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1 1 KS3 SCIENCE - BIOLOGY KS3 SCIENCE - BIOLOGY Skeleton & Muscles Skeleton & Muscles

SKELETON 2 2

3 3 The human Skeleton has 206 Bones The human Skeleton has 206 Bones Their main function is to protect, support and help movement Their main function is to protect, support and help movement

Mandible (jaw) SKELETON 4 4 Cranium (skull) Clavicle (collar bone) Vertebrae Radius Ulna Pelvis (hip) Humerus Sternum (breast bone) Ribs Femur Patella (kneecap) Tibia Fibula The main bones The main bones

SKELETON 5 5 Bones need to be rigid and strong, so they are mostly tubes, with a hollow middle that has marrow inside it Bones need to be rigid and strong, so they are mostly tubes, with a hollow middle that has marrow inside it Bones are about 1 / 3 organic tissue (e.g. cells, fibres, blood vessels) 2 / 3 minerals (mostly calcium) Bones are about 1/3 1/3 organic tissue (e.g. cells, fibres, blood vessels) 2/3 2/3 minerals (mostly calcium)

JOINTS 6 6

7 7 Joints which allow free movement are called Synovial joints - they are either hinge joints like the knee, or ball and socket joints like the hip Joints which allow free movement are called Synovial joints - they are either hinge joints like the knee, or ball and socket joints like the hip

JOINTS 8 8 Bones which meet in a joint are tipped with Cartilage to cushion them and stop them wearing away Bones which meet in a joint are tipped with Cartilage to cushion them and stop them wearing away

JOINTS 9 9 Surrounding the joints is a Synovial membrane, which encloses Synovial fluid to cushion the joint and reduce friction Surrounding the joints is a Synovial membrane, which encloses Synovial fluid to cushion the joint and reduce friction

JOINTS 10 Bones are held together by strong fibres called Ligaments Bones are held together by strong fibres called Ligaments

MUSCLES 11

MUSCLES 12 The human body has over 650 Muscles, which are made up of fibres The human body has over 650 Muscles, which are made up of fibres

MUSCLES 13 Muscles can only pull, they cannot push - they contract when nerve impulses stimulate the cells in the muscle to get shorter and fatter Muscles can only pull, they cannot push - they contract when nerve impulses stimulate the cells in the muscle to get shorter and fatter

MUSCLES 14 Some muscles do this involuntarily e.g. Heart muscles Some muscles do this involuntarily e.g. Heart muscles Muscles can only pull, they cannot push - they contract when nerve impulses stimulate the cells in the muscle to get shorter and fatter Muscles can only pull, they cannot push - they contract when nerve impulses stimulate the cells in the muscle to get shorter and fatter

MOVEMENT 15

MOVEMENT 16 Muscles are attached to bones by Tendons Muscles are attached to bones by Tendons

MOVEMENT 17 Since they can only pull, not push, muscles must work in pairs in order to move limbs Since they can only pull, not push, muscles must work in pairs in order to move limbs Biceps Triceps

MOVEMENT 18 To bend the arm the biceps contract, to straighten it the triceps contract To bend the arm the biceps contract, to straighten it the triceps contract Biceps Triceps

MOVEMENT 19 To bend the arm the biceps contract, to straighten it the triceps contract To bend the arm the biceps contract, to straighten it the triceps contract

MOVEMENT 20 People who exercise more grow bigger muscles that seem to bulge People who exercise more grow bigger muscles that seem to bulge