1. MUSCULAR SYSTEM

2. CHAPTER 10 THE MUSCULAR SYSTEM AND HOMEOSTASIS IN THIS CHAPTER, YOU WILL LEARN: THERE ARE THREE TYPES OF MUSCLE TISSUE. SKELETAL MUSCLE PRODUCES BODY MOVEMENT, MAINTAINS BODY TEMPERATURE, AND PROVIDES SUPPORT FOR THE BODY. MUSCLE FIBRES ARE FILLED WITH MYOFIBRILS THAT HOUSE THIN (ACTIN) AND THICK (MYOSIN) CONTRACTILE PROTEIN MYOFILAMENTS. ACTIN AND MYOSIN SLIDE PAST EACH OTHER DURING A MUSCLE CONTRACTION.

3. THE MUSCULAR SYSTEM & HOMEOSTASIS IN THIS CHAPTER, YOU WILL LEARN: CREATINE PHOSPHATE, FERMENTATION, AND AEROBIC CELLULAR RESPIRATION PROVIDE ENERGY FOR MUSCLE CONTRACTIONS. THREE TYPES OF SKELETAL MUSCLE ARE FOUND IN DIFFERENT PARTS OF THE BODY. MUSCLES ATROPHY WITH INADEQUATE STIMULATION AND CAN HYPERTROPHY WITH APPROPRIATE REPEATED STIMULATION. THE MUSCULAR SYSTEM WORKS WITH OTHER BODY SYSTEMS TO MAINTAIN HOMEOSTASIS.

4. MOVEMENT AND MUSCLE TISSUE IN THIS SECTION, YOU WILL: OBSERVE & COMPARE THE 3 TYPES OF MUSCLE TISSUE DESCRIBE THE ACTION OF ACTIN & MYOSIN IN MUSCLE CONTRACTION & HEAT PRODUCTION IDENTIFY SOURCES OF ENERGY FOR MUSCLE CONTRACTION

5. THREE TYPES OF MUSCLES

6. MUSCLE CELLS

7. THREE TYPES OF MUSCLES SMOOTH MUSCLE INVOLUNTARY LONG CELLS WITH TAPERED ENDS MONONUCLEATE SLOW CONTACTING – DOES NOT FATIGUE EASILY FOUND IN CERTAIN BLOOD VESSELS, IRIS OF THE EYE, DIGESTIVE SYSTEM (INTESTINE)

8. THREE TYPES OF MUSCLES CARDIAC MUSCLE UNIQUE TO THE HEART STRIATED & BRANCHED MONONUCLEATE INVOLUNTARY WITH INNATE ABILITY TO BEAT

9. THREE TYPES OF MUSCLES SKELETAL MUSCLE LONG POLYNUCLEATE CELLS (FIBRES) CONTRACTION IS VOLUNTARY (35% ♀ MASS 42% ♂ MASS) TUBULAR AND STRIATED

10. IDENTIFY THE MUSCLE TYPE Smooth Muscle Skeletal Muscle Cardiac Muscle

11. FUNCTIONS OF SKELETAL MUSCLES SUPPORT – ALLOW US TO STAND AND REMAIN UPRIGHT MOVE BONES – ALLOW US TO MOVE AND HAVE FACIAL EXPRESSION HELP MAINTAIN BODY TEMP – RELEASE LARGE AMOUNTS OF HEAT HELP PROTECT ORGANS AND STABILIZE JOINTS

12. COOPERATION OF SKELETAL MUSCLE WHEN MUSCLES CONTRACT THEY SHORTEN THEY CAN ONLY PULL BECAUSE OF THIS MUSCLES MUST WORK TOGETHER TO BEND JOINTS (WORK IN PAIRS - ANTAGONISTIC MUSCLES ) EXAMPLE: BICEP AND TRICEP

