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Demystifying the Muscular System: From Skeletal to Smooth and Cardiac Muscles

Explore the intricacies of the muscular system, from the skeletal muscle's structure and contraction steps to the functions and disorders of smooth and cardiac muscles. Dive into muscle movement, exercise effects, ATP pathways, and more.

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Demystifying the Muscular System: From Skeletal to Smooth and Cardiac Muscles

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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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