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47 Cards in this Set
- Front
- Back
Types of muscular tissue:
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-Skeletal
-Cardiac -Smooth |
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Most skeletal muscles move___________.
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Bones
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Alternating light & dark bands, as seen when examined w/a microscope
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Striated
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Skeletal muscle tissue works mainly in a ________ manner.
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voluntary
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most skeletal muscles also are controlled____________ to some extent
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subconsciously
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without conscious control
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subsconsciously
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found only in the walls of the heart
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cardiac muscle tissue
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striated like skeletal muscle
action is involuntary (contraction &relaxation of the heart) |
cardiac muscle tissue
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-located in the walls of hollow internal structures (blood vessels, airways, & many organs)
-lacks the striations of skeletal & cardiac muscle tissue -usually involuntary |
smooth muscle tissue
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What are the functions of muscular tissue?
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-Producing body movements
-stabilizing body positions -moving substances w/in the body -generating heat |
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Properties that enable muscle to function and contribute to homeostasis: Properties of Muscular Tissue
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-Electrical Excitability(ability to respond to stimuli)
-Contractility(Ability to contract forcefully when stimulated) -Extensibility(ability to stretch w/out being damaged0 -Elasticity)ability to return to an original length |
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connective tissue components
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-fascia
-epimysium -perimysium -endomysium -tendon -aponeurosis |
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Dense sheet or broad band of irregular connective tissue that surrounds muscles.
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fascia
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the outermost layer of muscle tissue
that separates 10-100 muscle fibers into bundles called fascicies |
epimysium
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surrounds numerous bundles of fascicies
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perimysium
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separates individual muscle fibers from one another
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endomysium
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cord that attaches a muscle to a bone
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tendon
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broad, flattened tendon
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aponeurosis
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the plasma membrane of a muscle cell
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sarcolemma
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-connect the plasma membrane to the interior of the cell
-muscle action potentials travel through them -ensures that action potential excites all parts of the muscle fiber at the same time |
transverse (T) tubules
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The cytoplasm of a muscle fiber
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Sarcoplasm
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-includes glycogen used for synthesis of ATP and a red-colored proten called myoglobin, which binds oxygen molecules
-myoglobin releases oxygen when it is needed for ATP production |
Sarcoplasm
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Neurons that stimulate skeletal muscle to contract are_______________.
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Somatic motor neurons
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An enlargement of existing muscle fibers
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Hypertrophy
(how muscle growth occurs) |
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testosterone and human growth hormone
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stimulates hypertrophy
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These retain the capacity to regenerate damaged muscle fibers
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Satellite cells
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Thread-like structures which have a contractile function
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Myobibrils
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-Membranous sacs which encircles each myofibril
-stores calcium ions -release of calcium ions triggers muscle contraction |
Sarcoplasmic reticulum (SR)
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Function in the contractile process
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Filaments
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basic functional unit of a myofibril
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Sarcomeres (compartments of arranged filaments)
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Z discs
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-Separate one sarcomere from the next
-thick and thin filaments overlap one another |
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A Band
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-darker middle part of the sarcomere
-thick and thin filaments overlap |
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I Band
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-lighter, contains thin filaments (no thick filaments)
-Z discs pass through the center of each |
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H Zone
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Center of each A band which contains thick but no thin filaments
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M Line
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supporting proteins that hold the thick filaments together in the H zone
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The Sliding Filament Mechanism
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-Myosin heads attach to and "walk" along the thin filaments at both ends of a sarcomere
-Progressively pulls the thin filaments toward the center of the sarcomere -Z discs come closer together and the sarcomere shortens -Leads to shortening of the entire muscle |
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Synapse
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Where communication occurs between a somatic motor neuron and a muscle fiber
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synaptic cleft
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gap that separates the two cells
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neurotransmitter
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chemical released by the initial cell communicating with the second cell
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Describe the way nerve impulses elicit a muscle action potential.
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1.) RElease of acetylcholine-nerve impulse arriving at the synaptic end bulbs causes many synaptic vesicles to release ACh into the synaptic cleft
2.)Activation of ACh receptors-binding of ACh to the receptor on the motor end plate/opens ion channel & allows flow of Na to the inside of the muscle cell 3.)Production of muscle action potential-inflow of Na makes the inside of the muscle fiber more positively charged, triggering a muscle action potential 4.)Termination of ACh activity-ACh effects last only briefly because it is rapidly broken down by acetylcholinesterase` |
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4 steps of the contraction cycle
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1.) ATP hydrolysis-reorients and energizes the myosin head
2.)Formation of cross-bridges-myosin head attaches to the myhosin-binding site on actin 3.) Power stroke-during the power stroke the crossbridge rotates, sliding the filaments 4.) Detachment of myosin from actin -as next ATP binds to the myosin head, the myosin head detaches from actin -contraction cycle repeats as long as ATP is available -Continuing cycles apply the force that shortens the sarcomere |
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3 ways muscle fibers produce ATP
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-creatinephosphate
-anaerobic cellular respiration -aerobic cellular respiration |
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Inability of muscle to maintain force of contraction after prolonged activity
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muscle fatigue
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Factors contributing to muscle fatigue
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-inadequate release of calcium ions from the SR
-depletion of creatine phosphate -insufficient oxygen -depletion of glycogen and other nutrients -buildup of lactic acid and ADP -failure of the motor neuron to release enough acetylcholine |
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Oxygen Debt
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the added oxygen that is taken into the body after exercise
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3 ways oxygen debt is used to restore muscle cells to the resting level
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-converts lactic acid into glycogen
-synthesizes creatine phosphate and ATP -replaces the oxygen rem9oved from myoglobin |
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consists of a motor neuron and the muscle fibers it stimulates
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motor units
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