1. Skeletal Muscle Actions
Chapter 5: The Muscular System Section 2
Lesson 5.2
Skeletal Muscle Actions

2. Skeletal Muscle the motor unit skeletal fiber types
muscular strength, power, and endurance

3. The Motor Unit
group of muscle fibers under the control of one motor neuron

4. Generating Action Potentials
acetylcholine crosses the synaptic cleft at the neuromuscular junction
depolarization takes place on muscle fiber
action potential begins

5. Contraction of the Sarcomeres
sarcomeres shorten by actin filaments sliding along myosin filaments – INCLUDE THESE 2 LABELED DRAWINGS IN YOUR NOTES! 

6. Maximum Tension and Return to Relaxation
action potential always causes entire motor unit muscle fibers to contract
all-or-none law

7. Review and Assessment True or False?
1. An action potential causes one half of the fibers in the motor unit to contract.
2. Acetylcholine crosses the synaptic cleft at the neuromuscular junction.
3. The sarcomeres lengthen by myosin filaments sliding over actin filaments.

8. Skeletal Muscle Fiber Types
slow-twitch
fast-twitch
type Iia – intermediate between slow and fast
type Iib – fastest (1/7 the time of slow twitch)

9. Skeletal Muscle Fiber Architecture
parallel fiber arrangements
fusiform
bundled
triangular
pennate fiber arrangements
unipennate
bipennate
multipennate

10. Muscular Strength rotary force that muscles can produce at a joint
the maximum weight you can lift is a measurement of muscular strength

11. Muscle Power force x velocity
how fast you can sprint is a measurement of muscle power

12. Muscle Endurance muscle tension/time
how far you can run is a measurement of muscle endurance

13. Review and Assessment
Match these words with 1–5 below: muscle endurance, muscular strength, muscle power, Type I, Type IIb. 1. force x velocity 2. muscle tension/time 3. rotary force that muscles can produce at a joint 4. slow twitch, slow fatigue 5. fast twitch, fast fatigue