In the epiphyseal plate, cartilage grows __.
A) by pulling the diaphysis toward the epiphysis B) by pushing the epiphysis away from the diaphysis C) from the edges inward D) in a circular fashion
The Correct Answer and Explanation is:
The correct answer is B) by pushing the epiphysis away from the diaphysis.
Explanation:
The epiphyseal plate, also known as the growth plate, is a layer of cartilage located between the epiphysis (the rounded end of a long bone) and the diaphysis (the shaft of the bone). It plays a crucial role in the growth of bones, particularly in lengthening during childhood and adolescence.
Bone growth occurs through a process called endochondral ossification, which happens in the epiphyseal plate. In this process, cartilage cells (chondrocytes) undergo division and maturation, eventually being replaced by bone tissue as the individual matures. Here’s how the process works:
- Cartilage growth: The chondrocytes in the epiphyseal plate undergo rapid division in the proliferative zone of the cartilage. This division of cartilage cells adds new cartilage tissue, which pushes the epiphysis (the bone end) away from the diaphysis (the shaft of the bone).
- Maturation of cartilage: As the cartilage cells mature, they enlarge and form columns. These larger cells create a scaffold that supports further growth of the bone.
- Calcification and ossification: In the hypertrophic zone, the chondrocytes eventually die and their extracellular matrix becomes calcified. Osteoblasts then invade this area and begin the process of converting the cartilage into bone in the ossification zone, turning the cartilage into hard bone material.
Thus, the overall effect of the growth in the epiphyseal plate is that it pushes the epiphysis away from the diaphysis, which is why answer B is correct. This mechanism allows the bone to elongate as a person grows.
It’s important to note that once a person reaches adulthood, the epiphyseal plate gradually ossifies and becomes the epiphyseal line, at which point bone lengthening stops. This typically occurs around the ages of 18-25, depending on the individual.