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35 Cards in this Set
- Front
- Back
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What are the three types of muscle tissue |
1. Cardiac muscle 2. Smooth muscle 3. Skeletal muscle |
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Cardiac muscle |
- striated -involuntary |
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Skeletal muscle |
- Striated -voluntary |
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Smooth muscle (blood vessels, stomach etc.) |
- non- striated - involuntary |
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Sarcolemma |
cell membrane
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Sarcoplasm
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cytoplasm
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terminal cisternae- lateral sacs
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end of segments expand to form saclike regions
- stores calcium |
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sarcomere
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-functional unit of skeletal muscle
-found between two z-lines - (connects thin filaments of two adjoining sarcomeres) |
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What does the ATPase site do?
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- splits ADP --> ADP + Pi
- Energy released is transferred to myosin head which causes the head to be "cocked" |
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What happens to create the "cocked" position
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ATP is split into ADP and Pi
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When ADP and Pi leave the myosin head, what event is occurring
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Change in myosin shape
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If myosin is attached to actin, what happens when a new, fresh ATP then binds to the ATPase site?
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Myosin head detaches from actin
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What are the steps involved in the sliding filament mechanism/ excitation contraction coupling?
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1. AP travels down the motor neuron to NMJ
2. AP travels down T-tubules 3. Ca++ released from SR 4. Ca++ binds with Troponin which causes Tropomyosin to move away 5. Actin Active sites exposed 6. Myosin cross-bridges bind with actin 7. ADP and Pi released from myosin to change myosin shape 8. Myosin head bends towards the center= power stroke 9. Actin slides over myosin 10. New ATP binds to myosin to detach it from actin 11. cycle is repeated |
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What are the steps of muscle relaxation
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1. motor neuron APs stop
2. AChE breaks down ACh at NMJ 3. Muscle fiber APs stops 4. Reuptake of Ca++ in SR 5. TT complex (troponin, tropomyosin) cover actin active sites |
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Length-tension relationship
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-Sarcomeres can generate the most tension when the overlap of filaments is optimal
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Motor unit
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Motor neuron and muscle fiber it onnervates
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Why can we control our finger movement very precisely to draw a picture
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because its a finely controlled movement- it contains fewer fibers per motor until
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If we tried to contract our leg and draw with our foot it wouldn't work well, why is that?
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because it is a coarsely controlled movement- it has larger numbers of fibers per motor unit
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Twitch |
-brief, weak contraction
- produced from SINGLE AP -too short and weak to be useful -Doesn't take place in the body |
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What is a twitch produced from
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A single action potential
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Does a twitch take place in the body
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No
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Twitch-summation
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- If muscle fiber is stimulated to twitch again before it has completely relaxed
- Sustained elevation of systolic calcium |
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What does sustained elevation of systolic calcium cause?
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twitch-summation
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Tetanus |
-Sustained contraction
- Occurs if muscle fiber is stimulated so rapidly that it does not have a chance to relax between stimuli -caused by greater cross bridge cycling |
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What does greater cross-bridge cycling do? |
causes tetanus |
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The first energy source you will tap into to provide the ATP needed to jump up right now would be? |
Phosphocreatine |
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We store ATP by donating that terminal phosphate to? |
creatine |
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Smooth muscle |
Found in walls of hollow organs and tubes |
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What role does calmodulin play in smooth muscle contraction |
Ca++ binds to calmodulin |
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what are the two types of smooth muscle |
Multi unit Single unit |
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Where would you find multi unit |
- large blood vessels - large airways to lungs |
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Where would you find single unit |
- visceral smooth muscle |
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Multi unit |
Must be stimulated by nerves |
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Single unit |
- exhibit pacemaker activity |
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Smooth muscle contraction |
1. AP causes VG Ca++ channels to open 2. Ca+ in cell interacts with calmodulin 3. Ca+ calmodulin complex activates enzymes 4. Causes myosin heads to be phosphorylated 5. Myosin interacts with actin 6. Contractions are slow and sustained |
