BIOL 1050H Lecture Notes - Lecture 3: Membrane Potential, Erector Spinae Muscles, Earwax
16 Jan 2018
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Muscle types: skeletal, cardiac, smooth specialized for transforming atp into force/motion. Striated muscle attached to bone: striations from arrangement of internal contractile proteins. Muscle cell = muscle fibre: can be 30 cm long! Skeletal muscle contraction depends on stimulation from neurons. Cranial nerves head and neck skeletal muscles. Spinal nerves arise from spinal cord in intervertebral foramina, supplying muscles below neck. Motor unit: neuron and all the muscle fibers it innervates. T-tubules invagination of the sarcolemma (cell membrane) Sarcoplasmic reticulum (sr: smooth er forms a network around each myofibril, ca ++ stored here. Membrane potential change in t-tubules trigger ca ++ release from sr. Fibrous proteins that carry out the contraction: thick filaments. Heads directed outward in a helical array around the bundle: thin filaments. Two intertwined strands of fibrous actin: string of globular actin subunits that can bind to the head of myosin molecule, elastic filaments.
