Muscle.pdf

SLIDING FILAMENT MODEL OF MUSCLE CONTRACTION
• Suggested by H. Huxley & A.F. Huxley – 1954
• Thin filament slide past thick filaments
• Actin & Myosin overlap to greater degree
• Cross bridges of myosin attaches to binding site on Actin
• Cross bridge contract to pull actin in center of Sarcomere
• Z line brought closer together
• I band shortens
• H zone disappers
• Length of sarcomere decreases
Motor Unit:
• All fibers (Cells) innervated by single motor neuron
• (One motor neuron supply to many fibers)
• Nerve impulse reaches at neuromuscular junction (Junction between axon terminal of motor neuron and 
sarcolemma 
• Stimulation to Motor Unit
• Stored Ca
++
is released from sarcoplasmic reticulum
• Ca
++
binds with troponin
• Troponin pulls the tropomyosin exposing the binding sites on actin for cross bridge
• Muscle Contraction
• Hydrolysis of ATP
• cross bridges to their initial position i.e goes to the cycle
Rigor Mortis:
• Death of person
• ATP level falls
• Cross bridges not detaches from thin filament
• & firmly bound
• Stiffness of body
Energy for Muscle Contraction
Under Normal Condition: