Musculoskeletal System Study Materials

1. What does the musculoskeletal system consist of? muscles, bones, joints, and connective tissues 2. What do musmechanical energy cles convert ATP into? 3. What are the three muscle types? 4. What does skele- bone, skin, or fascia tal muscle attach to? 5. What does striat- light and dark bands are visible with a microscope ed mean? 6. Is skeletal mus- yes cle striated? 7. Are skeletal mus- yes, besides reflex movements cles movements voluntary? 8. What are the 3 movement, posture, and heat production main functions of skeletal muscle? 9. How do skeletal they pull on bones which shortens muscle fibres and the muscles move? bones to which they are attached move closer skeletal, cardiac, and smooth 10. Which bone usu- insertion bone ally moves when a skeletal muscles pulls on it? 1 / 12 11. What is an agonist muscle? the muscle that is actively contracting 12. What is an antag- the muscle that is relaxing onist muscle? 13. What is a prime mover? the muscle that is causing most of the movement 14. What is a syner- the muscles that are helping gist? 15. What is a concentric muscle contraction? when the length of a muscle shortens as tension is being generated 16. What is an eccentric muscle contraction? when a muscle lengthens as tension is being generated (e.g. muscles act as a brake running downhill) 17. What is an when a muscle changes length whilst generating tension isotonic muscle contraction? 18. What is an isometric muscle contraction? when a muscle's length does not change when generating tension (e.g. pushing something that won't move) 19. What is a tonic muscles maintaining body position (posture) where only muscle contrac- a few fibres shorten tion? 20. Describe Type I muscle fibres. slow-twitch resist fatigue oxidative/aerobic contain lots of myoglobin (muscle haemoglobin) and mitochondria 21. in postural muscles as they can hold position for long periods 2 / 12 Where are Type I muscle fibres mainly found? 22. Describe Type IIb larger diameters muscle fibres. more anaerobic produce rapid, forceful contractions fatigue quickly not much myoglobin or mitochondria fast-twitch (used in sprinting) 23. Describe Type IIa intermediate muscle fibres. have many mitochondria but not much myoglobin do not fatigue as quickly as IIb cannot generate as much explosive energy as IIb fast oxidative muscles 24. Why does the body shiver? muscles produce heat when contracting and some of this heat will be absorbed by the blood and distributed around the body 25. Where is cardiac it forms the contractile tissue of the heart muscle found? 26. Is cardiac muscle yes striated? 27. Describe cardiac uninucleate, branching cells that join together at intercamuscle cells. lated discs 28. What does unin- each muscle cell has a nucleus associated with it ucleate mean? 29. Is cardiac muscle autorhythmic and involuntary voluntary or involuntary? 30. Where is smooth GI tract, walls of arteries, arterioles, and veins, attached muscle found? to hair follicles, in the walls of hollow organs, can form sphincters 3 / 12 31. Is smooth muscle striated? no 32. Is smooth muscle voluntary or involuntary? involuntary 33. What are the excitability, conductivity, contractility, extensibility, and properties of elasticity smooth muscle? 34. What is excitabil- responds to neurotransmitters ity? 35. What is conduc- propagates electrical signals over membrane tivity? 36. What is contrac- shorten and generate force tility? 37. What is extensi- can be stretched without damage bility? 38. What is elastici- return to original shape after being stretched ty? 39. Describe skeletal muscle fibre anatomy. long cylindrical cells with several nuclei appearing just under the plasma membrane 40. What is sarcolemma? muscle cell plasma membrane 41. What is sarcolemma made from? many cells fused together 42. What is sarcoplasm? muscle cell cytoplasm 4 / 12 43. What does sarcoplasm contain? myofibrils myoglobin large amounts of stored glycogen sarcoplasmic reticulum T tubules 44. What is sara form of endoplasmic reticulum which forms a network of coplasmic retic- interconnecting tubules that surround each myofibril and ulum? also form end sacs (terminal cisternae) 45. What does the SR do? regulates calcium ions, by storing them at rest and then releasing them when a muscle is stimulated to contract 46. What