Flashcards Muscle Cell and Contraction: Key Terms and Mechanisms

Myocardial Cells

cardiac muscle cell

Motor Unit

motor neuron and all skeletal muscle fibers stimulated by the branches of its axon

Recruitment

successive stimulation of more and larger motor units to produce increasing strengths of muscle contraction

Myofibril

consists of successive sarcomeres; pattern provides the striations characteristic of striated muscle cells

Myosin

protein that forms A bands; thick filament

Actin

structural protein; thin filament

Sarcomere

structural subunit of a myofibril; between Z lines

Cross Bridge

action produces sliding of the filaments; part of myosin protein

Tropomyosin

filamentous protein attaches to actin; acts to inhibit and regulate the attachment of myosin cross bridges to actin

Troponin

protein found in thin filament; binds to Calcium

Calcium Release Channel

proteins allowing Calcium to diffuse down its concentration gradient

Voltage Gated Calcium Channel

respond to membrane depolarization by undergoing a shape change

Excitation-Contraction Coupling

means by which electrical excitation of a muscle results in muscle contraction; achieved by Calcium

Gap Junction

region of fusion between two adjacent cells; electrical synapse

Calmodulin

receptor protein for Calcium in smooth muscles

Muscle Fatigue

reduction in the ability of a muscle to generate force

Sarcoplasmic Reticulum

surrounds each myofibril and serves to store Calcium when the muscle is at rest

Graded Contraction

allow contraction strength to vary due to number of motor units active

Latch State

muscle holds tension for long periods

Twitch

rapid contraction and relaxation of a muscle fiber

Summation

additive effects of contractions of different muscle fibers

Tetanus

smooth sustained contraction of a muscle

Isotonic Contraction

muscle contraction in which the muscle changes in length and maintains same amount of tension

Isometric Contraction

muscle contraction in which there is no appreciable shortening