PE unit 1

Functions of the skeletal system

Support

Support

Provides the framework of the body

Protection

Protects vital organs from injury.

Movement

Bones act as levers and provide attachment sites for muscles to produce movement.

Mineral storage

Stores calcium and phosphorus for release when required.

Blood cell production

Red bone marrow produces red blood cells

Fat storage

Yellow bone marrow stores triglycerides as an energy reserve.

Major bones

Cranium, pelvis and mandible

Fibrous joint

A joint joined by dense connective tissue that allows little or no movement.

Cartilaginous joint

A joint joined by cartilage that allows slight movement.

Synovial joint

A freely movable joint surrounded by a joint capsule containing synovial fluid.

Ball-and-socket joint

Allows movement in all planes including rotation

Hinge joint

Allows flexion and extension

Pivot joint

Allows rotational movement

Flexion

Decreases the angle between two bones.

Extension

Increases the angle between two bones.

Abduction

Movement away from the body's midline.

Adduction

Movement towards the body's midline.

Rotation

Movement around the longitudinal axis of a bone.

Plantar flexion

Movement at the ankle that points the toes downward.

Dorsiflexion

Movement at the ankle that lifts the toes towards the shin.

Major muscles

Deltoid, gluteus maximus

Concentric contraction

A muscle contraction in which the muscle shortens while producing force.

Eccentric contraction

A muscle contraction in which the muscle lengthens while producing force.

Isometric contraction

A muscle contraction in which the muscle develops tension without changing length and no joint movement occurs.

Parallel muscle fibres

Fibres run parallel to the muscle's long axis

Pennate muscle fibres

Fibres attach obliquely to a tendon

Type I (slow-twitch) muscle fibres

Slow contraction speed

Type II (fast-twitch) muscle fibres

Fast contraction speed

Agonist

The prime mover responsible for producing a movement.

Antagonist

The muscle that opposes the action of the agonist.

Stabiliser

A muscle that contracts isometrically to stabilise a joint or body segment during movement.

Reciprocal inhibition

The agonist contracts while the antagonist relaxes to allow smooth movement.

Motor unit

A motor neuron and all the muscle fibres it innervates.

All-or-nothing principle

Once the threshold stimulus is reached

Size principle

Motor units are recruited from the smallest to the largest according to the force required.

Lever system

Bones act as levers

First-class lever

Fulcrum is between the effort and the load.

Second-class lever

Load is between the fulcrum and the effort.

Third-class lever

Effort is between the fulcrum and the load

Overtraining syndrome

A chronic condition caused by excessive training without adequate recovery

Arthritis

Inflammation of one or more joints causing pain

Osteoporosis

A condition characterised by decreased bone mineral density

Protective equipment

Reduces the risk or severity of injury by absorbing or dispersing impact forces.

Taping

Provides external support to joints and muscles and limits excessive movement.

Braces

Provide stability to injured or unstable joints during activity.

Training

Improves muscular strength

Nutritional supplements

Products used to support performance

Creatine supplementation

Increases phosphocreatine stores to improve ATP resynthesis during high-intensity exercise and improve strength and power.

Anabolic steroids

Synthetic forms of testosterone that increase muscle mass and strength but can cause serious health effects and are prohibited by WADA.

Growth hormone

A hormone that increases muscle growth and tissue repair but can cause serious health effects and is prohibited by WADA.