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PHYS2
Muscle I
| Question | Answer |
|---|---|
| What is smooth muscle? | Surrounds hollow cavities and tubes |
| Which is responsible for bronchodialition and contstriction/ | Smooth |
| What links bones to muscles? | Tendons |
| What is a straition? | A banding pattern when viewed in microscope |
| What causes it? | thich and thin filaments that are organized into bundles |
| What are those bundles called? | myofibrils |
| What is a sarcomere? | One unit of repeat in a myofibril |
| What composes thich filments? | myosin |
| Thin filaments? | Actin and troponin and tropomyosin |
| What is the A band? Its shade? | Thich filaments located in middle of each sarcomere; it is dark |
| What filaments composes a sarcomere? | Two thin filaments |
| How are they anchored? | One end overlaps thick filament, the other hangs on the z-line |
| What is the Z-line? | Defines a sarcomere; from one z-line to another = 1 sarcomere |
| What are cross bridges? | Portions of myosin that extend from thick toward thin filaments |
| What happens when a force produces shortening of skeletal muscle fiber? | Cross bridgles push/pull thin filaments towards center WITH NO SHORTENING OF THE THICK OR THIN FILAMENTS |
| How many cross bridges does it take to move a thin filament? | Many; remember, you're in a 3D world |
| What are the two contractile proteins on which the muscle depends on to generate force and movement? | Actin and mysoin |
| Which is the thick filament? | myosin |
| Which is the thin? | Actin |
| What does the globular head of myosin contain? | A binding site for actin and an site to split ATP |
| What kind of protein is actin? | A globular protein |
| What prevents the cross-bridge from interacting with actin molecule when muscle is relaxing? | Treptomyosin |
| What are the four steps of cross-bridge cycling? | Attach cross-bridge to thin filament, move cross bridge to make thin filament move, detach cross-bridge from thin filament in relaxation, get cross bridge in position to do it again |
| SLIDING FILAMENT MODEL | SEE FIG. 9-8 |
| First step: | 1. Increase calcium in cell |
| Why? | B/c calcium binds to troponin to cause it to change shape to expose actin |
| Second: | Use ATP to make cross bridge to change shape to pull on actin |
| What does this lead to? | -->contraction of sarcomere |
| When would rigor mortis arise? | In the absence of ATP |
| Why? | We can't release actin-->no movement |
| Where does hydrolysis of ATP occur? | In resting muscle cell |
| How would ATP set up muscle reaction to happen again? | It binds to myosin to dissociated cross bridges bound to actin |
| MEAT AND POTATOES | MEAT AND POTATOES |
| Why don't we have excitation all the time in muscles? | B/c in a resting muscle, tropomyosin is bound to actin, so cross bridges can't bind to actin filaments |
| So what do we do to get movement? | We increase calcium ions in body |
| What do the increase in calcium ions lead to? | They bind to troponin on thin filaments and make troponin change shape |
| What does this change in shape of troponin lead to? | Moves tropomyosin, which exposes the actin |
| How do we get to an increase in calcium, then? | AP makes SR, which stores calcium, to release some |
| What does the SR wrap around? | T-tubules |
| So, we're done with the excitation, how do we get the muscle to relax? | Using ATP, we get calcium in SR via ATPase pump |
| NEUROMUSCULAR JUNCTION | JUNCTION |
| What are motor neurons? | Myelinated nerve cells that go to skeletal muscles |
| How many motor neurons does a neuron innevervate? | Several at a single specific stie |
| What composes a motor unit? | neuron with fiber it innervates |
| What is the motor end plate? | region of muscle that is below axon terminal |
| What neurotransmitter is released at neuromuscular junction? | ACh |
| Where does it bind? | motor end plate |
| What does it lead to? | opening of ion channels to let in Na and K |
| What does this lead to? | depolarization of the ned plate membrane |
| MEAT AND POTATOES | MEAT AND POTATOES |
| What do we need to stop action of cell/ | ATP to get calcium back into sarcolemma and ACh breakdown |
| INHIBITION OF NEUROMUSCULAR JUNCTION TRANSMISSION | PROBLEMS |
| Curare causes what? | binds to Ach receptors, but doesn't activate them, so Ach not degraded-->paralysis |
| Pesticides and nerve gas? | Ach not degraded, muscle stayes depolarized--> paralysis |
| What does botox do? | Blocks release of Ach |
Created by:
talkglitter2486