Skeletal System
Muscular System
Circulatory System
Skin
Teeth
Injuries
Training
more to come...
Maintain Body Temperature
Maintain Posture
Muscles can contract or shorten, thus becoming thicker. This is called contractability.
Muscles can stretch with application of force. This is called extensibility.
Muscles also can return to original shape and size after being stretched and contracted. This is called elasticity.
Muscles will waste away if not worked/used. This is called atrophy.
In response to increased work muscles enlarge. This is called hypertrophy.
Muscles are fed from the circulatory system by capillaries (small blood vessels) that penetrate the fibres.
These muscles controls things inside the body and is found in the walla of hollow structures eg. intestines & blood vessels. It is an involuntary muscle, which means we can not consiously move it. They are made of single muscle cells.
Cardiac Muscles
This type of muscle makes up the walls of the heart, and that is the only part in the body that this particular type of muscle is found. A cardiac muscle is different from the others because it can contract and relax without external nerve stimulation, this means it can beat by itself. This type of muscle is also involuntary (we cannot consiously move it). They are made of branched muscle cells.
Skeletal Muscle
This muscles, as its name suggests, is mainly attached to the skeleton. It makes up around 40% of our body weight! Skeletal muscles are voluntary, so we can move them when we please. They are made of bundles of fibres which are made up of myofibrils.
Slow Twitch Fibres
These fibres contract quite slowly (thus their name).
They can't supply large amounts of energy at one time, but can distribute lots of energy over a long period of time and do not fatigue. This is why people with a higher percentage of slow twtch fibres are better at endurance activites.
Fast Twitch Fibres
Like their name, fast twitch fibres contract very quickly and produce quick bursts of high amounts of energy. The downfall to these kind of muscle fibre is that they tire quickly, that is why they are used for activities that require speed and power.
Components from largest to smallest:
Muscle Belly (epimysium) --> Fibre Bundle (perimysium) --> Individual Muscle Fibre (endomysium) --> Myofibril --> Actin/Myosin
(The picture on the left is colour-coded to match the components above).