anatomy presentation ho 5(Muscles)

8/14/2019 anatomy presentation ho 5(Muscles)

1/38

MusclesMuscles

Muscle is one of our 4 tissue typesMuscle is one of our 4 tissue types

and muscle tissue combined withand muscle tissue combined withnerves, blood vessels, and variousnerves, blood vessels, and various

connective tissues is what makesconnective tissues is what makes

up those muscle organs that areup those muscle organs that arefamiliar to us.familiar to us.

Muscles are quite complex and asMuscles are quite complex and as

well find out, they are a marvel ofwell find out, they are a marvel of 1


2/38


3/38

MuscleMuscle

FunctionsFunctions Maintenance of postureMaintenance of posture

Muscle contraction isMuscle contraction is

constantly allowing us toconstantly allowing us to

remain upright.remain upright.

The muscles of your neckThe muscles of your neck

are keeping your head upare keeping your head up

right now.right now.

As you stand, your legAs you stand, your leg

muscles keep you on twomuscles keep you on two

feet.feet.2.2. ThermogenesisThermogenesis

Generation of heat. OccursGeneration of heat. Occurs

via shivering anvia shivering an

involuntary contraction ofinvoluntary contraction ofskeletal muscle.skeletal muscle.3


4/38

MuscleMuscle

FunctionsFunctions1.1. Stabilization ofStabilization of

jointsjoints Muscles keep theMuscles keep the

tendons that cross thetendons that cross thejoint nice and taut.joint nice and taut.

This does a wonderfulThis does a wonderfuljob of maintaining thejob of maintaining theintegrity of the joint.integrity of the joint.

ll the things muscles do fall under one of these 4 categories.

4


5/38

3 Types of Muscle Tissue3 Types of Muscle Tissue

5


6/38

Characteristics of MuscleCharacteristics of Muscle

TissueTissue1.1. ExcitabilityExcitability

The ability to receive and respond to aThe ability to receive and respond to astimulusstimulus In skeletal muscle, the stimulus is aIn skeletal muscle, the stimulus is a

neurotransmitter (chemical signal) release by aneurotransmitter (chemical signal) release by aneuron (nerve cell).neuron (nerve cell).

In smooth muscle, the stimulus could be aIn smooth muscle, the stimulus could be aneurotransmitter, a hormone, stretch,neurotransmitter, a hormone, stretch, pH,pH, PcoPco22,,

oror PoPo22. (. (the symbolthe symbol means a change inmeans a change in)) In cardiac muscle, the stimulus could be aIn cardiac muscle, the stimulus could be a

neurotransmitter, a hormone, or stretch.neurotransmitter, a hormone, or stretch.

The response is the generation of anThe response is the generation of anelectrical impulse that travels along theelectrical impulse that travels along the

plasma membrane of the muscle cell.plasma membrane of the muscle cell. 6


7/38

Characteristics of MuscleCharacteristics of Muscle

TissueTissue1.1. ContractilityContractility

The ability to shorten forcibly whenThe ability to shorten forcibly when

adequately stimulated.adequately stimulated. This is the defining property of muscle tissue.This is the defining property of muscle tissue.

2.2. ExtensibilityExtensibility The ability to be stretchedThe ability to be stretched

3.3. ElasticityElasticity The ability to recoil and resume originalThe ability to recoil and resume original

length after being stretched.length after being stretched.

7

Sk l l l h


8/38

Skeletal Muscle theSkeletal Muscle the

organorgan

Skeletal muscleSkeletal muscleorgans areorgans aredominated bydominated bymuscle tissue butmuscle tissue butalso containalso contain

nervous, vascularnervous, vascularand assortedand assortedconnective tissues.connective tissues.

The whole muscle isThe whole muscle issurrounded by asurrounded by a

layer of denselayer of denseirregular connectiveirregular connectivetissue known as thetissue known as theepimysium.(epimysium.(epiepi= ?,= ?,mysiummysium=muscle).=muscle).

8


9/38

SkeletalSkeletal

Muscle theMuscle the

organorgan

Epimysium surroundsEpimysium surroundsseveral bundles knownseveral bundles knownas fascicles.as fascicles.

