1. Muscle are the machines converting ____________ energy to ____________energy! What are the functions of muscles? BIOL 2010 Human Anatomy & Physiology I

2. What are the types of muscle tissue? * Smooth* Cardiac* Skeletal BI 201 Human Anatomy & Physiology

3. What are the attributes of muscles tissue? All muscle tissue has 4 common characteristics: ____________ Respond to stimuli with electric current Ability to shorten when stimulated Can be stretched up to 3 times contracted length Recoils to resting length after tension released

4. Muscles are comprised of different components: 1) ___________________ These are connective tissue in a hierarchical structure that attach individual muscle cells to each other, to other bundles (__________), to tendons to periostea and bone itself These are _____ excitable and NOT _______________ Will force of contraction be totally exerted on target part? What are muscles made of?

5. 2) _________________ Vessels necessary for transporting blood to and from muscle tissue travel through the connective tissue. Nerves necessary for ________________ __________to initiate muscle contraction also travel through the connective tissue What are muscles made of?

6. 3) Contractile components Muscles (whole) are comprised of… Fasciculi, which are… Many individual muscle cells (muscle fibers)… Each with a cell membrane (____________), cytoplasm (______________), organelles and ___________… made of _____________ What are muscles made of?

7. Structure of the 2 myofilaments: Thin (Actin) 3 parts… Thick (Myosin) What are myofilaments and how are they different? A.D.A.M. sliding filament theory #3-16)

8. What are muscles made of?

9. Another View… What are muscles made of?

10. Ca2+ ions bind with __________ which causes ___________t o “slide off” the active sites on the actin Exposed active sites are bound to heads of myosin forming a ______________ Now how do we convert an action potential (electric signal) into a contraction?

11. When cross-bridges form, then energy stored in myosin heads is released as mechanical motion of heads “snapping back” pulling thin filaments towards each other (____________). Now how do we convert an action potential (electric signal) into a contraction?

12. ATP is used to release cross-bridge ATP is then converted to ADP to “re-cock” the myosin head (____________) Now how do we convert an action potential (electric signal) into a contraction?

13. Where the motor neuron and the muscle fiber interact is called the ________________________ How does an action potential in a motor neuron result in an “action” in the muscle fiber?

14. 1)1) 2) Ca2+ triggers release of neurotransmitters from synaptic vesicles. 3) Acetylcholine diffuses across cleft & binds with receptor on Na+ channels. 4)4) 1 2 3 4 How does excitation-contraction coupling occur?

15. How do you stop this thing? ____________________ is an enzyme that breaks down Acetylcholine into acetic acid and choline. _________ is pumped back into presyntapic terminal. _______________… What results? Curare (plant extract)

16. Now how do we convert an action potential into a contraction? Muscle fibers are covered with invagination called ____________________ (T tubules), which functionally bring the plasma membrane (sarcolemma) and extracellular fluid into the interior of the cell. (Excitation-contraction coupling)

17. On either side of the T tubules is an enlarged area of the ___________________ (smooth endoplasmic reticulum) called cisternae. A T tubule and the __________ on either side make up a triad. Now how do we convert an action potential into a contraction?

18. Ca2+ ions are pumped into the lumen (cavity), up to 2000 times conc. grad. When action potential reaches T tubules… _________diffuse towards the myofibrils and their myofilaments Now how do we convert an action potential into a contraction?

19. Ca2+ ions bind with troponin which causes tropomyosin to… Exposed active sites are bound to heads of myosin forming a ________________ Now how do we convert an action potential into a contraction?

20. When cross-bridges form, then energy stored in ________ _______ is released as mechanical motion of heads “snapping back” pulling thin filaments towards each other (Power stroke). Now how do we convert an action potential into a contraction?

21. ATP is used to release cross-bridge ATP is then converted to ADP to “re-cock” the myosin head (_______________) Now how do we convert an action potential into a contraction?

22. What about relaxation? Myofibrils CAN NOT exert a force in two directions!!! So in this sense relaxation is passive. It depends on: 1) Series-Elastic components (elasticity) 2)2) 3)3) However, relaxation DOES require energy! Where and Why? ?Rigor mortis?

