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A&P Chapter 9
Muscle
| Question | Answer |
|---|---|
| Muscle is... | an organ, covered by fascia and epimysium |
| Fascicle is... | a tissue covered by perimysium |
| Motor unit | one nerve cell + attached muscle cells, contractions are "all or none" as a unit when stimulated |
| Fiber is... | 1 muscle cell, up to 1 ft long, multinucleate, and covered by endomysium |
| Myofibril is... | 1 contracting organelle, full length of cell, covered by sarcoplasmic reticulum |
| what is a contracting section of a myofibril, attached end-to-end by z-discs | a Sarcomere |
| what is a "thin" filament at each end (think AMY) | Actin filament |
| what is a "thick" filament in the middle (think KARKOW) | Myosin |
| Actin filament is an assembly of what three proteins? | 1. Actin protein: has attachment sites for myosin 2. Tropomysin: forms long strands to cover actin sites 3. Troponin: binds Ca to move tropomyosin and expose attachment sites on actin |
| Myosin filament is an assembly of what? | Myosin proteins. Myosin proteins have a head capable of forming cross-bridges t othe actin sites |
| When can cross bridges form? | only when Ca is present and the actin sites are exposed. |
| What does the Sliding Filament Theory say? | That actin filaments are grabbed by myosin heads and slide toward each other - to contract you need to "get your actin together" -Each sarcomere pulls on its neighbor like tug-o-war - This makes the whole myofibril shorten and the cell contracts. |
| How do the striations correspond? | A Band= dark striation: myosin filament length I Band= light striation: 2 ends of "bare" actin H Band= light mid-band" middle of "bare" myosin |
| Depolarization causes what in the muscle twitch sequence? | Ca Entry |
| What is myofilament? | A thread of bundled proteins (actin and myosin) |
| Skeletal movement is done by... | pulling only |
| posture is maintained by... | by maintaining tone-partial contraction |
| what do sphincters control? | "openings" such as your rectum |
| how is heat generated? | by shivering |
| A muscle twitch involves what? | one motor units, and begins with an axon of a neuron caring an action potential (AP) |
| In the muscle twitch sequence what does the AP (action potential) cause? | The AP causes axon terminal depolarization |
| ACh (acetylcholine) vesicles undergo what? | Exocytosis |
| where is there ACh (acetylcholine) diffusion at? | Across the synaptic cleft |
| what causes the Na entry in the muscle twitch sequence? |
Created by:
mheidenreich
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