6Structure of the BoneBone is made up of living cells which form flexible fibres.These are supplied with food and oxygen by blood vessels.The fibres are surrounded by hard minerals mainly calcium phosphate.Our bones grow as we get bigger, providing a hard, strong framework.
8Composition of Bone Inorganic minerals make bones hard and strong. The organic parts, the living cells, give the bones flexibility.If the minerals are removed from a bone by soaking it in acid, the bone becomes very soft and pliable (rubbery).If the organic parts are removed by burning the bone, it becomes very brittle.
9Joints Joints are found at many places in the skeleton. They are formed where bones of the skeleton meet.Joints allow different kinds of movement, E.g.Ball & socket at the hip and shoulderHinge joint at the elbow and kneeGliding joint at the ankle and wrist.
12Structure of a Joint Structure Function Ligaments Hold the bones in placeSynovial fluidLubricate the jointSynovial membraneSecretes synovial fluidCartilageShock absorber to protect the ends of the bones
14Human Arm Our arms and legs provide mobility. Muscles are joined to bones by TENDONS.When a muscle contracts, the tendon pulls the bones and the arm moves.
15Human ArmMovement is brought about by pairs of muscles which work against each other.If one muscle bends the arm, then another will straighten it.Muscles which work in pairs like this are called ANTAGONISTIC pairs.
17Sports InjuriesStrenuous activities like sports can cause injury to joints and muscles.Some parts of the body are more likely to be injured than others, e.g. legs.The kinds of injuries you are likely to get are affected by the movements you make while playing each sport.Most injuries are caused by sudden changes in movement.
18Sports InjuriesFootballers sprain knees and ankles damaging ligaments.Runners suffer from torn muscles and tendons.Direct blows can cause fractures.
19Types of FractureSpiral fracture – e.g. a tennis player turns sharply.Green-stick fracture – usually found in children where the bone doesn’t snap completely but resembles a broken twig.Simple fracture – when the bone breaks but doesn’t break the skin.Compound fracture – when the bone breaks and does break the skin.
24ArthritisThe joints swell up and hurt and movement is difficult. There are 2 kinds of arthritis.
25Osteo-arthritis This occurs usually in older people. It is due to the everyday wear and tear of the joints.The smooth cartilage begins to break down so the joints lose their shock-absorbing properties.The bones no longer move smoothly against each other as the surfaces of the cartilage are bumpy.
27Rheumatoid ArthritisConnective tissue grows into the joint cavity and gradually hardens.The two bones become joined together, making movement impossible.This kind of arthritis can run in families and may start at any time, even in young people.