bio exam 4 part 3

• think and thin filaments never changes
• sarcomere shortens (10%)
• myosin moves toward barbed ends

• spring-titin
• links the z line to the M line
• small forces straighten 
• larger forces unfold domains

• 3MDa huge
• 2 components
• repeated structural models

it amplifies length change

you get more force

calcium ions and troponin

• heterotrimeric protein complex
• TnI, TnC, TnT

troponin subunit that binds to inhibitor

troponin subunit that binds to calcium

troponin subunit that binds to tropomyosin

• tropomyosin blocks A-M binding (lays in groove of actin filament)
• Tnc not bound to calcium-TnI-TnT-tropomyosin - actin groove

Ca-TnC-TnI-TnT-tropomyosin moves to a different position that allows actin and myosin to interact

multiple calcium spikes

myosin heads dissociated several percentages

the smallest unit of muscle controlled by nerve impulse

• higher frequencies of twitches (200 twitches/sec)
• activate more muscle fibers

motor neuron-depolarized-nerve terminal synapse neuron vascular junction releases acetylcholine-depolarizes membrane of muscle fiber (sarcolema)

• on plasma membrane of muscle cell
• senses depolarization and transfers to Ryanadine receptor on membrane of sarcoplasmic reticulum and opens its calcium channel

pumped up

• deep invagination of sarcolemma
• helps depolarization signal to DHP reach RyR in ser

interaction of 1 T-tubule with 2 SeR domains

fast, large force

• less dense, less organized
• individual heart beats are controlled by pace maker neuron cells in the heart
• there are non-neuronal controls of the heart as well gradual control