B5

Skeletons= for support and allowing it to move and protection of vital organs

Advantages of an internal skeleton: It can grow easily with the body, can easily attach itself to muscles and is more flexible than exernal skeletons.

Bones= living cells, they can grow and repair themselves

long bones eg:in thigh. They are hollow so are light and can move easily. Filled with bone marrow in the middle. (bone marrow= spongy substance that makes new blood cells).

Cartilage= living tissue, feels and looks rubbery. Can grow and repair itself but not as easily as bone. Ossification: blood vessels deposit calcium and phosphorus in the cartilage which over time turns to bone. Lots of cartilage in body= you're still growing. Cartilage covers the ends of your bones to stop them rubbing together.

Osteoporosis: calcium is lost from bones so become alot softer and more brittle so more likely to break- can be treated with calcium supplements though. Due to both bones and cartilage being made of living tissue, they can both become infected.