Chapter 5 A Muscular System.pdf123456789

for biological science use

1. EssentialsofHumanAnatomy&Physiology
For. Romualdo B. De Guzman, Jr., MSA, Mbio
Associate Professor II
Chapter5
The Muscular System

2. TheMuscularSystem
Musclesareresponsibleforalltypesof
bodymovement
Threebasicmuscletypesarefoundin
thebody
Skeletalmuscle
Cardiacmuscle
Smoothmuscle
Slide6.2
Copyright©2003PearsonEducation,Inc.publishingasBenjaminCummings

3. CharacteristicsofMuscles
Musclecellsareelongated
(musclecell=musclefiber)
Contractionofmusclesisduetothe
movementofmyofilaments–themusclecell
equivalentofthemicrofilamentsofcytoskeletons
Allmusclessharesome
terminology
Prefixmyoreferstomuscle
Prefixsarcoreferstoflesh

4. SkeletalMuscleCharacteristics
Mostareattachedbytendonstobones
Cellsaremultinucleate&cigar-shaped
Striated–havevisiblebanding
Voluntary–subjecttoconsciouscontrol
Cellsaresurroundedandbundledby
connectivetissue

5. ConnectiveTissueWrappingsof
SkeletalMuscle
Endomysium–
connectivetissue
aroundsingle
musclefiber
Perimysium–
aroundafascicle
(bundle)offibers
Figure6.1

6. ConnectiveTissueWrappingsof
SkeletalMuscle
Epimysium–coversthe
entireskeletalmuscle
Fascia–ontheoutside
oftheepimysium
Figure6.1

7. SkeletalMuscleAttachments
Epimysiumblendsintoaconnective
tissueattachment
Tendon–cord-likestructure
Aponeuroses–sheet-likestructure
Sitesofmuscleattachment
Bones
Cartilages
Connectivetissuecoverings

8. SmoothMuscleCharacteristics
Hasnostriations
Spindle-shapedcells
Singlenucleus
Involuntary–no
consciouscontrol
Foundmainlyinthe
wallsofholloworgans
–visceral
Arrangedintwosheets
orlayers Figure6.2a

9. CardiacMuscleCharacteristics
Hasstriations
Usuallyhasa
singlenucleus
Joinedtoanother
musclecellatan
intercalateddisc
Involuntary
Foundonlyinthe
heart Figure6.2b

10. FunctionofMuscles
Producemovement
Maintainposture
Stabilizejoints
Generateheat

11. MicroscopicAnatomyofSkeletal
Muscle
Cellsaremultinucleate
Nucleiarejustbeneaththesarcolemma
–plasmamembrane
Figure6.3a

12. MicroscopicAnatomyofSkeletal
Muscle
Sarcolemma–specializedplasma
membrane
Sarcoplasmicreticulum–specialized
smoothendoplasmicreticulum
Figure6.3a

13. MicroscopicAnatomyofSkeletal
Muscle
Myofibril
Bundlesofmyofilaments
Myofibrilsarealignedtogivedistinctbands
Iband=
lightband
Aband=
darkband
Figure6.3b

14. MicroscopicAnatomyofSkeletal
Muscle
Sarcomere
Contractileunitofamusclefiber
Figure6.3b

15. MicroscopicAnatomyof
Skeletal
Muscle
Organizationofthesarcomere
Thickfilaments=myosinfilaments
Composedoftheproteinmyosin
HasATPaseenzymes
Figure6.3c

16. MicroscopicAnatomyofSkeletal
Muscle
Organizationofthesarcomere
Thinfilaments=actinfilaments
Composedoftheproteinactinand
regulatoryproteins
Figure6.3c

17. MicroscopicAnatomyofSkeletal
Muscle
Myosinfilamentshaveheads
(extensions,orcrossbridges)
Myosin
and
actinoverlap
somewhat
Figure6.3d

18. MicroscopicAnatomyofSkeletal
Muscle
Atrest,thereisabarezonethatlacks
actinfilaments–theHzone
Sarcoplasmic
reticulum
(SR)–for
storageof
calcium
Figure6.3d

19. PropertiesofSkeletalMuscle
Activity
Irritability–abilitytoreceiveand
respondtoastimulus
Contractility–abilitytoshortenwhenan
adequatestimulusisreceived

