Mechanism and chemical changes occuring during muscle contraction
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Transcript of Mechanism and chemical changes occuring during muscle contraction
MECHANISM AND MECHANISM AND CHEMICAL CHANGES CHEMICAL CHANGES DURING MUSCLE DURING MUSCLE CONTRACTIONCONTRACTION
By Deepika of B.Sc final year
Myofibril
A Band ,I band
H zone
Z line
Sarcomere
Muscle proteins – contractile property
2 essential proteins are involved
Actin and Myosin
MYOSIN
Assembled myosin filament
Light meromyosin
Heavy Meromyosin
Head –
ATPase active site, actin binding site
ACTIN
Assembled actin filament
F – actin , G – actin
Tropomyosin
Troponin – 3
TN – I – inhibitory protein
TN – C - Site of Ca attachment
TN – T – Prevents bridges between actin and myosin
SLIDING FILAMENT MECHANISM OF MUSCLE CONTRACTION
Huxley and Hanson
1. 2 sets of filaments
2. Thin filaments slide over thick filaments
3. There is no change in A band
I band and H zone dec or disappear
SERIES OF EVENTS IN CONTRACTION
Step 1 : Depolarization of sarcolemma
Step 2 : Release of Ca ions
Step 3 : Conformational changes in actin
Step 4 : Formation of Actomyosin complex
Step 5 : Interaction of thick and thin
filaments
• Power stroke
Ratchet mechanism
Walk along mechanism
ROLE OF CALCIUM
Ca
Troponin
Tropomyosin
Actin
Myosin
CHEMICAL CHANGES DURING MUSCLE CONTRACTION
ATP utilization
• Polymerization of G-action to F-actin
G-actin + ATP F-actin + ADP + iP
• Formation and dissociation of Actomyosin
Actin + Myosin Actomyosin
ATP ADP
ATPase
REPHOSPHORYLATION OF ATP
1.Phosphagen
Creatine phosphate
Creatine phosphate + ADP ATP + Creatine
2 .Breakdown of muscle carbohydrate
Lactic acid formation
Muscle fatigue
Oxygen debt
Cori cycle
4/5th of lactic acid = glycogen
1/5th of lactic acid = water + Carbondioxide
Thanku…….