The Skeleton and Muscles

Why Do We Need A Skeleton? It supports our body (creates room for the lungs etc.) It allows us to move Protects vital organs Why is the skull so thick? To protect the brain Why do we need ribs? To protect the lungs and heart

The Skeleton There are about 206 bones in the average human body Babies are born with 300 bones

Joints Joints are places where two bones join They allow movement Cartilage and synovial fluid prevent bones wearing away

Parts Of The Joint Ligaments: Hold two bones together at a joint Cartilage: Connective tissue that prevents two bones from wearing each other out No cartilage or synovial fluid is a cause of arthritis Tendons: Holds muscle to bone http://www.kidshealth.org/misc/movie/bodybasics/bodybasics_knee.html

Types Of Joints Ball and socket e.g. hip and shoulder Allow lots of movement http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/ball_and_socket_joint.shtml

Types Of Joints Hinge e.g. knee, elbow etc. Allow forward and backward movement, but no sideways movement http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/hinge_joint.shtml

Types Of Joints Saddle e.g. fingers Allow us to grasp things http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/saddle_joint.shtml

Types Of Joints Fixed Joints e.g. the bone in the skull These joints do not move http://www.bbc.co.uk/science/humanbody/body/factfiles/skull/frontal_in_skull.shtml

Types Of Joints Slightly moveable joints e.g. the vertebrae Allow limited movement http://www.bbc.co.uk/science/humanbody/body/factfiles/spine/lumbar_vertebrae.shtml

Movement Bones cannot move on their own They are pulled by muscles

Muscles Muscles cannot push, they can only pull when they contract How do we push doors closed? Muscles work in antagonistic pairs, the bicep pulls the forearm up to the upper arm, the triceps straightens the arms. We use the triceps to close a door

Antagonistic Pairs The bicep flexes the arms The triceps extend the arm

Muscles In The Body There are about 650 muscles in the human body

Types Of Muscle There are three types: Cardiac muscle: beats on it’s own, never rests Involuntary muscle: this muscle works without us thinking about it e.g. breathing, peristalsis, pupil dilation Voluntary muscle: we have to think about moving these muscles e.g. skeletal muscles