| Explain the excitation-contraction coupling process | Excitation-contraction coupling refers to a series of events linking muscle excitation (the presence of an action potential in a muscle fibre) to muscle contraction (cross-bridge activity that causes the thin filaments to slide close together to produce muscle shortening). |
| Describe the cell contraction sequence | Impulse reaches axon’s synaptic knob Synaptic vesicles fuse with neurons from the membrane and release ACH via exocytosis. ACh binds to receptors on sarcolemma. Sodium channels open, allowing sodium to flow in. If enough sodium moves into the muscle cell, an impulse (action potential) develops. |
| Describe the function of skeletal muscle with an emphasis on muscle contraction | Contractile force is produced by the interaction of the thick and thin filaments. The interaction of actin and myosin produces muscle contraction. Calcium (tropomyosin) - Covers actin sites blocking interaction that leads to muscle contraction. Calcium (troponin) – with the absence of tropomyosin, actin and myosin bind, interact at cross bridges, resulting in muscle contraction. The thin filaments slide over the thick filaments during muscle contraction, but the filaments themselves don’t change length. This results in a shorter I and H band, but the A band does not change. |
| Describe the structure of skeletal muscle | Muscle consists of several muscle fibres lying parallel to one another and held together by connective tissue Single skeletal muscle cell is known as a muscle fibre (10-100 microns) Myofibrils -contractile elements of muscle fibre – About 1 micron in diameter (one-millionth of a meter) The appearance of striations – Displays alternating dark (the A bands) and light bands (the I bands) Sarcomere – functional unit of skeletal muscle (2 μm wide) and found between two Z lines (connects thin filaments of two adjoining sarcomeres) |
