1. Muscular System Chapter 6

4. The 3 Muscle Types The job of all muscles is to contract They are all fibrous because cells are elongated The 3 Muscle Types Are: –Skeletal Muscle –Cardiac Muscle –Smooth Muscle

5. Skeletal Muscle Cigar Shaped Multinucleated Striated Voluntary Can Be Involuntary When Reflexes Are Involved Very Strong and Fast But Need Rest Most Attached to Bone Skeletal Muscle Overview Of Skeletal Muscle

6. Skeletal Muscle Cell

7. Cardiac Muscle

8. Smooth Muscle Long thin nuclei and no striations

9. How are Muscles Structured? Muscle Cells have a plasma membrane called a Sarcolemma. The muscle fiber is enclosed in Endomysieum. (Endo=, Mys= ) Many Muscle fibers bound together make a Fascicle. The Fascicle is wrapped in a membrane called the Perimysieum (Peri= ).

10. Muscle Structure Continued Many fascicles are wrapped together by an Epimysium. (Epi= ) Epimysia attach to tendons or Aponeuroses. (Pg. 86) Tendons: Strong, Thin, and made up of collagen (dense connective tissue). Aponeuroses are sheet-like tendons.

11. Skeletal Muscle (pg. 174) Quiz Yourself

12. What is the major Organelle of the Muscle Cell? Myofibril(s)=Working unit of the muscle cell. Made of Subunits called sarcomeres. –Give muscles the striped or striated appearance –The light band is the I-band –The dark band is the A-band –Between the I-bands is the Z-line –Between the A-bands is the H-zone Match the Terms

13. Mechanism of muscle contraction The above micrographs show that the sarcomere gets shorter when the muscle contracts The light (I) bands become shorter The dark bands (A) bands stay the same length

14. Take a long deep breath, its not that bad. And remember a bicycle cannot stand alone, because it is two tired. Now lets go on. But lets first watch this short video clip. Overview of the Job of the Bands

15. So how do these bands work? The myofibrils are surrounded by the sarcoplasmic reticulum, a specialized form of smooth endoplasmic reticulum that releases calcium. They are made of bands of – Actin (the thin filaments) that make up the I- bands –Myosin (the thick filaments) that make up the A-bands

16. So what is the Molecular Basis of Muscle Contraction? (pg. 176) 1) Nerve sends out Acetylcholine or Ach 2) Motor Unit= All muscles triggered by nerve. (1 nerve  Triggers 100’s of cells) 3) The Sarcolema becomes permeable to Na+ 4) Na+ causes an action potential because it disturbs the electrical conditions of the sarcolema (pg.178)

17. How does ACh stimulate the muscle? ACh causes the sarcolema to release Calcium (Ca+) Ca+ binds to the actin causing it to change shape. Myosine finds actin’s new shape attractive and grabs hold.

18. What happens after the Myosin grabs hold? (pg. 179) Myosin’s head snap towards the H-band of the sarcomere. ATP releases and re-cocks the myosin Only some myosin heads move at one time. Over all: Pg. 181 Description of Muscle movement

19. How does the muscle relax? When the action potential ends: –Sarcomere absorb Ca+ –ATP releases myosin heads –Actin takes on its former and less attractive shape. –Muscle Cells can relax Best Movie on Muscle Contraction Revisited

20. Write one paragraph explaining how a muscle works. Do this from memory. This will help you learn.

21. So, What is this Action Potential? Action Potential –Electrical Current or Charge –In order to return the cell to its original condition, K+ is pumped into the cell by the sodium potassium pump. Fig 3.10 Sodium/ Potassium Pump

22. How do muscles work together? Prime Mover: Major muscle doing the bulk of the work contracting. Synergist: Group of muscles working together to contract. Antagonist: Muscle that works against the prime mover and or synergists. How do Muscles work Together?

23. http://www.bbc.co.uk/science/humanbody/ body/interactives/3djigsaw_02/index.shtml ?muscleshttp://www.bbc.co.uk/science/humanbody/ body/interactives/3djigsaw_02/index.shtml ?muscles http://www.healthchecksystems.com/exerc ise1.htm#hyperhttp://www.healthchecksystems.com/exerc ise1.htm#hyper

24. Types of Muscle Movements

31. To exercise the: Quadriceps

32. To exercise the: Gastronemius

33. To exercise the: Hamstring Group Includes the bicepts femoris

34. Exercise the: Trapezius

35. Exercise for: Latissimus Dorsi

36. Exercise for: Deltoid

37. Exercise For: Gluteus Maximus

38. Exercises for: Oblique

39. Exercises for: Rectus Abdominus

40. Exercise for: Pectoralis Major Push up: Works Pecs on The Up-Motion

41. Exercises for: Bicep

42. Exercises for: Triceps

43. Now Quiz Yourself! See if you know your muscles… Another good Quiz site

44. Interesting Aspects: Some of us may have a spare muscle: the Plantaris muscle 1 in 10 don’t. Want to see it? Click the link. Groin pull? Here is the problem: Groin Pull Plantaris In Action