13. MUSCLE FUNCTION MUSCLES ARE ONLY CAPABLE OF CONTRACTING THUS MUST OCCUR IN PAIRS

14. MUSCLE STRUCTURE MUSCLES -> BUNDLES OF MUSCLE FIBRES -> BUNDLES OF MYOFIBRILS ->MYOFIBRILS ARE MADE OF MYOFILAMENTS (ACTIN & MYOSIN) Muscle Muscle Fibre Bundle Muscle Fibre Myofibril Myofilaments Actin Myosin

15. MUSCLE ↓ MUSCLE-FIBRE BUNDLE ↓ MUSCLE FIBRE ↓ MYOFIBRILS ↓ MYOFILAMENTS

16. MUSCLE STRUCTURE BLOOD VESSELS & NERVES RUN BETWEEN THE FIBRES BUNDLES MUSCLE CELLS CONTAIN ORGANELLES COMMON TO OTHER CELLS AND MANY MITOCHONDRIA NOTE: CELL MEMBRANE = SARCOLEMMA CYTOPLASM = SARCOPLASM HEMOGLOBIN ≈ MYOGLOBIN

17. COMPONENTS OF SKELETAL MUSCLE FIBRES ComponentDescriptionFunction Muscle fibresingle muscle cellresponsible for muscle contractions myoglobinO 2 -binding pigment in a skeletal muscle fibre stores oxygen for use during muscle contractions sarcolemmamembrane of a muscle fibresurrounds the muscle fibre and regulates the entry and exit of materials sarcoplasmcytoplasm of a muscle fibresite of metabolic processes for normal cell activities; contains myoglobin and glycogen (which stores energy for muscle contractions)

18. COMPONENTS OF SKELETAL MUSCLE FIBRES ComponentDescriptionFunction sarcoplasmic reticulum smooth endoplasmic reticulum in a muscle fibrestores calcium ions needed for muscle contractions Myofibrilsorganized bundles of myofilaments; cylindrical structures, as long as the muscle fibre itself contain myofilaments that are responsible for muscle contractions thick filamentfine myofilament composed of bundles of protein called myosin (about 11 nm in diameter) binds to actin and causes muscle contractions thin filamentfine myofilament composed of strands of protein called actin (about 5 nm in diameter) binds to myosin and causes muscle contractions

19. MUSCLE CONTRACTIONS INVOLVE THE ACTIONS OF TWO TYPES OF MYOFILAMENTS ACTIN MYOFILAMENT THIN HAVE TWO STRANDS OF ACTIN MOLECULES THAT WRAP AROUND EACH OTHER

20. MYOSIN FILAMENT THICK TWO STRANDS OF PROTEIN MOLECULES WOUND AROUND EACH OTHER 10X LONGER THAN ACTIN AND A DIFFERENT SHAPE

21. HOW MYOFILAMENTS CONTRACT WHEN A MYOFILAMENT CONTRACTS THE HEADS OF MYOSIN MOVE FIRST THESE HEADS ARE ATTACHED TO ACTIN MYOFILAMENTS HEAD BENDS BACK AND INWARD PULLING THE ACTIN MYOFILAMENT REQUIRES ATP TO WORK PART OF THE SLIDING FILAMENT MODEL HTTP://WWW.LEARNALBERTA.CA/CONTENT/SEB20/HTML/INTERACTIVELAUNCHER.HTML?INTERACTIVE=MYOFILAMENTCONTRACTION.SWF

23. ROLE OF CALCIUM WHEN AT REST MYOSIN HEADS ARE NOT BOUND TO ACTIN BECAUSE THEY ARE BLOCKED BY TROPOMYOSIN CALCIUM IS NEEDED TO MOVE THE TROPOMYOSIN CALCIUM AND TROPONIN BIND TO MAKE A COMPLEX WHICH BINDS TO TROPOMYOSIN, MOVING IT OUT OF THE WAY HTTP://WWW.LEARNALBERTA.CA/CONTENT/SEB20/HTML/INTERACTIVELAUNCHER.HTML?INTERACTIVE=BREAKDOWN_ATP_CROSSBRIDGEMOVEMENTDURINGMUSCLECONTRACTI ON.SWF HTTP://WWW.LEARNALBERTA.CA/CONTENT/SEB20/HTML/INTERACTIVELAUNCHER.HTML?INTERACTIVE=BREAKDOWN_ATP_CROSSBRIDGEMOVEMENTDURINGMUSCLECONTRACTI ON.SWF

