1. GCSE Physical Education
The Muscular System

2. 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

3. 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.

4. 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.

5. 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.

6. 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.

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

8. 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.

9. EFFECTS OF EXERCISE TASK…
WHAT ARE THE EFFECTS OF EXERCISE?
INCLUDE:
FIBRES LENGTHEN AND SHORTEN
EXTRA WASTE PRODUCTS CREATED
EXTRA BLOOD
ANAEROBIC AND AEROBIC
LACTIC ACID
CRAMP

10. HOW DO MUSCLES WORK?
DRAW UP A TABLE TO GIVE AND EXPAIN EXAMPLES OF EACH

11. Concentric contraction
1. Isotonic Contraction
The muscle changes length as it works; either lengthening or shortening.
Shortening is called a concentric contraction. Give examples
Lengthening is called an eccentric contraction. (Acts as a break)
The hamstrings and quadriceps in the legs work in this way when performing squats.
The 'biceps curl' is a good example of isotonic contraction.
Shortening
Concentric contraction
Force
Lengthening
Eccentric Contraction

12. 2. Isometric Contraction
The muscle stays the same length as it works.
As a result there is no movement.
The muscles in the back are a good example - the trapezius works in this way when maintaining our posture.
The hand push is another good example of isometric contraction.
NAME SPORTS THAT REQUIRE ISOMETRIC CONTRACTION
Force
Force
There is no movement!

13. Antagonistic pairs

14. 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

15. Homework

16. EXPAIN IN DETAIL WHAT IS MEANT BY:
HYPERTROPHY
ATROPHY