Ch. 50 D Flashcards
What does a response in muscle activity come from?
input from the nervous system
what does muscle contraction rely on?
interactions between thin filaments (actin) and thick filaments (myosin)
What does skeletal muscle do?
moves bones and the body
What are the units of hierarchy in muscles? (5)
1) Muscle
2) fascicle
3) muscle fiber
4) myofibrals
5) sarcomere
what is a fascicle?
bundle of muscle fibers
how are myofibrils arranged?
longitudinally
What is a sarcomere?
smallest functional unit of muscle
bordered by z lines
What is special about z lines?
where thin filaments attach
explain the basics of the sliding filament model
thin and thick filaments ratchet past each other longitudinally, powered by myosin molecules
Why are skeletal muscles called striated?
arrangement of myofilaments create dark and light band patterns
Explain the simple process of muscle contraction? (4)
1) head of myosin binds to actin filament
2) cross-bridge is formed
3) cross bridge pulls thin filaments towards sarcomere
4) cycle of binding and releasing is repeated
What is the term for the binding of the head of myosin to actin filament?
cross-bridge
What inhibits actin and myosin from interacting? How?
tropomyosin and troponin complex, by covering myosin binding sites on actin
What binds to the troponin complex to expose myosin binding sites?
Ca2+
explain the signaling process (6)
1) stimulus from motor neuron action potential makes a synapse with muscle fiber
2) The synaptic terminal releases acetylcholine
3) acetylcholine depolarizes muscle cell
4) action potential travel to interior muscle fiber along the transverse tubules
5) causes sarcoplasmic reticulum to release Ca2+ initiating muscle fiber contraction
6) motor input stops
