Muscoskeletal System Cheat Sheet

1. What does the musculoskeletal system consist of? - muscles - bones - joints - connective tissues 2. What do muscle mechanical energy cells convert ATP into? 3. Describe skeletal striated + under voluntary control muscles: 4. Are skeletal mus- yes, besides reflex movements cle movements voluntary? 5. What is skeletal bones, skin / fascia via the tendons muscle attached to? 6. What does striat- light + dark bands are visible with a microscope ed mean? 7. What are the 3 movement, posture + heat production main functions of skeletal muscle? 8. How do skeletal they pull on bones which shortens muscle fibres + bones muscles move? to which they are attached move closer 9. Which bone usu- insertion bone ally moves when a skeletal muscles pulls on it? 10. What do agonist contract ( muscle that is actively contracting) muscles do? 11. relax + lengthen 1 / 12 What do antagonist muscles do? 12. What is a prime mover? the muscle that is causing most of the movement 13. What is a syner- the muscles that are helping gist? 14. What is a concentric muscle contraction? when the length of a muscle shortens as tension is being generated 15. What is an eccentric muscle contraction? when a muscle lengthens as tension is being generated (e.g. muscles act as a brake running downhill) 16. What is isotonic when a muscle changes length whilst generating tension muscle contraction? 17. 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) 18. What is tonic muscles maintaining body position (posture) where only muscle contrac- a few fibres shorten tion? 19. Describe Type I muscle fibres: - slow-twitch - resist fatigue - oxidative/ aerobic - contain lots of myoglobin (muscle haemoglobin) and mitochondria 20. Where are type 1 muscle fibres mainly found? in postural muscles as they can hold position for long periods 21. 2 / 12 Describe type IIb - larger diameters muscle fibres: - more anaerobic - produce rapid, forceful contractions - fatigue quickly - not much myoglobin/mitochondria - fast - twitch (used in sprinting) 22. 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 23. What are fast-twitch fibres? high force contractions for small durations e.g. short distance runners 24. What are slow-twitch fibres? weak force contractions for longer durations e.g. long distance runners 25. Why does the body shiver? muscles produce heat when contracting and some of this heat will be absorbed by the blood + distributed around the body 26. What happens if proteins get too warm + denature causing the muscle to too much heat stop working is produced by muscles when they contract? 27. Where is cardiac it forms the contractile tissue of the heart muscle found? 28. Is cardiac muscle yes striated? 29. Describe cardiac uninucleate, branching cells that join together at intercamuscle cell: lated disks 3 / 12 30. What does unin- each muscle cell has a nucleus associated with it ucleate mean? 31. Is cardiac mus- autorhythmic and involuntary cle voluntary/involuntary? 32. Where is smooth GI tract, walls of arteries, arterioles, + veins, attached muscle found? to hair follicles, in the walls of hollow organs, can form sphincters 33. Is smooth muscle striated? no 34. Is smooth mus- involuntary cle voluntary / involuntary? 35. What are the - excitability properties of - conductivity smooth muscle? - contractility - extensibility - elasticity 36. What is excitabil- responds to neurotransmitters ity? 37. What is conduc- propagates electrical signals over the membrane tivity? 38. What is contrac- shorten + generate force tility? 39. What is extensi- can be stretched without damage bility? 40. What is elastici- return to original shape after being stretched ty? 41. muscle cell plasma membrane 4 / 12 What is sarcolemma? 42. What is sarcolemma made from? many cells fused together 43. What is sarcoplasm? muscle cell cytoplasm 44. What does sarcoplasm contain? - myofibrils - myoglobin - large amounts of stored glycogen - SR (sarcoplasmic reticulum) - T tubules 45. What does the SR do? - regulates calcium ions, by storing them at rest + then releasing them when a muscle is stimulated to contract 46. 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? 47. 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 48. What are triads? - successive groups of 3 membranous structures - terminal cisternae, T tubules, terminal cisternae 49. What are myofib- the contractile parts of muscle cells rils? 50. Describe myofib- - run in parallel rils: - extend the length of the cell - densely packed together with mitochondria in between 51. What is a myofib- small contractile units = sacromeres ril made up of? 5 / 12 52. Describe dark bands in striations: anisotropic (polarise visible light) = A bands 53. Describe light bands in striations: isotropic (non-polarising) = I bands 54. What are H zones? - slightly lighter zone in the middle of A bands - H zone is the most visible in relaxed muscles 55. What is the M line? dark line in the middle of the H zone 56. What is the Z line/disk? dark line in the middle of the I band 57. What is the sar- - the smallest contractile unit comere? - the region between 2 Z lines 58. Describe thick and thin filaments: - thick filaments extend the length of A bands - thin filaments extend across I bands + partway into A bands 59. Describe myosin: - thick filament with a rodlike tail with 2 globular heads ( = called cross bridges) - heads possess ATPase activity + split ATP for energy during contraction 60. Describe actin: thin filaments with subunits for myosin heads to attach during contraction 61. How does actin form a helical structure? 2 strands of actin coil around each other 62. What is tropomyosin? A protein that spirals around filament cores + when relaxed blocks actin's attachment sites for myosin 63. bind to actin, tropomyosin + Ca2+ ions 6 / 12 What does troponin do? 64. What do troponin actin-myosin interactions, therefore muscle contraction + and tropomyosin relaxation control? 