are T (transverse) tubules? from the sarcolemma forming hollow tubes that penetrate into the cell near the location of terminal cisternae 47. What happens to they travel along the sarcolemma and continue down action potentials T tubules deep into muscle cells close to the terminal in the sarcolem- cisternae of the SR ma? 48. Why are T they contain extracellular fluid so they can aid the delivery tubules hollow? of oxygen and glucose to the deeper parts of muscle cells 49. What are triads? successive groupings of three membranous structures terminal cisternae-T tubules-terminal cisternae 50. What are myofib- the contractile parts of muscle cells rils? 51. Describe myofib- run in parallel rils. extend the length of the cell densely packed together with mitochondria in between made up of sarcomeres that are arranged in chains 52. What are sarcomeres? small contractile units 53. 5 / 12 Describe dark bands in striations. anisotropic (polarise visible light) called A bands 54. Describe light bands in striations. isotropic (non-polarising) called I bands 55. Describe an A band. slightly lighter zone in the middle called H zone H zone is most visible in relaxed muscles the middle of a H zone has a dark line called the M line 56. Describe an I band. middle of an I band has a dark line called the Z line a sarcomere is the region between two Z lines 57. Describe thick and thin filaments. thick filaments extend the length of A bands thin filaments extend across I bands and partway into A bands 58. Describe myosin. thick filaments are mostly made of myosin a strand of myosin has a rodlike tail and two globular heads (called cross bridges) heads possess ATPase activity and split ATP for energy during contraction 59. Describe actin. thin filaments are mostly made of actin subunits of actin filaments contain sites to which myosin heads attach during contraction two strands of actin coil around each other to form a helical structure 60. What is tropomyosin? a protein that spirals around filament cores and when relaxed blocks actin's attachment sites for myosin 61. What is troponin? binds to actin tropomyosin and calcium ions 62. What is titin? a stretchy protein that attaches thick filaments to Z lines it helps to stabilise sarcomeres 6 / 12 63. What is myomesin? connects to titin and adjacent thin filaments 64. What is nebulin? inelastic protein that aligns thin filaments 65. What is dystrophin? links thin filaments to sarcolemma and transmits tension generated to tendons 66. Describe the sliding mechanism of actin and myosin filaments. 1. myosin cross bridges pull on thin filaments. 2. thin filaments slide inwards. 3. Z lines come toward each other. 4. sarcomeres shorten. 5. muscle fibres shorten. 6. muscle shortens. 7. thick and thin filaments do not change length. 67. Describe what happens at a neuromuscular junction. 1. nerve terminals release ACh into the NMJ. 2. ACh binds to nicotinic ACh receptors on the postsynaptic membrane. 3. two ACh molecules open each nicotinic ACh receptor, which allows sodium ions to diffuse into the sarcoplasm from the SR, causing depolarisation, and generating an action potential. 4. as the sarcolemma is polarised at rest, this action potential depolarises it and spreads down T tubules to the triad regions. 5. calcium ions bind to troponin, which alters its confirmation to shift tropomyosin. 8. myosin cross bridges attach and pull thin filaments towards the centre of the sarcomere. 68. Describe the 1. myosin heads hydrolyse ATP and become reoriented contraction cycle and energised. of myosin heads. 2. myosin heads bind to actin, forming cross bridges. 3. myosin heads rotate toward the centre of the sarcomere (power stroke). 4. as myosin heads bind ATP, the cross bridges detach from actin. contraction cycle continues if ATP is available and calcium ion level in the sarcoplasm is high. 7 / 12 69. Describe muscle 1. ACh is hydrolysed by AChE enzymes, found on the relaxation. surface of the motor end plate and in the basal lamina, to form acetic acid and choline. 2. motor end plate potentials stop. 3. calcium ion release from the SR stops. 4. active transport pumps calcium ions back into the SR. 5. tropomyosin-troponin complexes shield myosin binding sites on actin. 