muscular system 1

muscular system 1

1. Functions

   • Movement
     • Skeletal muscles
       • Attach to bones by tendons
       • If contract; can move
     • Smooth muscle
       • On organ walls
       • Contraction produce movement
     • Cardiac muscle
       • Produce atrial and ventricular contractions
       • Pump blood from heart to blood vessels
   • Stability
     • Hold bones tightly (stabilize joints)
     • Small muscles hold vertebrae together (stabilize spinal column)
   • Cntrol of body openings and passages
     • Sphincters: valve formed by muscles
     • Control movement subs in n out of passages
   • Heat production
     • Heat released w/ muscle contraction
     • Helps maintain body T

2. Muscle cells

   • Myocytes (muscle fibers)
   • Sarcolemma (cell membrane)
   • Sarcoplasm (cytoplasm of cell)
   • Myofibrils (long structures in sarcoplasm)

3. Types of muscle tissue

   • Skeletal muscle (attach to bones n skin of faces)
     • Produce body movement n facial expression
     • Voluntary
     • Neurotransmitter acetylcholoine (muscle contract)
     • Muscle release anzyme acetylcholinesterase (muscle relax)
   • Smooth muscle (walls of hollow organs, blood vessels)
     • Moves contents through organs
     • Vasoconstriction (narrow blood vessel by small muscle)
     • control: Involuntary
     • Multiunit smooth muscle
       • In iris and walls of blood vessels
       • Responds to neurotransmitter and hormones
     • Visceral smooth muscle
       • Walls of hollow organs
       • Responds to neurotransmitter
     • Peristalsis
       • Acetylcholine
       • Push subs through tubes of body
   • Cardiac muscle (wall of heart)
     • Pump blood through heart
     • Involuntary
     • Self exciting (does not need nerve to contract)
     • Acetylcholine (slows heart rate)
     • Norepinephrine (speed up rate)

4. Production of energy for muscle

   • ATP (adenosine triphosphate)
     • Chemical E for sustained muscle contractions
   • Ways to make E
     • Creatine phosphate (rapid production of E)
     • Aerobic respiration (uses body's store of glucose)
     • Lactic acid (small amount of ATP)
   • Oxygen debt
     • Pyruvic acid convert to lactic acid
       • Conversion to glucose require more E n oxygen to make ATP
         • Oxygen debt
       • Muscle fatigue
   • Muscle fatigue (lost ability to contract)
     • Accumulation of lactic acid
     • Interruption of blood supply to a muscle
     • Motor neuron loses ability to release acetylcholine

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