Muscular System

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Body in Action – Muscular System
Roughly 40% of your body mass is made up of muscle, the key purpose of which is to move the bones of your body. In this assignment muscle movements and short and long term responses to exercise will be looked at.

Types of Muscle
Within the body, there are three different types of muscle. 1. Cardiac Muscle
2. Skeletal Muscle
3. Smooth Muscle

Cardiac Muscle
This is specialised muscle of the heart (BTEC National Sport Book 1). This is an involuntary type of muscle and is continuously working within the walls of the heart. This muscle does not tire quickly and each contraction along with a relaxation can be called a heartbeat.

Skeletal Muscle
Skeletal muscle is a type of striated muscle, usually attached to the skeleton. Skeletal muscles are used to create movement, by applying force to bones and joints; via contraction. ( Unlike cardiac muscle, skeletal muscle is voluntary and can sometimes be known as voluntary muscle.

Smooth Muscle
Smooth muscle can also be known as involuntary muscle. These muscles are functioned by the nervous system and are contracted without thought. These muscles can be found in the digestive system.

Fibre Types
All skeletal muscle contains a mixture of fast and slow twitch fibres. Slow-twitch fibres contract slowly and can be used for longer periods of time. Fast-twitch fibres contract quickly and provide strength and speed, though they also tire more quickly. To a large extent this fibre combination is hereditary, so if you want to become the next gold medal winner at the Olympics it is dependant on your parents. The duration and intensity of your activity will influence the physiology of your muscle tissue and the development of your muscle fibres. Endurance athletes tend to develop a greater percentage of slow-twitch muscle fibres, while power athletes tend to develop a greater percentage of fast-twitch muscle fibres. ( Slow twitch fibres are known as type 1 and fast twitch known as type 2.

Type 1
These fibres have very strong aerobic ability for oxidation, they contract very slowly, and they are very useful in endurance activities. They do not tire quickly and have high levels of mitochondria to produce high levels of energy. These are needed in endurance sports such as skiing and cycling.

Type 2a
These are fast-oxidative fibres. These have the stored glycogen and enzymatic properties of FG fibres, in addition to high levels of oxidative enzymes, which assist aerobic metabolism. They have the best of both worlds. ( These fibres are used in middle-distance sports, including the 400 and 800m.

Type 2b
These are known as fast glycolytic fibres. They contain low myoglobin content and few blood capillaries. These are needed for quick sports, which take little time, such as the 100m sprints.

Characteristics of muscle tissue
Fibre TypeType 1 fibresType 2a fibresType 2b fibres
Contraction timeSlowFastVery fast
Size of motor neuronSmallLargeVery large
Resistance to fatigueHighIntermediateLow
Activity used forAerobicLong term anaerobicShort term anaerobic Force productionLowHighVery high
Mitochondrial densityHighHighLow
Capillary densityHighIntermediateLow
Oxidative capacityHigh HighLow
Glycolytic capacityLowHighHigh
Major storage fuelTriglyceridesCP, glycogenCP, glycogen

Major Muscles
It would be unattainable for you to do anything without your muscles. Absolutely everything that you visualize with your brain is spoken as muscular motion. The only ways for you to express an idea are with the muscles of your larynx, mouth and tongue, with the muscles of your fingers or with the skeletal muscles. As there are more than 640 muscles in the human body, it would be difficult to remember them all and their different functions, in the...
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