1. Muscular System

2. Facts about muscles… A skeleton cannot move by itself > 40% of the mass of the average human body is muscle Found everywhere in your body Power every movement from moving your lips to blinking your eyes

3. Types of Muscle Tissue: Skeletal Smooth Cardiac

4. 3 Types of Muscle Tissue: Type Voluntary/ Involuntary FoundStriations (stripes) StructureNucleus Skeletal Smooth Cardiac

5. Skeletal Muscles Voluntary Found attached to bones Yes, striations Cells are long and thin Many Nuclei

7. Smooth Muscles Usually involuntary Found in hollow organs (i.e. stomach, blood vessels, sm & lrg intestine) No striations Spindle-shaped (draw a spindle) One nucleus

9. Cardiac Muscle Involuntary Cardio= –Greek word for Heart Found in the Heart Striations Intercalated Discs One to two nuclei

11. Type of muscle?

17. Skeletal Muscle Breakdown Muscle Bundle Fibers (cells) Myofibril Filaments –Actin –Myosin

19. Closer look at the filaments: Actin: Myosin:

20. Closer look at the filaments: Actin: thin filaments on outside Myosin:

21. Closer look at the filaments: Actin: thin filaments on outside Myosin: thick filaments in the middle

22. Closer look at the filaments: Z lines:

23. Closer look at the filaments: Z lines: attach the actin together Actin Myosin Z lines

24. Closer look at Actin and Myosin

25. Muscle contraction: Myosin heads grab and pull on actin

26. Muscle contraction Myosin heads grab and pull on actin

27. Muscle relaxed: Muscle contracted: Draw a picture of this in your notes

28. Muscles work in pairs

30. Superficial muscles of the face

31. Anterior superficial muscles

32. Posterior superficial muscles

33. Superficial muscles of the thigh

34. Muscle Contraction Myofibrils are made of filaments Striations are formed by a pattern of thick and thin filaments made of protein Thick filaments are made of the protein myosin Thin filaments are made of the protein actin Filaments are arranges in units called sarcomeres Sarcomeres are separated by from eachother by regions called Z discs

35. Actin and Myosin: Cause muscles to contract A muscle contracts when thin filaments slide over thick filaments Myosin forms a cross-bridge with actin The cross bridge changes shape pulling the actin filament toward the center of the sarcomere The distance between the Z discs decreases The cross-bridge then detaches

36. Control of Muscle Contraction An enzyme produces an impulse causes the release of Calcium ions (Ca+) allowing actin and myosin to interact The muscle remains contracted until the impulse ceases Calcium ions pumped back into storage and contraction ends Contraction of a single muscle fiber is an all-or- none process! Most skeletal muscles work in opposing pairs- when one contracts the other relaxes