1.9 Muscle contraction Flashcards
What are two roles for ATP in skeletal muscle contraction?
- ATP binds to myosin, causing release of the head from actin. Energy released from ATP hydrolysis re-energies the myosin head - this ultimately provides the energy for cross bridge movement and force generation
- In the SR: Ca-ATPase hydrolyses ATP in order to take up Ca ions back into SR to end a muscle contraction
How does oxidative phosphorylation of ADP produce energy for contraction?
Aerobic respiration; Glucose converted to pyruvic acid which goes into the citric acid cycle/electron transport chain
- slow
- moderate levels of activity
- uses blood borne fuels as well as muscle glycogen
How does phosphorylation of ADP in the cytosol produce energy for contraction?
Produces a lot of ATP usage
- absence of oxygen
- lactic acid by product
- requires muscle glycogen and or blood borne
How does phosphorylation of ADP by creatine phosphate produce energy for contraction?
Creatine to creatine kinase to phophocreatine
- very rapid
- onset of muscle contraction
- short duration only
- amount of ATP produced limited by initial CP in cell
What are type I muscle fibres?
Slow oxidative
- low myosin ATPase activity
- high oxidative capacity
- smaller diameter (weaker); fatigue resistance
What are type IIa muscle fibres?
Fast oxidative glycolytic
- high myosin ATPase activity
- high oxidative + glycolytic capacity
What are type IIb muscle fibres?
Fast glycolytic
- high myosin ATPase activity
- high glycolytic capacity
- larger diameter (stronger); fatigue easily
What can fibre type be influenced by?
Genetics Training Age Lifestyle Diet
What is isometric muscle contraction?
Load = force (muscle)
What is concentric muscle contraction?
Load < force (muscle) - muscle shortens
What is eccentric muscle contraction?
Load > force (muscle) - muscle lengthens
