Muscle Notes

Topics: Muscle, Skeletal muscle, Myosin Pages: 3 (735 words) Published: September 26, 2013
Epimysium- covers the entire muscle
Perimysium- covers..?
Endomysium- covers the individual muscle fibers
Sarcomere- smallest contractile element of muscle fiber, extends from z-line to z-line Myofilament- responsible for contraction
Striated- the color variations on the muscle fiber. Has to do with the amount of protein and the way it reflects light. Myosin- globular protein
Bulb like heads come in contact with the active sites on actin Active sites are not exposed when in the resting position.
Tropomysin- the regulatory protein the hides the active sites when not stimulated Sarcoplasmic reticulum- lines either side of the t-tubule
T-tubule- comes from the muscle fiber, the z-disks

T tubule and the cistaline? make up the triad

Skeletal muscle contraction
Must be stimulated by action potentials, at a nerve ending
Propagate an electoral current or action potential sarcolemma (surrounding area of the muscle) Have a rise in intracellular Ca2+ level; the final trigger for contraction Linking the electoral signal to the contraction is excitation-contraction coupling Very tightly coupled

In muscle its usually all or nothing

Neuromuscular junction
Each muscle has a motor neuron that innervates
Attaches to muscle fibers via external branching
Some activate more than others based on the motor fineness needed for the activity Nervous input (action potential) comes down the muscle fiber to the axonal ending Synaptic vesicles- has acetocholine- takes neural message and translates it into a chemical message Axonal ending does not come in direct contact, it forms the synaptic cleft Opens the ca channel gate and works its way inside the terminal axon, causes the enzymes to bind to the vesicles causing them to release ach. Through exocytosis, the ach is released across the cleft. Sarcolemma receptors specific for ach. Na channels open and moves na into sarcolemma and potassium leaves and goes into cleft. Acetocholine esterase gets all the ach...
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