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HL Bio > 11.2– movement > Flashcards

11.2– movement Flashcards

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Biology 101 flashcards
1
Q

what is the general function of bones and exoskeletons?

A
  • provide anchorage for muscles
  • act as levers
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2
Q

what are 3 specific functions of the skeletal system?

A
  1. provide structural support
  2. provide protection for organs
  3. act as attachment points for muslces
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3
Q

how are bones connected to other bones?

A

by ligaments

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4
Q

ligaments are found in between…

A

bones

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5
Q

tendons are found in between…

A

muscles and bones

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6
Q

muscles work in _________ pairs

A

antagonistic

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7
Q

what are the parts of an insect leg?

A

femur, tibia, tarsus

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8
Q

what are the muscles involved in the jumping of an insect?

A

flexor muscle and extensor muscle

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9
Q

how do antagonistic muscle pairs in an insect leg help the insect jump?

A
  • when the flexor muscle contracts, the extensor muscle relaxes
    • tibia and femur are brought closer together
    • causes retraction of hind quarters -> prepares insect for pushing off the ground
  • when the extensor muscle contracts, the flexor muscle relaxes
    • tibia is pushed away from femur
    • causes extension of the hind quarters -> jump
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10
Q

label a diagram of the human elbow

A

-

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11
Q

which part of the arm anchors the muscle?

A

the humerus

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12
Q

what are the parts of the arm that act as a forearm level?

A

radius for biceps and ulna for triceps

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13
Q

the biceps ______ the forearm

A

bends/flexes

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14
Q

the triceps ______ the forearm

A

straightens/extends

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15
Q

what does the joint capsule do?

A

it seals joint space and limits range of movement to provide stability

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16
Q

the synovial fluid functions to…

A

provide food, O2 and lubrication to the cartilage

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17
Q

what is the function of the cartilage?

A
  • it reduces friction, allowing smooth movement
  • it absorbs shock and distributes load
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18
Q

why are skeletal muscle fibres multinucleated? (short)

A
  • muscle cells fuse together to form a long fibre
  • nuclei of the cells do not degenerate -> thus fused muscle fibre contains multiple nuclei
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19
Q

what is the specialised feature of muscle fibres that provides energy?

A

muscle fibres have a large no. of mitochondria for ATP for contraction

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20
Q

muscle cells have specialised endoplasmic reticulum called _______ which is adapted to store _____

A

sarcoplasmic reticulum, Ca ions

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21
Q

muscle fibres contain ________

A

myofibrils

22
Q

what are the two types of myofilaments?

A

thin, actin
thick, myosin

23
Q

what is the continuous membrane surrounding the muscle fibre called?

A

sarcolemma

24
Q

sarcolemmas contain…

A

T tubules

25
Q

protein myofilaments myosin and actin make up a ______

A

sacromere

26
Q

what are the adaptations of a skeletal muscle fibre? (5) (mnemonic: FMSMT)

A
  1. made up of Fused skeletal muscle cells
    • reduces the need for strong junctions between muscle cells to withstand forces of contraction
  2. contains large no. of Mitochondria
    • to generate ATP for muscle contraction
  3. contains Sarcoplasmic reticulum
    • to store and release Ca ions for muscle contraction
  4. contains Myofibrils
    • w thin actin and thick myosin filaments for muscle contraction
  5. contains T-tubules
    • runs deep into muscle fibre
    • allows for action potential to travel down the t-tubule to sarcoplasmic reticulum
27
Q

what do Z-discs do?

A

they hold the myofilaments in place

28
Q

draw a labelled diagram of a sacromere

A

-

29
Q

what does tropomyosin do when a muscle is at rest? (short)

A
  • tropomyosin fibres wrap around actin filaments -> preventing myosin heads from binding to actin filaments
  • thus no contraction takes place
30
Q

what are the 4 key steps of muscular contraction?

A
  1. depolarisation and Ca ion release
  2. actin + myosin cross-bridge formation
  3. sliding mechanism of actin and myosin filaments
  4. sarcomere shortening = muscle contraction
31
Q

what triggers the release of acetylcholine into the motor end plate?

