KINE3440 Lec2: Muscle Structure and Function PDF

Simplified structure and composition of muscle - Contractile - Thing filament - Thick filament - Myosin - Elastic Filament - Inelastic filament Origin of muscle tension - Active components - Descending motor commands - Reflexes - Passive components...

Simplified structure and composition of muscle - Contractile - Thing filament - Thick filament - Myosin - Elastic Filament - Inelastic filament Origin of muscle tension - Active components - Descending motor commands - Reflexes - Passive components - Weak crossbridge binding - Titin Active component of muscle tensions - Driven by motor neuron - Causes strong actin-myosin coupling Temporal summation and force - Twitch - Latency period, contraction time, relaxation time - Spatial summation - Temporal summation - Tetanic contraction Passive component of muscle tensions - Intrinsic stiffness - Passive elasticity Force-length relationship - Isolated muscle fiber - Related to sarcomere length, how much junction can there be between actin and myosin - Whole muscles - Passive tensions Force-speed relationship - Isometric, concentric, and eccentric contractions - Dependant on rate of excitation-contraction rate Clinical aspects of muscle - Myopathies - Types - Congenital myopathies - Acquired myopathies Lambert-eaton myasthenic syndrome - Autoimmune disorder - Antibodies against presynaptic CA2+ - Clinical - Weakness, limbs before eyes - Etiology - Autoimmune - RX - Plasmapheresis - Immunosuppressants Myasthenia Gravis - Autoimmune disorder - Etiology - Unclear - Antibody to nicotinic Ach receptor - S&S - Weakness proportional to use - RX - Plasmapheresis - Immunosuppressants Somatosensory receptors - Types - Mechanoreceptors - Touch, proprioception - Chemoreceptors - Nociception - Thermoreceptors - Temperature Afferent fibres - Nomenclature - Calibre and myelination - 2 naming conventions - Roman numerals - Letters Cutaneous sensations - Types of cutaneous sensations - Touch - Temperature - Pain - Receptive field concept Receptive field - For cutaneous senses: - Region of skin which can generate activity in a single afferent neuron - Can overlap Dermatome - Skin region associated with a single spinal nerve root Peripheral nerve distribution - Skin region innervated by specific peripheral nerve Key nerves - Upper limb - Radial, ulnar - Lower limb - Anterior aspect - Femoral - Posterior aspect - Sciatic Subcutaneous sensations - Proprioception - Muscle spindles - Golgi tendon organs - Other - Free endings