25. ENERGY FOR MUSCLE CONTRACTION CREATINE PHOSPHATE (AKA PHOSPHOCREATINE)(CF. ATP) ANAEROBICALLY DONATES A PHOSPHATE GROUP TO ADP TO FORM ATP DURING INITIAL INTENSE MUSCULAR EFFORT (SIMILAR NEURONAL FUNCTION IN THE BRAIN)

26. Creatine phosphate builds up and is stored in resting muscle. For the muscle to contract, it needs to acquire ATP. (A) When the muscle starts contracting, it breaks down stored creatine phosphate. This generates some ATP that is used immediately. (B) To continue contracting, the muscle carries out aerobic cellular respiration as long as oxygen is available. When the oxygen has been used up, the muscle can carry out fermentation for a limited period of time. Fermentation results in only a small amount of ATP compared with the amount produced by aerobic cellular respiration, and lactate builds up. Once the muscle resumes resting (purple box), creatine phosphate builds up again.

27. ENERGY FOR MUSCLE CONTRACTION AEROBIC RESPIRATION PROVIDES ATP ENERGY AS O 2 IS AVAILABLE OCCURS IN MITOCHONDRIA MYOGLOBIN (CF. HEMOGLOBIN) IN THE MUSCLES STORES O 2 TO BE USED BY THE MUSCLE WHEN ACTIVITY BEGINS

28. ENERGY FOR MUSCLE CONTRACTION ANAEROBIC RESPIRATION SMALL AMOUNTS OF ATP PRODUCING LACTIC ACID CRAMPING & FATIGUE AFTER 2-3 MINS LACTIC ACID IS METABOLIZED BACK TO PYRUVATE

29. OXYGEN DEBT MUSCLES CAN FUNCTION WITH AN O 2 DEBT MORE THAN OTHER TISSUES BENEFITS OF AEROBIC TRAINING: INCREASED ABILITY OF CARDIOVASCULAR SYSTEM TO DELIVER O 2 INCREASED MITOCHONDRIA TO PROCESS O 2

30. ISOMETRIC & ISOTONIC CONTRACTION ISOMETRIC MUSCLE VS. MUSCLE CAN RAPIDLY INCREASE MUSCLE SIZE & STRENGTH ISOTONIC INVOLVES MOVEMENT

31. BODY POSTURE MANY OF THE MUSCLES OF THE BODY EMPLOY ISOMETRIC CONTRACTIONS TO SUPPORT THE BODY OR SOME PART OF IT (EXAMPLE: HEAD SUPPORT)

32. MUSCLE TONE IS THE RESULT OF SUSTAINED CONTRACTIONS OF DIFFERENT PARTS OF A MUSCLE (GOOD MUSCLE TONE – MUSCLE ALWAYS UNDER A SMALL AMOUNT OF TENSION AND READY FOR ACTION)

33. TENDONS & LIGAMENTS TENDONS ATTACH MUSCLE TO BONE LIGAMENTS ATTACH BONE TO BONE

34. MUSCLE TWITCH INDIVIDUAL MUSCLE CELLS CONTRACT FULLY OR NOT AT ALL (ALL-OR- NONE RESPONSE) HEAVY LOADS USE MORE CELLS LIGHT LOADS USE LESS CELLS

35. SLOW TWITCH FIBERS SLOW TWITCH FIBERS ARE USED FOR JOGGING AND BIKING CONTRACT SLOWLY AND RESIST FATIGUE PRODUCE MOST OF THEIR ENERGY AEROBICALLY (WITH OXYGEN) THEY ARE DARK IN COLOR BECAUSE THEY HAVE MANY MITOCHONDRIA AND MYOGLOBLIN (RESPIRATORY PIGMENT) THEY ALSO HAVE MORE CAPILLARY BEDS TO BE CONTINUALLY SUPPLIED WITH OXYGEN.

