enzyme that converts retinol into retinal

What is the enzyme that releases retinol | from its storage form in the liver?

Retinyl palmitate

Vitamin A deficiency may improve iron deficiency | anaemia. True or false?

False. It worsens it.

What are the fat-soluble vitamins?

A, D, E, K

Chemical name for Vit D

Cholecalciferol