1. Ch. 6 The Muscular System

2. You are selected for an internship at the National Space Biomedical Research Institute in Houston, Texas. Part of your job is to monitor the health of the astronauts for the National Aeronautics and Space Administration (NASA) before, during, and after a space mission. By chance, your time in the lab corresponds with the return of an American astronaut from the International Space Station. She just spent 171 days in the space station and is now getting back to her research studies on earth. Unfortunately, it was discovered that she would have to go through at least 3 weeks of physical therapy. You learned from reading her physical health report that she lost 30% of her skeletal muscle mass. Most of it occurred within the last 2 months of the mission in space. The normal muscle loss during a space mission is less than 20%. A majority of muscle atrophy results from disuse, yet she followed all the exercise programs NASA requires. Your job is to assist the research team in investigating her problem. Determine the most likely cause of her accelerated loss of muscle mass. Case Study Investigation

3. Muscle cells are composed of specialized contractile cells that allow them to change shape and shorten or contract. Over half the body’s mass is composed of muscle tissue, and over 90% of this muscle tissue is involved in skeletal movement. Muscles require glucose, oxygen, calcium and electrolytes and release metabolic wastes. Overview Chapter 6 – The Muscular System

4. Three types of muscle are found in the human body: a) Cardiac muscle (slightly striated & involuntary; b) Skeletal muscle (striated & voluntary) c) Smooth muscle (non-striated & involuntary) Muscle

5. 1. Origin: stationary bone the muscle attaches to (zygomatic arch) 2. Body: rest of the muscle (masseter) 3. Insertion: moveable bone the muscle attaches to (mandible) Musculature: Gross Anatomy

6. Origin: Scapula / Humerus Body Biceps Brachii Insertion: Radius Tendon attachs muscle to bone Sacs of synovial fluid btwn tendon & bone for lubrication

7. raises eyebrow closes eyes smile muscle closes lips yes/no muscle closes jaw extends head / neck closes jaw

8. adducts upper arm deltoid abducts arm Muscles of the Trunk flex trunk adducts arm

9. flexes forearm pronates & supinates flexes elbow extends elbow MUSCLES of the ARM

10. flexes thigh + lower leg (middle quadricep) (lateral quadricep) (medial quadricep) Vastus intermedius (inner quadricep) plantar-flexes ankles dorsi-flexes ankles plantar-flexes ankles Quadriceps extend the leg

11. extends thigh (lateral hamstring (middle hamstring) Hamstrings flex the leg adducts thigh (medial hamistring)

12. Synergist = muscles that help the prime mover Antagonist = muscle that produces the opposite movement as prime mover Prime mover =muscle responsible for the movement Basic Skeletal Muscle Function 1. Skeletal Movements = pulling on bone (relaxation / contraction)

13. 2. Posture / Muscle Tone: balance weight distribution and hold muscles in position a. tonic contraction: only a few muscles contract at a time; NO shortening and NO movement

14. 3.Regulate Organ Volume a. sphincters: bands of smooth muscle that prevent outflow of fluids from hollow organs

15. 4.Move substances within the body : a. cardiac muscle – pumps blood b.smooth muscle – moves food through digestive sys. (peristalsis)

16. 5.Heat Production: when muscles contract they produce heat a.Hypothermia – decrease in body temp below normal b. Hyperthermia – increase in body temp above normal

17. Concept Check #1 1.What are muscles composed of that allow them to do their jobs? specialized contractile cells 2. What are 5 functions of the muscular system. 1- movement 2- posture 3- regulate organ volume 4 – move substances w/I body 4- heat production 3. If I were to flex my elbow which muscle would be the prime mover, synergist, and antagonist? Prime mover – main muscle responsible for movement (bicep) Synergist – other muscles that help PM (brachioradialis) Anatogonist – produces opposite movement (tricep)