Each fascicle is a bundleEach fascicle is a bundleof super-long skeletalof super-long skeletal

muscle cells (musclemuscle cells (musclefibers), surrounded by afibers), surrounded by alayer of dense irregularlayer of dense irregularCT called the perimysiumCT called the perimysium((periperi=around).=around).

Each muscle cell extendsEach muscle cell extends

the length of the wholethe length of the wholemuscle organ and ismuscle organ and issurrounded by a finesurrounded by a finelayer of loose connectivelayer of loose connectivetissue, the endomysium.tissue, the endomysium.

The epi-, peri-, andThe epi-, peri-, andendomysium are allendomysium are all

continuous with onecontinuous with oneanother.another.

9


10/38

In this photomicrograph, you should notice: the epimysium on the left,the multiple fascicles, the translucent perimysium partitioning them , andthe multiple muscle fibers making up the fascicles.

10


11/38

Skeletal MuscleSkeletal Muscle

Blood & Nerve Blood & Nerve

SupplySupply Each skeletal muscleEach skeletal muscle

is typically suppliedis typically suppliedby one nerve, anby one nerve, anartery and one orartery and one ormore veins.more veins. What is the functionWhat is the function

of each of these 3of each of these 3items?items?

They all enter/exitThey all enter/exitvia the connectivevia the connective

tissue coverings andtissue coverings and 11

Sk l l M lSk l t l M l


12/38


AttachmentsAttachments

Most span joints and are attached to bones.Most span joints and are attached to bones. The attachment of the muscle to the immoveableThe attachment of the muscle to the immoveable

bone in a joint is its origin, while the attachmentbone in a joint is its origin, while the attachmentto the moveable bone is its insertion.to the moveable bone is its insertion.

12


13/38

Indirect attachmentsare typical. Themuscle CT extendsand forms either acordlike structure (atendon) or asheetlike structure(aponeurosis) whichattaches to the

periosteum orperichondrium.

Muscle attachmentsmay be direct or

indirect.

Direct attachments are lesscommon. The epimysium is fusedto a periosteum or aperichondrium.

13


14/38


MicroanatomyMicroanatomy

Each skeletal muscle cell is knownEach skeletal muscle cell is known

as a skeletal muscle fiberas a skeletal muscle fiberbecause they are so long.because they are so long. Their diameter can be up to 100um and theirTheir diameter can be up to 100um and their

length can be as long as 30cm.length can be as long as 30cm. Theyre so large because a single skeletalTheyre so large because a single skeletal

muscle cell results from the fusion of hundredsmuscle cell results from the fusion of hundredsof embryonic precursor cells called myoblasts.of embryonic precursor cells called myoblasts. A cell made from the fusion of many others isA cell made from the fusion of many others is

known as a syncytium.known as a syncytium. Each skeletal muscle fiber will have multipleEach skeletal muscle fiber will have multiple

nuclei. Why?nuclei. Why? 14


15/38

MuscleMuscle

fiber PM isfiber PM isknown asknown assarcolemsarcolemmama

MuscleMusclefiberfiber

cytoplasmcytoplasmis knownis knownasassarcoplassarcoplasmm

Sarcoplasm has lots of mitochondria (why?), lots ofglycogen granules (to provide glucose for energy needs)

as well as myofibrils and sarcoplasmic reticuli.

Sarcolemma has invaginations that penetrate throughthe cell called transverse tubules orT tubules.

15

S l iS l i


16/38

SarcoplasmicSarcoplasmic

ReticulumReticulum

Muscle cell versionMuscle cell versionof the smoothof the smoothendoplasmicendoplasmicreticulum.reticulum.

Functions as aFunctions as acalcium storagecalcium storagedepot in muscledepot in musclecells.cells.

