Muscular system

Muscular system

1. Classification of muscle:

   • Skeletal muscle
     • Smooth muscle
       • Cardiac muscle
         • Short/branched, connected by intercolated discs, striated, central nucleus
           • Function: contract heart and pump blood
             • Control: Automaticity (pacemaker cells) under neural control
               • Metabolism: aerobic
       • Spindle shaped, single/central nucleus, non-straited
         • Location: walls of b.vessels, digestive, respiratory, urinary/reproductive organs
           • Structure: forms sheets, bundles, sheeths
             • Functions: reg. blood flow, move materials in dig.system, alter kidney filtration, elevation of hairs
               • Control: Automatic, neural, hormonal - Metabolism: Aerobic
     • One cell, muscle fibre, largest, multinucleated and striated
       • Location: attached to bones through ligaments
         • Functions: Locomotion, posture, soft tissue support, maintaining body temp, store nutrients
           • Control: Neural at single neuromuscular junction
             • Metabolism: aerobic and anaerobic

2. Structure of skeletal muscle

   • Connective tissue organisation
     • Epimysium: dense layer of collagen fibres, separates muscle from its surrounding tissues
       • Perimysium: Bundles of muscle fibres (fascicles) + blood vessels/nerves
         • Endomysium: Surrounds individual muscle fibres, contains capillaries, nerves and satellite cells

3. Structure of muscle fibre

   • Plasma membrane (sarcolemma): separates sarcoplasm and extra cellular fluid
     • Sarcoplasmic reticulum: important for muscle contraction, regulates intracellular Ca2+ concentration
       • Transverse T-tubules: Continuations of the sarcollemma, allow the contraction impulse to reach deep into the muscle
         • Triad: Area where T-tubes and sarcoplasmic reticulum work together to sense intracellular voltage and Ca2+ concentration
           • Mitochondria: provide energy for muscle contraction (O2)
             • Myofibrils: sub-units responsible for muscle contractions

4. Skeletal muscle classifications

   • Slow oxidative: Type 1a
     • Fast oxidative: Type 2a
       • Fast glycolytic: Type 2b