UNIT 2 NATURAL SCIENCE: THE LOCOMOTOR SYSTEM

The locomotor system consists of bones and muscles that work together so we can move. The locomotor system is involved in the function of sesitivity. It carries out the orders sent from the brain by producing movement.

THE SKELETAL SYSTEM

The skeletal system is the structure that gives our body its shape. It also supports our body, allows us to move, and protects delicate organs, like the brain, lungs and heart. The skeletal system is made up for all bones of our body.

• BONES: all bones are hard and rigid and contain mineral substances such as calcium, but they are also organs that consume nutrients and grow. Bones can have different shapes. In our body, there are three main types of bones: 
• FLAT BONES: such as the bones in the cranium.
• LONG BONES: such as the femur.
• SHORT BONES: such as the vertebrae.

• JOINTS: can be fixed or movable.
• The joints that connect the bones in the cranium cannot move, so they are examples of fixed joints.
• Elbows and wrists can bend, so they are examples of movable joints.

MUSCLES

The muscular system consists of all the muscles in the body. Muscles are organs which can change in length and shape. They can be attached to bones, like the skeletal muscles, or found internal organs, like heart.

SKELETAL MUSCLES

Skeletal muscles make the bones move. They are attached to bones by tendons, made of flexible tissue. When a muscle is relaxed, it is long and thin. When a muscle is contracted, it is shorter and thicker.

There are over 600 skeletal muscles in your body. They are located in the head, torso and limbs.

HOW THE LOCOMOTOR SYSTEM WORKS

The skeletal system and the skeletal muscles make up the locomotor system. The muscles in this  system receive orders from the brain and the spinal cord, and work with the bones to make the body move. 

When a muscle receives an order, it contracts and pulls the bones attached to it. Once the order is performed, the muscle relaxes and the bones return to their original position.

Most muscles work in pairs. One muscle contracts while the other one relaxes. These muscles are called antagonists, for example, the biceps and triceps in the arm.

There are two movements:

• FLEXING MOVEMENT: the biceps contracts and the triceps relaxes. The biceps pulls the radius, so the arm bends at the elbow.
• EXTENDING MOVEMENT: the biceps relaxes and the triceps contracts. The triceps pull the ulna, so the arm straightens.

HEALTHY HABITS

• Calcium is a mineral which helps bones to harden, and vitamin D helps the body to absorb calcium. Calcium and vitamin D are found in: milk, diary products, sardines, salmon and green vegetables.
• In order to stay healthy, we need to sleep. Sleep needs vary with age. Children need between 10 and 12 hours of sleep per day, adults only need 8 hours.
• You have to make a warm up before practice any kind of exercise.
• It is neccesary that you have a good posture in order to protect your spinal column.

INJURIES TO THE LOCOMOTOR SYSTEM

• Bone fractures: these happen when bones break or crack. In order for the bone to heal properly, it needs to be held in place with a plaster cast.
• Sprains: these involve damage to ligaments, usually caused by twisting.
• Muscle strains: these consist of an involuntary and prolonged muscle contraction. They may be caused by excessive effort or bad posture.