The Muscular System

Muscular System Model

       Our Muscular Sysytem's most obvious role is to help us move. That's probably what most of you know without us telling you anything. However, did you know that there are a variety of very large muscles and very small muscles in our body? There is such a variety of these little and big muscles, that scientists believe that 40% of our  body is muscle. But even though muscles are really important and efficient, they don't do it all on their own. Tendons and ligaments help out a lot. At every joint, there are tendons and ligaments to help out. As muscles don't connect directly to bones, they wouldn't be that useful alone. When they would contract, the muscles wouldn't really move anything. That is why muscles are connected to tendons instead. Now when the muscles contract, the tendons pull back on the muscles and cause the reaction of movement. However, ligaments are pretty important too. Ligaments are what connect bones. They connect at the end of the muscles, to prevent the bones from slipping and sliding, and force them to bend. 

      There are three types of muscles in our muscular system: Smooth Muscles, Skeletal Muscles, and Cardiac  Muscles. Each type of muscle is different, because it has a different job to perform. Also, each muscle type is specialized to do a different task. 

Smooth Muscles

      Smooth muscles operate on their own, and are not under the control of the brain. They are called Smooth muscles because they appear smoother than the other types of muscles. Smooth muscles are found in the stomach, blood vessels, eyes, and digestive system. They are used to move food through the digestive system, regulate blood flow, and decrease the size of pupils when too much light is present. Smooth muscles only have one nuclei. They are connected to each other, allowing electric pulses to pass through them.

Skeletal Muscles

      Skeletal muscles are usually attached to bones. They are often called Striated muscles because of their striped appearance. The brain operates them, and tells them what to do. The cells of the Skeletal muscles are long (sometimes over 30 cm), and unlike the Smooth muscles, contain many different nuclei. 

Cardiac Muscles

      Cardiac muscles are special types of tissue that are found only in the heart. They are striped like the Skeletal muscles, and not under the control of the brain like the Smooth muscles. They operate independently.  They are also connected to one another, allowing electric pulses to pass through them, like the Smooth muscles as well.


Lactic Acid
    Working muscles generate energy anaerobically. This energy comes from glucose through a process called glycosis, in which glucose is broken down or metabolized into a substance called pyruvate through a series of steps. When the body has plenty of oxygen, pyruvate is shuttled to an aerobic pathway to be further broken down for more energy. When oxygen is limited in the body, pyruvate converts to a substance called lactate, which allows glucose breakdown to continue. During the time of high anaerobic energy production, lactate levels can reach high levels. A side effect of high lactate level is an increase in the acidity of the muscle cells.
     

Thanks to kidsbiology.com, and library.thinkquest.org for the information. If you have anything to add or complain about, please feel free to comment.