Muscular System

1. Muscular System

2. BELLRINGER 2/3/15 • What are the functions of muscles?

3. Muscles

5. Types of Muscle ~ 50% of body weight Work in groups to perform a function • Skeletal • Striated • Voluntary • Multinucleated • Smooth • Nonstriated • Involuntary • Cardiac • Striated • Involuntary • Intercalated disks

6. General Functions of Muscular System • Movement • Skeletal muscle contractions move body in whole or part • Heat Production • Muscle cells produce heat via catabolism to maintain temperature homeostasis • Posture • Continued partial contraction of muscle in order to perform many functions

7. Characteristics of all Muscle • Excitability • Respond to stimuli • Contractility • Actively shorten to exert a pull • Tension that can be harnessed by CT • Extensibility • Continue to contract over range of resting lengths • Ex: smooth muscle can be stretched to several times its original length and still contract on stimulation • Elasticity • Return to original length after contraction

8. -mysium=CT membrane and tendon sheath Myofilaments

9. Muscle Fiber Arrangement Parallel Pennate Bipennate Sphincter Convergent

10. Muscle Attachment DoesNOTmove when muscle contracts Doesmove when muscle contracts

11. Naming Muscles • Location • Function • Shape • Fiber direction • Number of heads/divisions • Points of attachment • Muscle size

12. Location Function Fiber Direction Shape

13. Number of divisions Size

14. Raises eyebrows Frowning Blinking Mastication Laughing Whistling, smiling Puckering Mastication Flexes head

15. Moves head Moves head Flexes head

16. Superficial Back Muscles • Large, fan-shaped muscles provide force in a wide range of body positions • -EX: leaning back to straight vertical and all points in between. Shrugging, pulling scapulas together and down Rotator cuff muscles Stabilize shoulder joint, pull arm back Shoulder movement Pull the arm down, Stabilize torso during many movements (EX: bench press)

17. Trunk Muscles - Thorax Elevate ribs

18. Trunk MusclesAbdomen Flexes trunk Stabilizes Lower back Rotates abdomen

19. Upper Arm Flexes Upper arm Extends forearm

20. Flexors

21. Extensors

22. Upper Leg Deep muscle Vastus intermedius Biceps femoris Semimembranosus Quadricep Femoris Semitendinosus

23. Lower Leg Plantar flexion

24. Foot

25. Anal and Urogenital Muscles

26. Posture • Good Posture – body alignment that favors function with least work • Standing Position • Head and chest held high • Chin, abdomen, buttocks pulled in • Knees slightly bent • Feet firmly on ground 6 in. apart • Poor Posture - puts abnormal strain on ligaments and bones • Maintenance • Tonicity (muscle tone): muscles exert a pull against gravity • Continuous and passive partial contraction of muscles

27. Bellringer 2/24/15 Define the following (p.200 in textbook or notes): • Prime mover (agonist) • Antagonist • Synergist • Fixator FYI-Disease Diary Due Monday. Test next Wednesday (3/4/15)

28. Classification of Muscle Group Actions • Agonist (Prime Mover) • Muscle most responsible for movement • Antagonist • Opposes prime mover • Provides precision and control during prime mover contraction • Relaxes when prime mover contracts • Synergist • Aid prime mover • Contract at same time as prime mover • Fixator • Joint stabilizer • Maintains posture/balance during prime mover contraction

29. https://www.youtube.com/watch?v=4t2X2IvGyUE

30. Lever Systems 2nd Class 1st Class 3rd Class P = Force (push or pull) Contracting Muscle F = Fulcrum Joint L = Load Weights, etc

31. Get to know the muscles • Using your textbook, label the muscles on the handout.

32. Muscles & Age • Infancy & Childhood • Muscle coordination and control allows developmental sequences to occur • Aging • Muscles degenerate with age • Replaced with CT

33. Bellringer 2/4/15 • What is the name of the large superficial calf muscle? • What is the name of the muscle that raises your eyebrows? • What is the name of the muscle that allows you to blink? HW CHECK

