M.-ESQUEL.-INFORME.docx

7/24/2019 M.-ESQUEL.-INFORME.docx

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FISIOLOGA DEL MSCULO ESQUELTICO

Actividad 1:La contraccin muscular y el perodo de latencia

I. Pre-lab Quiz Results

1. Skeletal muscles are connected to bones byb. tendons.

2. Skeletal muscles are composed o !undreds to t!ousands o indi"idual cells calledc. ibers.

#. $!e term motor unit reers toc. one motor neuron and all o t!e skeletal muscle ibers it inner"ates.

%. $!e motor neuron and muscle iber intersect at &!at is calledd. t!e neuromuscular 'unction.

(. ) t&itc! isa. one contractile response to a sin*le action potential.

II. Predict Question+

Predict Question+ ,ill c!an*es to t!e stimulus "olta*e alter t!e duration o t!e latentperiod a. es/ c!an*in* t!e stimulus "olta*e &ill c!an*e t!e latent period durationproportionately.

III. Stop 0 $!ink Questions+

,!at is t!e period o time t!at elapses bet&een t!e *eneration o an action

potential and t!e start o muscle tension de"elopment in a muscle iberc. t!e latent period

,!at occurs durin* t!e latent period o t!ese isometric contractions

b. )ll t!e steps o ecitation-contraction couplin* occur.

I. 3periment 4ata+


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. Post-lab Quiz Results

1. )n action potential in a motor neuron tri**ers t!e release o &!ic! neurotransmitterb. acetylc!oline


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2. $!e term skeletal muscle iber reers toa. an indi"idual skeletal muscle cell.

#. $!e *raded depolarization in t!e skeletal muscle iber t!at is elicited in response to oneaction potential rom t!e motor neuron is called

c. an 3PP 5end-plate potential6.

%. ,!ic! o t!e ollo&in* is not a p!ase o a skeletal muscle t&itc!b. !yperpolarization p!ase

(. ) skeletal muscle t&itc! isa. one contractile response to a sin*le action potential.

7. ,!ic! o t!e ollo&in* correctly matc!es t!e t&itc! p!ase &it! its deinitiond. t!e contraction p!ase+ t!e time bet&een t!e end o t!e latent period and peak muscletension

8. ) suiciently stron* electrical stimulus applied to an isolated/ mounted skeletal muscleinduces t!e de"elopment o muscle orce/ or muscle tension. ,!ic! o t!e ollo&in*statements concernin* t!is obser"ation is truec. $!e electrical stimulus mimics acetylc!oline release at a neuromuscular 'unction

I. Re"ie& S!eet Results

1. 4eine t!e terms skeletal muscle iber/ motor unit/ skeletal muscle t&itc!/ electricalstimulus/ and latent period.

9ibras musculares es:uel;ticas+ estsculo y el inicio de la contraccin muscular.

2. ,!at is t!e role o acetylc!oline in a skeletal muscle contraction

La acetilcolina se diunde en el sarcolema de la ibra muscular y se une a los receptoresen la placa de etremo del motor :ue inician un cambio en la permeabilidad a los iones:ue se traduce en una despolarizacin *radual del potencial de la placa de etremo.


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#. 4escribe t!e process o ecitation-contraction couplin* in skeletal muscle ibers.

Los acontecimientos :ue se producen en la delantera unin neuromuscular al potencial dela placa inal. 3l potencial de la placa inal desencadena una serie de e"entos :ue dancomo resultado la contraccin de un m>sculo.

%. 4escribe t!e t!ree p!ases o a skeletal muscle t&itc!.

3l perodo de latencia es el tiempo :ue transcurre entre la *eneracin de un potencial deaccin en la c;lula muscular y el comienzo de la contraccin del m>sculo.

)un:ue no se *enera nin*una uerza durante el perodo de latencia/ intracelularmente seproducen cambios :umicos 5incluyendo la liberacin de calcio desde el retculosarcoplsculo es:uel;tico


1. Skeletal muscle ibers are inner"ated 5stimulated6 byc. motor neurons.

2. ) sin*le action potential propa*atin* do&n a motor aon results ind. a sin*le action potential and a sin*le contractile e"ent in t!e muscle ibers it inner"ates.

#. In restin* skeletal muscle/ calcium is stored inc. t!e sarcoplasmic reticulum.

