BIO 240 - Exam 3 - Muscles (3.1 A-C)
Functions of skeletal muscle - ANS-move the body, maintain posture, protect and
support, secrete cell signals, regulate elimination of materials, and produce heat
Characteristics of the skeletal mucsle tissue - ANS-Excitability, Conductivity,
Contractibility, Extensibility, and Elasticity
Excitiability - ANS-Ability of muscles to respond to a stimulus
Conductivity - ANS-sedning an electrical change down the length of the cell membrane
Contractability - ANS-filaments slide past each other - causes movement
Extensibility - ANS-ability to be stretched
Elasticity - ANS-return to original length following a lengthening or shortening
Development of Muscle fibers - ANS-multiple myoblasts fuse together and form a
multi-nucleated muscle fiber
Satellite Cell - ANS-support cells that are used for repairing the muscle fibers
Layers of skeletal muscle - ANS-Tendon, epimysium, perimysium, endomysium
Tendon - ANS-A fusion of epimysium, perimysium, and endomysium
Epimysium - ANS-Dense CT; covers the entire outside of skeletal muscle
Endomysium - ANS-Delicate layer; Surrounds individual muscle fibers and provides
electrical insulation, capillary support and binding to neighboring cells.
Perimysium - ANS-Dense; Connective tissue surrounding a fascicle
Connective Tissue Components - ANS-Tendon, Aponeurosis, Deep Fascia, and
Superficial Fascia
Tendon (CTC) - ANS-cord like structure of dense regular CT
, Aponeurosis - ANS-thin, flattened sheet of dense irregular tissue
Deep fascia - ANS-dense irregular connective tissue superficial to epimysium;
separates individual muscles and bind ones with similar functions
Superficial Fascia - ANS-Areolar and adipose CT superficial to deep fascia;
Separates muscles from skin
Somatic Nervous System Control - ANS-Fibers of ONE motor unit are dispersed
through out the muscle
Small motor units - ANS-Fewer muscle fibers; rapid and precise movement
Large motor units - ANS-Hundreds to thousands of muscle fibers; large amount of force
Sarcolemma - ANS-plasma membrane of a muscle fiber
Sarcoplasm - ANS-cytoplasm of a muscle cell; contains mitochondria and multiple
nuclei
Myofibril - ANS-tightly packed filament bundles found within skeletal muscle fibers
sarcoplasmic reticulum - ANS-specialized endoplasmic reticulum of muscle cells
terminal cisternae of SR - ANS-Expanded ends of the sarcoplasmic reticulum found on
either side of a t-tubule. Important in calcium storage used in muscle contraction
T tubules - ANS-Also called transverse tubules, these are deep invaginations of the
plasma membrane found in skeletal muscle cells. These invaginations allow
depolarization of the membrane to quickly penetrate to the interior of the cell.
Triad - ANS-the group of three (2 terminals and 1 T-tubule)
Neuromuscular Junction - ANS-Where motor neuron innervates the muscle; contains a
synaptic knob, cleft and motor end plate
End Plate Potential - ANS-1. action potential - down the motor neuron axon with an
influx of calcium at the synaptic knob
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