BIPN%20100%20Sheet%207%20Student%20Version0 - Patricia Pepa...

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Patricia Pepa OH: 11-11:50 Café Roma Handout 7: Skeletal Muscles and Cardiac I. Skeletal Muscles a. A skeletal muscle is a collection of muscle fibers. b. Attached to bones via tendons or connective tissue c. Muscle Terminology 1. Muscle cell=muscle fiber 2. Cell membrane=sarcolemma 3. Cytoplasm=sarcoplasm 4. Endoplasmic reticulum=sarcoplasmic reticulum d. T-Tubules-Invaginations in muscle’s plasma membranes that allow depolarization to penetrate interior of cell e. striated muscle (alternating dark and light bands) f. ___________ (voluntary/involuntary) and is controlled by the motor cortex via the motor neurons in the spinal cord. Also controlled by reflex. II. Skeletal Muscle CONTRACTION a. Myofibrils -bunch of proteins to carry out contraction 1. Myosin (Thick filaments) and Actin (Thin filaments) 2. Sliding Filament Theory of Contraction 1. Myosin and actin stay at a FIXED length and slide past one another, moving the Z disks closer together. 2. ________________ shortens , NOT FILAMENTS. b. The Molecular Basis of Contraction (fig 12-9) 1. Tight binding in rigor state 2. ________ binds to myosin, causing myosin to COME OFF actin. 3. ATPase activity of myosin hydrolyzes ATP ADP and Pi. 1. Now ADP and Pi are bound to myosin ii. Myosin head swings over and binds WEAKLY to NEW actin molecule. iii. Release of Pi causes the POWER STROKE 1. POWER STROKE-myosin pushes actin filaments toward center of sarcomere iv. Myosin head releases ADP and resumes at tightly bound rigor state again.
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Patricia Pepa OH: 11-11:50 Café Roma 4. If it takes 10 of these cycles to complete a contraction, how much ATP is used? c. If ATP is always available, what keeps the filaments from continuously interacting? d. What happens at the neuromuscular junction to cause contraction ? 1. _________________ is released from somatic motor neuron 2. Ach channels open, which allow Na+ and K+ to cross the membrane. Na+ net flux. 3. Action potential travels down muscle fiber and into T-tubules 4. T-tubules contain ______ RECEPTORS that are MECHANICALLY LINKED to ______________ RECEPTORS in the SARCOPLASMIC RETICULUM. Ca++ is then released 5. Ca++ initiated contraction.
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BIPN%20100%20Sheet%207%20Student%20Version0 - Patricia Pepa...

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