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Lecture 5

Lecture 5-Muscle.docx

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Biological Sciences
Stefan Rusyniak

Lecture 5Muscle TerminologyHierarchyMuscles are a different type of tissue 3 different types of muscle tissue discussedLowest form of organizationmyofilaments actin and myosin filaments are 2 main proteins and organized together to form large bundlesmyofibrilsSkeletal muscle cells as muscle fibres if he talks about muscle fibretalking about whole cellMature muscle cell is myoblast skeletal muscle myoblast fuse together to produce myocyteSarcosomething to do with muscleSarcosomemuscle cell but confusing cause use this to refer to mitochondria in muscle cell wont use this term frequentlySarcoplasmic Reticulumused to store calcium ions in muscle fibreComposition of MusclesFibroblasts because muscle tissues closely associated with connective tissueMyoblastsimmature muscle fibres actively producing actin and myosin filaments required by these cells pale nucleus with genes activated when we produce protein that is in the cytoplasm NOT FOR EXPORTdue to RER it is basophilic due to ribosomesPurkinje Fibrespecialized kind of cardiac fibre NEVER REFER TO IT AS A PURKINJE CELLCollage type Ibecause muscle tends to associated with connective tissueElastic fibres some muscle cells can produce these components themselves blood vessels arteries spleen in some cases these components s produced by fibroblasts associated with the tissue themselvesNeed to attach muscle fibre to connective tissue because ligaments connect bone to bone and need to be elastic because need to stretchalong the back has a lot of ligaments that stretch not bone muscle to bonetendons not elastic because when you stretch you stretch the muscles because muscles are elastic enough in this case muscles pull against tendonProperties of MuscleAbility to recoil contractilityExcitability able to sense an input and start a depolarizationimportant because if you look at long muscle fibres such as in biceps Only have to stimulate one part of the muscle for the whole thing to start contracting dont have to stimulate the whole area spread throughout the whole muscle fibre some muscle fibres are connected to each other by gap junctions therefore excitation can spread to neighbouring musclesThe SarcomereBasic unit of contractilityHow myofilaments are arranged filamentsdense regionmore proteins less electrons passing throughMany sarcomeres stacked on top of one anotherActin filamentsthin filaments thin strand of protein interacting with troponin and tropomysin which covers up binding sites of the surface of moleculeallows myosin heads to interact and bind to them and pull against the actinEnd of z line is another sarcomereLight band with z line in middleI band
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