1. Muscular System
Chapter 45.3

2. Muscular System
Major Function = Allows body to move & provides force that pushes substances through out the body.
Voluntary vs. Involuntary:
conscious vs. unconscious

3. Muscle Types
Skeletal -responsible for the moving parts of the body. -voluntary muscles Smooth Muscle -forms muscle layers found in the walls of the stomach, intestines, blood vessels, and other internal organs. -involuntary muscle Cardiac Muscle -makes up the walls of the heart. -involuntary

4. Muscle Structure
Organizational Structure: 1. muscle 2. bundle of muscle fibers 3. muscle fiber (cell) 4. myofibril 5. sarcomere 6. proteins: actin (thin filament) myosin (thick filament) -gives a striated appearance.

5. Muscle Structure

6. Muscle Contraction
-Sarcomere’s are the functional units of muscle contraction. Contain the proteins actin and myosin that interact with each other. Muscle Contraction = shorter sarcomere Muscle Relaxation = longer sarcomere Driven by ATP! Muscle Contraction Clip

8. Muscle Movement of Bones
-Skeletal muscles are attached to bones via tendons. Origin- point where the muscle attaches to the stationary bone. Insertion- point where the muscle attaches to the moving bone.

9. Flexors- a muscle that bends a joint
Flexors- a muscle that bends a joint. Extensor- a muscle that straightens a joint. Flexors and Extensors work together, one contracts, one relaxes!

10. Muscle Fatigue Muscle fatigue is a result of depletion of ATP
A state of continuous contraction occurs (i.e.. Muscle cramps)
Lack of oxygen availability is called oxygen debt.
Oxygen debt leads to an accumulation of lactic acid, which produces the soreness you may experience after prolonged exercise.