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Chapter 6 Muscular System

Learn about the functions, structure, and movement of the muscular system. Discover the three types of muscle tissue and how they work together to produce movement. Understand the key terms and processes involved in muscle contraction and relaxation.

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Chapter 6 Muscular System

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  1. Chapter 6Muscular System

  2. Muscular System • 700 muscles in the human body • Functions: • Moving the body’s framework • Maintaining posture • Producing heat • Assisting lymph transport • Muscle mass makes up 40% of an average person’s body weight

  3. Muscular System • Muscles are arranged in layers • All muscular movement is made possible through nerve impulses acting on tissue, causing contractions • Optimal function is achieved through muscles, tendons, ligaments, bones, and nerves working in concert

  4. Word Parts Definition Example

  5. Word Parts Definition Example

  6. Word Parts Definition Example

  7. Word Parts Definition Example

  8. Word Etymology brevis short bucca cheek femur thigh gloutos buttock

  9. Word Etymology pteron wing, feather pteryx wing rectur straight teres round, smooth vastus great

  10. Medical Term Parts Used as Prefixes brachy- short bucco- cheek, mouth fascio- fascia pterygo- wing-shaped

  11. Medical Term Parts Used as Suffixes -trophic nutrition, nourishment

  12. Muscular System Preview • Key characteristic of muscle is its ability to contract when stimulated by nerves to produce movement • Nerve impulse travels to muscle tissue, exciting the muscle to contract • Accomplished through functioning of several muscle structures that shorten to produce contraction

  13. Structures of the Muscular System • Muscle cells/muscle fibers • Muscle tissue • Sarcomere • Sarcolemma • Sarcoplasm

  14. Muscular System Structure Key Terms muscle cells muscle fibers/myofibrils muscle fibers muscle cells muscle tissue tissue composed of contractile fibers

  15. Muscular System Structure Key Terms sarcolemma sheath surrounding muscle cell sarcoplasm intercellular material of a muscle cell sarcomere functioning unit of the muscle

  16. Muscle Fiber

  17. Muscle Fiber • Individual muscle fiber has many parts • Sarcolemma = outer cell membrane • Sarcoplasm = cytosol within a muscle fiber • Myofibrils = contractile fibers (thread-like) within muscle • Contain contractile proteins that enable muscle to contract • Sarcomeres = functional units of a myofiber that cause muscles to shorten

  18. Muscle Tissue • Three types of muscle tissue • Skeletal • Smooth • Cardiac

  19. Skeletal Muscle Tissue • Attaches to skeletal system by tendons • Provides movement • Also called striated muscle • Voluntary control • Contracts and relaxes rapidly

  20. Skeletal Muscle Tissue

  21. Smooth Muscle Tissue • Nonstriated • Involuntary controlled • Appears nonstriped • Hollow organs and blood vessels are lined by smooth muscle • Contracts and relaxes slowly

  22. Smooth Muscle Tissue

  23. Cardiac Muscle Tissue • Found only in the heart • Permits constant pumping action • Appears striated • Involuntary • Cardiac muscle fibers contract as a rhythmic unit and are self-stimulated

  24. Cardiac Muscle Tissue

  25. Muscle Tissue Key Terms skeletal muscle muscle associated with the skeleton smooth muscle muscle in viscera walls and blood vessels peristalsis progressive waves of contraction cardiac muscle heart muscle

  26. Muscle Tissue Key Terms tendons fibrous bands or cords attaching muscle to bone or muscle to other body parts aponeuroses tendon sheets fascia fibrous tissue between muscle that form sheaths

  27. Muscle Movement • Muscle movement is produced by pulling on bones • Origin = end of muscle that is attached to a immovable part • Insertion = end of muscle that is attached to a movable part • When contraction occurs, one muscle typically produces movement in one direction, while another muscle produces movement in another direction. • Bones serve as levers • Joints serve as fulcrums

  28. Muscle Movement: Contraction • Occurs within the musculature • Requires • Motor neuron (nerve cell that excites a muscle) • Muscle fiber • Threshold stimulus (level of stimulation) must be exceeded • Results from a sliding movement within the myofibrils • Byproduct is heat

  29. Muscle Movement • Energy is required • Molecules that supply energy are • ATP (adenosine triphosphate) • ATP supplies energy for muscle fiber contraction. • CP (creatine phosphate) • CP (present in muscle tissue and an energy-storing substance) synthesizes ATP as it decomposes • Active muscles depend on cellular respiration

