MUSCULAR SYSTEM. Our muscular system is formed by muscles, and tendons (held to muscles to move our body). Muscles are organs that move the skeleton. They are formed by muscle fibers, that can contract and relax under the orders from nerves cells.
Muscles move our body and different organs. They use a lot of energy supplied by blood (oxygen, glucose and other nutrients, and blood also remove waste products from them). 1.- TYPES OF MUSCLES: A.- Smooth muscles: we can’t control them, (their movements are involuntary). They are in our digestive system, blood vessels‌ B.- Cardiac muscles: they form our heart. Their movement are very strong. C.- Skeletal Muscles: they form our muscular system, are joint to our bones and their movements are voluntary (we can control them). Their fibers are very long, and our brain can give orders to them. 2.- HOW OUR MUSCLES WORK: If a muscle contracts, move a tendon held to a bone and produce a movement. There are always two opposite muscles (or antagonist muscles) for example one to bend and another to stretch the arm.