To achieve P4 I will be describing the structure and function of the muscular system.
The muscular system is made up of the muscles in the body, there are more than 600 and tendons that connect them to the skeleton.
Function

Movement
Skeletal muscles are arranged in pairs on opposite sides of joints. As one muscle contracts, the opposing muscle must relax to cause movement.
Posture
Muscle are also needed to provide stability to the body. It is kept with the contraction of muscles e.g
Heat

Many skeletal muscles contract isometrically in order to stabilise and look after active joints during movement.
There are three different types of muscle these are called cardiac, skeletal and smooth.

Cardiac
Skeletal (voluntary)
Smooth (involuntary)
These muscles are found only in the walls of the heart. These muscles fibres are short and striated and contract automatically and rythmatically. Also they do not tire and work continuously through life. If these muscles where to stop it would cause death
These are attached to the bones of the skeletal system and move voluntary by control of the brain and nerves. In appearance these are striated they work hard but tire easily.
These are found in the walls of the digestive system, blood vessels and urinary system they are a spindle shape cells that interlock. Smooth are not striated and are regulated by the automatic nervous system (ANS). It is capable of slow but sustained contraction and does not tire easily.

The muscle that is contracting