20. NerveStimulustoMuscles
Skeletal
musclesmust
bestimulated
byanerveto
contract
Motorunit
Oneneuron
Musclecells
stimulatedby
thatneuron

21. NerveStimulustoMuscles
Neuromuscular
junctions–
associationsite
ofnerveand
muscle
Figure6.5b

22. NerveStimulustoMuscles
Synapticcleft–
gapbetween
nerveand
muscle
Nerveand
muscledonot
makecontact
Areabetween
nerveandmuscle
isfilledwith
interstitialfluid

23. TransmissionofNerveImpulseto
Muscle
Neurotransmitter–chemicalreleasedby
nerveuponarrivalofnerveimpulse
Theneurotransmitterforskeletalmuscleis
acetylcholine(ACh)
Neurotransmitterattachestoreceptorson
thesarcolemma
Sarcolemmabecomestemporarily
permeabletosodium(Na+)thatrushesinto
thecellgivingitapositivecharge

24. TransmissionofNerveImpulseto
Muscle
Sodiumrushingintothecellgeneratesan
actionpotential
Oncestarted,musclecontractioncannotbe
stopped
Toreturntorestingstate
Potassiumions(K
+
)diffuseoutofthecell
Sodium-potassiumpumppumpssodiumand
potassiumbacktotheiroriginalpositions

25. TheSlidingFilamentTheoryof
MuscleContraction
Activationbynerve
causesmyosin
heads(cross
bridges)toattachto
bindingsitesonthe
thinfilament
Myosinheadsthen
bindtothenextsite
ofthethinfilament
whenATPispresent
Figure6.7

26. TheSlidingFilamentTheoryof
MuscleContraction
Thiscontinuedaction
causesaslidingofthe
myosinalongtheactin
Theresultisthatthe
muscleisshortened
(contracted)
Calciumionsare
required
fortheattachmentof
myosincrossbridgesto
actin
Figure6.7

27. TheSlidingFilamentTheory
Figure6.8

28. ContractionofaSkeletalMuscle
Musclefibercontractionis“allornone”
Withinaskeletalmuscle,notallfibersmay
bestimulatedduringthesameinterval
Differentcombinationsofmusclefiber
contractionsmaygivedifferingresponses
Gradedresponses–differentdegreesof
skeletalmuscleshortening
Changingfrequencyofstimulation
Changingnumberofmusclecellsstimulated

29. TypesofGradedResponses
Twitch
Single,briefjerkycontraction
Notanormalmusclefunction
Figure6.9a,b

30. TypesofGradedResponses
Tetanus(summingofcontractions)
Onecontractionisimmediatelyfollowedby
another
Themuscledoes
notcompletely
returntoa
restingstate
Theeffects
areadded
Figure6.9a,b

31. TypesofGradedResponses
Unfused(incomplete)tetanus
Somerelaxationoccursbetween
contractions
Theresultsaresummed
Figure6.9c,d

32. TypesofGradedResponses
Fused(complete)tetanus
Noevidenceofrelaxationbeforethe
followingcontractions
Theresultisasustainedmusclecontraction
Figure6.9c,d

33. MuscleResponsetoStrongStimuli
Muscleforcedependsuponthenumber
offibersstimulated
Morefiberscontractingresultsin
greatermuscletension
Musclescancontinuetocontractunless
theyrunoutofenergy

34. EnergyforMuscleContraction
Initially,musclesusedstoredATPfor
energy
BondsofATParebrokentoreleaseenergy
Only4-6secondsworthofATPisstoredby
muscles
Afterthisinitialtime,otherpathways
mustbeutilizedtoproduceATP

35. EnergyforMuscleContraction
Directphosphorylation
Onlymusclecellscontain
creatinephosphate(CP)
CPisahigh-energy
molecule
AfterATPisdepleted,ADPis
left
CPtransfersenergytoADP,
toregenerateATP
CPsuppliesareexhaustedin
about20seconds
Figure6.10a

36. EnergyforMuscleContraction
AerobicRespiration
Seriesofmetabolic
pathwaysthatoccurin
themitochondria
Glucoseisbrokendown
tocarbondioxideand
water,releasingenergy
Thisisaslowerreaction
thatrequirescontinuous
oxygen
Figure6.10c

