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Topic 9 Muscular System
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9.1
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Functions: Movement Posture Supports/shields Guards Maintains body temp Provide nutrients
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At ends of muscles… Tendons Aponeurosis
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Fascia… Epimysium Perimysium Endomysium Entire Fascicles
Houses each fiber Myosatellites 9.2(1,2,3)
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9.2(4,5,6)
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9.3(1-3)
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Myofibril 100-1000s Myofilament Thick & thin Sarcomere
Functional unit of contractile proteins.
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Sarcoplasmic Reticulum Ca-ion pumps Gated channels
T tubules: Sarcolemma Channel Sarcoplasmic Reticulum Ca-ion pumps Gated channels 9.3(4,5)
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Filamentous actin Globular actin Nebulin Tropomyosin Troponin
Structure of thin filaments Filamentous actin 2 twisted rows… Globular actin Has active sites Nebulin Tropomyosin Covers the active site Troponin Binds to… Receptors for… 9.4.1
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300 molecules of tails & heads Titin Core Prevents overstretching
Structure of thick filaments Myosin 300 molecules of tails & heads Titin Core Prevents overstretching 9.4.2
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Cross-bridges
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9.4.3
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Neuromuscular Junction: Voluntary motor neuron Synaptic terminal
Action potential Synaptic terminal 9.6.1
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Synaptic cleft Motor end plate Special membrane Junctional folds
Many nucleic,mito, & receptors
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Motor Units
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Neurotransmitters Chemical compounds In vesicles
When released, stimulate contractions Acetylcholine
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Stimulus for contraction
2 9.6(1-8)
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Contraction 9.7(1-6)
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Relaxation ACh is … Gated channels… Ca-ion pumps… Troponin…
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ATP Must regenerate ATP Glycogenglucose Creatine phosphate
Energy sources for contraction ATP Must regenerate ATP Glycogenglucose Creatine phosphate 6x more abundant
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Oxygen supply: Enough O2 at rest Strenuous activity… RBC & Hemoglobin…
anaerobic respiration RBC & Hemoglobin… Myoglobin… Reddish-brown pigment Temporary storage Better attraction
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Oxygen debt: O2 needed to restore… Muscle fatigue: Fuel depletion K+ accumulation Lactic acid Fibers don’t respond to stimuli Cramps…
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Threshold stimulus… All-or-none response Tension Frequency of stim
Requires certain strength of stimulation All-or-none response Tension Frequency of stim # of fibers stim 9.9.3
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9.10.1
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9.10.2
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9.10.3
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9.10.4
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Inc. # of fibers involved
Muscle tone: When at rest… Partially contracted For posture Recruitment: Inc. # of fibers involved 9.10.5
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Fast vs slow twitch Tension time: Content: Color: Supply:
Types of muscle fibers Fast vs slow twitch Tension time: Content: Color: Supply: Rapid yet wears out -Abundant Mb & mito red high Slower yet prolonged Low Mb & mito white low 9.14(1,2)
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Types of contractions
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Muscles to Know
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10.4.1
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10.4.2
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10.6.1
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10.6.2
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10.16(1,2)
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