18. 4. Give an example of how cardiac and smooth muscle move substances within the body. Cardiac muscle – pumps blood throughout the body Smooth muscle – moves food throughout the body (peristalsis; sphincters) 5. How does the origin and insertion of a muscle differ? Origin – immovable bone that muscle attaches to Insertion – movable bone that muscle attaches to The insertion bone moves towards the origin bone 6. Research the origin and insertion for the following muscles: Gastrocnemius: Origin: femur Insertion: calcaneous Pectoralis major: Origin: clavicle /sternum Insertion: humerus Concept Check #2

19. Skeletal Muscle Structure surrounds fassicles surrounds each surrounds entire muscle bundle of muscle cells http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13904http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13904 Muscle Structure Animation

21. Microcopic Muscle Cell Structure  skeletal muscle cells are long, cylindrical cells covered with an excitable (can transmit) membrane called the sarcolemma  proteins in sarcolemma responds to and transmits info to muscle cells causing them to contract  cytoskeleton of muscle cells contain myofilaments made up of protein a) thick: myosin b) thin: 1) actin 2) troponin 3) tropomyosin

22.  contractile unit of muscle is called a sarcomere (thousands/muscle cell) which is surrounded by a sarcoplasmic reticulum (stores/transports Ca for contraction)  Thick & thin myofilaments overlap within sarcomere  gives muscle its striated appearance & carries out contraction  chains of sarcomeres form myofibrils

23. Sarcomere Chain Structure http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter42/animations.html#http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter42/animations.html# - Sarcomere shortening bio book animation  1 sarcomere 

24. How Do Muscles Contract  contraction occurs when sarcomeres shorten simultaneously 1.Nerve Stimulation at the neuromuscular junction (motor neuron meets muscle fiber) Nerve cells release neurotransmitter acetylcholine which binds to sarcolemma and allows Na+ /K to cross membrane Flow of ions causes Ca to be released from SR; travels to sarcomere and initiates contraction phase http://www.galaxygoo.org/biochem/neur o/nmj_flash.html (basic neuromuscular junction animation)

25. 2.Muscle Contraction – takes place inside muscle cell Ca binds to troponin; moves it off the actin-binding site on tropomyosin so myosin can attach to actin ATP provides energy for myosin head to pull thick m.f across thin m.f. (shortening Z-lines of sarcomere) http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter10/animation__action_potentials_and_mu scle_contraction.htmlhttp://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter10/animation__action_potentials_and_mu scle_contraction.html - action potential and muscle contraction https://www.youtube.com/wat ch?v=jqy0i1KXUO4https://www.youtube.com/wat ch?v=jqy0i1KXUO4 - Crash Course in Contraction https://www.youtube.com/wat ch?v=CepeYFvqmk4https://www.youtube.com/wat ch?v=CepeYFvqmk4 - How a muscle cell is signaled

26. http://highered.mheducation.com/sites/0072495855/student_view 0/chapter10/animation__breakdown_of_atp_and_cross- bridge_movement_during_muscle_contraction.htmlhttp://highered.mheducation.com/sites/0072495855/student_view 0/chapter10/animation__breakdown_of_atp_and_cross- bridge_movement_during_muscle_contraction.html - good video

27. 3. Muscle Relaxation starts when neural stimulation stops Na+ and K+ ion levels completely recover SR retrieves most of its Ca Myosin heads release actin Troponin covers actin-binding site on tropomyosin

28. Rigor Mortis  muscle stiffness caused by Ca leakage out of SR into sarcomere after death Creatine phosphate, glycogen, & myoglobin (red chemical)  all serve as energy or oxygen reserves for muscle contraction https://www.youtube.com/ watch?v=mO6a9UZmtaghttps://www.youtube.com/ watch?v=mO6a9UZmtag – rigor mortis animation

