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Muscular System

Muscular System. Types of Muscle. Skeletal Striated Voluntary Multinucleated Smooth Nonstriated Involuntary Cardiac Striated Involuntary Intercalated disks. ~ 50% of body weight Work in groups to perform a function. General Functions of Muscular System. _________________

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Muscular System

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  1. Muscular System

  2. Types of Muscle • Skeletal • Striated • Voluntary • Multinucleated • Smooth • Nonstriated • Involuntary • Cardiac • Striated • Involuntary • Intercalated disks ~ 50% of body weight Work in groups to perform a function

  3. General Functions of Muscular System • _________________ • Skeletal muscle contractions move body in whole or part • _________ ______________ • Muscle cells produce heat via catabolism to maintain temperature homeostasis • ______________ • Continued partial contraction of muscle in order to perform many functions

  4. Characteristics of all Muscle • Excitability • ____________ to stimuli • Contractility • Actively _____________ to exert a pull • Tension that can be harnessed by CT • Extensibility • Continue to contract over range of ____________ ___________ • Ex: smooth muscle can be stretched to several times its original length and still contract on stimulation • Elasticity • ______________ to original length after contraction

  5. -mysium=CT membrane and tendon sheath

  6. Muscle Fiber Arrangement ___________ ___________ _________ ___________ ___________

  7. Muscle Attachment Does ________move when muscle contracts Does move when muscle contracts

  8. Naming Muscles • Location • Function • Shape • Fiber direction • Number of heads/divisions • Points of attachment • Muscle size

  9. Location Function Shape Fiber Direction

  10. Number of divisions Size

  11. ___________ eyebrows _______________ _______________ _______________ _______________ _________________, smiling _______________ _______________ _________ head

  12. Moves head Moves head Flexes head

  13. Superficial Back Muscles • Large, ____-shaped muscles provide force in a wide range of body positions • -EX: leaning back to straight vertical and all points in between. Shrugging, pulling scapulas together and down Rotator cuff muscles Stabilize shoulder joint, pull arm back Shoulder movement Pull the arm down, Stabilize torso during many movements (EX: bench press)

  14. Trunk MusclesThorax _____________________ribs

  15. Trunk MusclesAbdomen Flexes trunk Stabilizes Lower _________ Compresses abdomen

  16. Upper Arm __________ Upper arm ___________forearm

  17. Flexors

  18. Extensors

  19. Upper Leg Deep muscle Vastus intermedius Biceps femoris Semimembranosus Quadricep Femoris Semitendinosus

  20. Lower Leg Plantar flexion

  21. Foot

  22. Anal and Urogenital Muscles

  23. Classification of Muscle Group Actions • Agonist (Prime Mover) • Muscle most responsible for _________________ • Antagonist • _______________ prime mover • Provides precision and control during prime mover contraction • Relaxes when prime mover contracts • Synergist • _____ prime mover • Contract at same time as prime mover • Fixator • Joint _____________ • Maintains posture/balance during prime mover contraction

  24. Lever Systems ___ Class ___ Class P = Force (push or pull) Contracting Muscle F = Fulcrum Joint L = Load Weights, etc ___Class

  25. Posture • Good Posture – body alignment that favors function with ________ work • Standing Position • Head and chest held high • Chin, abdomen, buttocks pulled in • Knees slightly bent • Feet firmly on ground 6 in. apart • Poor Posture - puts abnormal strain on ligaments and bones • Maintenance • ___________ (muscle tone): muscles exert a pull against gravity • Continuous and passive partial contraction of muscles

  26. Muscles & Age • Infancy & Childhood • Muscle coordination and control allows developmental sequences to occur • Aging • Muscles degenerate with _________ • Replaced with __________

  27. Space between actin Muscle cell (fiber) cytoplasm H zone Basic contractile unit of muscle fiber Sarcoplasm Z line Muscle fiber membrane Bundle of microfilaments; almost fill sarcoplasm Length of myosin heads (wide, dark stripes) Length of actin (thin, light stripes) Allows impulse traveling down T tubule to stimulate adjacent sacs Allows impulses to travel along sarcolemma deeper into muscle cell (fiber) Network of tubules and sacs: pumps calcium ions in from sarcoplasm to store in sacs

  28. Myofilaments protein molecules Holds tropomyosin in place Covers active site On actin Attracted to actin and forms crossbridge

  29. Excitation & Contraction Impulse sent to muscle fiber Muscle fiber creates movement Synaptic cleft Motor endplate Synaptic vesicle Neuromuscular junction (neurotransmitter)

  30. Contraction tropomyosin troponin • Synaptic vesicle travels down motor neuron and binds to motor endplate • Acetylcholine released into synaptic cleft • Ach binds to receptor on sarcolemma • Impulse travels along sarcolemma and down t-tubules • Calcium released from sarcoplasmic reticulum • Calcium binds to troponin causing conformation change • tropomyosin shifts to expose active site on actin • myosin heads bind to actin • actin filaments are pulled past the myosin head; head unattaches and reattaches to a new site….repeat • _______________ __________________________ Theory - sliding of thin filaments toward center of each sarcomere shortens the myofibril and muscle fiber.

