Calcium ions bind to troponin molecule, shape change that moves tropomyosin away from actin active site. Generates a little ATP, also lactic acid. Weaker contractions, muscle fatigue from lack of ATP Conditioning trains muscles to handle high lactic acid concentrations Panting after exercise repays oxygen debt as lactic acid converted back to glucose, ATP and CP reserves rebuilt. Antagonist - produces movement opposite the agonist. Antagonist is relaxed when agonist contracts.
Gap junctions connect cells or fibers.
Electrical signal passes cell to cell, coordinate contraction Cross-bridges attach longer, so less ATP needed to maintain high force. Human white fibers get energy from glycolysis, few mitochondria. Lots of mitochondria Lots of capillaries around fiber to bring O2.