Lesson 33. BIOCHEMISTRY OF CONNECTIVE TISSUE

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Task

Guidelines for performing the task

1

Recall the main types of connective tissue

1. Name the types of connective tissue.

2. Name the principal connective tissue cells

2

Study the structure of collagen

1. List the principal connective tissue fibers.

2. Write down the types of collagen. Give examples of features of its α-chains.

3. Write down the classification of collagen.

4. Write down the chemical formula of amino acids typical of tropocol-lagen

3

Consider the metabolism of collagen

1. Write down the reaction of proline and lysine hydroxylation in po-lypeptide chain of collagen.

2. Make a schematic description of the stages of collagen biosynthesis: ribosomal stage, posttranslational modifications, extracellular conversions. What is the role of ascorbic acid in collagen maturation?

3. Write down the reaction catalyzed by lysyl oxidase and indicate formation of collagen cross-links .What is the role of Cu²⁺ in activation of this enzyme?

4. Give examples of collagenases and tissue inhibitors of metallopro-teinases.

5. Give examples of collagen degradation markers.

6. Reticulin: describe its structure, chemical composition and biological significance

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Task

Guidelines for performing the task

4

Study the structure and metabolism of elastin

1. Characterize tropoelastin.

2. Describe structural features of elastin. Write down the formula

of desmosine, lysine and norleucine. Explain the role of desmosin in the structure of matured elastin.

3. Describe structure of fibrillin and its importance in formation of elastin.

4. Indicate the role of elastases in elastin catabolism.

5. Characterize the significance of antitrypsin in protection of elastin

5

Consider the non-collagenic proteins of ground substance of extracellular matrix

1. Write down the main extracellular matrix glycoproteins and describe their biological significance.

2. Write down formulas of repeated units of glycosaminoglycans (GAGs).

3. Make a schematic drawing of supramolecular aggregates of glycos-aminoglycans in proteoglycans. Write down the classification of proteo-glycans and describe their biological significance.

4. Write down the scheme biosynthesis of hyaluronic acid.

5. Write down types of GAGs that are found in the skin, cartilage, cornea, corpus vitreum, synovial fluid, bones and the aortic wall.

6. List the main functions of proteoglycans.

7. Describe the main features of glycosaminoglycan catabolism

6

Study the features of chemical structure and metabolism of cartilage

1. List the collagenic proteins in cartilage.

2. Write down proteoglycans, glycoproteins and small proteoglycans prevailing in cartilage tissue.

3. Note the features of cartilage metabolism caused by lack of capillaries

7

Recall cellular composition of bone tissue

1. Describe osteoblasts and their function.

2. Characterize osteoclasts as destroyers of the bone matrix.

3. Explain the definitions of terms remodeling of bone and basic metabolic unit

8

Study the features of chemical composition and metabolism of bone tissue

1. List the features of chemical composition of bones.

2. Describe the composition of collagen fibers - basic collagen and minor collagens.

3. Describe the prevailing non-collagenic proteins of the ground substance: bone sialoprotein II, osteopontin, osteonectin, proteoglycans, osteocalcin, bone alkaline phosphatase. Characterize their role in bone metabolism.

4. Characterize the chemical composition of hydroxyapatite of bone tissue as its mineral constituent.

5. Write down the daily requirement for Ca²⁺ depending on the periods of childhood, adolescence and adulthood.

6. Describe the role of hydrolytic lysosomal enzymes in the processes of bone resorption

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Task

Guidelines for performing the task

9

Consider

regulation of bone metabolism: osteogenesis, remodeling and mineralization

1. List the main hormones taking part in regulation of bone metabolism.

2. Consider the main mechanisms of the effect of parathyroid hormone, osteocalcin and vitamin D on bone formation and Сa²⁺ metabolism.

3. Write down the formula of vitamin D₃, and describe the reactions of its hydroxylation in the liver and kidneys. Write down the main signs of calcitriol deficiency in children (rickets).

4. Characterize the effect of androgens, estrogens, insulin, growth hormone, glucocorticoids on biogenesis and resorption of bones

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Consider the changes in chemical composition and metabolism of connective tissue in aging and diseased state

1. Describe age-related structural changes in the connective tissue.

2. Whsat disease is called mucopolysaccharidosis? Give examples of mucopolysaccharidosis.

3. Explain the mechanism of development of changes in connective tissue at scurvy.

4. Describe connective tissue changes in diffuse connective tissue diseases (DCTD) - rheumatism, rheumatoid arthritis, dermatomyosi-tis, systemic lupus erythematosus, periarteritis nodosa, and other