1. The Muscular System: Interesting Facts
Human Bio 11

2. Interesting Facts You have more than 650 muscles.
Muscles make up 40% of your body mass.

3. Interesting Facts Muscles contract (shorten).
They pull on bones, producing movement.
You are constantly moving.
Even when you are sleeping.
Muscle cells cannot partially contract.
They either contract 100% or do not contract at all.

4. Interesting Facts Shivering: Cramp:
When you are cold, your muscles produce rapid contractions to generate body heat.
Cramp:
A painful muscle contraction.

5. Interesting Facts Spasm: Tetanus:
A rapid involuntary contraction of a muscle.
Example: an eye twitch
Tetanus:
A persistent, severe contraction that can be caused by a bacterial infection.
A tetanus shot can help prevent this.
Example: tetanus can cause lock jaw.