1. The Muscular System Key Concepts
What types of muscles are found in the body?
Why do skeletal muscles work in pairs?

2. Key Terms Involuntary muscle Voluntary muscle Skeletal muscle Tendon
Striated muscle
Smooth muscle
Cardiac muscle

3. There are about 600 muscles in the human body

4. Types of Muscles
Involuntary Muscles – Muscles that are not under your conscious control – involved in breathing and digesting food
Voluntary Muscles – Muscles that are under your conscious control – smiling, turning a page, getting out of a chair
Three types of muscle tissue:
Skeletal, smooth and cardiac

5. Skeletal muscle
Attaches to and moves bones
Looks striated or banded under a microscope
Move only when you want them to: voluntary
React quickly and tire quickly
Tendon – strong connective tissue that attaches muscle to bone

7. Smooth Muscle
Smooth – found on the inside of many internal organs – Ex. Stomach
Involuntary
Help to control breathing, blood pressure, and movements of the digestive system
No striations or bands
React slowly, tire slowly

8. Cardiac Muscle Found only in the heart
Some characteristics of both skeletal and smooth
Involuntary
Striated
Does not tire
Contracts repeatedly
heart beat

9. Muscles at Work
Skeletal muscles only contract when they receive a message from nervous system.
Muscles do work only by contracting or shortening.
For movements need 2 muscles or groups of muscles (always work in pairs)
Ex. Biceps and triceps work together to bend and straighten your arm.

10. Muscular Strength and Flexibility
Exercise makes individual muscle cells grow in size – that makes the whole muscle thicker
The thicker the muscle the stronger it is
Stretching makes muscles more flexible
Prepares muscles for exercise or play

11. Muscle Injuries
Muscle strain or pulled muscle – when muscles are overworked or overstretched
Tendons can also be overstretched or partially torn
Muscle cramp – whole muscle contracts strongly and stays contracted