36. FAST TWITCH FIBERS FAST TWITCH FIBERS RE USED IN SPRINTING AND WEIGHT LIFTING THEY GENERATE POWER QUICKLY BUT CAN FATIGUE QUICKLY THEY ARE RICH IN GLYCOGEN (GLUCOSE) BECAUSE THEY DEPEND ON ANAEROBICALLY (NO OXYGEN) PRODUCED ENERGY THEY ARE LACKING MITOCHONDRIA AND MYOGLOBIN (OXYGEN)

37. DIFFERENT TYPES OF MUSCLE FIBRES INTERMEDIATE-TWITCH (TYPE III) FAST TWITCH WITH HIGH AEROBIC CAPACITY ENDURANCE TRAINING CAN INCREASE PROPORTION OF THESE FIBERS IN A MUSCLE GENETIC COMPONENT

38. DIFFERENT TYPES OF MUSCLE FIBRES SKELETAL MUSCLES HAVE DIFFERENT PROPORTIONS OF FAST-TWITCH AND SLOW-TWITCH FIBRES. THUS, THE FORCE AND RESPONSE TIMES OF THEIR CONTRACTIONS DIFFER.

39. MYOGRAMS These graphs show the force of muscle contraction with time. (A) A simple muscle twitch has three periods: latent, contraction, and relaxation. (B) When a muscle is not allowed to relax completely between stimuli, the contraction gradually increases in intensity until it reaches a maximum, which is sustained until the muscle fatigues.

40. MUSCLES, HEALTH, AND HOMEOSTASIS IN THIS SECTION, YOU WILL: EXPLAIN HOW THE SKELETAL MUSCLES OF THE MOTOR SYSTEM SUPPORT OTHER BODY SYSTEMS TO MAINTAIN HOMEOSTASIS IDENTIFY CONDITIONS THAT IMPAIR THE HEALTHY FUNCTIONING OF MUSCLES AND TECHNOLOGIES THAT ARE USED TO TREAT OR PREVENT THESE CONDITIONS DESCRIBE THE BENEFITS OF EXERCISE FOR MAINTAINING THE HEALTHY STRUCTURE AND FUNCTIONING OF MUSCLES

41. MUSCLE ATROPHY UNUSED MUSCLES WILL LOSE SIZE, TONE AND POWER INITIALLY REVERSIBLE BUT MAY BECOME PERMANENT Fig. 10.10

42. MUSCLE HYPERTROPHY EXERCISE INDUCED INCREASE IN MUSCLE MASS MUSCLE FIBRES GET LARGER (NOT MORE) MYOFIBRILS GET THICKER & SPLIT

43. BENEFITS OF TRAINING MUSCLES STAY AEROBIC LONGER HAVE INCREASED BLOOD SUPPLY BETTER GLYCOGEN STORAGE

44. MUSCLES & HOMEOSTASIS MUSCLE CONTRACTION PRODUCES HEAT -> THERMAL HOMEOSTASIS CARDIAC & LYMPHATIC SYSTEMS RELY ON WELL FUNCTIONING MUSCLES SUPPORT OF INTERNAL ORGANS & MANY OTHER ACTIVITIES ARE SUPPORTED BY THE MUSCULAR SYSTEM

45. DISORDERS OF THE MUSCULAR SYSTEM MUSCULAR DYSTROPHY HEREDITARY CONDITION SKELETAL MUSCLES DEGENERATE AND ARE REPLACED BY FATTY AND FIBROUS TISSUE POOR BLOOD CIRCULATION -> ACCELERATED MUSCLE DEGENERATION