%. 4urin* t!e latent period or an isometric contractionc. t!e cellular e"ents in"ol"ed in ecitation-contraction couplin* occur


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Predict Question+ )s t!e stimulus "olta*e is increased rom 1.@ "olt up to 1@ "olts/

&!at &ill !appen to t!e amount o acti"e orce *enerated &it! eac! stimulus

c. $!e acti"e orce &ill irst increase and t!en plateau at some maimal "alue ast!e stimulus "olta*e increases.


,!at do you see in t!e acti"e orce display &!en t!e stimulus "olta*e is set to @.@/

and &!y does t!is obser"ation make sensea. @.@@ *A t!ere &as no acti"ation o skeletal muscle ibers by t!is stimulus.

,!at is t!e lo&est stimulus "olta*e t!at induces acti"e orce in t!e skeletal

muscleb. t!res!old "olta*e

3nter t!e t!res!old "olta*e or t!is eperiment in t!e ield belo& and t!en click

Submit to record your ans&er in t!e lab [email protected] "olts

3nter t!e maimal "olta*e or t!is eperiment in t!e ield belo& and t!en click

Submit to record your ans&er in t!e lab report.1@.@ "olts

I. 3periment 4ata+


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1. Cotor unit recruitment reers toa. an increase in t!e number o acti"e muscle ibers to increase t!e orce de"eloped in amuscle.

2. )cti"e tension 5or orce6 in a skeletal muscle iber results roma. acti"ation o cross brid*e cyclin* "ia increased intracellular calcium le"els.

#. $!e DDDDDDDD is t!e minimal stimulus needed to cause a depolarization o t!e muscleplasma membrane 5sarcolemma6.d. t!res!old "olta*e

%. Ey deinition/ t!e DDDDDDDD is t!e amount o stimulus re:uired to successully recruit allt!e muscle ibers into de"elopin* acti"e orce.c. maimal "olta*e

(. ,!y &as a maimal "olta*e obser"ed in t!is eperimentb. )t t!e maimal "olta*e/ all t!e muscle ibers contained in t!is muscle are depolarizedand t!ey all de"elop acti"e orce 5t!at is/ t!ey &ere all successully recruited6.


1. 4escribe t!e eect o increasin* stimulus "olta*e on isolated skeletal muscle.Speciically/ &!at !appened to t!e muscle orce *enerated &it! stron*er electrical

stimulations and &!y did t!is c!an*e occur ?o& &ell did t!e results compare &it! yourprediction

) medida :ue aumenta la tensin de estmulo pasado la tensin de umbral del m>sculo/ lacantidad de uerza en todo el m>sculo aumenta. Fada "ez :ue el "olta'e se aument lauerza *enerada por el m>sculo tambi;n aument. 3sto se produce por:ue a medida :ueaumenta la tensin/ y se entre*a a todo el m>sculo/ m


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2. ?o& is t!is c!an*e in &!ole-muscle orce ac!ie"ed in vivo3l aumento de la corriente el;ctrica pro"oca un aumento pro*resi"o en la cantidad de

uerza muscular basado en la cantidad de la corriente el;ctrica. 3n la etapa inicial/ la

corriente el;ctrica debe superar la tensin umbral. =na "ez :ue el "olta'e de estmulo "a

msculo entero. Fada "ez msculo es:uel;tico aislado se despolarizaron y todos

desarrollaron uerza acti"a. )s :ue cada una de las ibras estaban in"olucrados en la

uerza acti"a *enerada a partir de la tensin msculo es:uel;tico


1. durin* a single t&itc! o a skeletal muscleb. maimal orce is ne"er ac!ie"ed.

2. ,!en a skeletal muscle is repetiti"ely stimulated/ t&itc!es can o"erlap eac! ot!er andresult in a stron*er muscle contraction t!an a stand-alone t&itc!. $!is p!enomenon iskno&n as

c. &a"e summation.

#. ,a"e summation is ac!ie"ed bya. increasin* t!e stimulus re:uency 5t!e rate o stimulus deli"ery to t!e muscle6.

%. ,a"e summation increases t!e orce produced in t!e muscle. )not!er &ay to increaset!e orce produced by a muscle is tod. increase t!e number o acti"ated motor units.


Predict Question 1+ )s t!e stimulus re:uency increases/ &!at &ill !appen to t!e

muscle orce *enerated &it! eac! successi"e stimulus ,ill t!ere be a limit to t!isresponseb. )s t!e stimulus re:uency increases/ t!e muscle orce *enerated by eac!successi"e stimulus &ill increase. $!ere &ill be a limit to t!is increase.


