Kontrakcija mišića — разлика између измена

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{{multiple image | direction = vertical | width = 300 | footer = Muscle contractions underlie movement | image1 = Skeletal muscle.jpg | alt1 = Top-down view of skeletal muscle | caption1 = Hijerarhijska organizacija skeletalnih mišića | image2 = Colostethus_flotator_jumping.jpg | alt2 = Frog jumping | caption2 = Kontrakcije skeletalnih mišića omogućavaju kičmenjacima, kao što su žabe, da se kreću.}}
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'''Kontrakcija mišića''' je aktivacija mesta kojima se generiše [[Tension (physics)|tenzija]] unutar [[Myocyte|mišićnih vlakana]].<ref name="Widmaier et al 2008">{{cite book|url=|title=Vander's Human Physiology: The Mechanisms of Body Function|last1=Widmaier|first1=Eric P. |last2=Raff|first2=Hersel |last3=Strang|first3=Kevin T.|date=2010|publisher=McGraw-Hill|isbn=0-321-98122-7|edition=12th|series=|volume=|location=New York, NY|pages=250–291|language=|chapter=Muscle|doi=|authorlink=}}</ref><ref name="Silverthorn 2016">{{cite book|url=|title=Human Physiology: An Integrated Approach|last=Silverthorn|first=Dee Unglaub|date=2016|publisher=Pearson|isbn=0-321-98122-7|edition=7th|series=|volume=|location=San Francisco, CA|pages=377–416|language=|chapter=Muscles|doi=}}</ref> U [[fiziologija|fiziologiji]], mišićna kontrakcija ne mora neophodno da označava skraćivanje mišića pošto se mišićne tenzije mogu proizvesti bez promena dužine mišića, kao što je držanje teške knjige ili tegova u fiksnoj poziciji.<ref name = "Widmaier et al 2008" /> Terminaciji mišićne kontrakcije sledi '''mišićna relaksacija''', koja je vraćanje mišićnih vlakana u njihov stanje niske tenzije.<ref name = "Widmaier et al 2008" />
 
'''Kontrakcija mišića''' je aktivacija mesta kojima se generiše [[Tension (physics)|tenzijanaprezanje]] unutar [[Myocyte|mišićnih vlakana]].<ref name="Widmaier et al 2008">{{cite book|url=|title=Vander's Human Physiology: The Mechanisms of Body Function|last1=Widmaier|first1=Eric P. |last2=Raff|first2=Hersel |last3=Strang|first3=Kevin T.|date=2010|publisher=McGraw-Hill|isbn=0-321-98122-7|edition=12th|series=|volume=|location=New York, NY|pages=250–291|language=|chapter=Muscle|doi=|authorlink=}}</ref><ref name="Silverthorn 2016">{{cite book|url=|title=Human Physiology: An Integrated Approach|last=Silverthorn|first=Dee Unglaub|date=2016|publisher=Pearson|isbn=0-321-98122-7|edition=7th|series=|volume=|location=San Francisco, CA|pages=377–416|language=|chapter=Muscles|doi=}}</ref> U [[fiziologija|fiziologiji]], mišićna kontrakcija ne mora neophodno da označava skraćivanje mišića, pošto se mišićne tenzije mogu proizvesti bez promena dužine mišića, kao što je držanje teške knjige ili tegova u fiksnoj poziciji.<ref name = "Widmaier et al 2008" /> Terminaciji mišićne kontrakcije sledi '''mišićna relaksacija''', koja je vraćanje mišićnih vlakana u njihovnjihovo stanje niske tenzije.<ref name = "Widmaier et al 2008" />
Kontrakcije mišića se mogu opisati na bazi dve promenljive: dužine i napetosti.<ref name = "Widmaier et al 2008" /> A muscle contraction is described as isometric if the muscle tension changes but the muscle length remains the same.<ref name = "Widmaier et al 2008" /><ref name="Aidley 1998">{{cite book|url=|title=The Physiology of Excitable Cells|last=Aidley|first=David J.|date=1998|publisher=Cambridge University Press|isbn=0-521-57421-8|edition=4th|series=|volume=|location=New York, NY|pages=323–335|language=|chapter=Mechanics and energetics of muscular contraction|doi=}}</ref><ref name = "Sircar 2008">{{cite book | last = Sircar | first = Sabyasachi | chapter = Muscle elasticity | title = Principles of Medical Physiology | publisher = Thieme | series = | volume = | edition = 1st | date = 2008 | location = New York, NY | pages = 113 | language = | url = | doi =| isbn = 1-588-90572-1}}</ref><ref name="Bullock et al 2001">{{cite book|url=|title=NMS Physiology|last1=Bullock|first1=John|last2=Boyle|first2=Joseph|last3=Wang|first3=Michael B.|date=2001|publisher=Lippincott Williams and Wilkins|isbn=|edition=4th|series=|volume=578|location=Baltimore, Maryland|pages=37–56|language=|chapter=Muscle contraction|doi=|authorlink=}}</ref> In contrast, a muscle contraction is isotonic if muscle length changes but the muscle tension remains the same.<ref name = "Widmaier et al 2008" /><ref name = "Aidley 1998" /><ref name = "Sircar 2008" /><ref name = "Bullock et al 2001" /> If the muscle length shortens, the contraction is concentric;<ref name = "Widmaier et al 2008" /><ref name = "Kumar 2004">{{cite book | last = Kumar | first = Shrawan | chapter = Introduction and terminology | title = Muscle strength | publisher = CRC Press | editor = Shrawan Kumar | series = | volume = | edition = 1st | date = 2008 | location = Boca Raton, FL | pages = 113 | language = | url = | doi =| isbn = 0-415-36953-3}}</ref> if the muscle length lengthens, the contraction is eccentric. In natural movements that underlie [[Animal locomotion|locomotor activity]], muscle contractions are multifaceted as they are able to produce changes in length and tension in a time-varying manner.<ref name="Biewener 1998">{{cite book|url=|title=Animal Locomotion|last=Biewener|first=Andrew A.|date=2003|publisher=Oxford University Press|isbn=0-198-50022-X|edition=|series=Oxford Animal Biology Series|volume=|location=New York, NY|pages=15–45|language=|chapter=Muscles and skeletons: The building blocks of animal movement|doi=}}</ref> Therefore, neither length nor tension is likely to remain the same in muscles that contract during locomotor activity.
 
