Digestion of minerals during bone resorption – Medicine MCQ

Which of the following substances produced by osteoclasts is responsible for digestion of minerals during bone resorption?
A. Hydrochloric acid
B. Acetic acid
C. Cathepsin K
D. Sclerostin

Correct answer : A. Hydrochloric acid

Osteoclasts – cells responsible for bone resorption

• Mature osteoclasts attach to bone and form a tight sealing zone.
• They secrete hydrochloric acid and proteolytic enzymes like cathepsin K.
• HCl is involved in digestion of bone minerals.
• Cathepsin K is responsible for degradation of collagen.
• Sclerostin (SOST) is a glycoprotein produced by osteocytes which inhibits bone formation.

Ref: Davidson’s Principles and Practice of Medicine, 22nd Edition, p1062