65. What is titin? A stretchy protein that attaches thick filaments to Z lines It helps to stabilise sarcomeres 66. What is myomesin? connects to titin and adjacent thin filaments 67. What is nebulin? Inelastic protein that aligns thin filaments 68. What is dystrophin? links thin filaments to sarcolemma and transmits tension generated to tendons 69. 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 + thin filaments do not change length 70. Describe the sliding mechanism of actin and myosin to cause muscle contraction: 1) Ca2+ binds to troponin altering its conformation, to shift tropomyosin 2) myosin cross bridges attach + pull thin filaments toward centre of the sarcomere 3) sarcomeres, muscle fibres, muscle shortens ( contraction) 71. Describe what 1) Nerve terminals release ACh into the NMJ happens at 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. 7 / 12 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. 6) myosin cross bridges attach and pull thin filaments towards the centre of the sarcomere 72. Where is acetyl- By acetylcholinesterase (AChE) enzymes found on the choline hydrol- surface of the motor end plate + in basal lamina to form ysed in musacetic acid + choline cles? 73. Describe the sliding mechanism of actin and myosin to cause muscle relaxation: - motor end plats signals stop - Ca2+ release from the SR stops - active transport pumps Ca2+ ions back into the SR - troponin-tropomyosin complexes shield myosin binding sites on actin 74. Describe the 1) myosin heads hydrolyse ATP and become reoriented contraction cycle + 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 75. Describe circular - arranged in concentric rings muscle fibre bun- - surrounds external body openings which close by condles: traction e.g. surrounding mouth and eyes 76. Describe conver- - wide origin gent muscle fibre - converge towards a single tendon bundles: 77. Describe pen- short nate muscle fibre - attach obliquely to a central tendon bundles: - bundles attaching to 1 side of tendon = unipennate 8 / 12 - bundles attaching to opposite sides of tendon = bipennate 78. What is the skeleton? - rigid framework of connected bones that gives form to the body - protects/supports soft tissues + provides attachments for muscles 79. How many bones 206 are in the human skeleton? 80. Describe the axi- - consists of 80 bones al skeleton: - divided into the skull, vertebral column + bony thorax regions 81. What is the ap- the bones of the limbs + their girdles pendicular skeleton? 82. What do pectoral attach the upper limbs to the body trunk girdles do? 83. What do pelvic girdles do? secure the lower limbs 84. What are articu- - sites where 2 or more bones meet (joints) lations? - hold the skeleton together - give the skeleton flexibility 85. What are the 2 - functional classifications of - structural joints? 86. What does func- amount of joint movement tional mean? 87. What does struc- material binding the bones together tural mean? 9 / 12 88. What are synarthroses? immovable joints e.g. skull sutures 89. What are amphiarthroses? slightly movable joints e.g. vertebrae 90. What are diarthroses? freely movable joints e.g. shoulder, ankle 91. What are fibrous generally immovable material in between joints? 92. What are carti- rigid / slightly movable material in between laginous joints? 93. What are synovial joints? freely movable material in between 94. What are sutures seams that occur between bones of the skull, bones fuse (fibrous joints)? into a single unit by adulthood 95. What are syndesmoses (fibrous)? - bones connected by a cord/sheet of fibrous connective tissue - the joint has ' give', but no true movement 96. What are gomphoses (fibrous)? tooth peg-in-socket joint 97. What are syncartilage bars / plates that connect together bones + allow chondroses (car- bone growth in epiphyseal plates tilaginous)? 98. What are symcompressible + resilient cartilage pads that permit limited physes (cartilagi- movement nous)? 99. What are the parts of a synovial joint? - articular cartilage - joint cavity - articular capsule 10 / 12 - synovial membrane - synovial fluid 100. What is articular glassy, smooth, spongey cartilage cushions opposing cartilage? bone surfaces 101. What is a joint cavity? cavity in joint filled with synovial fluid 102. What is an articu- - double layered capsule enclosing the joint cavity lar capsule? - outer layer is a tough flexible fibrous capsule 103. What is a synovial membrane? composed of loose connective tissue, lining the fibrous capsule + all non-cartilage-covered surfaces 104. What is synovial a small amount of slippery fluid occupies all free spaces fluid? in the joint capsule, reduces friction within the joint 105. What are the - gliding types of syn- angular ovial joint move- - rotation ments? 106. Describe gliding flat surfaces that slip over 1 another resulting in displacemovements: ment 107. Describe angular increasing/decreasing the angle between 2 bones: movements: - flexion ( decreases angle) - extensions ( increases angle) - abduction (moving away) - adduction (moving towards) - circumduction ( cone shaped movement) 108. Describe rotaturning a bone around its own axis e.g. hip and shoulder tion movements: joints 109. 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 11 / 12 110. What is muscular genetic condition that causes a progressive weakness dystrophy? and degeneration of skeletal muscles 111. What is myasthe- A progressive autoimmune condition where nAChRs are nia gravis? destroyed in the NMJ, causing muscle weakness 112. What is rheuma- An autoimmune + inflammatory condition that may affect toid arthritis? the joints of fingers, wrists, feets, etc. 113. What is osteoporosis? loss of bony tissue, resultingng in bones at a higher risk of fracture 12 / 12