X. Muscle AnatomyChapters 9.1, 10.1 & 10.2A. Muscle Characteristics1. Compositiona. Muscle, epithelial, connective, and nervous tissues2. Propertiesa. Excitabilityb. Contractilityc. Extensibilityd. Elasticity3. Tissue Typesa. Skeletalb. Cardiacc. SmoothB. Skeletal Muscles1. Functionsa. Body Movementb. Facial communication & swallowingc. Volume control in the eard. Temperature Regulationi. Muscle contraction releases heate. Storage of materialsi. Sphincters retain and release materials2. Cellsa. Muscle Cellsi. Elongated cellsii. Called muscle fibersb. Satellite cellsi. Act in muscle repair3. Connective tissue coveringsa. Endomysiumi. Areolar tissueii. Around each cellb. Perimysiumi. Dense irregular tissueii. Around bundles of cells1) Bundle = fasciclec. Epimysiumi. Dense irregularii. Around muscled. Fasciai. Dense irregular tissueii. Over multiple muscles4. Attachmentsa. Connective tissue connectionsi. Tendonsii. Aponeurosesb. Muscles extend across jointsi. Origin = less movable attachmentii. Insertion = more movable 5. Movement a. Agonists (prime movers) – perform movementb. Antagonists – provide resistancec. Synergists – assist prime mover i. True synergists – Add tensionii. Fixators – hold joints steadyC. Microscopic Skeletal Muscle Structure 1. Organelles:a. Multinucleateb. Many mitochondriac. Some renamedi. Cell membrane = sarcolemmaii. Cytoplasm = sarcoplasmiii. Endoplasmic reticulum = sarcoplasmic reticulum 1) Stores calcium for contraction2. Specialized structuresa. Transverse tubulesi. deep tunnels of sarcolemma through cellb. Myoglobini. Oxygen transporting pigmentc. Myofibrilsi. thread-like organelles; contractileii. Made of protein strands called myofilaments1) Thin Filamentsa) Actin – long twisted chains of globular proteins2) Thick Filamentsa) Myosin – double-headed “golf club-like” protein laid end-to endD. Skeletal Muscle Cell Contraction1. All-or-Nothinga. Cells cannot contract partway2. Sliding Filament Theorya. Sarcomeres shorten, not filaments b. Actin and myosin myofilaments slide over each otherc. Overlap of thin & thick filaments