Minggu 4 & 5 Sistem Otot

Chapter 9 - Muscular System Three Types of Muscle Tissues Skeletal Muscle • usually attached to bones • under conscious control • striated

Cardiac Muscle • wall of heart • not under Smooth Muscle conscious • walls of most viscera, control blood vessels, skin • striated • not under conscious control • not striated

Structu re o f a S keletal Musc le Skeletal Muscle • organ of the muscular system • skeletal muscle tissue • nervous tissue • blood • connective tissues • fascia • tendon • aponeuroses

Structu re o f a S keletal Musc le • epimysium • perimysium • fascicle • endomysium • muscle • fascicles • muscle fibers • myofibrils • thick and thin filaments

Sk elet al M uscle Fi ber • sarcolemma • sacroplasm • sarcoplasmic reticulum • transverse tubule • triad • cisterna of sarcoplasmic reticulum • transverse tubule

• myofibril • actin filaments • myosin filaments • sarcomere

Structu re o f a S keletal Musc le

Sa rcomer e

• I band • A band • H zone • Z line • M line

Myofila men ts Thick Filaments • composed of myosin • cross-bridges

Thin Filaments • composed of actin • associated with troponin and tropomyosin

Neu ro mu sc ular J unction • site where axon and muscle fiber communicate • motor neuron • motor end plate • synaptic cleft • synaptic vesicles • neurotransmitters

Mo tor U nit • single motor neuron • all muscle fibers controlled by motor neuron

St imu lu s for Con tra ct io n

• acetylcholine (ACh) • nerve impulse causes release of acetylcholine from synaptic vesicles • binds to acetylcholine receptors on motor end plate • generates a muscle impulse • muscle impulse eventually reaches sarcoplasmic reticulum

Exci tati on Co ntra ction C ou pli ng

• muscle impulses cause sarcoplasmic reticulum to release calcium ions into cytosol • calcium binds to troponin to change its shape • position of tropomyosin is altered • binding sites on actin exposed • actin and myosin bind 9-11

Slid in g Fila men t Th eory • When sarcromeres shorten, thick and thin filaments slide past one another • H zones and I bands get narrower • Z lines move closer together

Cros s-b rid ge Cy clin g • actin and myosin cross-bridge bind • myosin crossbridge pulls actin •ADP and phosphate released from myosin • new ATP binds to myosin • linkage between actin and myosin cross-bridge break •ATP splits •myosin cross-bridge goes back to original position

Rela xation • acetylcholinesterase – breaks down acetylcholine • muscle impulse stops • calcium moves back into sarcoplasmic reticulum • myosin and actin binding prevented

Energy So urces fo r Co ntra cti on 1) Creatine phosphate

2) Cellular respiration

• creatine phosphate – stores energy that quickly converts ADP to ATP

Oxyg en S uppl y a nd Cellula r R esp ir ati on • Anaerobic Phase • glycolysis • produces little ATP

• Aerobic Phase • citric acid cycle • electron transport chain • produces most ATP • myoglobin stores extra oxygen

Oxygen Debt Oxygen debt – amount of oxygen needed by liver to convert lactic acid to glucose • oxygen not available • glycolysis continues • pyruvic acid converted to lactic acid • liver converts lactic acid to glucose

Muscle Fa tig ue • inability to contract • commonly caused from • decreased blood flow • ion imbalances • accumulation of lactic acid • cramp – sustained, involuntary contraction

Hea t P rod uct ion

• by-product

of cellular respiration • muscle cells are major source of body heat • blood transports heat throughout body

Muscu la r R es pon ses Threshold Stimulus • minimal strength required to cause contraction Recording a Muscle Contraction • twitch • latent period • period of contraction • period of relaxation • refractory period • all-or-none response

Su mma tion • process by which individual twitches combine • produces sustained contractions • can lead to tetanic contractions

Recr uitm ent of Moto r Un its

• recruitment - increase in the number of motor units activated • whole muscle composed of many motor units • as intensity of stimulation increases, recruitment of motor units continues until all motor units are activated

Su stain ed Con tract ion s

• smaller motor units recruited first • larger motor units recruited later • produces smooth movements • muscle tone – continuous state of partial contraction

Ty pes of Co ntract ion s • isotonic – muscle contracts and changes length • eccentric – lengthening contraction

• concentric – shortening contraction • isometric – muscle contracts but does not change length

