The tensile strength of bone, its ability to resist stretching and pulling forces, is mainly provided by:

Case Study: The Mystery of the Brittle Bones Mr. Jones, a 65-year-old man, has been experiencing increasing fragility in his bones. He reports several fractures over the past few years from minor falls. A recent bone density scan revealed significantly reduced bone mass. Blood tests showed normal levels of calcium and vitamin D3. However, further analysis indicated elevated levels of parathyroid hormone and increased osteoclast activity. Histological examination of a bone biopsy showed a decrease in the thickness of the lamellae in his osteons, but the collagen fibers appeared structurally normal. The normal levels of vitamin D3 in Mr. Jones’s blood suggest that his body is likely:

Canaliculi are small canals that connect osteocytes within lacunae and transport blood.

Case Study: The Mystery of the Brittle Bones Mr. Jones, a 65-year-old man, has been experiencing increasing fragility in his bones. He reports several fractures over the past few years from minor falls. A recent bone density scan revealed significantly reduced bone mass. Blood tests showed normal levels of calcium and vitamin D3. However, further analysis indicated elevated levels of parathyroid hormone and increased osteoclast activity. Histological examination of a bone biopsy showed a decrease in the thickness of the lamellae in his osteons, but the collagen fibers appeared structurally normal. Based on Mr. Jones’s symptoms and the bone biopsy results, which of the following underlying processes is MOST likely contributing to his bone fragility?

Which of the following describes the sequence of events in fracture healing?

Appositional growth and intramembranous ossification are related processes that both contribute to increasing bone diameter.

Case Study: The Young Gymnast’s Injury Maya is a 14-year-old gymnast actively involved in high-intensity training. During a landing, she felt a sharp pain in her lower leg, and an X-ray revealed a fracture of her tibia in the metaphyseal region, close to the distal epiphysis. The fracture line runs at an angle through the diaphysis but does not penetrate the skin. The initial stage of Maya’s fracture healing will involve the formation of a:

Which of the following is a primary function of the skeletal system? 

The term ‘superior’ means away from the head, while ‘inferior’ means toward the head.

In a hypertonic solution, water will move into the cell, causing the cell size to increase.