Muscles

• Neuromuscular junction (NMJ)


  Where lower motor neurons communicate with muscle cells, 30 nm gap
• Sarcolemma


  Postsynaptic muscle cell membrane site which is folded to increase surface area full of nAChRs
• When muscle cells bind with acetylcholine they depolarize, which makes them contract (flex)
• Muscle fibers


  Individual cells where muscle contraction happens
• Sacromeres


  Functional units of contraction that make up muscle fibers
• Actin are thin filaments that act as scaffolding and myopsin are thick filaments that pull them together, shortening the sacromere and contracting the muscle
• Skeletal muscle


  Voluntary striated
• Cardiac muscle


  Involuntary striated
• Smooth muscle


  Involuntary smooth
• Fast twitch muscles


  Generate a lot of force but tire quickly (skeletal muscle)
• Slow twitch muscles


  Generate less force but can work for a long time (skeletal muscle)
• Agonist muscle


  Main mover muscle like the biceps brachii
• Synergistic muscle


  Supports the agonist muscle which can also be fixators (giving stability and support)
• Antagonist muscle


  Muscle that works opposite of the agonist muscle
• Smooth muscle


  Involuntary muscles embedded within internal organs like the stomach, intestines, blood vessels, and bladder
• Cardiac muscle


  Striated muscles not under conscious control
• Myasthenia gravis


  Autoimmune disorder where the nAChRs are destroyed, so muscles don't respond as much. Treatment involves inhibition of acetylcholinesterase which degrades acetylcholine.