1. GCSE Physical Education
The Muscular System

3. How does the muscular system produce movement?

4. Muscle Function
The main function of skeletal muscle is to produce movement.
Muscles are attached to the skeleton, so that they can contract and pull on bones
Muscles are attached to bones by tendons.
Muscles are attached at both ends
One end is called the origin, and is fixed to something rigid.
The other end – the insertion – is attached to the bone that moves.

5. Antagonistic pairs
As muscles can only pull, not push, they are usually arranged in antagonistic pairs
One muscle will bend (flex) the joint and the other will straighten (extend) the joint.
Whilst one muscle contracts (agonist), the other relaxes (antagonist). Allowing full movement at the joint.
E.g the bicep contracts to flex the elbow whilst the tricep relaxes.
This is known as an isotonic contraction
If both muscles contract together then no movement takes place. This is known as an isometric contraction.

6. Antagonistic pairs

7. These are the major muscles of the body…
The Muscular System
These are the major muscles of the body…
Deltoids
Trapezius
Pectorals
Biceps
Triceps
Latissimus Dorsi
Abdominals
Gluteals
Quadriceps
Hamstrings
Gastrocnemius
Front View
Back View

8. Muscles There are 3 types of muscles within the muscular system:
Voluntary (skeletal)
Involuntary
Cardiac

9. Voluntary (skeletal) muscle
Are under the control of our will
Attached to the skeleton
Made up of cylindrical fibres
Usually long and thin and found in pairs
The cannot push.

10. Involuntary muscles Found in the organs of our body
Digestive, circulatory and urinary systems
Controlled by the involuntary nervous system
Made of spindle shaped fibres

11. Cardiac Muscle Found in the wall of the heart Involuntary
Made up of interlaced fibres, which help the nervous impulses, sent by the brain to regulate our pulse and the force of our heart beat.
It never tires (as long as it has a good blood supply).

12. Functions of the Body Muscles
Position in the body
Main Action
Gluteals
In the middle of the body at the back, forming the bottom.
Pull or extends the legs back at the hips.
Hamstrings
At the top of each leg at the back.
Bend or flexes the legs at the knees.
Gastrocnemius
At the bottom of each leg at the back. Also known as the calf muscles.
Straighten the foot so you can stand on your toes.

13. Muscle
Position in the Body
Main Action
Trapezius
In the centre of the chest at the back of the body, spreading up.
Hold and rotate the shoulders and also move the head back and sideways.
Latissimus
Dorsi
At the back of the body, either side of the chest.
Extension and adduction of the shoulders and back behind your back.
Triceps
At the top of each arm at the back.
extension the arms at the elbow.

14. Muscle
Position in the Body
Main Action
Deltoids
In the upper part of the body, covering the shoulders.
Raise the arms in all directions at the shoulders. Abduction
Biceps
At the top of each arm at the front.
Flex the arms at the elbows.
Quadriceps
At the top of each leg at the front.
Extension the legs at the knees.

15. Muscle
Position in the body
Main Action
Pectorals
In the upper part of the chest at the front.
Raise the arms up, sideways and across the chest at the shoulders.
Abdominals
At the front of the body in the middle, just below the chest.
Pull in the abdomen and flex the spine so you can bend forward.

16. Structure of muscle
Muscles are made up of many muscle fibres, each of which contain many myofibrils.
These can either be slow twitch or slow twitch.

17. Types of Muscle Fibre Slow twitch (Oxidative) Fibres
Deep red in colour
Have a good Oxygen supply
They contract slowly, but can work for long periods of time without tiring.
Fast twitch (Glycolytic) Fibres
White in colour
A more forceful contraction, but fatigue relatively quickly.

18. Muscle Tone Muscle cells are never all resting at the same time.
Some are muscles are always ready for action – this is known as muscle tone.
One of the functions of muscle tone is that it keeps the body primed and ready for instant action.
Also keeps the body in an upright position
This is called POSTURE
Our joints are held firm by the flexor and extensor muscles both working at the same time

19. Exercise & the Muscular system
What are the immediate effects of exercise on the muscular system?
Exercise increases the body’s demand for Oxygen and glycogen as the muscles need more fuel to function.
Extra waste products are created, and extra blood needs to be pumped around the body to take these away.
Aerobic exercise can continue for a sustained period of time as the intensity is relatively low.
High intensity exercise will result in the production of lactic acid, if this builds up then exercise will cease as muscles begin to ache and possibly cramp.

20. What are the long term effects of exercise?
Increased muscle size: Hypertrophy
Training using the principle of progressive overload, applies stress to the skeletal muscles.
This results in them being damaged as the muscle fibres are pulled apart causing trauma.
The body rebuilds bridges between muscle fibres, and actually makes them slightly stronger
This requires up to 48 hours.

21. Potential injuries Atrophy Soft tissue injuries
Loss of muscle mass & strength due to stopping training.
Soft tissue injuries
Include tears, pulls & strains
Small muscle fibres may be torn from their attachment to a tendon
During intense competition muscle fibres contract & relax very quickly, & this can cause connective tissue & the blood vessels which run inside them to be torn.

22. Task Why do we warm up & cool down?
What should be included in a warm up?
Design an appropriate warm up for one of your chosen sports.