THE MUSCULAR SYSTEM

There are three types of Muscle

1. Smooth

2. Cardiac

3. Skeletal

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Muscle FactsSkeletal muscle

forms all of the red meat around your body.

They are what gives your body shape.

Over 40% of your body weight is skeletal muscle

Muscles on the Body

Muscles on the Body

How Muscles Work

Muscles are attached to bone by tendons.

Where the muscle is attached to a stationary bone is called the origin.

Where the muscle is attached to the moving bone is called the insertion.

How Muscles Work (continued)

Muscles usually work in pairs. The bicep contracts

(shortens) & flexes (bends) the elbow.

The tricep relaxes (lengthens) as this happens.

To straighten the elbow the opposite would happen, the bicep would relax & the tricep would contract.

This is called antagonistic muscle action, the working muscle is called the prime mover (agonist) the relaxing muscle is called the antagonist.

Muscle fibres Muscles are made up of

cells called muscle fibres.

The amount of fibres that contract depends on the force needed. E.g. more fibres contract when you lift a shot put than when you lift a pen.

There are 2 kinds of muscle fibre: SLOW TWITCH FAST TWITCH

Muscle fibre types

SLOW TWITCH – CONTRACT SLOWLY WITHOUT MUCH

FORCE RED IN COLOUR DON’T TIRE EASILY SUITED TO

ENDURANCE ACTIVITIES FAST TWITCH –

CONTRACT FAST WITH A LOT OF FORCE WHITE IN COLOUR TIRE EASILY SUITED TO ACTIVITIES

THAT REQUIRE BURST OF STRENGTH & POWER