  31. Motor Unit Smaller # fibers – more __________movement Larger # fibers – more ________________ contraction

  32. SR releasing Ca+2 All or NONE Ca+2 bind to troponin; Cross-bridging • Quick jerk due to ______ threshold stimulus • One twitch – 1/10 sec • Rarely occur • ___________________ step-like increase in contraction strength • Series of twitch contractions 1 sec apart • Muscle contracts more forcefully after it has • contracted a few times, then when it first contracts • Warm-up before exercise • Smooth, sustained contractions • Coordinated contractions of different motor units • Multiple twitch waves add together to sustain • muscle tension for longer time • Very short periods of _________________ between peaks of tension • Twitch waves _________ into a single, sustained peak

  33. Tonicity • Continual, partial contraction of a muscle • Flaccid • Muscles with _______ tone than normal • Spastic • Muscles with _______ tone than normal

  34. Length-tension Relationship Optimal length Strongest max contraction possible Overstretched Muscle can’t develop tension due to filaments too far apart Sarcomere compressed Muscle can’t develop tension

  35. Energy Sources • ATP • Hydrolysis into ADP yields energy required for contraction • ATP binds to __________ head in order to pull actin • Fibers continually resynthesize ATP from breaking down ____________ ______________ (requires glucose and oxygen) • Glucose & oxygen • Hemoglobin transfers _____ to muscle fiber • ________ stores glucose as glycogen • At rest: Excess O2 in sarcoplasm is bound to myoglobin temporarily • Exercise: O2 concen. decreases in muscle, so myoglobin resupplies muscle with O2

  36. Respiration • Aerobic Respiration • Requires ____ • Produces max amount of energy available from each glucose molecule • Anaerobic Respiration • Occurs when ______ of O2 • Forms ______ acid • During exercise • Muscles “burn” • O2 _______ • Heavy breathing during exercise in order to process lactic acid

  37. Muscle Fatigue • Muscles loses ability to contract due to lack of ________ • ________ _____ build up • Cramp – muscle contracts spasmodically, but does not ______ completely

  38. Most body movements are a result of _________ ________

  39. Change in Muscle Size • Atrophy – __crease in muscle size • Bed Rest: lose __% muscle strength/day • Hypertrophy – __crease in muscle size

  40. Myopathies • Myalgia - muscle pain due to overstretching/tearing of muscle fibers • Fibromyalgia – widespread muscle and CT pain • Strain – caused by overexertion/trauma and can lead to muscle tear • Myositis - any muscle inflammation • Fibromyositis - tendon inflammation along with myositis • Cramps • Painful muscle spasms • Due to mild myositis, fibromyositis, irritation, iron, and water imbalance • Charley Horse • Intense muscle spasms • Last few seconds to few hours • Caused by injury or overuse • Dehydration • Low K+ or Ca+2 • Nerve irritated • Treatment • Stop activity • Stretch and massage • Heat to relax muscle • Ice when spasm is over

  41. Myopathies • Contusion • Muscle bruise, local internal bleeding and inflammation • Crush injury: severe trauma to muscle, releasing fibers into bloodstream (life threatening) • Poliomyelitis (Poilio) • Viral infection of nerves controlling skeletal movement • Causes partial or full paralysis and death • Vaccine created in US in 1950s, but not everywhere • Muscular Dystrophy • Genetic disease caused by muscle atrophy • Some forms are fatal • Most common form is Duchenne Muscular Dystrophy (DMD) • Myasthenia Gravis • Autoimmune disease that attacks muscle cells at NM junction • Muscle weakness • Can become a crisis and affect all four limbs • Could die of respiratory failiure

  42. Myopathies • Hernias • “protrusion” • Reducible – can manipulate protruding organ back into abdominal cavity • Strangulated – blood flow to organ is stopped; obstruction, gangrene, pain. Vomiting, emergency surgery • Types • Inguinal – hernia extends into inguinal canal into scrotum or labia; affects more males • Femoral – affects more women below groin area due to pregnancy

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