Loose network ofLoose network ofthis membranethis membranebound organellebound organellesurrounds all thesurrounds all themyofibrils in amyofibrils in a

muscle fiber. Wemuscle fiber. Wewill see wh this is

16


17/38

MyofibrilsMyofibrils Each muscle fiber contains rodlike structuresEach muscle fiber contains rodlike structures

called myofibrils that extend the length of thecalled myofibrils that extend the length of thecell. They are basically long bundles of proteincell. They are basically long bundles of proteinstructures called myofilaments and their actionsstructures called myofilaments and their actionsgive muscle the ability to contract.give muscle the ability to contract.

The myofilaments are classified as thick filamentsThe myofilaments are classified as thick filaments

and thin filaments.and thin filaments.

17


18/38

18

M fil tM fil t


19/38

MyofilamentMyofilament

ss

2 types of myofilaments (thick & thin) make up2 types of myofilaments (thick & thin) make upmyofibrils.myofibrils.

Thick myofilaments are made the proteinThick myofilaments are made the protein

myosinmyosinA single myosin protein

resembles 2 golf clubswhose shafts have beentwisted about one another

About 300 of these myosinmolecules are joinedtogether to form a singlethick filament

19


20/38

Each thin filament is made up of 3 differentEach thin filament is made up of 3 different

types of protein: actin, tropomyosin, andtypes of protein: actin, tropomyosin, and

troponin.troponin. Each thin filament consists of a long helicalEach thin filament consists of a long helical

double strand. This strand is a polymer thatdouble strand. This strand is a polymer that

resembles a string of beads. Each bead is theresembles a string of beads. Each bead is the

globular protein actin. On each actin subunit,globular protein actin. On each actin subunit,

there is athere is a myosin binding sitemyosin binding site..

Loosely wrapped around the actin helix andLoosely wrapped around the actin helix and

covering the myosin binding site is thecovering the myosin binding site is the

filamentous protein, tropomyosin.filamentous protein, tropomyosin.

Bound to both the actin and the tropomyosin is aBound to both the actin and the tropomyosin is a

trio of proteins collectively known as troponin.trio of proteins collectively known as troponin.

20


21/38

Note the relationship between the thin and thick filaments

21


22/38

MyofibrilsMyofibrils

Each myofibril is made up 1000s of repeatingEach myofibril is made up 1000s of repeatingindividual units known as sarcomeres (picturedindividual units known as sarcomeres (picturedbelow)below)

Each sarcomere is an ordered arrangement ofEach sarcomere is an ordered arrangement of

thick and thin filaments. Notice that it has:thick and thin filaments. Notice that it has: regions of thin filaments by themselves (pinkishregions of thin filaments by themselves (pinkishfibers)fibers)

a region of thick filaments by themselves (purplea region of thick filaments by themselves (purplefibers)fibers)

regions of thick filaments and thin filamentsregions of thick filaments and thin filamentsoverlapping.overlapping.

22


23/38

SarcomereSarcomere

The sarcomere is flanked by 2 proteinThe sarcomere is flanked by 2 proteinstructures known as Z discs.structures known as Z discs.

The portion of the sarcomere whichThe portion of the sarcomere whichcontains the thick filament is known as thecontains the thick filament is known as theA band.A band. AA stands forstands for anisotropicanisotropic which is awhich is afancy way of saying that it appears darkfancy way of saying that it appears darkunder the microscope.under the microscope. The A band contains a zone of overlap (btwnThe A band contains a zone of overlap (btwn

thick & thin filaments) and an H zone whichthick & thin filaments) and an H zone which

contains only thick filamentscontains only thick filaments

23


24/38

The portionThe portionof theof thesarcomeresarcomere

which doeswhich doesnot containnot containany thickany thickfilament isfilament isknown as theknown as the

I bandI band. The I. The Ibandbandcontains onlycontains onlythin filamentthin filamentand is lightand is light

under theunder themicroscopemicroscope((it isit isisotropicisotropic)).. One I bandOne I band

is actuallyis actually

In the middle of the H zone is a structurecalled the M line which functions to hold thethick filaments to one another

24


25/38

Here we have several different crossHere we have several different cross

sections of a myofibril. Why are theysections of a myofibril. Why are they

different?different?

