Anatomy Lecture Exam Review

Anatomy Lecture Exam Review - Skeletal Muscles 1. Composed...

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Skeletal Muscles 1. Composed of Fasicles 2. Each fascicle is made up of muscle fibers 3. Each skeletal muscle is an organ 4. Attachments- Dense Regular CT: 2 forms a. Tendon = cord-like b. Aponeuroses = flat, sheet-like 5. Connective Tissue Wrappings a. Entire muscle is covered with Epimysium b. Each fascicle is covered with Perimysium c. Each muscle cell/fiber is covered with Endomysium Microscopic Anatomy of Skeletal Muscle 1. Each fiber cell is composed of myofibrils. 2. Each myofibril contains myofilaments a. Two kinds i. Thick Myofilaments = myosin protein ii. Thin Myofilaments = actin protein 3. Have organelle like structures- lysosome, nucleus, golgi bodies etc. a. Smooth E.R.= stores Ca++ ions and releases them during muscle contraction 4. Muscle Cell Membrane= Sarcolemma 5. Muscle Cytoplasm = Sarcoplasm 6. Transverse Tubules = a. Passageway for nutrients b. Exits for waste c. Allow nerve impulse to travel rapidly from sarcolemma to inner part of muscle cell 7. Banding Pattern (Striations)
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a. Light Bands = I-bands i. THIN MYOFILAMENTS ONLY b. Dark Bands = A-bands i. Thick and thin myofilaments c. Z-line (Z-disc) i. Darker portion in the middle of I-bands d. H-Zone i. Lighter portion in the middle of A-bands ii. ONLY THICK MYOFILAMENTS e. Sarcomere i. Runs from Z-line to Z-line (functional contractile unit) Contraction of Skeletal Muscle 1. Nerve impulse sent from brain/spinal cord to muscle via the axon of a motor neuron 2. The axon meets the muscle fiber/cell at the neuromuscular junction 3. The axon releases a neurotransmitter called acetylcholine which binds to the sarcolemma 4. A nerve impulse is generated in the sarcolemma and it passes down the T-tubules. As a results the sarcoplasmic reticulum releases Ca++ ions. 5. The Ca++ ions bind to the thin myofilaments which allows the thick myofilaments thin myofilaments. 6. Myofilaments slide over one another; sarcomere shortens; muscle contracts 7. When the nerve impulse stops, Ca++ ions return to the sarcoplasmic reticulum and the myofilaments slide back to their resting state. Muscles of Facial Expression
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Anatomy Lecture Exam Review - Skeletal Muscles 1. Composed...

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