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33 Cards in this Set
- Front
- Back
What are some properties of skeletal muscle?
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Voluntary, so innervated by the somatic nervous system
Striated due to Z lines, and multinucleate |
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What is the organization of skeletal muscles? (narrow to broad)
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sarcomere, myofibril, sarcoplasmic reticulum, sarcoplasm, sarcolema, myocyte
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What are the T tubules?
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In skeletal muscles, a way for ions to flow between sarcomeres so an action potential can propagate?
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What is the purpose of the sarcoplasmic reticulum?
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It stores Ca 2+ that can be released due to depolarization
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What is myoglobin?
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A protein in the muscle that binds to O2 with a higher affinity than hemoglobin
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What are red fibers known as?
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"slow twitch"; has a higher concentration of myoglobin, more mitochondria and uses aerobic respiration. Long distance runners have more red fibers than white.
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What are white fibers known as?
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"Fast twitch", contract quicker than red fibers but fatigue quicker. Use anaerobic respiration, so they have less myoglobin and less mitochondria. Short distance runners have more white fibers than red.
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What is calcium's role in a muscle contraction?
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Calcium must be released by the sarcoplasmic reticulum during depolarization in order to bind to troponin, which moves tropomyosin away to reveal the myosin binding sites on actin.
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What occurs in the first step of a muscle contraction, "initiation?"
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signal -- motor neuron -- nerve terminal -- acetylcholine released in neuromuscular junction -- binds to muscle cell receptors
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What occurs in the second step of a muscle contraction, the shortening of the sarcomere?
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The action potential goes through the T-Tubules to the sarcoplasmic reticulum. Calcium is released, binds to troponin making tropomyosin move to reveal the myosin binding cites on actin. An actin/myosin cross bridge forms and ADP/P is released, pulling on fibers.
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What bands in the sarcomere shorten during contraction? Which stay the same?
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H, I, Z bonds shorten. H is the thick fibers, I is the thin fibers and Z is the boundary between sarcomeres.
The A band, which is the overlap of thick and thin fibers, stays the same. |
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What occurs during muscle relaxation?
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ATP binds to myosin, causing it to release and relax. This ATP must be hydrolyzed to make the myosin change confirmation again, and Ca2+ must be added so the myosin binding sites can be revealed.
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What determines the force of a contraction?
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The number of muscle fibers stimulated simualtaneously
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What is Tonus?
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A state of constant low level contraction
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What occurs in a simple twitch?
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A latent period (has not hit threshold value yet), contraction, refractory period (absolute=cannot be stimulated at all; relative=can be stimulated but must have more force to do so)
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What are the properties of smooth muscle?
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Myogenic (does not need external signals to contract), controlled by the autonomic nervous system, uninucleate.
Occurs in the digestive tract, bladder, uterus, blood vessel walls, etc. |
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What are the properties of cardiac muscle?
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Uninucleate, involuntary, myogenic, striated
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What is the purpose of creatine phosphate?
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Can be hydrolyzed to create ATP immediately without going through cellular respiration first
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How is myoglobin useful during exercising?
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Can use the O2 it's holding on to in order to keep aerobic respiration going when O2 concentration is low
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What are ligaments?
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Dense connective tissue that holds bones together at the joints
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What are tendons?
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Dense connective tissue that holds bones and muscles together
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What is connective tissue?
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Made up of a sparsely scattered population of cells in a amorphous substance.
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What are the three fiber types of connective tissue?
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Collagenous fibers=composed of collagen, have great strength
elastic fibers=composed of elastin, give resilience reticular fibers=branched fibers joining connective tissue to other tissues |
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What are the two major cell types in connective tissue?
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fibroblasts = secrete substances that are components of extracellular fibers
macrophages=engulf bacteria and dead cells |
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What is dense connective tissue?
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Connective tissue with a high proportion of collagenous fibers
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What is the end of the muscle attached to stationary bone called?
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The origin (in limb muscles, proximal)
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What is the end of the muscle attached to the bone that moves during contraction called?
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The insertion (distal end in limb muscles)
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How do muscles work antagonistically?
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They work in pairs; one relaxes while the other contracts.
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How do muscles work synergistically?
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Other muscles assist the principle muscles during movement
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What does a flexor muscle do?
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Contract to decrease the angle of a joint
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What does an extensor muscle do?
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Contract to straighten a joint
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What does an abductor muscle do?
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Moves part of the body away from the midline
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What does an adductor muscle do?
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Moves part of body toward the midline
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