  30. Muscle Movement: Muscle Fatigue • Occurs when a muscle loses its ability to contract • Results from • Interruption of blood supply to the muscle • Lack of acetylcholine • Accumulation of lactic acid as a result of anaerobic respiration

  31. Muscle Movement: Muscle Relaxation • Involves • Calcium ions (Ca2+) • Sarcoplasmic reticulum (SR) = storage and release site of Ca2+ in a muscle fiber • After the Ca2+ is released, the SR reabsorbs the calcium, thereby halting the contraction process

  32. Muscle Movement Key Terms origin muscle end that remains fixed during contraction insertion muscle end that moves during contraction neuromuscular junctions myoneural junctions

  33. Muscle Movement Key Terms acetylcholine chemical involved in nerve impulse transmission adenosine triphosphate cell’s energy source myoglobin muscle hemoglobin, myohemoglobin

  34. Muscle Tone • Resting tension • Sustained contraction of portions of skeletal muscle achieves muscle tone • Essential for posture and balance • Atrophy describes muscle tissue wasting as a result of • disease • ischemia • nutritional deficiencies • Hypertrophy is enlargement of muscle tissue (ex: muscle builders)

  35. Muscle Tone Key Terms muscle tone muscle integrity achieved through active contraction of some fibers atrophy physiologic or pathologic muscle size reduction hypertrophy increase in size

  36. Basis for Naming Skeletal Muscles • Location • Fiber direction • Size • Number of origins • Shape • Origin • Insertion • Action • Point of achievement

  37. Naming Skeletal Muscles Key Terms abductors muscles that draw a body part away from the axis when contracted adductors muscles that draw a body part toward the median when contracted

  38. Naming Skeletal Muscles Key Terms extensors muscles that extend or stretch a limb or part flexors muscles that bend or flex a limb or part

  39. Pathology of Muscle System • Signs and symptoms • Muscle pain • Muscle weakness • Muscle disorders usually result from • Trauma • Tumor • Immune disorder • Improper nerve conduction • Inheritance • Infection

  40. Types of Muscle Diseases: Myopathy • Myopathy—disease of the muscles and muscle tissues that is either inherited or acquired • Acquired • Botulism • Fibromyalgia • Inherited • Muscular dystrophies (MDs) • Polymyositis

  41. Botulism • Serious form of food poisoning • Caused by eating contaminated food • Contains toxin, botulinum, most potent poison known • Signs and symptoms • Double vision • Light sensitivity • Blurred speech • Nausea • Vomiting • Inability to walk—muscle weakness

  42. Botulism (cont’d) • Treatment • Guanidine hydrochloride • Pulmonary ventilation • Recovery is gradual—up to 1 year

  43. Fibromyalgia • Unknown origin • Characteristics • Myalgia, stiffness • Tenderness • Signs and symptoms • Fibrosis • Fibrositis

  44. Fibromyalgia (cont’d) • Joint regions involved • Antecubital • Cervical • Sacroiliac • Patellar • Diagnosis • Patient history and physical exam

  45. Fibromyalgia (cont’d) • Treatment • Most common • Analgesics • Aspirin • NSAIDs • Proven successful • Chiropractic adjustments • Physical therapy • Medical massage

  46. Muscular Dystrophies (MDs) • Inherited disease/genetic disorder • Characteristics • Degeneration of muscle cells causing progressive muscle weakness • Muscles replaced by fat and connective tissue • Types • Duchenne’s muscular dystrophy (DMD) is the most common type • Pseudohypertrophic MD is an x-linked genetic disorder affecting only males

  47. Muscular Dystrophies (cont’d) • Diagnosis • Blood tests • Urine tests • Treatment • Physical therapy • Occupational therapy

  48. Myasthenia Gravis • Autoimmune disease • Weakness of skeletal muscles • Affects more women than men • Signs and symptoms • difficulty in chewing, swallowing, and talking • Diagnosis • history and physical examination • Treatment • cholinesterase inhibitors • corticosteroid therapy

  49. Polymyositis (PM) • Autoimmune disease • Causes myositis, myomalacia ,and atrophy • Affects mainly women • Signs and symptoms • Inability to raise arms over the head • Difficulty in walking

  50. Polymyositis (cont’d) • Diagnosis • History • Physical examination • Treatment • Steroids to minimize inflammation • Immunosuppressants • Physical therapy • Medical massage

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