A

the action potential from a motor neuron

32
Q

how is depolarisation spread throughout muscle fibres?

A

by the T tubules on the sarcolemma

33
Q

which part of the sarcomere releases Ca ions?

A

sarcoplasmic reticulum

34
Q

what triggers the release of Ca ions by the sarcoplasmic reticulum?

A

depolarisation

35
Q

what happens during depolarisation and Ca ion release? (3)

A
  • action potential from a motor neuron triggers the release of acetylcholine into the motor end plate
  • acetylcholine initiates depolarisation within the sarcolemma -> spreads through muscle fibre via T tubules
  • depolarisation triggers sarcoplasmic reticulum to release stores of Ca ions
36
Q

what are the binding sites on the myosin heads blocked by?

A

the troponin and tropomyosin complex

37
Q

how are the binding sites on myosin heads exposed?

A

Ca ions bind to troponin on actin, reconfiguring the troponin and tropomyosin complex

38
Q

the _______________ form a cross bridge with ____________________

A

myosin heads, actin filaments

39
Q

what happens during actin and myosin cross-bridge formation? (3)

A
  1. on actin, the binding sites for the myosin heads are covered by a blocking complex comprised of troponin and tropomyosin
  2. Ca ions bind to troponin on tropomyosin -> reconfiguring the complex -> this exposes the binding sites on actin for myosin heads
  3. the myosin heads then form a cross-bridge with actin filaments
40
Q

what binds to myosin to break the cross bridge between actin and myosin

A

ATP

41
Q

ATP hydrolysis causes myosin heads to _______________ and _________

A

change balance, swivel

42
Q

what happens during the sliding mechanism of actin and myosin? (5)

A
  • ATP binds to the myosin head, breaking the cross-bridge between actin and myosin
  • ATP hydrolysis causes myosin heads to change position and swivel -> pulls the actin filaments toward the center of the sarcomere -> releases ADP+Pi
  • new ATP molecule binds to the myosin head -> causes it to detach from actin filament
  • ATP is hydrolysed to ADP+Pi -> myosin head can re-cock back into high energy stage for next cycle
43
Q

which part is the ‘sliding mechanism’?

A

the pulling of actin filaments toward the center of the sarcomere by the swivelling of myosin heads

44
Q

when do the myosin heads return to its original conformation?

A

when it swivels

45
Q

how do sarcomeres shorten? (short)

A

dragging of actin pulls the Z lines closer together, shortening the sarcomere

46
Q

how do individual sarcomeres lead to muscle contraction? (short)

A
  • individual sarcomeres become shorter in length
  • contraction of muscle fibres as a whole
47
Q

what are the events in muscle contraction? (7)

A
  1. action potential from a motor neuron triggers the release of acetylcholine into the motor end plate
    • acetylcholine initiates depolarisation within the sarcolemma -> spreads through muscle fibre via T tubules
  2. depolarisation triggers sarcoplasmic reticulum to release stores of Ca ions
  3. Ca ions bind to troponin on tropomyosin and cause tropomyosin to move
    • exposing binding sites on actin for myosin heads
  4. Pi released from myosin heads
    • myosin heads bind to actin -> forms cross bridge
  5. myosin heads, having hydrolysed ATP to ADP+Pi, have high energy state
    • chemical energy is used for the myosin heads to swivel, pulling the actin filaments toward the center of the sarcomere
    • releases ADP
  6. new ATP molecule binds to the myosin head
    • causes it to detach from the actin filament
  7. ATP is hydrolysed to ADP+Pi
    • re-cocks the myosin head into high energy state
    • another cycle can begin
48
Q

in electron micrographs, A bands are ______

A

darker

49
Q

the lighter part of electron micrographs are

A
  • I bands
  • actin is present, myosin is not
50
Q

identify if the muscle in the electron micrograph is relaxed or contracted:

A

-

HL Bio (53 decks)

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