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what 3 structures directly control the muscle contraction?
what is HUxley's sliding filament theory based on?
Huxleys sliding filament theory) how do muscles contract?
contraction is based on shortening of sarcomeres throughout the muscle
Huxleys sliding filament theory) what do thick and thin filaments do?
overlap and slide past one another
**greater overlap= shorter muscle
contractile elements) what is thick filament made up off?
contractile elements) thick filament- what are the 2 heads of this filament used for?
-ATP bindig site
-actin binding site
contraction cycle) relaxed muscle- are the filaments overlapping?
contraction cycle) relaxed muscle- are there any action potential from the nerve going on?
contraction cycle) relaxed muscle- When at this stage, are the myosin bidning sites on actin exposed or covered?
covered by troponin
contraction cycle) where is the calcium stored?
within the terminal cisternae of the sarcoplasmic reticulum
what are myofibrils made up off?
- *thick and thin
contraction cycle) AP along the nerve- what does this cause calcium to do?
causes calcium to enter cytoplasm and surround the myofibrils
contraction cycle) AP along the nerve- with what structure does the calcium bind with?
contraction cycle) Ap along the nerve- when calcium binds with troponin, what happens?
it causes troponin to change shape which will make tropomyosin expose the myosin binding sites
contraction cycle) what is cross bridge attachment?
- myosin binds to actin
- *the thick and thin filament are interacting
contraction cycle) what happens in power stroke pahse?
flexion of myosin head and tail that causes to pull thin filament along
contraction cycle) what results from a power stroke?/
in sarcomere shortening
contraction cycle) why does cross bridge detachment occurs?
so that the myosin head cna bind to a different location to do another power stroke and keep pushing the thin filament along
contraction cycle) what causes the release of myosin head from the actin?
ATP attaching to the myosin head
contraction cycle) how is the myosin head activated?
it cleaves ATP to create ADP and Pi
contraction cycle) what cleaves the ATP into 2 molecules on the myosin head?
How does the ATP activate the myosin head?
it gets actviated by the energy that is given off when hydrolyzing the ATP to ADP and inorganic Pi
(regulation of contraction) 3 things seen in nerve side on alpha motor neuron
-calcium channels in nerve membrane
(regulation of contraction) muscle side- what is motor end plate?
muscular side of nueromuscular junction
(regulation of contraction) msucle side- whatare junctional folds?
folds in sarcoplasmic reticulum that increase the surface area
(regulation of contraction) muscle side- what type of receptors do they contain?
what is synpatic cleft?
space between nerve and muscle
(regulation of contraction) what does the action potential cuase the voltage channel o calcium to do?
open and allows calcim to enter terminal bouton
(regulation of contraction) what 3 things happen when calcium rushes in through the voltage gated channels?
(regulation of contraction) in a relaxed state, where is calcium concentrated higher on inside or outside?
- *calium goes in when AP occurs
(regulation of contraction) what does acetylcholine do when it crosses the synapse?
binds to receptors on motor end plate
(regulation of contraction) what does acetylcholine binding with receptors on motor end plate d0?
sarcolemma graded potential that is followed by AP
(regulation of contraction) what hydrolyzes the acetylcholine after an AP?
(regulation of contraction) why does acetylcholine get hydrolyzed?
we want to remove actylcholine after it has been there for ashort while or otherwise we would have APs that keep happening without needing them
what are the 10 events of excitation-contraction coupling?
-A-motor neuron AP >
-terminal bouton CA entry >
-synaptic vesicle fusion >
-Acetylcholine (Ach) release >
-Ach binding/ sarcolemmal GP >
-Sarcolemmal AP >
-T-tubule AP >
-terminal cisternea calcium release >
-calcium binds with troponin >
-cross bridge formation and contraction
what brings the AP to the area of myofibrils?
what causes the terminal cisternae to relaese calcium?
T-Tubules arriving wth AP in the area of triad bc there are voltage gated channels in the terminal cisternae
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