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Muscular System

Muscular System. Muscular System Functions:. 1. produce movement 2. Maintain posture 3. Stabilize joints 4. Generate heat 5. Move substances (fluid, food etc). Properties of Muscles: . Excitability : capacity of muscle to respond to a stimulus

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Muscular System

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  1. Muscular System

  2. Muscular System Functions: • 1. produce movement • 2. Maintain posture • 3. Stabilize joints • 4. Generate heat • 5. Move substances (fluid, food etc)

  3. Properties of Muscles: • Excitability: capacity of muscle to respond to a stimulus • Contractility: ability of a muscle to shorten and generate pulling force • Elasticity: ability of muscle to recoil to original resting length after stretched

  4. Muscular System • Muscles are responsible for all types of body movement – they contract or shorten and are the machine of the body • Three basic muscle types are found in the body • Skeletal muscle • Cardiac muscle • Smooth muscle

  5. Skeletal Muscles: structure

  6. Muscle Coverings: • Epimysium–tissue that covers the entire skeletal muscle. Separates the muscle from all other organs • Fascicle–A group of muscle fibers • Perimysium- surrounding a group a fascicle. Contains blood vessels and nerves. • Endomysium- surrounds individual muscle fiber. Also has blood vessels and nerves.

  7. Muscle Coverings:

  8. Head and Neck Muscles

  9. Muscles of the cephalic area:

  10. Trunk Muscles

  11. Muscles of the Anterior Trunk area:

  12. Muscles of the Posterior Trunk area: latissimusdorsi

  13. Muscles of the Posterior and Anterior Leg: Anterior of leg Posterior of leg

  14. Types of Ordinary Body Movements • Flexion – decreases angle of joint and brings two bones closer together • Extension- Increase the angle or extending something • Rotation- movement of a bone in longitudinal axis (back and forth), shaking head “no”

  15. Types of Ordinary Body Movements • Abduction: Moving away from the body or anatomical position • Adduction: Moving towards the body or anatomical position. • Circumduction: moving in a circular motion

  16. Types of Ordinary Body Movements • Flexion – decreases angle of joint and brings two bones closer together • Extension- Increase the angle or extending something • Rotation- movement of a bone in longitudinal axis (back and forth), shaking head “no”

  17. Types of Ordinary Body Movements • Abduction: Moving away from the body or anatomical position • Adduction: Moving towards the body or anatomical position. • Circumduction: moving in a circular motion

  18. Anatomy of Skeletal Muscles: • Cells are multinucleate

  19. Anatomy of Skeletal Muscles: • Myofibril- The smallest unit • Bundles of myofilaments • Myofibrils are aligned to give distinct bands • I band = light band • A band = dark band

  20. Anatomy of Skeletal Muscles: • Sarcomere- one segment on a myofibril (from Z disc to Z disc) • (these are what allow the muscle to contract and move)

  21. Anatomy of Skeletal Muscles: • Components of a Sarcomere: • Thick filaments = myosin filaments • Has ATP • (for energy to be broken down and used in order to move)

  22. Anatomy of Skeletal Muscles: • Components of a Sarcomere: • Thin filaments = actin filaments

  23. How skeletal muscles move or “slide” • Thin Actin slide past the thick Myosin so that the actin and myosin filaments overlap • In the relaxed state, thin and thick filaments overlap only slightly • In order for this process to start sodium must ender the cell (active transport) and the nervous tissue sends a signal to begin contraction

  24. How skeletal muscles move or “slide” • Step 1: Activation by nerve causes Calcium to be released. • Step 2: This allows the myosin heads to attach to the actin. • Step 3: ATP is used and broken down in order to “pull” the myosin over the actin (contracting the muscle) • Step 3: Myosin heads then bind to the next site of the actin filament and get ready for a second contraction. This shortens the Z line and they over lap. • Step 4; They continue until the muscle contracts and the two over lap more and more until the H zone disappears. • Step 5: To release the contraction the Calcium is taken back into the muscle fibers which covers the location so myosin can’t bind. Now the muscle is relaxed • IF calcium doesn’t go back in the contraction is prolonged and called a charlie horse or Cramp!

  25. How skeletal muscles move or “slide”

  26. How skeletal muscles move or “slide” • Within a skeletal muscle, not all fibers may be stimulated during the same interval • Muscle force depends upon the number of fibers stimulated • More fibers contracting results in greater muscle tension • Muscles can continue to contract unless they run out of energy

  27. Energy for Muscle contraction and fatigue • Muscles use stored ATP for energy • Only 4-6 seconds worth of ATP is stored by muscles

  28. Energy for Muscle contraction and fatigue • 1. After this initial time, other pathways must be utilized to produce ATP • Muscle cells contain creatine phosphate (CP) • CP regenerates new ATP • CP supplies only last 20 seconds

  29. Energy for Muscle contraction and fatigue • 2.Glycolysis • Reaction that breaks down glucose with or without oxygen to make ATP • Without Oxygen glucose breaks into lactic acid which is what builds up and produces muscle fatigue.

  30. Muscle Fatigue and Oxygen Debt • When a muscle is fatigued, it is unable to contract • The common reason for muscle fatigue is oxygen debt or lactic acid build up. • Oxygen is required to get rid of accumulated lactic acid

  31. Disorders relating to the Muscular System • Muscular Dystrophy: inherited, muscle enlarge due to increased fat and connective tissue, but fibers degenerate and atrophy • MyasthemiaGravis: progressive weakness due to a shortage of acetylcholine receptors

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