the Body
Think of the body as divided into seven systems:
(click on the underlined links to learn more)
- [ bones ]
- [ brain and nerves ]
- [ muscles ]
- [ respiration ]
- [ circulation ]
- [ digestion ]
- [ glands ]
All are connected and interdependent, though each has a special network of its own.
Muscles comprise 36% of female body weight. There are two kinds, voluntary and involuntary, and they perform as the names imply. Involuntary muscles are lighter and function without any indication of their activity. They are hidden away in the body and controlled by the involuntary nervous system. It is impossible to consciously set them in motion or stop them. Their continuous release and contraction is slow and rhythmic; through this action several functions are performed such as pushing food through the digestive channels and pumping the blood.
There are 556 muscles, each consisting of many individual fibres. The longest are 3-4 cm and some are less than a millimetre. All muscles exist at birth and grow in size without increasing in number. Strength comes after expansion of each fibre as muscles are made to work. Muscles also have connective tissue which helps to bind the fibres together and secures them to the bones. These take the form of tendons, sinews and bursae - pockets of fluid acting as pulleys at some of the joints. Most muscles are attached by tendon at just one end, but occasionally at both.
The impulses causing a muscle fibre to twitch are electrical, mechanical or chemical. The time between the arrival of a stimulus at a fibre and the start of contraction is between two and four thousandths of a second.
[ the Body ]
Think of the body as divided into seven systems:
(click on the underlined links to learn more)
- [ bones ]
- [ brain and nerves ]
- [ muscles ]
- [ respiration ]
- [ circulation ]
- [ digestion ]
- [ glands ]
All are connected and interdependent, though each has a special network of its own.
Return to [ the Body ] Index page!