+ Biology Revision B5 The Living Body

+ B5 – Skeletal Systems Study some examples of skeletal systems in the animal kingdom looking at the advantages of different types. Appreciate that skeletons may be made of chitin, bone or cartilage in different organisms and at different ages Explore the incidence, detection and types of bone fractures. Explain how the arm bending and straightening is achieved in terms of joints and muscles.

+ Starter activity Write down as many of the names of the bones as you can, and how many bones we have in total

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+ Function of the skeleton Support Protection A framework for muscle attachment and so allow movement

+ Types of skeleton Internal skeleton e.g. humans External hard skeleton e.g. crabs and prawns, made up of chitin. Has joints and muscle attachment for movement but does not allow for growth so animals have to shed it and it takes while for their new one to harden (vulnerable).

+ Animals with no skeletons Animals without skeletons that do not have a skeleton can get quite large as the water supports them. Fluid pressure inside an earthworm is enough to support it so it does not need a skeleton.

+ Internal skeletons Fish, amphibians, birds, mammals etc. have skeletons made of bone. Animals such as sharks, dogfish, rays, and skates have a skeleton which is made solely of cartilage.

+ Human skeleton Also has cartilage as well as bone e.g. tip of nose, ear lobes, and end of long bones of limb bones and ribs.

+ Bones and cartilage These are both living tissues so they have blood vessels and nerves, and can grow.

+ More about bone When a fertilised egg starts to develop, the skeleton is made of cartilage (this is mainly protein). At about 6 weeks, minerals are deposited (calcium phosphate), the bone becomes ossified and is turned into bone. Children have more cartilage at the end their bones compared to adults as they are still growing.

+ Telling the age of bone Forensic scientists can tell the age of bone according to how much cartilage is still present.

+ Infection of cartilage and bone Both bones and cartilage can be infected by pathogens

+ Paramedics and bones Do not move a patient who has a suspected bone fracture especially if it if the back or neck, and the spinal cord could become injured.

+ Structure of the long bone (femur) Both ends are covered in smooth cartilage to allow it to move easily in the joints. Outer part of shaft is hardened bone (protection against compression). Hollow so lighter but still strong. Bone marrow in the centre to store fat and to make new blood cells.

+ Breaks (fractures) in bone Common in children with rickets, the bones tend to bend and not break

+ Simple fracture Bone is broken but the skin is intact

+ Compounds fracture Bone broken and it sticks out of the skin

+ Key facts Doctors use x-rays to diagnose a break before treatment Old people with osteoporosis (soft bones) are more susceptible for fractures, which can occur as they are frail and more likely to fall.

+ 5a In good shape Skeletons No skeleton – e.g. worms Exoskeleton – e.g. insect made of chitin Endoskeleton – e.g. shark made of cartilage; human bone with some cartilage Advantages of endoskeleton: 1. Framework of body 2. Can grow with body 3. Easy to attach muscles 4. Flexibility Human skeleton starts as cartilage by is ossified by the addition of calcium & phosphorus. Amount of cartilage present determines growth stage

+ 5a In good shape Long bone structure: Head covering of cartilage Shaft, bone marrow with blood vessels Cartilage & bone are living tissue Bones are strong but easily broken Types of fractures: Simple Compound Green stick

+ 5a In good shape Joints Where 2 or more bones meet Joined by ligaments Bones moved by muscles, attached by tendons Synovial joints e.g. ball & socket, hinge Advantages & disadvantages of joint replacement?

+ 5a In good shape The arm Biceps & triceps are antagonistic muscles Arm is like a lever: Biceps contract, triceps relax -> arm raises

+ Questions Read pages of separate science textbooks and answer all questions. Draw diagrams of the different bones and joints

+ Plenary Name 3 types of bone fracture Explain how an embryo skeleton changes from being cartilage to bone. Why do you think there is a higher rate of osteoporosis in Scandinavia?