29. unique muscle composition is genetically determined https://www.23andme.com/health/Muscle-Performance/ - 23 and Me genetic testing https://www.23andme.com/health/Muscle-Performance/ Types of Skeletal Muscle Fibers FeatureSlow Red Twitch Fibers (Type I) Fast White Twitch Fibers (Type IIb) SizeSmallestlargest Mitochondrialarge amount (get ATP through aerobic processes) small amount (get ATP through anaerobic processes) Colorred (high myoglobin content) white (low myoglobin content) Speed of Contractions SlowFast Resistance to Fatigue High (very fatigue resistant)Low (not fatigue resistant) ActivitiesMaintaining posture, endurance activities (i.e. marathon runners) Muscle: soleus Rapid, intense movements of short duraction (i.e. sprinters, throwing a ball or weight lifting) Muscle: gastrocnemius / vastus lateralis

30. Concept Check #3 7. List the three membranes of muscle in order from superficial to deep then explain how they each differ. epimysium – membrane that surrounds the entire muscle perimysium – membrane that surrounds each fascicle endomysium – membrane that surrounds each fiber (cell) 8. What is the name given to the membrane that surrounds a muscle cell and why is it important? sarcolemma; responds to signals from other cells/environment and transmits the information to the muscle cells causing them contract 9. Why is the sarcoplasmic reticulum that surrounds the sarcolemma so important? Stores the calcium needed to unlock/move the troponin/tropomyosin cover on the myosin binding sites.

31. Concept Check #4 10. Draw a picture of a sarcomere and label the two different myofilaments and explain how it relates to the sliding filament theory. Myosin binds to actin and pulls on it. The myofilaments overlap each other causing the distance between each Z-line to shorten. With hundreds of sarcomeres within a muscle cell it causes the cell to shorten. 11. Why is Ca necessary for starting a muscle contraction. Attaches to troponin which holds the tropomyosin on top of the myosin-binding sites on actin. This unlocks/changes it’s shape in order to remove it and allow myosin to bind to actin.

32. Skeletal Muscle Action  skeletal muscle structure responds to the amount of work it must do 1. irregular use or lack of neural stimulation causes  a loss of sarcomere proteins  decrease in muscle strength  decrease in muscle size = hypotrophy or atrophy 2. regular use & increased blood flow causes  increase in muscle strength  increase in muscle size = hypertrophy  Increased blood flow = enlarges muscle diameter = muscle strength  Heavy muscle use = sarcomere density = muscle diameter  Some ppl can increase sarcomere density and strength w/o a significant increase in diameter……genetic differences and variations in blood flow

33. Skeletal Muscle Action  shortening of the muscle brings the insertion closer to the origin  threshold stimulus - minimal level of stimulus required to cause a fiber to contract  muscle cells are controlled by different motor units with different threshold levels so not all muscles contract at the same time  All or None Theory – a fiber contracts completely or not at all; It’s the difference in picking up 1 textbook or 25 textbooks. http://study.com/academy/lesson/how-motor-unit-summation-develops-muscle-tension.htmlhttp://study.com/academy/lesson/how-motor-unit-summation-develops-muscle-tension.html - study. Com (partial)

34. Skeletal Muscle Action  muscles can be categorized by the effect it has on joint motion abductor – muscles that move a bone away from the midline (deltoid, gluteus maximus) adductor – muscles that move a bone closer to the midline (gracilis, pectoralis major) extensor – muscles that increase the angle of a joint (tricep, quadriceps) flexor – muscles that decrease the angle of a joint (bicep, hamstrings) sphincter – muscles that decrease the size of an opening (esophogeal sphincter, rectal spincter)

35. Skeletal Muscle Action  isotonic contractions: when a muscle is actively shortening or lengthening ex. lifting weights  isometric contractions: no movement but muscle is contracted and tension is building ex. pushing against an immovable object

36. Fatigue during muscular exercise: b.v. in muscles dilate & blood flow and O2 delivery increases muscle fatigue occurs after extended or strong muscle contractions and O2 & ATP can’t supply muscle fibers fast enough oxygen debt – amount of O2 taken in to “pay back” resting metabolic conditions if O2 is unavailable, glucose is converted into lactate which helps break down glucose for energy production of lactic acid in the body causes soreness

