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

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

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

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

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

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

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.

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)

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

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

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

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

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