Kontrakcije mišića se mogu opisati na bazi dve promenljive: dužine i napetosti.<ref name = "Widmaier et al 2008" /> AMišićna musclekontrakcija contractionse isopisuje describedkao asizometrijska, isometricako ifse themišićna musclenapetost tensionmenja, changes but the musclea lengthmišićna remainsdužina theostaje sameista.<ref name = "Widmaier et al 2008" /><ref name="Aidley 1998">{{cite book|url=|title=The Physiology of Excitable Cells|last=Aidley|first=David J.|date=1998|publisher=Cambridge University Press|isbn=0-521-57421-8|edition=4th|series=|volume=|location=New York, NY|pages=323–335|language=|chapter=Mechanics and energetics of muscular contraction|doi=}}</ref><ref name = "Sircar 2008">{{cite book | last = Sircar | first = Sabyasachi | chapter = Muscle elasticity | title = Principles of Medical Physiology | publisher = Thieme | series = | volume = | edition = 1st | date = 2008 | location = New York, NY | pages = 113 | language = | url = | doi =| isbn = 1-588-90572-1}}</ref><ref name="Bullock et al 2001">{{cite book|url=|title=NMS Physiology|last1=Bullock|first1=John|last2=Boyle|first2=Joseph|last3=Wang|first3=Michael B.|date=2001|publisher=Lippincott Williams and Wilkins|isbn=|edition=4th|series=|volume=578|location=Baltimore, Maryland|pages=37–56|language=|chapter=Muscle contraction|doi=|authorlink=}}</ref> InU contrast,kontrasu as muscletim, contractionmišićna iskontrakcija isotonicje ifizotonijska muscleako lengthse changesdužina butmišića themenja, musclea tensionmišićna remainsnapetost theostaje sameista.<ref name = "Widmaier et al 2008" /><ref name = "Aidley 1998" /><ref name = "Sircar 2008" /><ref name = "Bullock et al 2001" /> IfAko these musclemišićna lengthdužina shortenssmanjuje, thekontrakcija contraction isje concentrickoncentrična;<ref name = "Widmaier et al 2008" /><ref name = "Kumar 2004">{{cite book | last = Kumar | first = Shrawan | chapter = Introduction and terminology | title = Muscle strength | publisher = CRC Press | editor = Shrawan Kumar | series = | volume = | edition = 1st | date = 2008 | location = Boca Raton, FL | pages = 113 | language = | url = | doi =| isbn = 0-415-36953-3}}</ref> ifdok theako musclese lengthmišićna lengthensdužina povećava, the contractionkontrakcija isje eccentricekcentrična. InPri naturalprirodnim movementspokretima thatkoji underliesu u osnovi [[Animal locomotion|locomotorlokomotorne activityaktivnosti]], musclemišićne contractionskontrakcije aresu multifacetedvišeznačne, aspošto theyone aremogu ableda toproizvedu producepromene changesu indužini lengthi andnapetosti tensionu inmaniru akoji time-varyingvarira tokom mannervremena.<ref name="Biewener 1998">{{cite book|url=|title=Animal Locomotion|last=Biewener|first=Andrew A.|date=2003|publisher=Oxford University Press|isbn=0-198-50022-X|edition=|series=Oxford Animal Biology Series|volume=|location=New York, NY|pages=15–45|language=|chapter=Muscles and skeletons: The building blocks of animal movement|doi=}}</ref> ThereforeStoga, neitherniti length nor tension isdužina, likelyniti tonapetost remainostaju theisti sameu inmišićima muscleskoji thatsu contractkontrahuju duringtokom locomotorlokomotorne activityaktivnosti.
Kod kičmenjaka, [[skeletal muscle]] contractions are neurogenic as they require [[Synapse|synaptic input]] from [[motor neurons]] to produce muscle contractions. A single motor neuron is able to innervate multiple muscle fibers, thereby causing the fibers to contract at the same time. Once innervated, the protein filaments within each skeletal muscle fiber slide past each other to produce a contraction, which is explained by the [[sliding filament theory]]. The contraction produced can be described as a twitch, summation, or tetanus, depending on the frequency of [[action potentials]]. In skeletal muscles, muscle tension is at its greatest when the muscle is stretched to an intermediate length as described by the length-tension relationship.
 
