1. The Muscular System The Human Body Lesson
Let’s just say the heroes of the 1980’s action movies used their muscular system more than kind words to solve their problems.
The Muscular System
The Human Body Lesson

2. What is the Muscular System?
The muscular system is what moves the body
You have about 650 muscles in your body.
Muscles make up about 40% of your total body weight.
There are two main types of muscles.
Ummm I don’t think your circulatory system should be showing like that.

3. The Two Main Types of Muscle
Skeletal Muscle (Striated) is muscle that is attached to our bones and move them.
Our biceps and triceps are skeletal muscles.
Smooth Muscles are found in the blood vessels, the skin, and organs such as the esophagus, stomach, and intestines.
These muscles push food and blood through our body but do not move the skeleton.
There is a third kind of muscle found only in the heart which is called Cardiac Muscle.
Gymnasts must have complete control of their skeletal muscles.

4. Voluntary and Involuntary Muscles
Muscles that you have control over are called Voluntary Muscles.
These are found in your arms, legs, fingers, toes…all over your body!
Involuntary Muscles are out of your control.
These are your smooth muscles and cardiac muscle.
There are a few muscles that are normally involuntary but can be controlled at times. (diaphragm, eyelids, tongue.)
That look says, “Go ahead and try to take my lunch money.”

5. How Do Muscles Work? Muscles can only pull, they cannot push!
Many skeletal muscles work in pairs to move bones.
The bicep on your upper arm works with the tricep underneath it to bend the elbow.
When muscles pull or contract too long, or too strong, you can get a cramp.
When muscles relax they expand.

6. How do Muscles Work?
The Achilles Tendon is the largest tendon in the human body.
Skeletal muscles are attached to the bones with thick rubberband-like cords called tendons.
Muscles need energy in order to work.
Special enzymes in the muscles break down food to get energy.
As the muscle works, it produces waste called lactic acid.
If too much lactic acid builds up, the muscle loses some ability to contract.