1. Muscular System

2. Functions of the Muscular System
Allows movement
Maintains posture
Stabilizes joints
Gives the body shape
Generates heat

3. 2 Categories of Muscles Muscles you can control
Voluntary Muscles
Involuntary Muscles
Muscles you can control
Examples: muscles in your arms and legs
Muscles you cannot control
Examples: heart, stomach, diaphragm

4. 3 Types of Muscle: Skeletal
Skeletal: muscles that move bones
Striated (striped)
Voluntary
Tires easily
Found in bundles

5. 3 Types of Muscle: Smooth
Smooth: muscles that control internal organs
No striations
Involuntary
Makes up internal organs (stomach, intestines)
Does not tire

6. 3 Types of Muscle: Cardiac
Cardiac: muscle that makes up the heart
Striated (striped)
Involuntary
Does not tire

7. Remember… What are ligaments?
Strong bands of tissue that connect bones to each other at a joint

8. Tendons
Strong bands of tissue that attach a muscle to a bone

9. Muscular Injuries Sprain: ligaments stretched or torn
Strain: muscles stretched or torn
Cramp: a muscle involuntarily contracted that will not relax

10. Fun Fact!
Sartorius: longest muscle in the human body

11. How skeletal muscles work
Muscles only contract
They pull, they don’t push
Skeletal muscles work in pairs
Example in the arm:
When the biceps contracts, the triceps relaxes
When the triceps contracts, the biceps relaxes

12. Energy Muscles use energy to move
When muscles run out of energy = muscle fatigue
When true fatigue hits, a muscle cannot be contracted even when stimulated

13. 2 Types of Exercise Aerobic Exercise (air exercise)
Jogging, biking, swimming
Makes muscles stronger, more flexible, and more resistant to fatigue
Increases metabolism
Enlarges heart
Lungs become more efficient
DOES NOT increase muscle mass much

14. 2 Types of Exercise Anaerobic Exercise (no air exercise) Weightlifting
Increases muscle mass
Does not increase endurance

15. Muscle Basics Myofibril: a muscle cell
Sarcomere: a tiny contractile unit of a muscle
A myofibril is made of many, many sarcomeres

16. Muscle Basics
One sarcomere is made of interlocking actin and myosin