EXSS 276 1st Edition Lecture 18 Outline of Last Lecture I. Integration of Sensory and Motor InfoII. Summary of Integration CentersIII. Conscious Control of MovementIV. Learning and MemoryOutline of Current LectureI. Types of Muscle TissueII. Functions of Muscle TissueIII. PropertiesIV. Skeletal MuscleCurrent LectureI. Types of Muscle Tissuea. Skeletali. Primarily attached to bonesii. Striatediii. Voluntaryiv. Multinucleatedb. Cardiaci. Forms wall of the heartii. Striatediii. Involuntaryiv. Uninucleated c. Smoother (visceral)i. Located in visceraii. Non-striated (smooth)iii. Involuntary II. Functions of Muscle Tissuea. Produce body movementsb. Stabilize body positionsc. Regulate organ volumesi. Bands of smooth muscle called sphinctersd. Movement of substances w/in the bodyi. Blood, lymph, urine, air, food and fluids, sperme. Produce heatThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Involuntary contractions of skeletal muscle (shivering)III. Propertiesa. Excitability: ability to respond to stimuli and produce electrical signalsi. Auto-rhythmic electrical signalsii. Chemical stimuli: hormonal responses, neurotransmittersb. Contractility: ability to shorten and generate force once excitedc. Extensibility: ability to stretch without damaging tissuei. Smooth and cardiac muscle mostlyd. Elasticity: ability to return to normal length after being extendede. Thermal: ability to produce heat energyIV. Skeletal Musclea. Characteristicsi. Attaches to bone, skin, or fasciaii. Striated w/ light and dark bands1. Dark band due to A band: actin and myosin (thick and thin overlapcreates band) 2. Light pink: I band, actin aloneiii. Voluntary control of contraction and relaxationiv. Multinucleated b. Tissuei. Each skeletal muscle is separate organ composed of many cells called fibers; i.e. bicep = one organii. Muscle fibers = muscle cellsc. Part of Skeletal Musclei. Connective tissue1. Epimysium: surrounds whole muscle2. Perimysium: surrounds bundles (fascicles) of 10-100 muscle cells3. Endomysium: separates individual muscle cells4. *All connective tissue layers extend beyond muscle belly for form the tendond. Muscle Composition and Structurei. Skeletal muscle bundle => fascicles => muscle fibers => myofibrils => sarcomeres => filamentsii.iii. Sarcolemma: muscle cell membrane1. Nuclei are just below iv. Transverse tubules (T tubules)1. Tiny invaginations of sarcolemma2. Filled w/ ECF and quickly spread muscle action potential to all parts of the fiberv. Sarcoplasm1. Muscle cell cytoplasm2. Contains lots of glycogen for energy production and myoglobin foroxygen storagevi. Sarcoplasmic Reticulum (SR)1. System of tubular sacs similar to smooth ER in non-muscle cells2. Stores calcium in relaxed muscle3. Release of calcium triggers muscle contractionvii. Details of Filaments and Z discs1. Thick and thin filaments overlap at bond of overlap: A banda. Peripheral ends of A band2. I band: just actin (troponin, tropomyosin)3. H zone: middle of A band, only thick filament4. M line: cutting middle of H zone, midlinea. Supporting proteins holding thick filaments togetherviii. Muscle Proteins1. Myofibrils have 3 kinds of proteina. Contractile proteinsi. Myosin and actinii. Thick filaments: myosin1. Each molecule resembles two golf clubs twisted together (myosin head)2. Heads (cross bridges) extend toward thin filaments3. Tail-held in place by M line proteinsiii. Thin filaments: actin, troponin, tropomyosin1. Myosin-binding site2. Covered by tropomyosin in relaxed muscle3. Thin filaments held in place by Z lines4. Troponin holds/moves tropomyosinb. Regulatory proteins (turn contraction on/off)i. Troponin and tropomyosinc. Structural proteinsi. Provide proper alignment, elasticity and extensibility, link myofibrils to sarcolemma and extracellular matrixii. Titin, myomesin, nebulin, dystrophin (don’t need