Task 1

Muscle fibres exist all over our body and they are all different on their own way even though they may seems to look all the same in diagrams we see in the books and on the internet. They vary in shape size and their functions vary to where they are in the body. Below I have placed a diagram of a singular muscle fibre.

Fast Twitch Fibres:

Some books define a fast twitch fibre as a fibre in that causes the myosin can split ATP very quickly.

However, fast twitch fibres also demonstrate a higher capability for electrochemical transmission of action potentials and a rapid level of calcium release and uptake by the sarcoplasmic reticulum. The fast twitch fibres rely on a well developed, short term, glycolytic system for energy transfer and can contract and develop tension at 2-3 times the rate of slow twitch fibres.

Slow Twitch Fibres:

The slow twitch fibres generate energy for ATP re-synthesis by means of a long term system of aerobic energy transfer. They tend to have a low activity level of ATPase, a slower speed of contraction with a less well developed glycol tic capacity. They contain large and numerous mitochondria and with the high levels of myoglobin that gives them a red pigmentation they have been demonstrated to have high concentration of mitochondrial enzymes, thus they are fatigue resistant.

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The 2 main categories of muscle fibres become 3 when we split the white muscle fibres into 2 sections.

So we expand further:

Type I

Slow oxidative (also called slow twitch or fatigue resistant fibres), contain large amounts of myoglobin, mitochondria, many blood capillaries, generate ATP by the aerobic system, hence the term oxidative fibres, split ATP at a slow rate, slow contraction velocity, resistant to fatigue, found in large numbers in postural muscles, needed for aerobic activities like long distance running.

Type IIa

These are fast oxidative fibres (also called fast twitch A or fatigue resistant fibres). These fibres ...

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