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Christina Nappi,, Valentina Clinton Rachel Phillips Ainslie Lee, Dominique Simpson Period 4,

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Presentation on theme: "Christina Nappi,, Valentina Clinton Rachel Phillips Ainslie Lee, Dominique Simpson Period 4,"— Presentation transcript:

1 Christina Nappi,, Valentina Clinton Rachel Phillips Ainslie Lee, Dominique Simpson Period 4,

2 Muscle contraction  Muscle contractions function due to the Sliding Filament Theory, which allows myosin heads to attach to binding sites and create sliding motions.

3 Diagram of Filaments See page 192 Figure 6.7 (a)- (b)

4 Step 1  After an impulse creates an action potential across the sarcolemma, calcium ions are released from storage areas.  Shown of page 193 figure 6.8 (a)

5 Step 2  This release of calcium triggers the cell to contract.  As calcium binds to protein receptors on actin filaments. This exposes myosin binding sites on the actin after their shape/position has been changed on the filaments.  The myosin heads can attach to those binding sites so the heads start to search for a place to bind.  As shown on page 193, figure 6.8 (b)

6 Step 3  The myosin heads are “cocked”, and the myosin attaching to actin causes the heads to pivot to the center of the sarcomere.  The actin and myosin are still connected at this point, so the thin filaments are also pulled to the center of the sarcomere.

7 Step 3  The energy needed to release the myosin heads so they can continue to attach to binding sites on the filament later on comes from ATP.  After action potential ends and calcium ions are reabsorbed, the receptor proteins go back to their original shape. They block myosin from attaching, so the cell relaxes and contraction ends.  As shown on page 193, figure 6.8 (c)

8 The End


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