37. Aging and Pathology of the Skeletal System many disorders of the musculature are due to interactions with the skeletal and nervous systems Strains vs. Sprains strains – overworking the muscle’s force on joints and tendons  pain and swelling of fascia, joints, ligaments, and tendons  nerves signal pain when stretched or swollen (stiff) sprains – more severe; sudden or violent stress on a joint/muscle  tearing of ligament, muscle, or tendon and damage to nearby blood vessels  requires time for tissue and protein replacement  To keep swelling down apply cold 1 st followed by continuous warmth to speed healing

38. contusions – related to sprains; direct hit(s) to a muscle

39. Myopathy / Neuromuscular disorders  inability of the nervous system to communicate properly to muscles 1. mitochondrial myopathies – group of neuromuscular diseases caused by genetic abnormalities of the mitochondria; muscles can’t produce energy from food; muscles become easily cramped

40. 2. myosistis ossificans (2 types – 1 st non-hereditary; 2 nd hereditary) – caused by damage to soft tissues @ muscle; bone growing within muscle tissue; pain during contraction

41. 3. muscular dystrophy- involves progressive weakness in the voluntary muscles; inability of nervous system to stimulate muscle action; results in atrophy and wasting

42. Affect of Steroids on Muscles  boost body’s ability to produce muscle  prevent muscle breakdown & decreases recovery time  resemble chemical structure of testosterone  {T} directs the body to produce more or enhance male characteristics (like increased muscle mass, etc)

44. Aging of the Muscular System  sarcopenia (natural muscle loss due to aging process)  cachexia (muscle loss usually associated with AIDS, cancer, starvation, anorexia, bulimia); slower form reduces bodies ability to rebuild muscle structure  decrease in neural stimulation -> atrophy  malnutrition / undernutrition  decrease in carbs and proteins  less energy and nutrients for repair and maintenance  decline in sex hormones and insulin-like growth factor –1 (IGF- 1); needed for muscle cell growth, maintenance, & repair  physical therapies  1)artificial up-regulation with electrical pulses (causes muscles to retain protein) 2)muscle massages

45. Concept Check #5 12. List 2 things that can happen when muscles are used irregularly. Regularly? IrregularyRegularly? 1- cells lose sarcomere protein 1. muscle size increases 2- contraction strength decreases 2. muscle strength increases 3- muscle size decreases 13. How do hypertrophy and hypotrophy (atrophy) differ? Hypertrophy – increase in muscle size Hypotrophy (atrophy) – decrease in muscle size 14. Do all the muscle fibers (cells) in my arm contract when I pick up a pencil? Use the terms threshold stimulus and all or none theory in your explanation. Muscle fibers (cells) have different threshold stimuli. Picking up a pencil won’t meet every fibers threshold requirement so not all will contract. If they are, they will contract full as per the all or none theory.

46. Concept Check #8 15. How do strains, sprains, and contusions differ? strains  overworked muscles, joints, tendons, ligaments sprains  suddent/violent stress on a muscle, joint, tendon, ligament contusion  very deep bruise 16. Name and describe 2 different types of myopathies. muscular dystrophy – progressive weakness of muscles myosistis ossificans – bone develops w/in muscle 17. What is cachexia in terms of muscle aging. Quickened muscle loss due to the inability to rebuild muscle 18. Describe 4 factors that contribute to muscle aging. neural stimulation, decrease in sex hormones, poor nutrition, natural causes

47. Case Study Investigation  Selected for an internship at National Space Biomedical Research Ins.  Required to monitor astronauts for NASA before, during, and after a space mission.  American astronaut spent 171 days in the space stations has to go through 3 weeks of physical therapy.  She lost 30% of her skeletal muscle even after following all the exercise programs NASA required. The average is less than 20%.  Questions: 1.Why did the American lose 30% of her skeletal muscle after her mission to space? Be specific. 2. She lost 10% more than the average astronaut. What else associated with her mission could have contributed to the American’s muscle loss?