muscle contraction

Created by

Emily Strozynska

Cards (10)

evidence for sliding filament contraction 
I band becomes narrower
Z lines move closer together
H zone becomes narrower
A band remains the same width
creatine phosphate  
enables a phosphate group to be added to ADP to form ATP
fast twitch  
white
Type II
anaerobic respiration
slow twitch  
red - rich in blood
Type I
aerobic respiration
Role of ATP in muscle contraction 
Hydrolysis of ATP + Pi releases the energy required for the myosin head to detach from actin filament after the power stroke
On the actin filament  
calcium ions remain present so actin binding sites are still exposed
calcium ions released from the sarcoplasmic reticulum bind to troponin and change tropomyosin's shape. This exposes the actin binding sites
tropomyosin is blocking acting binding sites so muscle is relaxed
On the myosin filament 1
Myosin head changes shape as a result of binding to the actin filament. This pulls the two filaments along one another. ADP+Pi are released as a result of this shape change.
ADP+Pi are bonded to myosin heads. This means they are active and ready to bond if actin binding sites are exposed
ATP breaks down ADP+Pi and the cycle is able to repeat, if provided with a ready supply of ATP
On the myosin filament 2 
active myosin heads are now able to bind with the newly exposed actin binding sites. This produces tension in the muscles
ATP can now bind to the myosin head. This causes it to release from the actin
muscle relaxed  
no calcium present
troponin not bound to calcium
tropomyosin blocking binding sites on actin
myosin not attached to actin
muscle contraction 
calcium present - released from the sarcoplasmic reticulum into the sarcolemma
troponin bound to calcium
tropomyosin moved to binding sites on actin exposed
myosin attached to actin
ADP + Pi bound to myosin when it binds to actin
breakdown of ATP provides the energy for myosin head to move and detach