25

Here is a longitudinal section of skeletal muscleHere is a longitudinal section of skeletal muscle


26/38

Here is a longitudinal section of skeletal muscle.Here is a longitudinal section of skeletal muscle.

See the multiple nuclei (N) pressed against theSee the multiple nuclei (N) pressed against the

side of the muscle fibers. The light I bands andside of the muscle fibers. The light I bands and

dark A bands are labeled for you. What do youdark A bands are labeled for you. What do you

think the F stands for?think the F stands for?

26


27/38

T-Tubules and the SRT-Tubules and the SR EachEach

musclemusclefiber hasfiber has

many T-many T-tubulestubules TypicallyTypically

eacheachmyofibrilmyofibrilhas ahas a

branch ofbranch ofa T-tubulea T-tubuleencirclingencirclingit at eachit at eachA-IA-Ijunctionjunction

At each A-IAt each A-Ijunction,junction,the SR willthe SR willexpand andexpand and

form aform adilated sacdilated sac

Each T-tubule will be flanked by aterminal cisterna. This forms aso-called triad consisting of 2terminal cisternae and one T-

tubule branch. 27


28/38

28


29/38

Smooth MuscleSmooth Muscle Involuntary, non-striated muscle tissueInvoluntary, non-striated muscle tissue Occurs within almost every organ, formingOccurs within almost every organ, forming

sheets, bundles, or sheaths around othersheets, bundles, or sheaths around othertissues.tissues.

Cardiovascular system:Cardiovascular system: Smooth muscle in blood vessels regulates bloodSmooth muscle in blood vessels regulates blood

flow through vital organs. Smooth muscle alsoflow through vital organs. Smooth muscle alsohelps regulate blood pressure.helps regulate blood pressure. Digestive systems:Digestive systems:

Rings of smooth muscle, called sphincters,Rings of smooth muscle, called sphincters,regulate movement along internal passageways.regulate movement along internal passageways.

Smooth muscle lining the passagewaysSmooth muscle lining the passageways

alternates contraction and relaxation to propelalternates contraction and relaxation to propelmatter through the alimentary canal.matter through the alimentary canal.

29


30/38

Smooth MuscleSmooth Muscle

Integumentary system:Integumentary system: Regulates blood flow to the superficial dermisRegulates blood flow to the superficial dermis Allows for piloerectionAllows for piloerection

Respiratory systemRespiratory system Alters the diameter of the airways and changesAlters the diameter of the airways and changes

the resistance to airflowthe resistance to airflow

Urinary systemUrinary system Sphincters regulate the passage of urineSphincters regulate the passage of urine Smooth muscle contractions move urine intoSmooth muscle contractions move urine into

and out of the urinary bladderand out of the urinary bladder

30


31/38


Reproductive systemReproductive system MalesMales

Allows for movement of sperm along the maleAllows for movement of sperm along the male

reproductive tract.reproductive tract.

Allows for secretion of the non-cellular components ofAllows for secretion of the non-cellular components of

semensemen

Allows for erection and ejaculationAllows for erection and ejaculation

FemalesFemales Assists in the movement of the egg (and of sperm)Assists in the movement of the egg (and of sperm)

through the female reproductive tractthrough the female reproductive tract

Plays a large role in childbirthPlays a large role in childbirth

31


32/38


Smooth muscle cells:Smooth muscle cells: Are smaller: 5-10um inAre smaller: 5-10um in

diameter and 30-200um indiameter and 30-200um inlengthlength

Are uninucleate: contain 1Are uninucleate: contain 1centrally placed nucleuscentrally placed nucleus

Lack any visible striationsLack any visible striations Lack T-tubulesLack T-tubules Have a scanty sarcoplasmicHave a scanty sarcoplasmic

reticulumreticulum Smooth muscle tissue is innervated by the autonomic nervous

system unlike skeletal muscle which is innervated by the somaticnervous system (over which you have control)

Only the endomysium is present. Nor perimysium or epimysium.

32


33/38


Smooth muscle is always maintaining aSmooth muscle is always maintaining anormal level of activity creatingnormal level of activity creatingmuscle tone.muscle tone.

