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. Considering Wolff’s law, if Mr. Jones reduces his physical activity further due to his fear of fractures, what would be the MOST likely long-term effect on his bone density? 

Appositional growth results in an increase in bone:

Yellow bone marrow primarily consists of fat.

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. If Mr. Jones’s condition progresses significantly without intervention, which of the following bone types would likely be MOST affected by the overall reduction in bone mass and density?

Long bones are characterized by their:

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?