Chapter 11: Muscles Flashcards
(42 cards)
Universal Characteristics of Muscle
Responsiveness Conductivity Contractility Extensibility Elasticity
Sarcolemma
plasma membrane of a muscle fiber
Sarcoplasm
Cytoplasm of a muscle fiber
Myofibrils
long protein bundles that take up most of the sarcoplasm
Thick filaments
several hundred myosin molecules
thin filaments
fibros actin, tropomyosin and troponin
Elastic Filaments
contain titin
a band
dark band
I band
alternating lighter band
H band
middle of Aband, thick filament only
Z disc
provides anchorage for thin and elastic filaments
Sarcomere
segment from Z disc to Z disc
Motor Unit
one nerve fiber and all muscle fibers innervated by it
Synapse
where a nerve fiber meets its target cell
Neuromuscular
Junction
when target cell is a muscle fiber
ACh
Stimulates muscle function
Stimulation
Electrical signal travels down the nerve
Signal triggers a release of ACh (leaves nerve by extocytosis)
ACh is received in the muscle
Is the chemical messenger
Enzymes later dissolve the ACh to “turn off” the muscle
Spastic Paralysis
continual contraction of muscles, possible suffering
Flaccid Paralysis
muscles are limp and cannot contract
Excitation
nerve action potentials lead to muscle action potentials
Excitation contraction coupling
action potential on sarcolemma activates myofilaments, preparing them to contract
Contraction
muscle fiber develops tension and may shorten
Relaxation
fiber relaxes and returns to its resting length
Optimum resting length
produces great force when muscle contracts