46. DISORDERS OF THE MUSCULAR SYSTEM BOTULISM (C. BOTULINUM) POTENTIALLY FATAL MUSCULAR PARALYSIS TOXIN PRODUCED BY BACTERIA PREVENTS THE RELEASE OF A ACETYLCHOLINE BY CELLS OF THE NERVOUS SYSTEM -> PARALYSIS

47. ASIDE: BOTOX BOTOX ® = TRADE NAME FOR BOTULINUM TOXIN A WHY ANYONE WOULD WANT TO HAVE A BOTULINUM TOXIN INJECTION? ANSWER: IF AN AREA OF THE BODY CAN'T MOVE, IT CAN'T WRINKLE! ANSWER: IF AN AREA OF THE BODY CAN'T MOVE, IT CAN'T WRINKLE! Hillary Clinton: before and after Botox

48. DISORDERS OF THE MUSCULAR SYSTEM CRAMPS PAINFUL MUSCLE SPASMS TRIGGERED BY STRENUOUS EXERCISE, EXTREME COLD, DEHYDRATION, SALT (ELECTROLYTE) IMBALANCE, LOW BLOOD GLUCOSE, OR REDUCED BLOOD FLOW

49. DISORDERS OF THE MUSCULAR SYSTEM CONTRACTURE ABNORMAL MUSCLE SHORTENING (NOT CAUSED BY NERVE STIMULATION) CAN RESULT FROM INABILITY TO REMOVE CALCIUM IONS FROM THE SARCOPLASM OR FROM THE CONTRACTION OF SCAR TISSUE (EXAMPLE: SEVERE BURNS)

50. DISORDERS OF THE MUSCULAR SYSTEM FIBROMYALGIA CHRONIC MUSCULAR PAIN AND TENDERNESS OFTEN ASSOCIATED WITH FATIGUE AND SLEEP DISTURBANCES CAN BE CAUSED BY INFECTIOUS DISEASES, PHYSICAL OR EMOTIONAL TRAUMA, OR MEDICATIONS CONSIDERED A CONTROVERSIAL DIAGNOSIS, DUE TO LACKING SCIENTIFIC CONSENSUS TO ITS CAUSE 9:1 ( ♀ : ♂ )

51. DISORDERS OF THE MUSCULAR SYSTEM CRUSH SYNDROME SHOCK-LIKE STATE FOLLOWING MASSIVE CRUSHING OF THE MUSCLES (EG. COLLAPSE OF A BUILDING OR A TRAFFIC ACCIDENT) ASSOCIATED WITH HIGH FEVER, HEART IRREGULARITIES (CAUSED BY K + RELEASED FROM THE MUSCLES), AND KIDNEY FAILURE (CAUSED BY BLOCKAGE OF THE RENAL TUBULES WITH MYOGLOBIN RELEASED BY THE TRAUMATIZED MUSCLES)

52. DISORDERS OF THE MUSCULAR SYSTEM DELAYED ONSET MUSCLE SORENESS PAIN & STIFFNESS FELT AFTER NOVEL STRENUOUS EXERCISE (BEGINS 8-24 HOURS AFTER EXERCISE, PEAKS 24-72 HOURS AFTER EXERCISE AND SUBSIDES OVER THE NEXT 5-7 DAYS) ASSOCIATED WITH TRAUMA TO THE MUSCLES, DISRUPTIONS IN THE MYOFIBRILS & SARCOLEMMA, AND INCREASED LEVELS OF BLOOD MYOGLOBIN AND MUSCLE- FIBRE ENZYMES

53. DISORDERS OF THE MUSCULAR SYSTEM MYOSITIS MUSCLE INFLAMMATION AND WEAKNESS RESULTING FROM INFECTION OR AN AUTOIMMUNE DISEASE

