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