DEXA Anatomy & Physiology of Bone Structure 2 — Questions and Answers
Question 1: Which bone cells are primarily responsible for resorbing old or damaged bone tissue?
- Osteoblasts
- Osteoclasts (Correct answer)
- Osteocytes
- Chondrocytes
Correct answer: Osteoclasts
Osteoclasts are large multinucleated cells that dissolve and resorb bone mineral and matrix during bone remodeling.
Question 2: The periosteum is best described as:
- The inner spongy layer of bone
- The vascular fibrous membrane covering the outer bone surface (Correct answer)
- The cartilage lining joint surfaces
- The central canal containing bone marrow
Correct answer: The vascular fibrous membrane covering the outer bone surface
The periosteum is a dense, vascular connective tissue membrane that covers the external surface of bones except at articular surfaces.
Question 3: Which of the following best describes trabecular (cancellous) bone architecture?
- Dense, solid matrix with haversian canals
- Sponge-like network of plates and rods called trabeculae (Correct answer)
- Avascular tissue composed of hyaline cartilage
- Solid cortical shell with no internal pores
Correct answer: Sponge-like network of plates and rods called trabeculae
Trabecular bone consists of an interconnected lattice of bony struts (trabeculae) enclosing spaces filled with bone marrow.
Question 4: In bone remodeling, what is the correct sequence of events?
- Formation → Resorption → Reversal → Quiescence
- Quiescence → Activation → Resorption → Reversal → Formation (Correct answer)
- Activation → Formation → Resorption → Quiescence
- Resorption → Activation → Formation → Reversal
Correct answer: Quiescence → Activation → Resorption → Reversal → Formation
The bone remodeling cycle proceeds from quiescence through activation, resorption, reversal, and finally formation before returning to quiescence.
Question 5: Which mineral constitutes the primary inorganic component of bone hydroxyapatite crystals?
- Magnesium phosphate
- Calcium phosphate (Correct answer)
- Sodium chloride
- Potassium carbonate
Correct answer: Calcium phosphate
Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] is the main mineral component of bone, composed predominantly of calcium and phosphate.
Question 6: The Haversian canal system (osteon) is a structural unit found primarily in which type of bone?
- Trabecular bone
- Woven bone
- Cortical (compact) bone (Correct answer)
- Cartilaginous bone
Correct answer: Cortical (compact) bone
Osteons with central Haversian canals housing blood vessels and nerves are the structural units of cortical (compact) bone.
Question 7: Which hormone produced by the parathyroid glands has the most direct effect on increasing serum calcium by stimulating bone resorption?
- Calcitonin
- Estrogen
- Parathyroid hormone (PTH) (Correct answer)
- Growth hormone
Correct answer: Parathyroid hormone (PTH)
PTH stimulates osteoclast activity to release calcium from bone, raising serum calcium levels when they fall below normal.
DEXA Anatomy & Physiology of Bone Structure 2
Which bone cells are primarily responsible for resorbing old or damaged bone tissue?