gradual process of lengthening, with synthesis of myofibrillar proteins
differentiation/maturation
origin of muscle tissue
mesoderm
multinucleated cell(from fusion of myoblasts)
skeletal muscle
oval nuclei is found at the periphery of the cell, under the cell membrane
skeletal muscle
made up of dense irregular connective tissue; holds groups of fascicles
epimysium
holds fascicles(bundles of fibers within a muscle)
perimysium
made up of delicate connective tissue; holds individual muscle fibers
endomysium
thick/dark filaments; anisotropic(birefringent in polarized light)
a-band
thin/light filament; isotropic(do not alter polarized light)
i-band
center of a-band
h-band
bisects h-band
m-line
protein that binds the thick filaments in place
myomesin
bisects the i band
z-line
thin filament; 2 strands of globular(g-actin) monomers in double helical formation; contains binding sites for myosin
actin
thick filament; 2 heavy and 2 light chains; heavy chains have ATP binding sites to contain troponin and tropomyosin
myosin
protein used to bind myosin to proteins of the m line and the disk line
titin
troponin that binds to calcium
troponin C
troponin that binds to tropomyosin
troponin t
troponin that binds to actin; inhibits
troponin i
events in muscle contraction
1) myosin heads hydrolysis ATP and become reoriented and energized
2) myosin heads binds to actin forming cross bridges
3)myosin heads rotate toward center of the sarcomere(power stroke)
4)myosin heads bind ATP, the crossbridges detatch from actinÂ
branching fibers; centrally located nucleus; involuntary contraction; presence of intercalated disk
cardiac muscle
represent junctional complexes between adjacent cardiac muscle cells
intercalated disk
equivalent to the zonula adherens between epithelial cells; anchoring sites for actin filaments of terminal structure
fascia adherentes
binds individual cardiac cells to one another
macula adherentes/desmosome
provides ionic continuity between cells; found in lateral portions
gap junction
generates and rapidly transmits contractile impulse to various parts of myocardium in precise sequence
purkinje fibers
elongated, non-striated, spindle shaped cells; cigar shaped nucleus; enclosed by basal lamina and reticular fibers which serve to combine the force generated by each smooth muscle fiber into a concerted action
smooth muscle
branching myelinated motor nerves; myoneural junction
motor end plate
receptors for proprioception
neuromuscular spindle
believed to be the regenerating cells of the skeletal muscle