Download - Muscular system
The Muscular System
Muscles allow you to…
move
hold your head up
Digest and control waste removal
breathe
Pump blood (cardiac m.t.)
Control blood flow (smooth m.t.)
Hold bones together
thermoregulate
Freeze-fractured muscle fiber…showing the “broken” myofibrils
Graded Muscle Responses
a. Muscle contractions vary in strength due to….
1. Frequency of stimulus
2. Strength of stimulus
a. The application of the first stimulus did not activate any motor units.
b. All motor units are active when the “level 6” stimulus was applied.
c. The application of a “level 10” stimulus would result in a stronger contraction than the “level 7 stimulus.”
d. Indicate which of the following would be best for lifting heavy objects and which would be best for performing surgery.
_________________ size of motor unit averages 1000 muscle cells
_________________ size of motor unit averages 14 muscle cells
Ponder this point……..
Types of Muscle Fibers
Slow twitch muscle fibers (Type I)
Fast twitch (Type II)
Type II A
Type II B
These studies and journal articles offer more insight on muscle fiber research:High-Intensity Training and Changes in Muscle Fiber Nature vs. Nurture: Can Exercise Really Alter Fiber Type Composition?Effects of Endurance Training on Muscle Fiber