PE

Main functions of the skeleton:

• Protection - give protection to the vital organs, such as heart, lungs, spinal cord and the brain - for example: the ribcage protects internal organs such as the heart.

• Shape and Support - to give shape and support to the body, thereby giving posture to the body - for example: to keep a good posture to prevent backache.

• Movement - to allow movement to the body, by providing areas or sites for muscle attachment. This also provides for a system of levers that help us to move - for example: for us to be able to carry out everyday activities such as picking things up and moving.

• Produce red and white blood cells - to produce red and white blood cells - for example: produces red blood cells that carry much needed oxygen to make our muscles work.
• Mineral storage - to act as a mineral store for minerals such as posphorous, calcium, potassium, maganese, magnesium, silica, iron, zinc, etc. - for example: iron helps in the transport of oxygen to moving muscles during physical activities.

Axial and Appendicular Skeleton:

• The axial skeleton is the main source of support and is the central part of the skeleton. It includes the cranium, the vertebral column and the rib cage, including twelve pairs of ribs and the sternum.
• The apendicular skeleton consists of the remaining bonds and includes the girdles that join these bones on to the axial skeleton.

Synovial or freely moveable joints consist of a joint capsule lined with a synovial membrane. There is lubrication provided for the joint in the form of synovial fluid. This is secreted into the joint by the synovial membrane - for example: the knee joint.

The functions of the synovial fluid are to:

• lubricate the joint
• protect(for example, cartilage)
• nourish the cartilage with nutrients
• help to stabilise the joint and keep the joint steady

Hinge joint: this allows movement in one place only (uniaxial) - for example, the knee joint. An example of a physical activity that uses this joint is sprinting when the knee joint allows the flexion and extension of the lower leg.

Ball and socket joint: this allows a wide range of movement and occurs when a round head of bone fits into a cupped shaped depression - for example, the should joint. An example of a physical activity that uses this joint is an athlete throwing a javelin when the shoulder joint allows the upper arm to move effectively.