Multiple Choice
Which of the following bone cell types is primarily responsible for initiating ossification of bone?
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6. Bones & Skeletal Tissue
Microscopic Anatomy of Bones - Bone Cells
2:43 minutesProblem 15
Textbook Question
(a) During what period of life does skeletal mass increase dramatically? Begin to decline?
(b) Why are fractures most common in elderly individuals?
(c) Why are greenstick fractures most common in children?
Verified step by step guidance1
For part (a), identify the life stages where skeletal mass changes significantly. Consider the periods of rapid growth such as childhood and adolescence for the increase, and later adulthood or aging for the decline.
For part (b), analyze the physiological changes in bone composition and structure that occur with aging, such as decreased bone density and changes in bone remodeling, which contribute to increased fracture risk in elderly individuals.
For part (c), understand the structural differences in children's bones compared to adults, focusing on the flexibility and composition of pediatric bones that make greenstick fractures more common.
Explain the concept of bone remodeling and how it affects bone strength and susceptibility to fractures at different ages.
Summarize how these factors together explain the timing of skeletal mass changes and the types of fractures common in different age groups.
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2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Skeletal Mass Development and Decline
Skeletal mass increases dramatically during childhood and adolescence due to rapid bone growth and mineralization, reaching peak bone mass in early adulthood. After this peak, bone remodeling continues but bone mass gradually declines with age, especially after middle age, leading to weaker bones.
Bone Fragility and Fractures in the Elderly
Fractures are most common in elderly individuals because aging causes decreased bone density and strength, often due to osteoporosis. This reduction in bone quality makes bones more brittle and susceptible to breaks even from minor falls or stresses.
Greenstick Fractures in Children
Greenstick fractures occur mostly in children because their bones are softer and more flexible compared to adults. Instead of breaking completely, the bone bends and cracks partially, similar to how a green twig breaks, due to the higher collagen content and ongoing bone development.
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