chapter7

• 1) skeletal (striated, voluntary)
• 2) visceral or smooth (nonstriated, involuntary)
• 3) cardiac (striated, involuntary)

• 1) movement (primary)
• 2) maintain posture
• 3) heat generation

• 1) excitability
• 2) contractility
• 3) extensibility
• 4) elasticity

• 1) sarcolemma (plasma membrane)
• 2) sarcoplasm (cytoplasm)
• 3) specialized organelles

surrounds sarcoplasm w/ openings scattered across surface that lead into a network of narrow tubules calles transverse tubules (T tubules)

• 1) encircled by T-tubules
• 2) 1-2um diameter - as long as the entire muscle
• 3) hudreds to thousands are contained in each muscle fiber
• 4) bundles of thick & thin myofilaments
• 5) responsible for muscle fiber contraction

protein filament that consist primarily of the proteins actin & myosin

• 1) protein found in protein filaments contained in myofilaments
• 2) actin molecules are found in the thin filaments
• 3) attracted to myosin

• 1) protein found in protein filaments contained in myofilaments
• 2) myosin molecules are found in the thick filaments
• 3) attacted to actin

• 1) scattered among the myofibrils, a source of glucose
• 2) breakdown of glucose & the activity of the mitochondria provide the ATP needed to power muscle contraction

• 1) forms tubular network around each myofibril
• 2) specialized for of endoplasmic riticulum

• 1) create a network of narrow tubules that form passageways through the muscle fiber
• 2) filled w/ extracellular fluid

• 1) expanded chamber of SR containing high concentration of calsium ions
• 2) wherever T-tubules encircles a miyofibril it is tightly bound to the membranes of the SR
• 3) located on either side of where T-tubules encircles a microfibril

it is formed where SR encircles a myofibril & a T-tubule lies sandwiched between a pair of terinal cisternae

when stored calsium ions are released from the terminal cisternae into the sarcoplasm.

• 1) what myofilament (thick & thin fillaments) are organized into
• 2) they are repeating functioning units
• 3) each myofibril consists of aprox 10k arranged end to end
• 4) smallest functional unit of the muscle fiber
• 5) interactions between thick & thin filaments here are responsible for muscle contraction

• 1) aprx 6hrs after death
• 2) skeletal muscles have depleted all glucose & ATP molecules
• 3) waste products accumulate (metabolic acids)
• 4) ATP gone -> sarcoplasmic riticulum cannot remove calcium ions from the sarcoplasm
• 5) myosin fibers can't separate from actin fibers, & rigor mortis, sustained contraction, sets in
• 6) 12-24hrs later, lysosomal enzymes from muscle cells breakdown contracted myofilaments, & muscles relax