Muscle Models Flashcards
aponeurosis
like a tendon, connective tissue layer forms a thin, flattened sheet of dense irregular tissue
connect muscle to bone
deep fascia
additional expansive sheet of dense irregular connective tissue external to epimysium
separates individual muscles, binds muscles with similar functions, contains nerve, blood, lymph vessels, fill space between muscles
endomysium
between fascicles
innermost layer, delicate areolar connective tissue layer surrounds and electrically insulates each muscle fiber
reticular protein fibers help bind neighboring muscle fibers and support capillaries
epimysium
wraps muscle
layer of dense irregular connective tissue surrounding whole skeletal muscle
protection
fascicles
bundles of many organized muscle fibers (myofibers)
keep together
gap junctions
protein pores between sarcolemma of adjacent cardiac muscle cells; provide low-resistance pathway for ion flow allowing action potential to move continuously resulting in synchronous contraction
muscle fibers (cells)
in fascicles
skeletal muscle cells, extraordinarily long, mulinucleated because of fused myoblasts
myofibrils
long, cylindrical structures composing 80% of volume of a muscle fiber; contain myofilaments
perimysium
around fascicles
surrounds fascicles, dense irregular connective tissue sheath contains extensive blood vessels and nerves that branch to supply muscle fibers within each fascicle
tendons
thick, cord like structure, dense regular connective tissue, 3 layers as they merge and extend past muscle fibers
attach muscle to bone, skin, or another muscle
A bands
central region of sarcomere containing entire thick filament; thin filaments partially overlap on ends
never changes length
Actin
protein of thin filaments
contains myosin binding site
H zone
no actin, most central portion of A band in a resting sarcomere, no thin filament overlap- only thick
disappears when thin is pulled past thick during maximum muscle contraction
I bands
extend from both ends of and are bisected by the Z disc, contain only thin filaments (light)
disappears during contraction as thin filaments are pulled past thick filaments
changes length during contraction
M line
thin transverse protein meshwork structure in center of H zone serving as attachment site for thick filaments and keeps thick filaments aligned during contraction/relaxation events
motor end plate
specialized region of sarcolemma with numerous folds to increase surface area covered by synaptic knob, vast acetylcholine receptors
motor neuron
nerve cells that transmit nerve signals from brain or spinal cord, axon branches to innervate numerous skeletal muscle fibers
motor unit
single motor neuron and the muscles it controls
size determines the degree of control
myofilaments
bundles of muscle protein fiber
myosin
protein makes up thick filaments; 2 strands with globular head and elongated tail
site for ATP to break into ADP and Pi
sarcolemma
plasma membrane of a skeletal muscle fiber
sarcomere
composed of overlapping thick and thin filaments, repeating microscopic cylindrical units
sarcoplasmic reticulum
internal membrane complex similar to smooth endoplasmic reticulum, surround bundles of myofibrils
synaptic cleft
extremely narrow fluid-filled spec separating synaptic knob and motor end plate
residing place of acetylcholinesterase (AChE)
