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62 Cards in this Set
- Front
- Back
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Contractility
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The characteristic that allows muscles to contract forcefully
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Excitability
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The characteristic that allows muscles to be stimulated by nerves and hormones
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Extensibility
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The characteristic that allows muscles to be stretched out
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Elasticity
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The characteristic that allows muscles to recoil back to normal length after being stretched out
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What are the four characteristics of muscles?
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Contractility, excitability, extensibility, elasticity
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What are the three regular muscle functions?
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Movement, posture, heat production
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What are the three types of muscles?
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Skeletal, smooth, cardiac
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Striated
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Refers to the distinct striped pattern in a muscle
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Voluntary muscles
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Muscles we can control
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Nonstriated
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Not striped
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Involuntary
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We cannot exercise conscious control
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Is cardiac muscle involuntary or voluntary?
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Involuntary
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Is smooth muscle involuntary or voluntary?
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Involuntary
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Is skeletal muscle involuntary or voluntary?
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Voluntary
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Belly
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the part of the muscle composed of actual muscle cells
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Fascicles
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Bundles of muscle cells
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Muscle fiber
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a muscle cell
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Endomysium
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A thin collagen layer each muscle cell is wrapped in
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Perimysium
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A collagen layer a fascicle is wrapped in
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Epimysium
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A collagen layer several fascicles are wrapped in
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Sarcolemma
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The plasma membrane of the muscle fiber
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Sarcoplasmic reticulum
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The endoplasmic reticulum of a muscle fiber
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T-tubules
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Tiny tubes of the sarcoplasmic reticulum 'sprouting' into the sarcolemma
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Myofibrils
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thread-like structures which are only a few micrometers apart and extend from one side of the cell to the other
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Myofilaments
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either actin myofilaments or myosin myolfilaments that are contained in the myofibril
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Sliding-filament model
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The model of the sarcolemma and the way it contracts
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*Sarcomere
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The repeating unit of a myofibril
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What are the two types of protein in a sarcomere?
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actin and myosin
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Cross bridge
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The combination of a myosin head with the active site of an actin myofilament
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A-bands
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The part of the myofibril the length of the myosin myofilament
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Z-disks
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A part of the myofibril that acts as a 'boundry' for the sarcomere
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I-bands
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That part of the myofibril that is not part of or touching the myosin myofilament
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H-zone
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The space in the myofibril between the actin myofilaments
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The actin myofilament contains three proteins: actin and what two others?
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Troponin and tropomyosin
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Power stroke
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The step of muscle contraction in which the length of the sarcomere shortens
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Return stroke
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The step of muscle contraction in which the myosin head is 'pumped back,' allowing it to perform the power stroke again, if necessary
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What are the five steps in the cycle of sarcomere contraction?
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1) the active sites are not exposed, but the heads of the myosin myofilament are ready. ADPs and Ps are attached to the myosin heads. 2)Ca2+ ions bind to the troponin. The active sight is exposed and the Ps (phosphate) is ejected from the heads so they can bind to the active sites. 3) The power stroke - the ADPs are ejected and the heads bend. 4) ATP molecules bind to the heads, causing them to release the active sites. 5) Return stroke - ATPs break into ADPs and Ps. these are still bound to the heads. the energy allows the heads to 'spring back.'
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*neuron
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The functional unit of the nervous system, a nerve cell
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*Synapse
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The interface between a nerve cell and another cell
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Neuromuscular junction
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A junction between the branch of an axon of a motor neuron and a muscle fiber
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Synaptic cleft
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The gap between the end of the axon and the muscle fiber
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Presynaptic terminal
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The very end of the axon of the motor neuron, just before the synaptic cleft
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Postsynaptic membrane
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The membrane of the muscle fiber that touches the synaptic cleft
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Synaptic vesicles
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vesicles inside the presynaptic terminal
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Acetylcholine
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a neurotransmitter that interacts with the membrane of a skeletal muscle fiber, creating a signal that ultimately makes the muscle contract
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*neurotransmitter
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A chemical released by a neuron. This chemical travels across the synaptic cleft, allowing the neuron to communicate with another cell
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Action potential
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an 'electric message'
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What are the seven steps that must happen in order for a muscle fiver to begin contracting?
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1) an action potential travels down the axon of a motor neuron. 2) Ach is released from the presynaptic terminal 3) Ach travels across the synaptic cleft 4) Ach interacts with the muscle fiber membrane to create a muscle action potential 5) the action potential travels down a T-tubule 6) Calcium ions are released from the sarcoplasmic reticulum 7) Calcium ions bind to the troponin in an action myofilament
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Rigor mortis
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(Latin = "the stiffness of death") a short-term stiffening that occurs after death because the cells can to longer produce ATP and the active transport stops, thus allowing calcium ions to leak out and causing the muscle to temporarily contract
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*Motor unit
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One motor neuron and all the muscle fibers it innervates
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Innervate
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to control
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*All-or-none law of skeletal muscle contraction
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An individual muscle fiber contracts with equal force in response to each action potential
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*Subthreshold stimulus
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A stimulus too small to create an action potential in a neuron
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*Threshold stimulus
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A stimulus strong enough to create one action potential in a neuron
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*Submaximal stimuli
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Stimuli of increasing strength that create more action potentials along more neurons
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*Maximal stimulus
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A stimulus which is strong enough to create action potentials in all the motor neurons innervating a whole muscle
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What do we say has happened to a motor unit if all the muscle fibers in it contract?
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It has been recruited
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*Muscle tone
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The state of partial contraction in a muscle, even when the muscle is not being used
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Atrophy
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The process by which cells shrink due to lack of use
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Aerobic Respiration
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A three step process in which glucose reacts with oxygen, and the energy from that process is used to turn ADP and P into ATP
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What is the name of the energy reserve that a cell will make if it has enough rest time between periods of high energy consumption?
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Creatine phosphate
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Anaerobic respiration
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the first step in aerobic respiration, glycolysis, which involves a glucose molecule being broken down into two pyruvic acid molecules and four ATPs. The process requires two ATPs.
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