70. Describe circular arranged in concentric rings muscle fibre bun- surrounds external body openings which close by condles. traction e.g. surrounding mouth and eyes 71. Describe conver- wide origin gent muscle fibre converge towards a single tendon bundles. e.g. pectoralis major 72. Describe parallel runs parallel to long axis of the muscle muscle fibre bun- e.g. biceps brachii dles. 73. Describe penshort nate muscle fibre attach obliquely to a central tendon bundles. bundles attaching to one side of the tendon are unipennate bundles attaching to opposite sides of the tendon are bipennate 74. What is the skeleton? rigid framework of connected bones that gives form to the body, protects/supports soft tissues, and provides attachments for muscles 75. How many bones 206 are in the human skeleton? 76. Describe the axial skeleton. 8 / 12 consists of 80 bones divided into the skull, vertebral column, and bony thorax regions 77. What is the ap- the bones of the limbs and their girdles pendicular skeleton? 78. What do pectoral attach the upper limbs to the body trunk girdles do? 79. What do pelvic girdles do? secure the lower limbs 80. What are articu- sites where two or more bones meet (joints) lations? hold the skeleton together give the skeleton flexibility 81. What are the two functional classifications of structural joints? 82. What does func- amount of joint movement tional mean? 83. What does struc- material binding the bones together tural mean? 84. What are synarthroses? immovable joints e.g. skull sutures 85. What are amphiarthroses? slightly movable joints e.g. vertebrae 86. What are diarthroses? freely movable joints e.g. shoulder, ankle 87. What are fibrous generally immovable material in between joints? 9 / 12 88. What are carti- rigid or slightly movable material in between laginous joints? 89. What are synovial joints? freely movable material in between 90. What are sutures seams that occur between bones of the skull, bones fuse (fibrous)? into a single unit by adulthood 91. What are syndesmoses (fibrous)? bones connected by a cord or sheet of fibrous connective tissue the joint has 'give', but no true movement 92. What are gomphoses (fibrous)? tooth peg-in-socket joint 93. What are syncartilage bars or plates that connect together bones, and chondroses (car- allow bone growth in epiphyseal plates tilaginous)? 94. What are symcompressible and resilient cartilage pads that permit limphyses (cartilagi- ited movement nous)? 95. What are the parts of a synovial joint? articular cartilage joint cavity articular capsule synovial membrane synovial fluid 96. What is articular glassy, smooth, spongey cartilage cushions opposing cartilage? bone surfaces 97. What is a joint cavity? cavity in joint filled with synovial fluid 98. What is an articu- double layered capsule enclosing the joint cavity lar capsule? outer layer is a tough flexible fibrous capsule 10 / 12 99. What is a synovial membrane? composed of loose connective tissue, lining the fibrous capsule and all non-cartilage covered surfaces 100. What is synovial small amount of slippery fluid occupies all free spaces in fluid? the joint capsule, reduces friction within the joint 101. What are the gliding types of synangular ovial joint move- rotation ments? 102. Describe gliding flat bone surfaces glide over one another, resulting in movements. displacement occur at intercarpal and intertarsal joints, and between flat articular processes of the vertebrae 103. Describe angular increase or decrease the angle between two bones movements. these movements include flexion (decrease angle), extension (increase angle), abduction (moving away), adduction (moving towards), and circumduction (cone shaped) 104. Describe rotaturning a bone around its own axis tion movements. e.g. hip and shoulder joints 105. What is a lever? a rigid bar that moves on a fixed point (fulcrum) when a force is applied to it the applied force (effort) is used to move a load 106. What is muscular genetic condition that causes a progressive weakness dystrophy? and degeneration of skeletal muscles 107. What is myasthe- a progressive autoimmune condition where nAChRs are nia gravis? destroyed in the NMJ, causing muscle weakness 108. What is rheuma- an autoimmune and inflammatory condition that may aftoid arthritis? fect the joints of fingers, wrists, feet, etc 109. 11 / 12 What is osteoporosis? loss of bony tissue, resulting in bones at a higher risk of fracture 12 / 12