BIO 1130 Lecture Notes - Lecture 2: Tetanus, Cellular Respiration, Sarcolemma

• School: University of Ottawa
• Department: Biology
• Course: BIO 1130
• Professor: Jon Houseman

Document Summary

Rod like tail (2 heavy chains) + 2 globular heads (ends of heavy chains + 4 light chains. Cross bridges are the business ends of the thick filaments_ Each thick filaments = -200 myosins; arrayed so central part smooth & each and studded with many myosin heads_ Binding sites for myosin heads (cross bridges) Strands are f-actin; 2 strands wound as a helix. Sarcoplasmic reticulum: elaborate web for er around each myofibril inside pm, most sr tubules run longitudinally; pairs of terminal cisternae across a-i junctions, role: regulate intracellular ca++ storage depot. At a-i junction sarcolemma penetrates cytoplasm to form hollow elongated tubes (t- tubules = transverse tubules) Triad: group of 3 structures: 2 terminal cisternae + 1 t-tubule in the middle. T-system: thousands (2/sarcomere) of t-tubules in a single muscle cell_ Role: increase surface area: muscle fiber shortens because sarcomeres shorten; filaments remain same length, think filaments slide over thick filaments_