MUSCLEMUSCLE

Skeletal MuscleSkeletal MuscleMuscle attaches to Muscle attaches to bones by tendons bones by tendons at both endsat both ends– The less movable The less movable

end (anchor) is end (anchor) is called the origincalled the origin

– The end where The end where bones moves is bones moves is called the insertioncalled the insertion

Skeletal Muscle (cont.)Skeletal Muscle (cont.)– Contraction pulls Contraction pulls

the insertion the insertion towards the origintowards the origin

– The middle is called The middle is called the BELLY.the BELLY.

Skeletal Muscle (cont.)Skeletal Muscle (cont.)Limb Muscles which Limb Muscles which cause angles to cause angles to decrease are called decrease are called FlexorsFlexors

Muscles that cause an Muscles that cause an angle in increase are angle in increase are called extensors.called extensors.

Abductors – lift limb Abductors – lift limb away from centeraway from center

Adductors – pull limb Adductors – pull limb towards body.towards body.

Skeletal Muscle (cont.)Skeletal Muscle (cont.)Each Muscle is Each Muscle is surrounded by a surrounded by a connective sheath connective sheath called EPIMYSIUM. called EPIMYSIUM. This sheath is This sheath is continuous with continuous with tendons.tendons.With in the muscle, With in the muscle, bundles of fibers are bundles of fibers are bound together by bound together by sheaths called sheaths called PERIMYSIUM.PERIMYSIUM.

Skeletal Skeletal muscle muscle (cont.)(cont.)

Skeletal muscle (cont.)Skeletal muscle (cont.)

Skeletal muscle (cont.)Skeletal muscle (cont.)

Skeletal muscle (cont.)Skeletal muscle (cont.)Muscle -> EpimysiumMuscle -> Epimysium

Fasicle ->Perimysium, endomysiumFasicle ->Perimysium, endomysium

Muscle Fiber -> SarcolemaMuscle Fiber -> Sarcolema

Myofibril -> striations, sarcomere, actin, Myofibril -> striations, sarcomere, actin, myosin.myosin.

SarcomereSarcomere

SarcomereSarcomereCell membrane of Cell membrane of muscle fibermuscle fiber called called Sarcolemma. Sarcolemma. – Muscle fibers contain Muscle fibers contain

long parallel Myofibrils.long parallel Myofibrils.– Myofibrils made up of Myofibrils made up of

repeating subunits calls repeating subunits calls Sarcomeres.Sarcomeres.

– These repeating These repeating bundles are seen as bundles are seen as striations.striations.

Sarcomere (cont.)Sarcomere (cont.)A sarcomere is a cylinder made up of A sarcomere is a cylinder made up of actin(thin) and myosin(thick) Filaments.actin(thin) and myosin(thick) Filaments.– These protein fibers cause the contractionThese protein fibers cause the contraction– Myosin filaments have protrusions called Myosin filaments have protrusions called

crossbridges.crossbridges.

ZonesZonesMultiple zones are identified within the Multiple zones are identified within the sarcomere.sarcomere.– ““H zone” mysoin filaments not overlapped by H zone” mysoin filaments not overlapped by

actin.actin.– ““A band” entire are occupied by myosinA band” entire are occupied by myosin

ZonesZones– ““I band” on either end of “A” where actin is, I band” on either end of “A” where actin is,

but not myosin connected to adjacent but not myosin connected to adjacent sarcomere.sarcomere.

– ““Z line” marks the end of sarcomere. Actin Z line” marks the end of sarcomere. Actin attached to.attached to.

– ““M line” middle of Sarcomere. M line” middle of Sarcomere.

This is what gives striations.This is what gives striations.

Sliding filament modelSliding filament model

Sliding Filament ModelSliding Filament ModelATP bonds to cross-ATP bonds to cross-bridges setting them in bridges setting them in a cocked position.a cocked position.Nerve signal allows CaNerve signal allows Ca++ to flood into to flood into sarcoplasmsarcoplasmCaCa++ ions attach to ions attach to binding sites on actin.binding sites on actin.ATP energizes ATP energizes crossbridge moving the crossbridge moving the filaments. ATP is filaments. ATP is broken down and broken down and released as cross released as cross bridge releasesbridge releases

Sliding filament modelSliding filament model

Sliding filament modelSliding filament model

Muscle ContractionMuscle ContractionMust have Ca+ Must have Ca+ ionsions– Used to bond with Used to bond with

actin site causing actin site causing activationactivation

– Allows crossbridges Allows crossbridges to bondto bond

– Source is Diet/bone Source is Diet/bone storagestorage

– Lack causes muscle Lack causes muscle cramps or Charlie cramps or Charlie Horses.Horses.

Muscle Contraction(cont)Muscle Contraction(cont)Must have ATP Must have ATP moleculesmolecules– Used to energize Used to energize

and flex mysin and flex mysin crossbridges.crossbridges.

– Source is Cellular Source is Cellular respiration in respiration in mitochondriamitochondria

– Lack of ATP and Lack of ATP and muscles cannot muscles cannot contract.contract.

ATP for MusclesATP for MusclesRemember?Remember?CC66HH1212OO66 + 6O + 6O22 -> 6CO -> 6CO22 + 6H + 6H22O + ATPO + ATP

ADP + P + “e” -> ATP(38)ADP + P + “e” -> ATP(38)

ATPATP– Glucose and OGlucose and O2 2 necessary necessary

for respiration to take for respiration to take place.place.

– Cells that are activated Cells that are activated excessively and cannot excessively and cannot supply Osupply O22 fast enough go fast enough go into Ointo O22 debt. debt.

– Cells will react and Cells will react and contract, but use Anaerobic contract, but use Anaerobic Respiration.Respiration.

CC66HH1212OO66 -> 2C -> 2C33HH66OO33 + 2ATP + 2ATP

ATP (anaerobic)ATP (anaerobic)– Results in “Oxygen Debt” or Results in “Oxygen Debt” or

lactic acid formationlactic acid formation– Causes Muscle FatigueCauses Muscle Fatigue– More lactic acid = more pain More lactic acid = more pain

= more fatigue= more fatigue– Recovery allows more O2, Recovery allows more O2,

which breaks down lactic which breaks down lactic acid, decreasing pain and acid, decreasing pain and increasing ATP synthesis.increasing ATP synthesis.

– Body changes hrt and Resp Body changes hrt and Resp rates to bring in more rates to bring in more glucose and Oglucose and O22