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Muscular System

Muscular System. CRASH COURSE. SKELETAL MUSCLE. Location: attached to bones/skin Control: voluntary Speed: rapid w/force but tires easily Layers : fibers- > endomysium ->fascicles-> perimysium - > muscle- > epimysium. SMOOTH MUSCLE. Location: visceral organs Control:

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Muscular System

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  1. Muscular System CRASH COURSE

  2. SKELETAL MUSCLE • Location: • attached to bones/skin • Control: • voluntary • Speed: • rapid w/force but tires easily • Layers: • fibers->endomysium->fascicles->perimysium-> muscle->epimysium

  3. SMOOTH MUSCLE • Location: • visceral organs • Control: • involuntary • Speed: • slow and sustained • Layers: • circular layer AND longitudinal layer for propelling substances • Shape: • fusiform

  4. CARDIAC MUSCLE • Location: • heart • Control: • involuntary; pacemaker • Speed: • slow • Shape: • figure 8 bundles

  5. FOUR FUNCTIONS • Movement • Posture • Stabilizing • Heat

  6. ANATOMY OF SKELETAL MUSCLE • Sarcolemma • plasma MB • Sarcoplasmicreticulum • ER = calcium storage • Distinct bands in muscle = • A (dark, thick, myosin) band • I (light, thin, actin) band

  7. STEPS OF CONTRACTION • motor unit forms at the synaptic cleft • neurotransmitter is released by nerve into synaptic cleft • neurotransmitter binds to receptor on muscle • sodium rushes into the cell and potassium rushes out (action potential) • calcium is released • myosin is activated (myosin head protrudes upward) • myosin binds to actin • actin slides closer together (contraction)

  8. GRADED RESPONSES • Twitch • single, contract and relax • Unfusedtetanus • continuous contractions with slight relaxation between each • Fused tetanus • continuous contractions without any relaxing between each

  9. ATP PATHWAYS • Direct phosphorylation: • 1 CP -> creatine & 1 ATP • used up quickly • Aerobic respiration: • 1 glucose -> 36 ATP • slow process • Anaerobic glycolysis: • 1 glucose -> 2 ATP & lactic acid • LACTIC ACID = CRAMPS

  10. MUSCLE USE • Overuse • Fatigue • oxygen debt • Remedy • remove lactic acid • replace oxygen • Contractions: • isotonic = shortening of muscle • isometric = no shortening of muscle

  11. EXERCISE • Aerobic (endurance) exercise: • inc mitochondria, oxygen storage, metabolism, coordination, resistance to fatigue • Isometric (resistance) exercise: • increased muscle size and strength • Lack of muscle use: • loss tone, paralysis, flaccid, atrophy

  12. MUSCLE MOVEMENT • Two attachment points: • insertion • origin • NAME THE MOVEMENT • NAME THE MUSCLE

  13. DISORDERS • Anabolic steroids: • advantages = inc size and strength • risks = bloated faces, infertility, liver damage, change in blood and cholesterol levels, psychiatric problems • Wryneck: • sternocleidomastoidmuscle (neck muscle) of baby contracts involuntarily • damage caused from difficult birth

  14. Common injection sites: • deltoid • gluteus medius • thigh muscles • Duschenne’s: • in males, btwn2-6 • symptoms = clumsy and freq falling • starts in extremities and goes upward • result = death • cause = lack of dystrophin

  15. Lockjaw • Cause: bacteria attacks NS • Symptoms: muscle spasms starting in jaw and moving on to trunk • Treatment: antibiotics & relaxants

  16. Myasthenia gravis: • rare disease in adult muscles • Symptoms = drooping upper eye lids, difficulty swallowing and talking • cause = shortage of ACh receptors, autoimmune • result = death from respiratory failure

  17. Cramps • start as spasms (involuntary contractions) • forceful contractions = cramps • causes = dehydration, low blood calcium, low potassium, meds, poor oxygen circ • Treatment = hydrate; replenish electrolytes; stretching/massaging

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