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Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding 1 Nervous System: Part V Interactions With The Muscular System Enduring Understanding 4.A.4.b Interactions among systems • Interactions and coordination between systems provide essential biological activities 2 The nervous and muscular system may not be specifically tested on the AP Biology Exam but have been chosen as the pair of systems that can clearly demonstrate functions of the nervous system which ARE on the Exam. See Learning Objectives 3.43 through 3.50 and 4.10. –Illustrative example: • Nervous and muscular 2 3 • The contraction of a muscle is a typical response generated by the nervous system. • Muscle contraction demonstrates the interdependence of the nervous and muscle systems. Today we will consider a very specific mechanism for a RESPONSE generated by the nervous system: Muscle contraction. We will learn how a muscle contracts when stimulated by a chemical signal. organ tissue 4 Describe the system to cell hierarchy. cell 5 Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding Arrange These In A Decreasing Hierarchy: 6 • • • • • • • Muscle Muscle fiber cell Actin Myofibril Muscle fibers in bundle Sarcomere Myosin Answers follow on next slide… CORRECTLY Arranged Into a Hierarchy: 7 8 9 • • • • • • • Muscle Muscle fibers in bundle Muscle fiber cell Myofibril Sarcomere Myosin Actin • What noticeable difference do you see in the relaxed and contracted sarcomere? What noticeable difference do you see in the relaxed and contracted sarcomere? (contracted is shorted) The components don’t change size. Just their position relative to each other changes. They stack up like a deck of cards. In the extended state, the thin and thick filaments are spread apart from each other. Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding In the contracted state the thin and thick filaments slide toward each other, stacking up and shortening the sarcomere. 10 11 12 Now lets examine contraction on a molecular level. To begin the animation, scroll across the bottom of the picture and press play. 13 13 14 The process of contraction requires the input of ATP to “reset” the myosin head of the thick filament. This is why muscles consume large amounts of energy. Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding 15 16 17 18 Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding 19 Ask them to think about what they would say if they were narrating this video clip. 20 Point out that the contraction requires the presence of calcium ions to expose the myosin binding sites. 21 22 23 • The arrival of the action potential causes the sarcoplasmic reticulum to release calcium All of this action is stimulated by the arrival of the action potential from the motor neuron! Take some time to tie together the nervous system’s role in stimulating the contraction. This image shows how you can have a graded response, contracting a muscle a little or a lot. The more motor units that receive the stimulus, the more contracted the muscle will become. Nervous System Part V: Interacionts with the Muscular System TEACHER NOTES needs coding Created by: 24 Debra Richards Coordinator of Secondary Science Programs Bryan ISD Bryan, TX