1. Muscular System

2. How do muscles work? Muscles can't push. They pull.
Muscles often work in pairs so that they can pull in different or opposite directions, like a finger that moves in different directions.

3. Muscular System: Involuntary/Voluntary
The muscular system moves the body.
The body has over 600 muscles.
Some muscles are called voluntary, that means that you choose to use them. How active you are depends on how much use they get!
Some muscles are called involuntary because they work without you thinking about them. These are muscles like the heart and digestive system.
Ligaments are strong connective tissue that attaches muscle to bone.

4. Function of Muscles Produce movement Maintain posture Stabilize joints
Generate heat

5. The Muscular System
Muscles are responsible for all types of body movement
Three basic muscle types are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle

6. Skeletal Muscle Characteristics
Most are attached by tendons to bones.

7. Skeletal Muscle Characteristics
Cells are multinucleate
Striated – have visible banding
Voluntary – subject to conscious control
Cells are surrounded and bundled by connective tissue

8. Cardiac Muscle Characteristics
Has striations
Usually has a single nucleus
Joined to another muscle cell at an intercalated disc
Involuntary
Found only in the heart

9. Smooth Muscle Characteristics
Has no striations
Spindle-shaped cells
Single nucleus
Involuntary – no conscious control
Found mainly in the walls of hollow organs

10. Comparison of Types of Muscle

11. - The Muscular System
Muscles at Work
Because muscle cells can only contract, not extend, skeletal muscles must work in pairs. While one muscle contracts, the other muscle in the pair relaxes to its original length.

12. Effects of Exercise on Muscle
Aerobics result in stronger muscles due to increase blood supply
Muscle fibers increase mitochondria and oxygen storage
Muscle becomes more fatigue
resistant
Heart enlarges to pump
more blood to body
Does not increase skeletal
muscle size

13. Effects of Exercise on Muscle
Results of increased muscle use from resistance training
Individual muscle cells make more contractile filaments & connective tissue increases
Increase in muscle size
Increase in muscle strength