54. CHAPTER REVIEW WHAT BODY SYSTEMS DO MUSCLES SUPPORT? HOW DO MUSCLES SUPPORT THESE SYSTEMS? EXPLAIN THE DIFFERENCE IN MUSCLE COMPOSITION BETWEEN A PERSON WHO IS NOT ACTIVE VERSUS SOMEONE WHO IS VERY ACTIVE? DESCRIBE TWO DIFFERENT TYPES OF MUSCLE INJURIES. RECOMMEND APPROPRIATE TREATMENTS FOR EACH. EXPLAIN HOW MUSCLES CHANGE WITH STRENGTH TRAINING? WITH ENDURANCE TRAINING? WITH INACTIVITY?

55. CONCEPT ORGANIZER

56. CHAPTER SUMMARY ALL MUSCLES DO THEIR WORK BY CONTRACTING. RELAXATION IS THE PASSIVE STATE OF A MUSCLE. THERE ARE THREE TYPES OF MUSCLE CELLS: SKELETAL, SMOOTH, AND CARDIAC. SKELETAL MUSCLE CELLS ARE ATTACHED TO THE BONES OF THE SKELETON, HAVE MANY NUCLEI, ARE STRIATED AND TUBULAR, AND CONTRACT VOLUNTARILY. SMOOTH MUSCLE CELLS ARE FOUND IN THE WALLS OF INTERNAL ORGANS, HAVE ONE NUCLEUS, ARE NOT STRIATED, AND CONTRACT INVOLUNTARILY. CARDIAC MUSCLE CELLS FORM THE WALLS OF THE HEART; HAVE ONE NUCLEUS, ARE STRIATED, TUBULAR, AND BRANCHED; AND CONTRACT INVOLUNTARILY.

57. CHAPTER SUMMARY THE FACT THAT SKELETAL MUSCLES CAN ONLY EITHER CONTRACT OR RELAX MEANS THEY CAN PULL BUT NOT PUSH. THEREFORE, THEY MUST WORK IN PAIRS TO MOVE ANY PART OF THE BODY—A RELAXED MUSCLE IS ONLY LENGTHENED WHEN THE OPPOSING MUSCLE CONTRACTS TO STRETCH IT. SKELETAL MUSCLE CONTRACTIONS ARE EXPLAINED BY THE SLIDING FILAMENT MODEL. SKELETAL MUSCLE PRODUCES HEAT AS WELL AS MOVEMENT AND ALSO SUPPORTS AND PADS THE BODY. EACH MUSCLE IS MADE UP OF CLUSTERS OF BUNDLES OF MUSCLE FIBRES, WHICH ENCLOSE BUNDLES OF MYOFIBRILS CONTAINING THIN MYOFILAMENTS OF ACTIN AND THICK MYOFILAMENTS OF MYOSIN. BLOOD VESSELS SUPPLY NUTRIENTS AND OXYGEN TO THE FIBRE BUNDLES AND REMOVE WASTES. THE OXYGEN FUELS THE CELLULAR RESPIRATION THAT SUPPLIES MOST OF THE ENERGY MUSCLES USE.

58. CHAPTER SUMMARY NERVES TRIGGER AND CONTROL MUSCLE CONTRACTIONS, WHICH LAST FOR ONLY A FRACTION OF SECOND IN EACH MUSCLE FIBRE. IT IS THE WAVE OF SUCCESSIVE CONTRACTIONS, OR TWITCHES, THAT RESULT IN A MUSCLE CONTRACTION. SKELETAL MUSCLES HAVE BOTH SLOW AND FAST-TWITCH FIBRES THAT ARE GOOD FOR EITHER ENDURANCE (SLOW- TWITCH) OR INTENSE (FAST-TWITCH) ACTIVITIES. USING THE SKELETAL MUSCLES IS THE ONLY WAY TO MAINTAIN AND BUILD THEIR FUNCTION.