Exoskeletons- Exoskeltons is the structure of the skeleton but on the outside of the body. It is a hard structured shell, exoskeletons are usually found on insects, crustaceans and mollusks. The advantages of an exoskeleton is that it is used for protection and to help against predators. It also prevents the creature from drying up. The exoskeleton contains chitin and when calcium carbonate is added, the exoskeleton will grow in strength and hardness.
Internal skeletons- Internal skeletons provide a framework and shape for the body, it grows with the body, easy to attach muscles to and also they have joints which is important for flexibility. The internal skeleton is made mostly of bones and cartilage. Humans and most animals have these structures, but animals like sharks internal skeletons are made completely of cartilage.
Long bones- long bones are hollow, they weigh less and are much stronger than hollow bones. The top of the bone is covered in slippery and hard cartilage to lubricate the movement against other bones. The shaft contains bone marrow and blood vessels.
Growing bones- All the bones in an embryo are made from soft and flexible cartilage. During growth the cartilage is replaced by calcium and phospherous salts (this makes the bone hard). This is commonly known as ossification. Children have cartilage in their bones because they're still growing. Adults only hace cartilage at the ends of their bones. whether a person is still growing or not can be determined by the amount of cartilage is present.
Broken bones- Broken bones can be defined by three ways;
A simple fracture- is when the bone breaks
A greenstick fracture- is when the bone doesnt break completely.
A compound fracture- is when the broken bone breaks through the muscle and skin.
If someone has a fracture is best not to move them especially if it is a spinal injury, as it could make it worse. Bones can repair and regrow themselves.
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