Kod kičmenjaka, kontrakcije [[Попречно-пругасти мишић|skeletalnih mišića]] su neurogenične, jer je neophodan [[Sinapsa|sinaptički input]] iz [[Пирамидални пут|motornih neurona]] da bi se proizvele mišićne kontrakcije. Pojedinačni motorni neuron ima sposobnost inervacije višestrukih mišićnih vlakana, što uzrokuje da se vlakna kontrahuju u isto vreme. Jednom inervirani, proteinski filamenti unutar svakog skeletalnog mišićnog vlakna klize jedan pored drugog kako bi došlo do kontrakcije, što je objašnjeno putem [[sliding filament theory|teorije kliznih filamenata]]. Proizvedene kontrakcije se mogu opisati kao trzaj, sabiranje, ili [[tetanus]], u zavisnosti od frekvencije [[Акциони потенцијал|akcionih potencijala]]. U skeletalnim mišićima, napetost mišića je najveća kad je mišić istegnut do intermedijerne dužine kao što je opisano relacijom dužine i napetosti.
Za razliku od skeletalnih mišića, kontrakcije [[smooth muscle|glatkih]] i [[cardiac muscle]]s are [[Myogenic contraction|myogenic]] (meaning that they are initiated by the smooth or heart muscle cells themselves instead of being stimulated by an outside event such as nerve stimulation), although they can be modulated by stimuli from the [[autonomic nervous system]]. The mechanisms of contraction in these [[muscle tissue]]s are similar to those in skeletal muscle tissues.
 
Za razliku od skeletalnih mišića, kontrakcije [[smooth muscle|glatkih]] i [[cardiac muscle|srčanih mišića]] su [[Myogenic response|miogene]] (što znači da njih iniciraju same ćelije glatkih ili srčanih mišića, umesto da su stimulisane spoljašnjim signalom, kao što je nervna stimulacija), mada one mogu da budu modulisane stimulusima iz [[Аутономни нервни систем|autonomnog nervnog sistema]]. Mehanizmi kontrakcija u tim [[muscle tissue|mišićnim tkivima]] su slični onima u skeletalnim mišićnim tkivima.
 
== Reference ==