Fat soluble vitamins

Question 1

Why are vitamins imp?

Answer 1

1. Organic compounds distinct from carbohydrate, proteins and lipids.
2. Natural components of foods that present in minute amounts.
3. Not synthesised by the body in amounts needed to meet the needs except for vit D but only the precursor is there and vit K
4. Essential for normal physiological function such as maintenance,
   growth, development and reproduction.
5. In their absence or insufficient supply, specific syndromes are caused.

Question 2

What are the classes of vitamins?

Answer 2

Fat soluble vitamins and water soluble

Question 3

What are the characteristics of fat soluble vitamins?

Answer 3

A. Absorbed passively

B. Transported with dietary lipids

C. Found in :

1. Cellular membranes
2. Lipid droplets

D. Excreted with feces

E. Can be stored

Question 4

What are the characteristics of water soluble vitamins?

Answer 4

1. Transported with active and passive transport
2. Not stored in the body
3. Excreted in the urine
4. Regular dietary consumption req

Question 5

What results in vit def?

Answer 5

1. Inadequate intake of food
2. Inadequate abs or metabolism

Treatment —> large doses of the vit by diff routes and ⬆️ the intake

Question 6

What is vit A ( retinoids )?

Answer 6

Refers to 3 comps:

1. Retinol
2. Retinal
3. Retinoids acids

Carotenoids in PLANTS —> B-carotene most imp

Question 7

What happens to retinol in the body?

Answer 7

In animals —> Esterified to a FA —> retinyl palmitate

In plants —> carotenoids are metabolized —> retinoids

Question 8

What is the role of retinal?

Answer 8

Essential in vision ( photoreception ) bcz it is the structural component of visual pigments of the rod and cone cells (which are photoreceptor cells) of the retina.

Question 9

What is the result of def of vit A?

Answer 9

A. Blindness

B. Night blindness —> nyctalopia

C. Xerophthalmia —> dry eyes —> if untreated can lead to corneal ulceration and ultimately blindness

D. Follicular hyperkeratosis —> hair follicles plugged by keratin —> goosy flesh —> dry, scaly, and rough.

Question 10

What results from def of vit D?

Answer 10

A. Rickets

B. Osteomalasia

C. Osteoporosis

Question 11

What are the characteristics of rickets?

Answer 11

abnormalities of the weight-bearing bones
bone pain
muscular tenderness
hypocalcemic tetany

Question 12

What is the results of rickets?

Answer 12

cannot withstand ordinary stress resulting in bowed legs “knock knees”
beaded ribs
pigeon breast
frontal bossing of the skull.

Question 13

What is osteomalacia?

Answer 13

A. reduction in bone density
B. the presence of pseudofractures in specific bones
C. muscular weakness.

Question 14

What is osteoporosis?

Answer 14

diminished bone mass

normal histological appearance

It is associated with age and particularly in post-menopausal women —> a multifactorial disease that is also associated with low estrogen levels.

Question 15

What results from hypervitaminosis D?

Answer 15

calcification of soft tissue (calcinosis) in organs including heart, lungs, kidney and ears (deafness). Patients often have headache and nausea.

Question 16

What is the function of vit E?

Answer 16

functions as an
antioxidant, where it protects the unsaturated phospholipids of the membrane from
oxidative degradation by free radicals (such as high reactive oxygen species).
Vitamin E has the ability to convert these radicals to harmless metabolites by
donating a hydrogen to them (free radical scavenging).

Question 17

What is true the toxicity of vit E?

Answer 17

1.Less toxic of fat soluble

2. very high dose of vitamin E decreases the body’s ability to use
   other fat-soluble vitamins —> disorders related to def of these vitamins
3. Impaired bone mineralization ( vit D )
4. Impaired hepatic vit A storage ( vit A )
5. Prolonged blood clotting ( vit K )

Question 18

What happens in def of vit E?

Answer 18

1. Vitamin E-deficient cells exposed to an oxidative stress experience more rapid injury and necrosis.
2. vitamin E deficiency targets:
   A. neuromuscular
   B. vascular
   C. reproductive systems

Question 19

What are the forms of vit K?

Answer 19

1. Phylloquinones vit K1 —> green plants
2. Menaquinones vit K2 —> bacteria
3. Menadione vit K3 —> synthetic —> potency twice as the other 2 forms —> converted to menaquinones in the LIVER

Question 20

Wha is the diff btwn vit K 1 2 3 ?

Answer 20

Both of vitamin K 1 series and vitamin K2 series have 2-methyl-1,4-nephthoquinone ring and alkylated side chains.

Vitamin K 3, on the other hand, has the ring structure, but no side chain

Question 21

What are the funcs of vit K?

Answer 21

1. Through vitamin K cycle, vitamin K plays an essential role in blood clotting. Vitamin K cycle is a process in which glutamic acid residues (GLA) in clotting plasma proteins (such as thrombin) are carboxylated by vitamin K to form carboxy-glutamate, where
   GLA bind calcium as part of blood coagulation process.
2. vitamin K (in hydroquinone form) is oxidised to be converted to an epoxide, then it is restored back to its hydroquinone form by epoxide reductase.
3. those who suffer from thrombosis, vitamin K cycle can be disrupted by inhibiting the re-generation of the reduced vitamin K (by drugs such as warfarin and dicumarol (anticoagulants).

Question 22

What results from def of vit K?

Answer 22

Hemorrhage —> severe cause of fatal anemia —> characterized by hypoprothrombinemia —> prolonged blood clotting time

Question 23

What happens during toxicity of vit K?

Answer 23

NO TOXCITY for vit K 1 & 2 but 3 —> can be toxic —> high doses —> haemolytic anemia in rats and jaundice in infants