Skeletal muscle - long cylindrical cells, many nuclei per cell, STRIATED, Voluntary, rapid contractions
Cardiac Muscle - Branching cells, one or two nuclei per cell, STRIATED, involuntary, medium speed contractions
Smooth muscle - Fusiform cells, one nucleus per cell, NONSTRIATED, involuntary, slow wave-like contraction
Nerve impulse reaches myoneural junction
Acetylcholine released from motor nerves and bind with receptors which allow sodium to enter
Sodium generates an Action Potential which travels down the T tubule.
Sacroplasmic reticulum releases calcium which bind with Troponin, Binding sites in the Actin filament are exposed.
Mysosin head attached to bind sites, creates a power stroke.
ATP energises Myosin head for other contractions. Action potentials cease. the muscle stops contracting
Creatine stores ATP
Creatine and Atp---- Creatine Phosphate and ADP
Lack of O2 - ATP deficit
Lactic acid builds up from anaerobic respiration
weakening and shrinking of a muscle - immobilisation, loss of neural stimulation
Muscle Hypertrophy and Tonus
Enlargement of a muscle, more capillaries, more mitochondria
caused by steroids and exercise which stimulate muscle growth and hypertrophy
Muscle Tonus - tightness of a muscle, some fibres always contracted
Tetany - sustained contraction - result of rapid sucession of nerve impulses
Refractory period - Brief period of time in which muscles cells will not respond to a stimulates
Types of contraction
Isometric Contraction - produces no movement, used in standing, sitting posture
Isotonic contraction - produces movement, walking or moving any part of the body