What is bone?
Bone is the hard connective tissue that makes up the majority of the skeleton. It has many roles within the human body, including:
- Support of body structures: The skeleton gives our body its recognizable shape and form
- Protection of vital organs: Such as the skull protecting the brain, and the ribs protecting the heart and lungs
- Facilitate movement: Bones form almost all of our joints such as the knee and hip, and allow us to move around effectively
- Production of red blood cells: Large long bones for example, the thigh bone (femur), are part of our body's system for making red blood cells, which takes place in the bone marrow. Red blood cells carry oxygen around our body
- Storage of vital minerals: Minerals such as calcium, phosphorous, silicon and multiple trace elements are stored in our bones
The Skeleton
As you can see above, and feel on your own body, all of our bones are different shapes. They are shaped the way they are for specific reasons; our bodies shape them while we are growing and developing, into the perfect shape required for the function each one of them must perform.
So, we have long bones such as our femur, irregular bones such as our knee-cap (or patella) and we have flat bones such as our shoulder blade (or scapula).
Bone itself is of two types.
- Cortical bone, which is flat and hard, arranged in sheets on the surface of our bones to give a hard outer layer that resists impact forces.
- Cancellous bone is a softer bone, which forms a honeycomb-like lattice of struts inside our bones called trabeculae. The structure of these trabeculae gives bone great strength against bending forces; we use the same process ourselves to reinforce many everyday structures such as corrugated cardboard.
The bones in our body exist in a dynamic equilibrium – there is constant remodelling of existing bone. Old bone is eaten up by specially designed cells called osteoclasts, a process complemented by the laying down of new bone by, other specialist cells called, osteoblasts. This keeps the bone healthy, alive and flexible.
