BIOL 305 Lecture Notes - Lecture 12: Mitochondrion, Glycogen, Muscle Fatigue
14 Oct 2015
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Types: skeletal muscles -voluntary, cardiac muscles - involuntary, smooth muscles - involuntary. 600 muscles in adult human body: grouped and paired. Act on skeletal system: each muscle has an origin - attachment to a stationary bone, generally closer to the body midline, each muscle has an insertion -attachment to a bone across a joint, contraction pulls insertion towards origin. Composition of muscles: single muscle, muscle bundle, also called fascicle, surrounded by fascia, fascia connect to tendon, then skeleton system, muscle cell (individual fibers, 10-100nm wide, multi nucleate. Fusion of several myoblasts during development: contain long cylindrical structures called myofibrils. Myofibrils are the contractile component of cells (striated muscle: sarcomere. Small amounts of contraction lead to a large combined effect. Myosin (thick: muscle activation: through neural activation, axons innervate muscle and make contact at the neuromuscular junction (nmj, motor neurons release acetylcholine, leads to waves of electrical activity (depolarization, t-tubules.