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Predict Question 2+ In order to produce sustained muscle contractions &it! an

acti"e orce "alue o (.2 *rams/ do you t!ink you &ill need to increase t!e stimulus"olta*eb. no


,as t!ere any c!an*e in t!e orce *enerated by t!e muscle durin* t!e second

stimulated t&itc!c. es/ t!e second t&itc! *enerated more muscle orce.

Is t!e total muscle orce *enerated by t!e !i*!er re:uency stimulation *reater t!an

t!e orce *enerated in pre"ious stimulationsa. es/ it is *reater t!an t!e pre"ious stimulations.

4oes t!e orce *enerated by t!e muscle c!an*e &it! eac! additional stimulus

b. )s t!e stimulus re:uency increased/ t!e muscle tension *enerated by eac!successi"e stimulus also increased/ and a limitin* maimum "alue &as obser"ed.

I. 3periment 4ata+


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1. ,!ic! o t!e ollo&in* is not one o t!e &ays t!at t!e body can increase t!e orceproduced by a skeletal muscled. application o !i*!er "olta*es to t!e &!ole muscle


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2. ,!en a muscle recei"es a stimulus re:uency t!at causes non-overlapping t&itc!es toollo& eac! ot!er closely in time suc! t!at t!e peak tension o eac! t&itc! rises in astep&ise as!ion up to a plateau "alue/ t!e result is kno&n asc. treppe.

#. In t!is eperiment t!e isolated skeletal muscle &as repetiti"ely stimulated suc! t!at

indi"idual t&itc!es o"erlapped &it! eac! ot!er and resulted in a stron*er musclecontraction t!an a standalone t&itc!. $!is p!enomenon is kno&n asc. &a"e summation.

%. ,a"e summation is ac!ie"ed bya. increasin* t!e rate o stimulus deli"ery 5re:uency6 to t!e muscle


1. ,!at is t!e dierence bet&een stimulus intensity and stimulus re:uency

Intensidad del estmulo+ se reiere a la uerza :ue se le coniere en este caso al musculo/:ue sera dada por el "olta'e.

9recuencia del estmulo+ 3s la rapidez con :ue se aplican los estmulos al musculo.

2. In t!is eperiment you obser"ed t!e eect o stimulatin* t!e isolated skeletal musclemultiple times in a s!ort period &it! complete relaation bet&een t!e stimuli. 4escribe t!eorce o contraction &it! eac! subse:uent stimulus. )re t!ese results called treppe or&a"e summation

La uerza de contraccin al realizar estmulos r


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3l t;rmino GsumacinH indica la adicin de contracciones indi"iduales para aumentar laintensidad de la contraccin muscular total. Sucede sumacin de tres ormas dierentes+aumentando el n>mero de unidades motoras :ue contraen simultltiples ibras+ Fuando el sistema ner"ioso central en"a una seal d;bilpara :ue contrai*a un m>sculo/ las unidades motores de ;ste :ue conten*an menos ym


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Predict Question+ )s t!e stimulus re:uency increases urt!er/ &!at &ill !appen to

t!e muscle tension and t&itc! appearance &it! eac! successi"e stimulus ,illt!ere be a limit to t!is responseb. )s t!e stimulus re:uency increases/ t!e muscle tension *enerated by eac!successi"e stimulus &ill increase. $!ere &ill be a limit to t!is increase.


,!at be*ins to !appen at around B@ msec

c. unused tetanus de"elops

?o& does t!e trace at 1#@ stimuliJsec compare &it! t!e trace at (@ stimuliJsec

b. 9used tetanus de"elops at t!is *reater stimulus re:uency.

?o& do t!e traces &it! 1%7K1(@ stimuli per second compare &it! t!e trace at 1#@

stimuli per secondd. Caimal tetanic tension de"elops &it! t!ese "ery !i*! stimulation re:uencies.

I. 3periment 4ata+


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1. $!e term tetanus reers tob. sustained muscle tension due to "ery re:uent stimuli.

2. ,!ic! o t!e ollo&in* distin*uis!es a state o unused tetanus rom a state o complete5used6 tetanusd. Cuscle tension increases and decreases bet&een dierent "alues or an unusedtetanus.

#. ,!en t!e stimulus re:uency reac!es a "alue beyond &!ic! no urt!er increases inorce are *enerated by t!e muscle/ t!e muscle !as reac!ed itsa. maimal tetanic tension.


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1. 4escribe !o& increasin* t!e stimulus re:uency aected t!e orce de"eloped by t!eisolated &!ole skeletal muscle in t!is acti"ity. ?o& &ell did t!e results compare &it! yourprediction

Fuando la recuencia de estmulo ue menor a la uerza estaba en su ni"el m


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#. ) decline in a muscleNs ability to maintain a constant le"el o orce/ or tension/ ater

prolon*ed/ repetiti"e stimulation iscalled

c. ati*ue.

