GCSE Physical Education The Muscular System

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

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.

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.

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.

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.

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

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.

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

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

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

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!

Antagonistic pairs

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

Homework

EXPAIN IN DETAIL WHAT IS MEANT BY: HYPERTROPHY ATROPHY