34. Muscle Contraction • https://www.youtube.com/watch?v=BMT4PtXRCVA

36. Space between actin Muscle cell (fiber) cytoplasm H zone Basic contractile unit of muscle fiber Sarcoplasm Z line Z line Muscle fiber membrane I band A band Bundle of microfilaments; almost fill sarcoplasm Length of myosin heads (wide, dark stripes) Length of actin (thin, light stripes) Allows impulses to travel along sarcolemma deeper into muscle cell (fiber) Network of tubules and sacs: pumps calcium ions in from sarcoplasm to store in sacs Allows impulse traveling down T tubule to stimulate adjacent sacs

38. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html

39. Myofilaments protein molecules Holds tropomyosin in place Covers active site on actin Attracted to actin and forms crossbridge http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__breakdown_of_atp_and_cross-bridge_movement_during_muscle_contraction.html

40. Contraction http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html tropomyosin troponin • Synaptic vesicle travels down motor neuron and binds to motor endplate • Acetylcholine released into synaptic cleft • Ach binds to receptor on sarcolemma • Impulse travels along sarcolemma and down t-tubules • Calcium released from sarcoplasmic reticulum • Calcium binds to troponin causing conformation change • tropomyosin shifts to expose active site on actin • myosin heads bind to actin • actin filaments are pulled past the myosin head; head unattaches and reattaches to a new site….repeat • Sliding Filament Theory - sliding of thin filaments toward center of each sarcomere shortens the myofibril and muscle fiber.

41. Excitation & Contraction Impulse sent to muscle fiber Muscle fiber creates movement Synaptic cleft Motor endplate Neuromuscular junction Synaptic vesicle (neurotransmitter) http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__function_of_the_neuromuscular_junction__quiz_1_.html

42. Motor Unit Smaller # fibers – more precise movement Larger # fibers – more powerful contraction

43. SR releasing Ca+2 All or NONE Ca+2 bind to troponin; Cross-bridging • Quick jerk due to brief threshold stimulus • One twitch – 1/10 sec • Rarely occur • Gradual, step-like increase in contraction strength • Series of twitch contractions 1 sec apart • Muscle contracts more forcefully after it has • contracted a few times, then when it first contracts • Warm-up before exercise • Smooth, sustained contractions • Coordinated contractions of different motor units • Multiple twitch waves add together to sustain • muscle tension for longer time • Very short periods of relaxation between peaks • of tension • Twitch waves fused into a single, sustained peak

44. Tonicity • Continual, partial contraction of a muscle • Flaccid • Muscles with less tone than normal • Spastic • Muscles with more tone than normal

45. Length-tension Relationship Optimal length Strongest max contraction possible Overstretched Muscle can’t develop tension due to filaments too far apart Sarcomere compressed Muscle can’t develop tension

46. Energy Sources • ATP • Hydrolysis into ADP yields energy required for contraction • ATP binds to myosin head in order to pull actin • Fibers continually resynthesize ATP from breaking down creatine phosphate (requires glucose and oxygen) • Glucose & oxygen • Hemoglobin transfers O2 to muscle fiber • Fiber stores glucose as glycogen • At rest: Excess O2 in sarcoplasm is bound to myoglobin temporarily • Exercise: O2 concen. Decreases in muscle, so myoglobin resupplies muscle with O2

47. Respiration • Aerobic Respiration • Requires O2 • Produces max amount of energy available from each glucose molecule • Anaerobic Respiration • Occurs when lack of O2 • Forms lactic acid • During exercise • Muscles “burn” • O2 debt • Heavy breathing during exercise in order to process lactic acid

48. Muscle Fatigue • Muscles loses ability to contract due to lack of ATP • Suspected imbalance of ions • Problems at the neuromuscular junction • Lactic acid build up • Cramp – muscle contracts spasmodically, but does not relax completely

49. Most body movements are a result of both types

50. Change in Muscle Size • Atrophy – decrease in muscle size • Bed Rest: lose 1% muscle strength/day • Hypertrophy – increase in muscle size