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2 out of 10

All changes occur in Joints due to aging except? (AIIMS MAY 2010)

A Water level decreases

B Proteoglycan production decrease

C Proteoglycan degradation increase

D Keratin level decrease

Ans. D Keratin sulphate level decrease
  1. Proteoglycans are a part of matrix which is secreted by chondrocytes.

a. half life of three months

b. provide compressive strength

c. regulate matrix hydration by providing a porous structure to trap and hold water

d. composed of subunits of glycosaminoglycans (GAG’s - disaccharide polymers)

i. chondroitin-4-sulfate (decreases with age)

ii. chondroitin-6-sulfate

iii. keratin sulfate (increases with age)

  1. Changes With Ageing

With ageing cartilage becomes hypocellular and has decreased elasticity.

  1. Chondrocytes

a. increase in size

b. increased lysosomal enzymes

c. cartilage becomes hypocellular (cells stop reproducing)

  1. Matrix

a. Proteoglycans

i. decrease in mass and size - decreased length of chondroitin sulfate chains

ii. change in proportion - increased keratin sulphate

iii. Increase in enzymatic degradation

b. Water content decreases

c. Protein content increases

So, during ageing there is decrease in water content, decrease production of proteoglycans and also increased degradation of proteoglycans resulting in decrease in their levels. But the proportion of proteoglycans also changes with Increased in keratin sulphate and decreased chondroitin sulphate levels.