%. ,!ic! o t!e ollo&in* is not t!ou*!t to be a contributin* actor to t!e de"elopment o

ati*ue

a. buildup o Fa2M in t!e muscle ibers


Predict Question+ I t!e stimulator is briely turned o or deined periods o time/

&!at &ill !appen to t!e len*t! o time t!att!e muscle is able to sustain maimal

de"eloped tension &!en t!e stimulator is turned on a*ainb. $!e len*t! o t!e rest period &ill proportionately increase t!e len*t! o time or

sustained muscle tension.


,!y does t!e stimulated muscle orce be*in to decrease o"er time despite t!e

maintained stimuli 5Oote t!at a decrease inmaimal orce indicates muscle ati*ue

is de"elopin*.6d. Core t!an one o t!ese ans&ers could be correct.

,!y did t!e len*t! o t!e inter"enin* rest period aect t!e len*t! o time t!e

skeletal muscle can maintain maimum tensiononce t!e stimulator is turned on

a*ainc. Intracellular concentrations o )4P and Pi declined durin* t!e rest period.

I. 3periment 4ata+


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.

Post-lab Quiz Results

1. 4urin* cross brid*e cyclin* in skeletal muscle/ orce is created by t!ec. po&er stroke o t!e myosin !eads

.2. $!e term tetanus reers toou correctly ans&ered+ b. sustained muscle tension dueto repetiti"e stimuli.

#. ) decline in a muscleNs ability to maintain a constant le"el o orce/ or tension/ ater

prolon*ed/ repetiti"e stimulation iscalledc. ati*ue.

%. 4urin* ati*uec. t!e number o acti"e cross brid*es be*ins to decline alt!ou*! t!e rate o stimulus

deli"ery5re:uency6 remains constant.

(. I an inter"enin* rest period is imposed on acti"e skeletal muscle

c. t!e de"elopment o ati*ue &ill be delayed


1. ,!en a skeletal muscle ati*ues/ &!at !appens to t!e contractile orce o"er timeFuando un m>sculo es:uel;tico ati*a la uerza contrsculo !a alcanzado la msculo se comienza a ati*ar y la uerza contr


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turned o t!an i t!e stimuli &ere allo&ed to continue &it!out interruption. 3plain

&!y t!is mi*!t occur. ?o& &ell did t!e results compare &it! your prediction

)l *irar el estimulador/ se crea un perodo de descansoA permitiendo as :ue las

concentraciones de las concentraciones intracelulares de


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Oote t!e dip in total orce at a muscle len*t! o @ mm. ,!y does t!is occurd. )t t!is muscle len*t!/ acti"e orce !as decreased in "alue and passi"e orce !as

not yet increased to a si*niicant "alue.

I. 3periment 4ata+


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1. ,!en a skeletal muscle is stimulated and *enerates orce but remains at a ied

len*t!d. t!e muscle is contractin* isometrically.


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2. ,!ic! protein is mostly responsible or t!e de"elopment o passi"e orce in a

muscled. titin

#. In skeletal muscle/ acti"e orce stimulated t!rou*! a ran*e o muscle len*t!sb. &ill utilize )$P !ydrolysis to dri"e t!e cross brid*e cycle.

%. ,!ic! i t!e ollo&in* is not depicted in a typical skeletal muscle isometric len*t!-

tension cur"ea. time

(. Caimal acti"e tension &ill be produced in a skeletal muscle iber &!ena. t!e iber is at its restin* len*t!.


1. ,!at !appens to t!e amount o total orce t!e muscle *enerates durin* t!e

stimulated t&itc! ?o& &ell did t!e results compare &it! your prediction9uerza total se "e alterada por la lon*itud inicial de reposo. Ci prediccin era

correcta en :ue al cambiar de cual:uier manera/ ya sea alar*ando o acortando

el m>sculo/ ambos m;todos cambiaron la uerza total *enerada por el m>sculo.

Si el m>sculo se alar*a la uerza pasi"a aumenta/ y si el m>sculo se acorta la

uerza acti"a aumenta.

2. ,!at is t!e key "ariable in an isometric contraction o a skeletal muscle3l m>sculo est< unido a un peso :ue ecede sus capacidades de pico de tensin.

3n la estimulacin/ la tensin subir< a un pico/ pero el m>sculo en su con'unto no

se puede acortar.

