Skeletal Muscle Actions
Chapter 5: The Muscular SystemSection 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 15 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