Muscles are the parts of the body that allow us to move in positions such as sit, stand, walk, run, bend, and reach. They make it possible for us to smile, play PlayStation, eat, and roll our eyes.
Muscles are attached to bones and tissues throughout the body. They give your body the shape that you have. Muscles work by relaxing and contracting. When they contract, muscles pull on bones or tissue where they are attached. It is the pulling motion that allows you to move and do the function that you want. When they relax, muscles let you rest.
Muscle Facts
- There are over 600 muscles in the human body. Some are small and delicate while others are large and sturdy.
- Muscles make up between 25 to 45 percent of your body weight.
- Muscles are made up of cells called muscle fibers.
- Lifting weights can make muscle fibers grow. That is why while skinny people and weightlifters have the same amount of muscles, the weightlifters will have bigger muscles.
- There are over 30 muscles in the face that allow you to smile, frown, look surprised, and much more.
- The largest muscle in the body is the gluteus maximus in your buttocks.
- The smallest muscle in the body is the stapedius, which is located in the middle ear.
Muscles Types
Skeletal Muscle: These are made up of thousands of fibers bundled together. Skeletal muscles are voluntary, meaning they will perform a specific action that you request of them, such as lifting a fork, but will stay relaxed when you are not using them.
Smooth Muscle: These muscles are smaller than skeletal muscles. They are involuntary, meaning they perform on their own and you do not have control over when and how they move. They are controlled by your nervous system. An example of this is your eyelid. You cannot control when and how many times you blink each day.
Cardiac Muscle: The heart is a muscle. It pumps blood throughout your entire body. It works on its own.
Types of Muscle Diseases
Heart conditions: When muscles do not get enough oxygen it can cause pain. If left without oxygen for too long, a muscle can stop working altogether. This is especially true of the heart where a person will experience a heart attack.
Nervous system conditions: The brain has an area called the basal ganglia. It produces cells and a chemical called dopamine. This chemical is necessary to send messages to the entire brain, which helps aid muscle movements. When the cells in the basal ganglia are damaged, less dopamine is made. This can result in conditions such as Parkinson's disease, ADHD, or schizophrenia.
Muscular Dystrophy: This is a severe form of muscle weakness. The disease can worsen slowly over time or be very aggressive and happen quickly. There is no cure for muscular dystrophy, but measures can be taken to make a person more comfortable if suffering from the disease.
Muscle Experiments
Pupil Response
Instructions: Students need to be in pairs for this experiment. Have one student be the observer and the other the one performing the experiment. Start in a well-lit area and have each observer notice the size of the performer's pupil. Next, have the performer go into a very dimmed room for about 2 minutes and then come out. The observer should notice that the performer's pupil is now larger. After a few minutes of being back in the lighted area, the performer's pupil will grow smaller again. Let the students switch places and try it again.
Why it Works: The involuntary muscles in the pupil contract in lighted areas to keep too much light from getting into the eye, which could damage vision.
Magic Raising Arms
Instructions: Have a student stand in a doorway with his arms at his sides. Have him stretch out his arms until the backs of his hands touch the doorframe. Tell him to push as hard as he can with the backs of his hands. You count to 30. Then have him step away from the doorframe and have his hands fall to his sides. His arms should start to rise.
Why it Works: Your brain has giving your muscles the message to raise your arms. When you stepped away from the doorframe, the last message is still traveling to your muscles, so your arms rise.