#. Eased on t!e uni:ue arran*ement o myosin and actin in skeletal muscle

sarcomeres/ eplain &!y acti"e orce "aries &it! c!an*es in t!e muscleNs restin*

len*t!.La uerza acti"a se *enera a partir de los ilamentos *ruesos de miosina/ se unen

a los ilamentos de actina del*adas/ con la participacin del ciclo del puente

cruzado y la !idrlisis de )$P. Fambios de datos uerza acti"a como la lon*itud

de reposo de los cambios musculares. Fuando se acorta la lon*itud en reposo

del m>sculo/ la cantidad uerza acti"a aumenta. Fuando se alar*a la lon*itud en

reposo del m>sculo/ la cantidad uerza acti"a disminuye. 3l cambio en la cantidad

uerza acti"a est< completamente causada por la cantidad de miosina unida a

actina. Fuanto msculo !ay msculo bceps se mantiene en una lon*itud i'a.


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Actividad #:Fontracciones isotnicas y relacin car*a-"elocidad


1. 4urin* an isotonic concentric contraction/ t!eb. orce *enerated by t!e muscle is *reater t!an t!e &ei*!t o t!e attac!ed load.

2. durin* an isotonic concentric contractionb. t!e latent period increases &it! !ea"ier loads.

#. durin* t!e latent period or an isotonic concentric contractionc. cross brid*es cycle and/ &!en muscle tension eceeds t!e load/ muscle

s!ortenin* occurs.

%. Cuscle s!ortenin* "elocitya. decreases &it! !ea"ier loads.

(. )n isotonic contraction o a muscle is one in &!ic!a. t!e len*t! o t!e muscle c!an*es


Predict Question+ )s t!e load on t!e muscle increases/ &!at &ill !appen to t!e

latent period/ t!e s!ortenin* "elocity/ t!e distance t!at t!e &ei*!t mo"es/ and t!e

contraction durationb. $!e latent period &ill decrease/ t!e s!ortenin* "elocity &ill decrease/ t!e

distance &ill increase/ and t!e contraction duration &ill increase.


,!at kind o contraction did you obser"e &!en you attac!ed t!e 2.@ *ram &ei*!t to

t!e skeletal muscle and stimulated a contractionc. isometric

I. 3periment 4ata+


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1. ,!ic! o t!e &ei*!ts allo&ed t!e astest muscle s!ortenin* "elocitya. @.(-* &ei*!t

2. ,!ic! o t!e &ei*!ts induced t!e lon*est latent period o t!e muscle

contractionc. 1.(-* &ei*!t

#. ,!ic! &ei*!t did t!e muscle contraction mo"e t!e *reatest distancea. @.(-* &ei*!t

%. ,!ic! o t!e &ei*!ts allo&ed t!e lon*est duration o muscle contractiona. @.(-* &ei*!t

(. )n isotonic contraction o a muscle is one in &!ic!a. t!e len*t! o t!e muscle c!an*es.


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7. ,!en litin* a !ea"y loadd. t!e muscle s!ortenin* "elocity is decreased in comparison &it! li*!ter loads

I.Re"ie& S!eet Results

1. I you &ere usin* your bicep muscles to curl a 8-k* dumbbell/ &!en &ould yourmuscles be contractin* isotonicallyFuando el brazo se etiende !acia aba'o !asta el punto de :ue sea recta. 5pero

no mientras :ue es recto6 y cuando el brazo se ele"a desde la posicin !acia

aba'o de nue"o a la posicin ele"ada.

2. 3plain &!y t!e latent period became lon*er as t!e load became !ea"ier in t!e

eperiment. ?o& &ell did t!e results compare &it! your prediction3l perodo de latencia se produce cuando !ay un aumento de la tensin

muscular/ pero no el mo"imiento o la contraccin del m>sculo. 3n el ciclo

puentes Fruzado y cuando la tensin muscular ecede la car*a/ el

acortamiento muscular sucede. Los latentes aumentos de ;poca como el pesode la car*a se !ace msculo.

#. 3plain &!y t!e s!ortenin* "elocity became slo&er as t!e load became !ea"ier

in t!is eperiment. ?o& &ell did t!e results compare &it! your predictionLa "elocidad de acortamiento se reiere a la "elocidad de la contraccin del

m>sculo acortando al le"antar una car*a. elocidad msculo se contrae m


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orce ,ill t!e muscle c!an*e len*t! ,!at is t!e name or t!is type o

contraction3l m>sculo se*uir< *enerando la uerza y duracin de cambio. 3sta es una

contraccin isotnica.

M.-ESQUEL.-INFORME.docx

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