23. How do we get a whole muscle response based on individual muscle fibers? Muscle fibers contract in an “All-or-none” fashion. To control force of a whole muscle contraction, you must control the _________ of muscle fibers contracting. Each motor neuron and the muscle fibers it innervates is called a _____________

24. Take 5!!! Not all skeletal muscles are organized with the same # of muscle fibers per motor unit. Which muscles would you expect to have >#s of muscle fibers/motor unit? Eye muscles or Quadriceps muscles Why? Discuss with your neighbor and predict an answer.

25. What are the attributes of a single muscle twitch? A single muscle twitch can be divided into distinct phases: Lag phase Contraction phase Relaxation phase (Refer to table 9.2 for specific events associated with each phase)

29. _________________ Increase in tension due to 2 things: 1) additional ____ in sarcoplasm 2) ___________ ________ already stretched What happens when frequency of stimulus increases?

30. Spatial Summation Increased stimulus strength results in additional motor units being recruited. Subthreshold Threshold Submaximal Maximal What happens when the strength of the stimulus increases?

31. Can muscles exhibit more than one type of contraction? __________ (metri~length) The muscle length doesn’t change… but tension does! _______ (iso~equal) The muscle tension doesn’t change but the length does! _______________ Muscle shortens under tension ? _______________ Muscle lengthens under tension

32. How does muscle performance relate to initial length of muscle? Muscles have an optimum length for maximal contraction force (tension).

33. Where do muscles get their energy? Immediate: (6 seconds of sprinting) Use up small amount of ____ present, then phosphorylation of ____ with other ADP and creatine phosphate (CP) Short-term: (30-40 seconds - 3 min.) _____________, using blood glucose and glycogen in the glycogen-lactic acid system Long-term: (Hours?!?) Respiratory and Cardiovascular systems catch up… _________________________

34. What are the ways in which muscles can fatigue? As the term implies, brain’s influence on motor neuron and muscular activity Fatigue resulting directly from muscle’s energy supply: ATP shortage Lactic acid build-up Depletion of What? Acetylcholine 1) ___________ 2) ___________ 3) ___________

35. How can you increase endurance? Since after several minutes, muscles depend mostly (90%) on aerobic respiration for ATP production, Endurance is dependent on… Also depends on organic nutrients particularly glucose and fatty acids… Carbohydrate loading can “pack” 4-5g/100g of muscle BUT also 2.7gH 2 O/1g glycogen

36. Even with great lung capacity, sustained activity will exceed O 2 supply… Resulting in _______ (Exercise rate - Resting rate). Breathing continues after exercise for the following reasons With high VO 2 max, can you exert indefinitely? Definitely NOT!

37. Are all muscle fibers created equal? Slow twitch (high-oxidative fibers, type I) As name implies slower “twitch” time Numerous mitochondria Myoglobin Fast twitch (low-oxidative fibers, fast glycolytic, type II) Fast “twitch” time Larger in diameter Poorer blood supply Fatigue rapidly

38. Take 5!!! What kind of exercise regimen is appropriate for people who are training to be endurance runners? What effect will the composition of their muscles, in terms of muscle fiber type, have on their ability to perform in an endurance race? Discuss with your neighbor and predict an answer.

39. What are the effects of exercise? High intensity (anaerobic) affects fast- twitch fibers greater than slow-twitch. Aerobic exercise improves vascularity and mass of slow-twitch fibers. Can you convert one fiber type to another? If so, which types are “convertible”? (Read the handouts and discuss these questions). You can’t add more muscle fibers, so how do muscles increase in size?

40. What is Muscular Dystrophy? Group of diseases that result in muscular atrophy and conversion to connective tissue. Duchenne’s MD is sex-linked The faulty gene is responsible for the production of dystrophin, which is found in the sarcolemma and is thought to be involved with resistance to mechanical stress AND/OR allows Ca2+ to leak from sarcoplasmic reticulum causing the activation of Phospholipase A, an enzyme that breaks down plasma membranes destroying the cell.

41. _________ Spindle shaped ____________ Non-striated… Why? Ca2+ works differently to regulate muscle contraction How is smooth muscle different? NOT an “All or None” contraction

42. How is smooth muscle different? Hormone binds with receptor G proteins cause Ca 2+ channels to open …

43. How is smooth muscle different? Myosin kinase becomes active Catalyzes ATP to ADP P used to “cock” myosin head ___________ removes phosphate