Bone Tissue & Growth
Zoom down to the cellular level and learn how bone tissue forms, grows, and continually remodels itself.
Bone as a living tissue
Bone is a dynamic connective tissue made of living cells embedded in a hard mineral matrix. It is organized into two main types: dense compact bone on the outside and lighter, porous spongy bone within.
Inside a long bone
A cross-section of a long bone shows compact bone on the outside, spongy bone within, and marrow at the core.
Bone builders
These cells build new bone matrix, laying down the collagen and minerals that harden into bone tissue.
Mature bone cells
Former osteoblasts that become embedded in the bone matrix and help maintain it.
Bone breakers
These cells break down old or damaged bone tissue, releasing calcium into the bloodstream.
A constant cycle
Bone is continuously broken down and rebuilt throughout life in response to stress, injury, and mineral needs.
From cartilage to bone
Most bones begin as cartilage in the embryo and are gradually replaced by bone tissue through a process called ossification, which continues into early adulthood at growth plates near the ends of long bones.
A tissue that never stops changing
Even in adulthood, roughly ten percent of the skeleton is replaced through remodeling each year, allowing bone to repair micro-damage and adjust its strength to the loads it regularly experiences.
The skeleton finishes the story it started in lesson one.
From the whole frame down to individual bone cells, every level of the skeletal system works together to support, protect, and move the body.