Smooth muscle can respond to stimuliSmooth muscle can respond to stimuli

by altering this tone in either direction.by altering this tone in either direction. Smooth muscle can be inhibited and relaxSmooth muscle can be inhibited and relax Smooth muscle can be excited and contractSmooth muscle can be excited and contract

Possible stimuli includePossible stimuli include

neurotransmitters, hormones,neurotransmitters, hormones, pH,pH, PcoPco22,, PoPo22, metabolites (such as lactic, metabolites (such as lactic

acid, ADP), or even stretch.acid, ADP), or even stretch.

33


34/38

Types of Smooth MuscleTypes of Smooth Muscle

Smooth muscle varies widely fromSmooth muscle varies widely from

organ to organ in terms of:organ to organ in terms of:

Fiber arrangementFiber arrangement Responsiveness to certain stimuliResponsiveness to certain stimuli

How would the types of integral proteins that aHow would the types of integral proteins that a

smooth muscle cell contained contribute to thissmooth muscle cell contained contribute to this??

Broad types of smooth muscle:Broad types of smooth muscle: Single unit (a.k.a. visceral)Single unit (a.k.a. visceral)

Multi unitMulti unit

34


35/38

Single Unit Smooth MuscleSingle Unit Smooth Muscle More commonMore common Cells contract as a unitCells contract as a unit

because they are allbecause they are allconnected by gapconnected by gap

junctions - proteinjunctions - proteincomplexes that span thecomplexes that span thePMs of 2 cells allowingPMs of 2 cells allowingthe passage of ionsthe passage of ionsbetween them, i.e.,between them, i.e.,allowing theallowing thedepolarization of one todepolarization of one tocause the depolarizationcause the depolarizationof another.of another.

Some will contractSome will contractrhythmically due torhythmically due topacemaker cells that havepacemaker cells that havea spontaneous rate ofa spontaneous rate ofdepolarization.depolarization.

35


36/38

Single Unit Smooth MuscleSingle Unit Smooth Muscle

Not directly innervated.Not directly innervated.Diffuse release ofDiffuse release ofneurotransmitters atneurotransmitters atvaricosities (swellingsvaricosities (swellingsalong an axon).along an axon).

Responsive to variety ofResponsive to variety ofstimuli including stretchstimuli including stretchand concentrationand concentrationchanges of variouschanges of variouschemicalschemicals

Found in the walls ofFound in the walls of

the digestive tract,the digestive tract,urinary bladder, andurinary bladder, andother organsother organs

36

Multi Unit SmoothMulti Unit Smooth


37/38

Multi-Unit SmoothMulti-Unit Smooth

MuscleMuscle

Innervated in motor unitsInnervated in motor unitscomparable to those ofcomparable to those ofskeletal musclesskeletal muscles

No gap junctions. Each fiberNo gap junctions. Each fiberis independent of all theis independent of all theothers.others.

Responsible to neural &Responsible to neural &hormonal controlshormonal controls

No pacemaker cellsNo pacemaker cells Less commonLess common Found in large airways to theFound in large airways to the

lungs, large arteries,lungs, large arteries,arrector pili, internal eyearrector pili, internal eyemuscles (e.g., the musclesmuscles (e.g., the musclesthat cause dilation of thethat cause dilation of thepupil)pupil)

Why is good to have theWhy is good to have thedigestive smooth muscledigestive smooth muscle37

CardiacCardiac


38/38

CardiacCardiac

MuscleMuscle

Striated, involuntaryStriated, involuntarymusclemuscle

Found in walls of theFound in walls of theheartheart

Consists of branchingConsists of branching

chains of stocky musclechains of stocky musclecells. Uni- orcells. Uni- orbinucleate.binucleate.

Has sarcomeres & T-Has sarcomeres & T-tubulestubules

Cardiac muscle cells areCardiac muscle cells arejoined by structuresjoined by structurescalled intercalated discscalled intercalated discs which consist of which consist of

d dd d

Notice the branchingand the intercalateddisc, indicated by theblue arrow.

38

Documents

anatomy presentation ho 5(Muscles)