Question

How do bones grow in length? Differentiate this process from appositional growth.

a) Through mitotic cell division
b) Via longitudinal expansion
c) Involving epiphyseal plate activity
d) Accelerated calcification process

Answer 1

Bones grow in length through mitotic cell division in the epiphyseal plate, while they increase in width through appositional growth. Chondrocytes divide in the epiphyseal plate, with one cell remaining near the epiphysis and one cell moving toward the diaphysis.

Step-by-step explanation:

Bones grow in length through the process of mitotic cell division in the epiphyseal plate. Chondrocytes, or cartilage cells, divide in the epiphyseal plate, with one cell remaining undifferentiated near the epiphysis and one cell moving toward the diaphysis. The cells that are pushed from the epiphysis mature and are destroyed by calcification, replacing cartilage with bone on the diaphyseal side of the plate and resulting in bone lengthening.

Appositional growth is a different process through which bones increase in width. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts produce new bone tissue beneath the periosteum via intramembranous ossification. This process, called modeling, increases the diameter of the diaphysis and the medullary cavity.

Answer 2

Bones grow in length through the activity of the epiphyseal plate by endochondral ossification, where chondrocytes divide, mature, and are replaced by bone tissue. Appositional growth, on the other hand, involves increasing the diameter of bones through the activity of osteoclasts and osteoblasts.

Step-by-step explanation:

How Do Bones Grow in Length?

Bones grow in length through the activity of the epiphyseal plate, which involves endochondral ossification. During this process, chondrocytes (cartilage cells) on the epiphyseal side of the plate divide mitotically. One of the resulting cells remains undifferentiated and stays near the epiphysis (end of the bone), while the other moves towards the diaphysis (shaft of the bone). These chondrocytes then mature and get replaced by new bone tissue as they are calcified, contributing to the lengthening of the bone.

Appositional Growth vs. Lengthening

Appositional growth, which is different from the lengthening process, refers to the increase in bone diameter. It occurs as osteoclasts resorb old bone tissue within the medullary cavity while osteoblasts create new bone beneath the periosteum, allowing the bone to grow wider even after the lengthening of the bones has ceased.