37. EnergyforMuscleContraction
Anaerobicglycolysis
Reactionthatbreaks
downglucosewithout
oxygen
Glucoseisbrokendown
topyruvicacidto
producesomeATP
Pyruvicacidis
convertedtolacticacid
Figure6.10b

38. EnergyforMuscleContraction
Anaerobicglycolysis
(continued)
Thisreactionisnotas
efficient,butisfast
Hugeamountsof
glucoseareneeded
Lacticacidproduces
musclefatigue
Figure6.10b

39. MuscleFatigueandOxygenDebt
Whenamuscleisfatigued,itisunableto
contractevenwhenstimulated
Thecommonreasonformusclefatigueis
oxygendebt
Oxygenmustbe“repaid”totissuetoremove
oxygendebt
Oxygenisrequiredtogetridofaccumulated
lacticacid
Increasingacidity(fromlacticacid)andlack
ofATPcausesthemuscletocontractless

40. TypesofMuscleContractions
Isotoniccontractions–“sametone”or
tension
Myofilamentsareabletoslidepasteach
otherduringcontractions
Themuscleshortens
Isometriccontractions–“same
measurement”orlength
Tensioninthemusclesincreases
Themuscleisunabletoshorten

41. MuscleTone
Somefibersarecontractedevenina
relaxedmuscle
Differentfiberscontractatdifferent
timestoprovidemuscletone
Theprocessofstimulatingvarious
fibersisunderinvoluntarycontrol

42. EffectsofExerciseonMuscle
Resultsofincreasedmuscleuse
Increaseinmusclesize
Increaseinmusclestrength
Increaseinmuscleefficiency
Musclebecomesmorefatigueresistant

43. MusclesandBodyMovements
Movementis
attaineddueto
amuscle
movingan
attachedbone
Figure6.12

44. MusclesandBodyMovements
Musclesare
attachedtoatleast
twopoints
Origin–
attachmenttoan
immoveablebone
Insertion–
attachmenttoa
movablebone
Figure6.12

45. TypesofOrdinaryBodyMovements
Flexion–brings2bonesclosertogether
Extension–increasesdistancebetween2
bones
Rotation
Abduction–movingalimbawayfromthe
midlineofthebody
Adduction–movingalimbtowardthemidline
Circumduction–combinationofallofthe
aboveexceptrotation

46. BodyMovements
Figure6.13

47. SpecialMovements
Dorsiflexion–liftingthefoot
Plantarflexion–depressingthefoot
Inversion–turnfootinward
Eversion–turnfootoutward
Supination–handfacingupward
Pronation–handfacingdownward
Opposition–touchingthumbtootherfingers

48. TypesofMuscles
Primemover–musclewiththemajor
responsibilityforacertainmovement
Antagonist–musclethatopposesor
reversesaprimemover
Synergist–musclethataidsaprime
moverinthesamemovementandhelps
preventrotationorunwantedmovement
Fixator–stabilizestheoriginofa
prime
moversoalltensioncanbeusedto
movetheinsertionbone

49. NamingofSkeletalMuscles
Directionofmusclefibers
Example:rectus(straight)oroblique(slanted)
Relativesizeofthemuscle
Examples:maximus(largest),
minimus
(smallest),longus(long)

50. NamingofSkeletalMuscles
Locationofthemuscle
Example:manymusclesarenamed
forbones(e.g.,temporalis,whichis
nearthetemporalbone)
Numberoforigins
Example:biceps,triceps,quadriceps
(two,three,orfouroriginsorheads)

51. NamingofSkeletalMuscles
Locationofthemuscle’soriginand
insertion
Example:sterno(onthesternum)cleido
(clavicle)mastoid(onthemastoidprocess)
Shapeofthemuscle
Example:deltoid(triangular)
Actionofthemuscle
Example:flexorandextensor(flexesor
extendsabone)

52. HeadandNeckMuscles
Figure6.14

53. TrunkMuscles
Figure6.15

54. DeepTrunkandArmMuscles
Figure6.16

55. MusclesofthePelvis,Hip,andThigh
Figure6.18c

56. MusclesoftheLowerLeg
Figure6.19

57. SuperficialMuscles:Anterior
Figure6.20

58. SuperficialMuscles:Posterior
Figure6.21