Final answer:
As a bone increases in diameter, the medullary cavity also increases in size due to the resorption of old bone by osteoclasts and the deposition of new bone beneath the periosteum by osteoblasts. This process is part of the bone's remodeling as it grows thicker and stronger.
Step-by-step explanation:
How Does the Medullary Cavity Change as Bones Increase in Diameter?
As a bone increases in diameter during appositional growth, the medullary cavity also increases in diameter. This is due to the activity of osteoclasts, which resorb old bone that lines the medullary cavity, and osteoblasts, which produce new bone tissue beneath the periosteum. While new bone is added to the outer circumference of the diaphysis, the simultaneous resorption of old bone at the medullary cavity's lining leads to an increase in the cavity's size. The enlargement of the medullary cavity accommodates the growing needs of the body, allowing for more space for marrow and the various functions it serves. This remodeling of bone ensures that as the bone becomes thicker and stronger, it does not become overly heavy or dense.
The process of bone growth involves the transformation of the epiphyseal plate into an epiphyseal line, and the medullary cavity plays a crucial role in the bone's structural development and overall health. During growth and remodeling, the cavity is carefully maintained to balance strength and density of the bone with the requirements of the bone marrow contained within.