Skeletal System

Muscular SystemWhat is the purpose of muscle?MovementPostureStabilize jointsGenerate heatTypes of MuscleCompare all three muscle types.Look at:Location/number of nucleiAssociated structuresWhat controls the muscle contraction?

You should be able to answer the Practice questions on page 301when finished.Skeletal Muscle

Smooth Muscle

Cardiac Muscle

Skeletal MuscleStructure of Skeletal MuscleMuscle (wrapped in fascia, epimysium) Fascicles (bundles of muscle fibers, wrapped in perimysium) Muscle Fibers (cells, wrapped in endomysium)

Myofibrils

FilamentsStructure of Skeletal Muscle

Skeletal Muscle FibersSkeletal muscle fiber = single muscle cellMultinucleatedStriatedMyofibrils: myosin (thick filaments) and actin (thin filaments)Myosin and actin alternate forming striations (light and dark areas)Skeletal Muscle FibersSarcomeres pattern of actin/myosin alternating throughout muscle fiberContractile unit of muscleSarcolemma cell membrane of muscle cellsSarcoplasm cytoplasm of muscle cells

Muscle Videohttp://www.youtube.com/watch?v=EdHzKYDxrKc Gross Muscle Anatomy

Muscle

Epimysium

Endomysium

Perimysium

Fascicle

Muscle fiber/cell

Myofibrils

Sarcolemma

Sarcoplasm

Skeletal Muscle Layout

Actin

Myosin

Z line

I band

A band

H zone

Sarcomere

Sarcoplasmic ReticulumMuscle Filaments (Myofibrils)Myosin: composed of many myosin fibersHeads and tailsForms cross-bridge with actinHeads of myosin come in contact with actin during muscle contractionActin: double strands twisted into a helixTroponin wraps around actinTropomyosin contact point for myosinMuscle Filaments: Actin

Troponin

Tropomyosin

Thin filamentMuscle Filaments: Myosin

Heads

Tails

Thick filamentSarcoplasmic ReticulumCorresponds with the endoplasmic reticulum in other cells

CisternaeEnlarged portions of SR on either side of the T tubuleTransverse tubules (T tubules)Extends into sarcoplasm, contains extracellular fluidSarcoplasmic Reticulum

T tubule

Sarcoplasmic reticulum

Sarcomere

Myosin

Actin

Sarcolemma

Mitochondria

MyofibrilSkeletal Muscle ContractionMuscle ContractionOccurs when thin and thick filaments slide past one anotherShortens sarcomeres/whole muscle cell

Stimulated by neuronsNeuromuscular JunctionMotor neurons control skeletal muscle

Neuromuscular junction: where nerve cell synapses with the muscleMotor end plate: specialized part of muscle to receive neural signals (higher amount of mitochondria, nuclei/SR)One motor neuron can innervate many muscle cellsMotor unit: neuron AND the muscle(s) it controls

Neuromuscular JunctionSynaptic CleftSeparation between the neuron and the muscleNerve fiber releases synaptic vesicles containing neurotransmitters into the synaptic cleftNeurotransmitter for Skeletal Muscle ContractionAcetylcholine (ACh)Increases membrane permeability to sodiumSodium influx causes muscle impulse which transmits the contraction along the muscleThrough the sarcoplasmic reticulum, cisternae, T tubulesSliding Filament TheorySarcomeres shorten through movement of actin and myosin sliding past one another, not shortening themselvesH zone, A bands narrowZ lines come closer togetherNeeds ATP (energy), Ca2+Sliding Filament Theoryhttp://www.youtube.com/watch?v=Vlchs4omFDM Summarize the contraction cycle in your textbooks (pg. 292)

Summarize relaxationWhat enzyme is needed? What does this enzyme do?When ACh breaks down, what happens?

Sliding Filament TheoryMyoglobinCellular respiration is critical in muscle contraction

Myoglobin stores oxygen in muscle cellsGives muscle the reddish/brown colorSimilar to what other molecule?

