Human Biology
The human body is covered by muscles, made up of more than 650 of them. The purpose of the muscular system is for the body to move, maintain posture, and produce heat. There are three different types of muscles tissues; cardiac, smooth, and skeletal. There are also two types of muscles are in the body; voluntary and involuntary. The ones which we can move are the voluntary muscles; the ones which move on their own, like the heart, are involuntary muscles.
When muscles move, they virtually have other muscles helping out. When one muscle flexes, its opposite relaxes, for instance; the tongue. The tongue works with other muscles in the mouth so that we can chew, swallow, and talk. Another good example of a unison muscle would be the heart. The heart is the most important muscle in our body. It's what pumps blood in and out of our veins and arteries, and is what gives our body oxygen. The heart is not only composed of cardiac muscle tissues. It is also joined with skeletal muscle. Without skeletal muscles, veins would not be able to get blood moving. They would have to rely on gravity and momentum o get through the body parts it needs to. As previously mentioned, the heart is an involuntary muscle. People do not have to think about making their heart beat; it happens naturally, like breathing.
Muscles make up 40% of the body's weight. The nervous system sends signals to the muscular system which cause the muscles to contract. Muscle contractions are what create movement. Skeletal muscles are a voluntary muscle. An example of a skeletal muscle would be an arm muscle. A teacher tells you to raise your hand, and that signal goes from your ears, to your brain, to your arm resulting in you raising your arm consciously. Cardiac muscle tissues, unlike skeletal muscle tissues, are linked together and not attached to bones. Smooth muscle tissue makes up the walls around most of the human body's organ systems. This tissue is controlled by both