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56 Cards in this Set
- Front
- Back
Functions of Muscular System
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Movement: think of muscles as ropes, muscles can only contract, shorten in length, pull, muscles cannot push
Heat production Posture and body support |
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Types of Muscles
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Smooth: non striated, involuntary
Cardiac: striated, involuntary Skeletal: striated, voluntary |
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Basic Properties of Muscles
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Irritability: response to stimulus
Contractality: active Extensibility: passive Elasticity: muscles return to original length |
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Skeletal Muscle Attachment: Origin
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doesn't move, muscle attachment more proximal
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Skeletal Muscle Attachment: Insertion
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attachment that is more distal, mobile
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Belly
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Body, main region that shortens and thickens when muscle contracts
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Fascicle
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Bundle of muscle cells, makes up muscle
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Epimysium
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dense irregular, surrounds skeletal muscle
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Peromysium
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surrounding fascicle
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Muscle Cell
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Muscle fiber, has a lot of nuclei that is pushed to outside
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Endomysium
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Membrane that surrounds the cell
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Sarcolemma
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Cell membrane of muscle cell
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Sarcoplasm
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cytoplasm of muscle cell
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Satellite Cells
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repair muscle cells after being damaged
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Myofibril
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made of myofilament (Thick-myosin, thin-actin)
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Sarcoplasmic Reticulum
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smooth endoplasmic reticulum in a muscle fiber, stores calcium ions needed for muscle contraction
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Terminal Cisternae
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expanded ends of the sarcoplasmic reticulum that are in contact with the transverse tubules, site of calcium ion release to promote muscle contraction
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Thick Filament
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Fine protein myofilament composed of bundles of myosin, bin to actin and and cause contraction
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Thin Filament
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Fine protein myofilament composed of actin, proponin and tropomyosin
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Actin
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double stranded contractile protein, bind to myosin to cause contraction
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Tropomyosin
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double stranded regulatory protein, covers the active sites on actin, preventing myosin from binding to actin
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Troponin
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Regulatory protein that holds tropomyosin in place and anchors to actin, when calcium ions bind to one of its subunits, this moves the tropomyosin off the actin active site and initiates muscle contraction
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Titin
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Filaments of an elastic protein, help return myofilaments to resting position after contraction, maintain positions of myofilaments in sarcomere
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A band
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dark band, over lap and repetition of thick and thin, gets bigger when contracts
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M Line
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middle of the thick filaments
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Z Disc
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Boundary of sarcomeres, connect the thin filaments to each other
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H Zone
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Area in the A band that doesn't have actin filaments
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Myofibril
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cylindrical structures that are responsible for contraction
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I Band
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light band, no over lap of thin and thick, gets smaller in contraction
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Sarcomere
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functional unit, areas in between z discs, where microfilament are organized
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Synaptic Knob
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end of axon terminal, rough ER (form vesicles, make protein)
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Motor Unit
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axon terminals of motor neurons and muscle fibers
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Synaptic Cleft
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Separates muscle and neuron
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Order of Events in Muscle Contraction
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1)Nerve impulse triggers release of ACh at neuromuscular junction, ACh binds to motor end plate receptor initiating a muscle impulse in the muscle fiber
2)The muscle impulses spreads quickly along to tubules causin release of calcium ions from terminal cisternae into the sarcoplasm |
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Muscle contraction
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1)Atp binds to myosin head, myosin releases actin
2) ATP turns into ADP and phosphate group, releases energy, cocks the myosin protein to high energy shape 3) Phosphate group released myosin, pushes actin filament, power stroke 4)ADP released |
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Muscle twitch
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Full stiumulation-contraction-relaxation cycle
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What does the amount of tension a muscle fiber produces during a twitch depend on?
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How many crossbridge attachments it forms
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What does number of crossbridge formation depend on?
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quantity of myofibrils per muscle fiber, number of byofilament per myofibril, length of muscle fibers when contraction begins, rate or frequency fiber is stimulated
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Latent Period
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begins at stimulation, lasts around 2 miliseconds, action potential floods over the carcolemma, causing calcium to release from sarcoplasmic reticulum , no tension
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Contraction Phase
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lasts around 100 miliseconds, crossbridge formation causes tension to increase to a maximum
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Relaxation Phase
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tension decreases as crossbridges detach, titin fibers in sarcomeres cause muscle fibers to return to resting length
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Summation
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muscle fiber doesn't have time to relax completely before another action potential causes it to contract again
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incomplete tetanus
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muscle fiber reaches maximum contraction, less time is allowed for relaxation (and rest) before a new action potential arrives
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complete tetanus
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muscle fiber doesn't have time to relax between action potentials, maximum tension maintained
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What does the amount of tension produced by skeletal muscle as a whole depend on?
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how frequently the muscle is stimulated (summation and tetanus)
How many muscle fibers are stimulated |
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Recruitment
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force generated by a muscle can be increased by recruiting more motor units
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Asynchronous recruitment
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partial avoids fatigue in submaximal contractions by alternating the action of the muscle's motor units, alternates muscles being used
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Muscle fatigue
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motor units fail one by one, force of muscle contraction gradually decreases
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Muscle tone
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resting tensions, more frequently and more intensely muscles are used, high tone
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Atrophy
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muscles that are not regularly stimulated, muscle fibers become weaker and smaller, inactivity continues, muscle fibers die
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What is ATP used for?
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cross bridge action
Calcium Pump Sodium/Potassium pump |
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At Rest
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ATP Generation greater than ATP consumption
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During excercise
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ATP Gen=ATP consumption
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Creatine phosphate
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more stable than ATP, used to phosphorylate ADP to ATP during contraction
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Aerobic Cellular Respiration
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Glucose + Oxygen yields Carbon dioxide + Water + 32 ATP
able to crank out more ATP than resting cell |
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Anaerobic Respiration
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Glucose yields 2 pyruvate (which yields 2 ATP)
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