Anaerobic ThresholdLactic acid thresholdMuscle forms lactic acid in absence of oxygenAnaerobic respiration

Muscle FatigueLoss of ability to contractCaused by: decrease in blood flow, ion imbalances, accumulation of lactic acid in muscle tissue

Cramps: sustained contraction of muscleChanges in extracellular matrix of muscle causes extended contractionHeat ProductionMuscle is a major source of body heatBlood transfers heat throughout body

Fast Twitch vs. Slow Twitch MusclesUse your textbook to compare and contrast fast twitch and slow twitch muscles

Give some examples for the ideal muscle types for different activitiesUse human and animals in your answer.Major Skeletal MusclesRemembering Muscle Nameshttp://www.youtube.com/watch?v=bUnzlkZGkvM

Muscles of the Headhttp://www.gwc.maricopa.edu/class/bio201/head/head1b.htm

Muscles of facial expressionMuscles of mastication

Muscles of Facial ExpressionEpicraniusFrontalisTemporalis Orbicularis occuliOrbicularis orisBuccinator

Muscles of Facial Expression

Muscles of MasticationMasseter elevates mandibleTemporalis elevates mandibleMuscles of the NeckSternocleidomastoid pulls head to one side, flexes neck, elevates sternum

Muscles of Mastication

Muscles of the Pectoral GirdleTrapezius rotates scapula, pull scapula (raise, medial, downward)Rhomboid major connects scapula with vertebraeRhomboid minor smaller than rhomboid major, connects scapula with vertebraeLevator scapulae elevates scapula

Muscles of Pectoral Girdle

Muscles of the Pectoral Girdle

Levator scapulaeTrapeziusRhomboid major and minor(external oblique)(Latissimus dorsi)(Deltoid)Before we can discuss the movement of the armBefore we can discuss the movement of the armWe need to get into the muscle actions:Flexor flexion bend at joint so angle between two parts gets closer togetherExtensor extension straightening joint so angle between two parts increasesAbductors abduction movement away from the midlineAdductors adduction movement toward the midlineRotators movement around an axis Muscles that move the Upper ArmPosterior: http://www.gwc.maricopa.edu/class/bio201/muscle/musc14.htm

Anterior: http://www.gwc.maricopa.edu/class/bio201/muscle/musc13.htmShoulder MusclesPosterior Shoulder:http://www.gwc.maricopa.edu/class/bio201/muscle/arm/shldrp.htm

Anterior Shoulder:http://www.gwc.maricopa.edu/class/bio201/muscle/arm/shldra.htm

Flexors that move the upper armCoracobrachialisScapula to middle of humerusFlexes and adducts armPectoralis majorThick muscle of upper chestFlexes, adducts, rotates arm medially

Extensors that move the upper armTeres majorScapula to the humerusAdduct and rotate arm mediallyLatissiums dorsi From middle of the back, around the side of your body and into the armpitExtend, adduct, rotate arm mediallyPull shoulder downward

Abductors that move the upper armDeltoidThick, triangular muscle that covers the shoulder jointConnects clavicle and scapula to the lateral side of the humerusAbducts arm

Rotators that move the upper armSubscapularisAnterior surface of scapulaConnects scapula and humerusRotate arm mediallyTeres minorScapula to humerusRotates arm laterally

Muscles that move the ForearmBiceps brachii

Triceps brachii

HandExtensor carpi radialis longusExtensor carpi radialis brevis

Both extend wrist, abduct hand

HandExtensor carpi ulnarisExtends wrist, adducts hand

Extensor digitorumExtends fingers

Flexor carpi radialis flexes wrist, abducts handFlexor carpi ulnaris flexes wrist, adducts hand

AbdomenRectus abdominus creates 6-packExternal oblique outermost layer, wraps around to the back of the bodyTransversus abdominus between external and internal obliqueInternal oblique within external oblique

Linea alba: band of tough connective tissue down medial line of abdomenMuscles of the Trunk

DeltoidPectoralis majorBiceps brachiiRectus abdominusTransversus abdominusInternal obliqueExternal obliqueMuscles that move the ThighGluteus maximusGluteus mediusGluteus minimus

Muscles that move the thighTensor fasciae lataeConnects ilium to lateral portion of thigh

Muscles that move the Leghttp://www.gwc.maricopa.edu/class/bio201/muscle/leg1.htm Muscles that move the legHamstring muscles:Biceps femoris (most lateral)Semitendonosis (middle)Semimembranosus (most medial)

Muscles that move the legSartorius hip to most distal, medial portion of the femur (medial portion of knee)

Muscles that move the legQuadriceps femoris group:Rectus femoris Vastus lateralisVastus medialis

Patellar tendon

Muscles that move the FootTibialis anterior

Gastrocnemius

Soleus