skeletal muscles
large multinucleate and striated
cardiac msucle
branched uninucleate also striated joined by intercalated disks
smooth muscle
small no striation
how are skeletal muscles organized
in antagonistic pairs around joints
muscle fascicle
bundle of fibers
muscle fiber
muscle cell
sarcoplasmic reticulum
endoplasmic reticulum
sarcolemma
cell membrane
what are T tubules
special indentations in the sarcolemma (cell membrane)
what do T tubules do
carry action potentials inside
what does the sarcoplasmic reticulum contain
calcium to trigger contraction
what are thick filaments
they have myosin which contain a tail hinge and 2 globular heads
what are thin filaments
they contain actin, tropomyosin(blocks myosin), nebulin (anchoring unit) and troponin (place where Ca can bind)
Z disks mark what
the ends of a sarcomere
what does Titin do
anchors the thick filament to the Z disk acts like a rubber band
What are the signal trasmission events at the neuromuscular junction
1. the action potential of a neuron open Ca channels
2. Ca causes the release of acetylcholine
3. Acetylcholine binds to receptors on the muscle
4. This causes a cation cahnnel to open and Na enters the cell casuing a depolarization
5. this causes a grade
how is excitation-contraction coupling work
1. action potential in muscle travels down T tubules
2. This causes Ca channels to open in the sarcoplasmic reticulum and releases Ca
3. Ca binds to troponin
4 troponin moves the tropomyosin to move allowing myosin to bind to action
5 contraction
what would happens to a skin fiber with high Ca and high ATP
contraction
what would happens to a skin fiber with low Ca and High ATP
muslce can be stretched but no contraction
what would happens to a skin fiber with high calcium and no ATP
muscle is stiff, no contraction, and it cannot be stretched
what would happens to a skin fiber with low Ca and No ATP
muscle can be stretched but no contraction
what happens when myosin binds ATP
it releases from action
what happens when myosin hydrolyzes ATP
the energy from ATP cocks myosin head
what happens when myosin releases ADP and P
it contracts
How does muscle relaz again
Calcium ATPase pumps calcium from cytoplasm back into sarcoplasmic reticulum.
this causes tropomyosin to move back into position