BIOL 302 – Histology – Muscle
Contraction – generation of force.
Muscle Tissue Metabolism
Contractions are ATP dependent
Highly metabolic – burn a lot of fuel and energy to contract
Many mitochondria – generate lots of power
Highly vascularized – nutrient and oxygen supply via capillaries
Muscle Tissue Types
Identify according to: organization, nuclei/cell morphology, contractile
Skeletal – striated
Cardiac – striated
Smooth – no striations
Myoepithelial – glands; can contract and expel secretions of exocrine glands
Myofibroblast – scar tissue; contract by using smooth muscle type actin-myosin
complex. These cells are then capable of speeding wound repair by contracting
the edges of the wound.
Pericytes – blood vessels; regulate capillary blood flow, the clearance and
phagocytosis of cellular debris, and the permeability of the blood–brain barrier.
Voluntary: moves skeleton and organs
Epimysium: layer of connective tissue, which covers the entire muscle.It is
composed of dense irregular connective tissue.
Perimysium: sheath of connective tissue that groups muscle fibres into bundles.
Endomysium: wispy layer of areolar connective tissue that covers each individual
muscle fiber. It also contains capillaries and nerves. It overlies the muscle fiber's
cell membrane: the sarcolemma.
Sarcolemma: cell membrane of striated muscle fibre cell.
Sarcoplasm: comparable to cytoplasm, but of muscle cells.
Sarcomere: functional or contractile unit of a muscle cell. Myofibril: cylindrical bundle of contractile proteins found within the muscle cell.
Filaments: thin (actin); thick (myosin)
Has repeated banding pattern of light and dark bands (myofibrils)
Multiple nuclei, located on periphy of the cells.
Fibres run parallel to each other
XS: Polygonal shaped cells; in bundles (fascicles); nuclei located on periphery
LS: long with visible striations; thin nuclei located on periphery; unbranched
M-line: middle; stays same size
A-band: actin (thin) + myosin (thick); stays same size