Bio 152: Muscle Contractions
26 Cards in this Set
Front | Back |
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Sarcomere
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-makes miyofibrils look striped.
-shorten when muscle contracts
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myofibrils
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many small strands within a muscle cell
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Muscle contraction: Step 1
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Myosin head of thick filiment is attached to ATP but not to the Actin in thin filiment (muscle is relaxed)
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Muscle contraction step 2
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-ATP hydrolizes to ADP
- the head of the myosin pivots
-myosin head binds to new actin site further down the thin filiment
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Muscle contraction step 3
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Inorganic phosphate is released and the head pivots back pulling the actin (Power Stroke)
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Muscle contraction step 4
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after ADP is released, a new ATP can come and bind to the myosin and causes the myosin to release from Actin
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Rigor Mortis
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When your muscles run out of ATP, happens after death.
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Thin Filament
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Actin
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Thick Filiement
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Myosin
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Tropomyosin
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coils aroind actin blocking binding site
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Troponin
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calcium binding site on Tropomyosin and actin
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calcium release Step 1
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action potential arrives at end of motor neuron
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calcium release Step 2
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releases neurotransmitter (ACh) into synaptic cleft
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calcium release Step 3
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(ACh) binds to ACh receptors triggering depolarization of muscle cell
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calcium release Step 4
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Action potentials propogate down the length of the muscle cells and into the T-tubules (which intersect with the sarcoplasmic reticulum)
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calcium release Step 5
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Action potential reaches end of T-tubules and activate protein which opens up Caa+ channels in the Sarcoplasmic reticulum.
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G-protein complex
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muscle contracts whe G-protein is activated
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one activated Phospholipase ?
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opens many Ca++ channels
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Bag of Calcium
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Sarcoplasmic reticulum
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SR has what channels?
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-Ca++ pump into it
-IP3-gated Ca++ channels
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Where does IP3 come from?
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IP3 = inositol triphosphate
inositol = part of phospholipid molecule in membrane
phospholipase = enzyme
...converts phospholipid molecule to
IP3 (+ other stuff)
only works when activated
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if Phospholipase is activate the muscle does what?
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contracts
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Is the phospholipase activation an amplification?
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yes because it causes many Ca++ channels to open
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Signal Dampening?
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cGMP + phosphodiesterase --> GMP
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Signal amplification
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cGMP + guanylate cyclase --> cGMP
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What activates Phospholpiase?
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G-Protein
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