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MUSCLES
Muscles are bundles of cells. They are like the engine of our body since they allow the body to move. It would be impossible to do anything without the muscles. They do everything from allowing us to walk to keeping our blood flowing. There are three types of muscles: the Skeletal Muscles, the Smooth Muscles and the Cardiac Muscle. They all work together to propel the body.

3. Skeletal Muscles
Humans have more than 600 skeletal muscles, which differ in size and shape according to the jobs they do. They help to support the bones in the skeleton and hold the body in position. Skeletal Muscles are the kind of muscles that we can see and feel and they are found in the arms, legs, trunk, neck and face. They are just beneath the skin and are loosely attached to it for they have to expand and contract easily. They are called voluntary muscles, which means we have control over them. For example, if you want to lift your leg, you consciously think about it and then do it.
Skeletal muscles are connected to our bones by tendons, and work in opposing pairs. That is, if we want to produce body movements such as walking, lifting and facial expressions, one muscle in the pair contracts while the opposite muscle relaxes. To move a voluntary muscle, your brain must send a signal through a system of nerves to the muscle. Skeletal muscles can be exercised and developed in 2 different ways: exercises like running increase the ability of the muscles for a long period of time and other exercises like weight-lifting make the muscle stronger and larger, but does not increase its endurance very much.

4. Smooth Muscles
These muscles are found on the walls of the stomach, intestines, blood vessels, bladder, airways and in the uterus. Smooth muscles contract involuntarily, which means that we have little or no control over them. They perform actions such as forcing food through the intestines, contracting the uterus in childbirth, and pumping blood through the vessels. Their contractions are controlled by various signals sent from the Central Nervous System, the muscle itself and the hormones. When all this occurs, you don’t even notice that it is happening.

5. Cardiac Muscle
This muscle is found only in your heart and it is a special type of muscle because it forms the walls of it. The cardiac muscle is also an involuntary muscle. Like the skeletal muscles, the cardiac muscle has to be exercised in order to grow and to be strong. Doctors usually prefer at least 20 to 30 minutes of exercise three to four times a week to keep the heart in good shape.