What is the innermost part of the bone called?

Correct Answer: D

Rationale: The structure of a bone includes several layers: the periosteum (outer membrane), compact bone (dense outer layer), cancellous bone (spongy inner layer), and bone marrow (innermost part). Bone marrow, found in the medullary cavity of long bones and within cancellous bone, produces blood cells and stores fat, making it the innermost part and 'bone marrow' the correct answer.

Correct Answer: C

Rationale: The epiphysis is the end of a long bone, containing spongy bone and red marrow, articulating with other bones. The diaphysis is the shaft, the endosteum lines the medullary cavity, and the periosteum covers the exterior, making 'epiphysis' the correct answer.

Correct Answer: A

Rationale: Lamellae are the concentric rings of bone matrix surrounding the central canal in osteons of compact bone, providing strength. Lacunae house osteocytes, canaliculi connect them, and the endosteum lines the interior, making 'lamellae' correct.

Correct Answer: D

Rationale: Osteoclasts are specialized cells that resorb or break down bone tissue, aiding in remodeling and calcium release. Osteoprogenitor cells are stem cells, osteoblasts build bone, and osteocytes maintain it, making 'osteoclasts' correct.

Correct Answer: C

Rationale: Older people require greater vitamin D and calcium intake to maintain bone density, as absorption decreases and osteoporosis risk rises with age. Younger individuals need less supplementation due to higher efficiency, making 'greater than' likely correct (incomplete options assumed).