security threat meaning, security threat definition | English Cobuild dictionary. security. 1 n-uncount Security refers to all the measures that are taken to protect a place, or to ensure that only people with permission enter it or leave it.
A muscle expands when it relaxes. The muscles in our bodies are attached to bones. They help the bones move, much like strings help a puppet move. But muscles can pull in only one direction. They cannot push.Each bone is usually attached to a pair of muscles.ones and muscles work like  ropes and levers. The muscles can only pull against the bone not  push it. So to bend your arm at the elbow, the â¦ bicep pulls the  lower arm up. To streighten your arm, the tricep pulls the lower  arm back out. the muscles have to work in pairs opposite each other  to make movement.
Explain the functions of cartilage in your skeletal system. The ends of bones are covered with a smooth, slippery thick layer of tissue called cartilage. It is flexible because it acts as a shock absorber. It makes movement easier by reducing friction that would be caused by bones rubbing together.ection 2 - 4. Explain how your muscles, bones and joints work together to move your body. The action of muscles, bones and joints working together is like a lever. In your body, bones are rods, joints are fulcrums and contraction and relaxation of muscles provide the force to move body parts.