Figure 10.6 Levels of Functional Organization in Skeletal Muscle Fiber

Figure 10.7 Thick and Thin Filaments

Sliding filament theory Sliding filaments- 30% decrease in fiber length Explains the relationship between thick and thin filaments as contraction proceeds Cyclic process beginning with calcium release from SR Calcium binds to troponin Trponin moves, moving tropomyosin and exposing actin active site Myosin head forms cross bridge and bends toward H zone ATP allows release of cross bridge

Figure 10.8 Changes in the appearance of a Sarcomere during the Contraction of a Skeletal Muscle Fiber Figure 10.8

Tension Created when muscles contract Series of steps that begin with excitation at the neuromuscular junction Calcium release Thick/thin filament interaction Muscle fiber contraction Tension

Figure 10.9 An Overview of the Process of Skeletal Muscle

Control of skeletal muscle activity occurs at the neuromuscular junction Action potential arrives at synaptic terminal ACh released into synaptic cleft ACh binds to receptors on post-synaptic neuron Action potential in sarcolemma

Figure 10.10 Skeletal Muscle Innervation Figure 10.10a, b

Figure 10.10 Skeletal Muscle Innervation PLAY Animation: Neuromuscular junction Figure 10.10c

Excitation/contraction coupling Action potential along T-tubule causes release of calcium from cisternae of SR Initiates contraction cycle Attachment Pivot Detachment Return

Figure 10.12 The Contraction Cycle

Figure 10.12 The Contraction Cycle