Fa st a nd Sl ow Twitc h Musc le Fi bers

Slow-twitch fibers (type I) • always oxidative • resistant to fatigue • red fibers • most myoglobin • good blood supply Fast-twitch glycolytic fibers (type II) • white fibers (less myoglobin) • poorer blood supply • susceptible to fatigue

Fast-twitch fatigueresistant fibers (type IIb) • intermediate fibers • oxidative • intermediate amount of myoglobin • pink to red in color

Smoot h M uscle F ibers Compared to skeletal muscle fibers • shorter • single nucleus • elongated with tapering ends • myofilaments randomly organized • no striations • lack transverse tubules • sarcoplasmic reticula not well developed

Types of Smoot h M uscle Visceral Smooth Muscle • single-unit smooth muscle • sheets of muscle fibers • fibers held together by gap junctions • exhibit rhythmicity • exhibit peristalsis • walls of most hollow organs

Multiunit Smooth Muscle • fibers function separately • irises of eye • walls of blood vessels

Smooth Mu scl e Co ntra cti on • Resembles skeletal muscle contraction • interaction between actin and myosin • both use calcium and ATP • both depend on impulses • Different from skeletal muscle contraction • smooth muscle lacks troponin • smooth muscle depends on calmodulin • two neurotransmitters affect smooth muscle • acetlycholine and norepinephrine • hormones affect smooth muscle • stretching can trigger smooth muscle contraction • smooth muscle slower to contract and relax • smooth muscle more resistant to fatigue

Card ia c M uscle • only in the heart • muscle fibers joined together by intercalated discs • fibers branch • network of fibers contracts as a unit • self-exciting and rhythmic • longer refractory period than skeletal muscle

Sk elet al M uscle Act ion s • origin – immovable end • insertion – movable end • prime mover (agonist) – primarily responsible for movement • synergists – assist prime mover • antagonist – resist prime mover’s action and cause movement in the opposite direction 9-30

Major S kelet al M uscle s

Major S kelet al M uscle s

Mus cl es o f F ac ia l E xpr essi on

Muscles of M ast ica tion

Muscl es of Fa ci al Exp ress io n an d Mas ticati on

Musc les T hat Move the Head a nd V erte bra l Co lumn

Musc les T hat Move the Pector al Gir dl e

Musc les T hat Move the Ar m

Dee p M usc les o f th e Ba ck a nd Neck

9-39

Musc les of the Sh oulder an d Bac k

Musc les o f th e An te rior Ch est a nd Ab do mi nal Wal l

Musc les T hat Move the Fo rear m

Musc les T hat Move the Han d

Muscl es of the Shoul der a nd A rm

Cros s Sect ion of t he Arm

Muscl es of the Shoul der a nd A rm

Muscl es of the Arm a nd Fo rea rm

Muscl es of the Arm a nd Fo rea rm

Cr oss S ectio n o f th e Forear m

Mus cl es o f th e A bdo min al Wal l

Mus cl es o f th e A bdo min al Wall

Mus cl es o f th e Pel vic Outlet

Musc les o f Pel vic O utlets and Uro genital D iap hra gm

9-53

Muscl es Tha t M ove the Thigh

Mus cl es That M ov e th e Leg

Musc les T hat Move the Fo ot

Musc les of the Th ig h a nd L eg

9-57

Musc les o f th e Th ig h a nd L eg

9-58

Muscl es of the Th ig h a nd Leg

Cr oss S ectio n o f th e Thigh

Muscl es o f t he L eg

Muscl es o f t he L eg

Muscl es o f t he L eg

9-63

Cros s Sect ion of t he L eg

Life-Sp an Ch anges • myoglobin, ATP, and creatine phosphate decline • by age 80, half of muscle mass has atrophied • adipose cells and connective tissues replace muscle tissue • exercise helps to maintain muscle mass and function

Clin ic al App lica tion Myasthenia Gravis • autoimmune disorder • receptors for acetylcholine on muscle cells are attacked • weak and easily fatigued muscles result • difficulty swallowing and chewing • ventilator needed if respiratory muscles are affected • treatments include • drugs that boost acetylcholine • removing thymus gland • immunosuppressant drugs • antibodies

Active vs. Inactive Muscle: Muscular Atrophy

Exercise and Diet Stimulates Muscle Development

Arnold Schwarzenegger – Body Builder, Actor, and Politician

Hans and Franz