Lesson 23. FAT SOLUBLE VITAMINS. ASCORBIC ACID AND VITAMIN P

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Task

Guidelines for performing the task

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Study the history of discovery of vitamins

1. List the nutrients that were considered necessary for nutrition in the late XIX century.

2. Consider the results of experiments by N.I. Lunin, C. Eijkman, K. Funk, N.D. Zelinsky, A.M. Bach, V.A. Palladin, P.A. Sosin

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Study the general concept of coenzyme

1. Which scientists established a link between vitamins and coenzymes?

2. Define in writing the term coenzyme.

3. Write down the classification of coenzymes

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Study nomenclature and classification of vitamins, and types of vitamin imbalance

1. Characterize the terms hypervitaminosis, hypovitaminosis, avitaminosis.

2. What is the difference betweem primary and secondary hypovi-taminosis?

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3. Define the term antivitamins and write down their classification. What is medical application of antivitamins? Write down examples.

4. List the diseases that lead to development of secondary hypovi-taminosis.

5. List non-specific symptoms of hypo- and avitaminosis.

6. Make a schematic classification of vitamins

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Consider vitamin-like substances

1. What are vitamin-like substances?

2. What is the difference between vitamins and vitamin-like substances?

3. Characterize the structure and biological significance of lipoic acid, choline, inositol, vitamin U

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Study fat-soluble vitamins A, D, E, K, PUFA and their biological significance

1. Draw and fill in a table for vitamins A, D, E, K

Other names

Chemical structure

Coenzyme form

Biological significance

Daily requirement

Principal dietary sources

Clinical manifestations of hypervitaminosis and avitaminosis

Use in medicine

2. Write the structure of active forms of vitamin A - retinal and retinoic acid. Write down the reaction of conversion of ß-carotene to retinol. Make a schematic drawing of the molecular mechanism of vision. Describe the effect of vitamin A on cell division.

3. Describe the process of vitamin D₃ synthesis from the precursor in the skin. Write down the formula of 1.25- dihydroxychole-calciferol. Explain hormone-like effects of calcitriol on metabolism of Ca²⁺ and PO₄^3-. List the main signs of its deficiency.

4. Describe the role of vitamin K in the blood clotting process.

5. Write down formulas of PUFA - linoleic, linolenic, ara-chidonic acids. List the features of the structure of ω-3 and ω-6 fatty acid families. List the main sources and biological significance of PUFA

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Consider water-soluble vitamins - ascorbic acid and vitamin P

1. Fill in the table:

Vitamin

Vitamin C

Vitamin P

Other names

Biological significance

Daily requirement

Principal dietary sources

2. Write down the redox reaction for ascorbic acid. Describe biological role of ascorbic acid: its participation in biosynthesis of collagen, in metabolism of aromatic amino acids (synthesis of adrenal hormones), in iron metabolism.

3. Write down the formula of rutin. Describe the biological role of this vitamin in regulation of vascular permeability