Structure Skeletal Muscle

8/9/2019 Structure Skeletal Muscle

1/47

Structure and Function of

Skeletal Muscle


2/47

Skeletal MuscleHuman body contains over 400skeletal muscles

40-50% of total body weightFunctions of skeletal muscle

Force roduction for locomotion and

breathingForce roduction for ostural su ortHeat roduction during cold stress


3/47

Structure of SkeletalMuscle!Connective Tissue

Covering

" imysiumSurrounds entire muscle

#erimysiumSurrounds bundles of muscle $bers

Fascicles

"ndomysiumSurrounds individual muscle $bers


4/47


5/47

Structure of SkeletalMuscle!MicrostructureSarcolemma

Muscle cell membrane

Myo$brils hreadlike strands within muscle $bers&ctin 'thin $lament(

ro onin ro omyosin

Myosin 'thick $lament(


6/47


7/47

Structure of SkeletalMuscle!The SarcomereFurther divisions of myo$brils

)-line

&-band*-band

+ithin the sarco lasmSarco lasmic reticulum

Storage sites for calcium

ransverse tubules erminal cisternae


8/47


9/47

he ,euromuscular unction

Site where motor neuron meets the muscle$ber

Se arated by ga called the neuromuscular cleftMotor end late

#ocket formed around motor neuron bysarcolemma

&cetylcholine is released from the motorneuron

.auses an end- late otential '"##(/e olari ation of muscle $ber


10/47

*llustration of the,euromuscular unction


11/47

Motor 1nitSingle motorneuron 2 muscle$bers it innervates"ye muscles 3 ! muscle nerveratioHamstrings 3 600! muscle nerveratio


12/47


13/47

Muscular .ontraction he sliding $lament model

Muscle shortening occurs due to themovement of the actin $lament overthe myosin $lamentFormation of cross-bridges between

actin and myosin $laments7eduction in the distance between )-lines of the sarcomere


14/47

he Sliding Filament Modelof Muscle .ontraction


15/47


16/47

.ross-8ridge Formation inMuscle .ontraction


17/47

Sliding Filament heory7est 3 uncharged & # cross-bridgecom le9

"9citation-cou ling 3 charged & # cross-bridge com le9: ;turned on<.ontraction 3 actomyosin 3 & # = &/# 2#i > energy7echarging 3 reload cross-bridge with & #7ela9ation 3 cross-bridges ;turned o?<


18/47

Muscle Function&ll or none law 3 $ber contractscom letely or not at allMuscle strength gradation

Multi le motor unit summation 3 moremotor units er unit of time

+ave summation 3 vary fre@uency ofcontraction of individual motor units


19/47

"nergy for Muscle.ontraction

& # is re@uired for musclecontraction

Myosin & #ase breaks down & # as$ber contracts

Sources of & #

#hos hocreatine '#.(AlycolysisB9idative hos horylation


20/47

Sources of & # for Muscle.ontraction


21/47

#ro erties of Muscle Fibers8iochemical ro erties

B9idative ca acity y e of & #ase

.ontractile ro ertiesMa9imal force roductionS eed of contractionMuscle $ber eCciency


22/47

*ndividual Fiber y esFast $bers

y e **b $bers

Fast-twitch $bersFast-glycolytic$bers

y e **a $bers*ntermediate $bersFast-o9idativeglycolytic $bers

Slow $bers y e * $bers

Slow-twitch $bersSlow-o9idative$bers


23/47


24/47


25/47

.om arison of Ma9imalShortening Delocities8etween Fiber y es


26/47

Histochemical Staining ofFiber y e


27/47

Fiber y es and#erformance

#ower athletesS rinters

#ossess high ercentage of fast $bers"ndurance athletes/istance runnersHave high ercentage of slow $bers

Bthers+eight lifters and nonathletesHave about 50% slow and 50% fast $bers


28/47


29/47


30/47

raining-*nduced .hangesin Muscle Fiber y e


31/47

Hy ertro hy andHy er lasia

*ncrease in si e *ncrease innumber


32/47

&ge-7elated .hanges inSkeletal Muscle

&ging is associated with a loss ofmuscle mass

7ate increases after 50 years of age7egular e9ercise training canim rove strength and endurance

.annot com letely eliminate the age-related loss in muscle mass


33/47

y es of Muscle

.ontraction*sometric

Muscle e9erts force without changing length

#ulling against immovable obEect#ostural muscles

*sotonic 'dynamic(.oncentric

Muscle shortens during force roduction

"ccentricMuscle roduces force but length increases


34/47

*sotonic and *sometric

.ontractions


35/47

*llustration of a Sim le

witch


36/47

Force 7egulation in Muscle y es and number of motor units recruited

More motor units greater force

Fast motor units greater force*nitial muscle length

;*deal< length for force generation

,ature of the motor units neural

stimulationFre@uency of stimulation

Sim le twitch: summation: and tetanus


37/47

7elationshi 8etween

Stimulus Fre@uency andForce Aeneration


38/47

Gength- ension

7elationshi in SkeletalMuscle


39/47


40/47

Force-Delocity 7elationshi&t any absolute force the s eed ofmovement is greater in muscle with

higher ercent of fast-twitch $bers he ma9imum velocity of shorteningis greatest at the lowest force

rue for both slow and fast-twitch $bers


41/47

Force-Delocity 7elationshi


42/47

Force-#ower 7elationshi&t any given velocity of movementthe ower generated is greater in a

muscle with a higher ercent offast-twitch $bers he eak ower increases withvelocity u to movement s eed of

00-600 degreesIsecond -Force decreases with increasingmovement s eed beyond this velocity


43/47

Force-#ower 7elationshi


44/47

7ece tors in MuscleMuscle s indle

/etect dynamic and static changes inmuscle lengthStretch reJe9

Stretch on muscle causes reJe9 contraction

Aolgi tendon organ 'A B(Monitor tension develo ed in muscle#revents damage during e9cessive forcegeneration

Stimulation results in reJe9 rela9ation of muscle


45/47

Muscle S indle


46/47

Aolgi endon Brgan


47/47

This powerpoint was kindly donated to

www.worldofteaching.com

http://www.worldofteaching.com is home to over athousand powerpoints submitted by teachers. This is acompletely free site and requires no registration. Pleasevisit and I hope it will help in your teaching.
http://www.worldofteaching.com/http://www.worldofteaching.com/http://www.worldofteaching.com/http://www.worldofteaching.com/

Structure Skeletal Muscle

Documents

Transcript of Structure Skeletal Muscle