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A/P Lab > Muscle Contraction > Flashcards

Muscle Contraction Flashcards

1
Q

Contraction model

A

-occurs due to shortening within the muscles

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2
Q

Actin and myosin

A

-contractile molecules that inhibit the process of shortening

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3
Q

Sliding filament model

A

Actin and myosin slide or move across each other forming a more compact unit

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4
Q

Cell structure

A
  • cellular level
  • sub cellular level
  • molecular level
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5
Q

Cellular level

A

Cell structures:

  • cell membrane: sarcolemma
  • cell nuclei: many present, just under the membrane
  • cell shape: long, threadlike, referred to as a fiber
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6
Q

Sub cellular level

A
  • there are many specialized organelles present

- sarcoplasmic reticulum and myofibrils

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7
Q

Sub cellular level

Sarcoplasmic reticulum

A
  • Specialized endoplasmic reticulum

- stores calcium needed for contraction

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8
Q

Sub cellular level

Myofibrils

A
  • cylinder shaped organelles passing through cell length

- composed of myofilaments

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9
Q

Molecular level

A

-large molecular structures are present in the myofibrils that are responsible for the contraction process: actin and myosin

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10
Q

Molecular level

Actin myofilaments

A
  • thin filaments composed of 3 parts: actin protein molecules, tropomyosin, troponin
  • anchored or attached to Z lines (disks)
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11
Q

Molecular level

Myosin myofilaments

A

-thick filaments composed of long rods with globular heads

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12
Q

Molecular level

Sarcomere

A
  • structural unit of myofibrils
  • composed of overlapping myosin and actin myofilaments inside Z-lines
  • many per myofibril; forming the contraction unit
  • contains everything from z-disk to z-disk
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13
Q

Events of contraction

A

nerve stimulus, calcium release, calcium action

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14
Q

Events of contraction

nerve stimulus

A

-nerve impulse (action potential) passes along the muscle cell membrane to the sarcoplasmic reticulum

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15
Q

Events of contration

calcium release

A

-calcium is released from storage and diffuses into the cytoplasm and myofibrils

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16
Q

Events of contraction

calcium action

A
  • calcium binds to the troponin molecule on actin myofilaments
  • exposes the active sites, allowing interaction between actin and myosin
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17
Q

Actin-myosin interaction a

A
  • linkages or crossbridges are formed between actin and myosin
  • the myosin head moves and pulls on the actin
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18
Q

Actin-myosin interaction b

A
  • the myosin head releases from one site on actin, resets and pulls on the actin at another site
  • the process is repeated many times very rapidly, moving actin across the myosin
  • this requires many atp molecules
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19
Q

Actin-myosin interaction c

A
  • myosin “walking” down actin causes shortening of the sarcomere units
  • as each sarcomere contracts, a myofibril shortens
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20
Q

Actin-myosin interaction d

A

-contraction ofthe myofibrils causes shortening of a whole muscle cell

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21
Q

Actin-myosin interaction e

A

-contraction of many muscle cells allows a whole muscle to move a body part

22
Q

Whole muscle contraction

contraction strength

A
  • in a whole muscle requires many motor units to be activated
  • a motor unit is a nerve cell and all the muscle cells that it controls
  • the ratio may vary from 1:50 to 1:500 in larger muscles
23
Q

Whole muscle contraction

energy requirements

A
  • many atp molecules are needed for formation of actin and myosin crossbridges during the contraction process
  • main source of atp is from glucose molecules
  • either aerobic or anaerobic metabolism of glucose produces the needed atp supplies during exercise
24
Q

absolute strength

A

-the maximum force exerted with the whole body, or part of the body, irrespective of body size or muscle size

25
Q

relative strength

A

-maximum force exerted in relation to body weight or muscle size

26
Q

muscle cross-sectional area (MSCA)

A

-measure by taking the girth of the forearm

27
Q

summation

A

-involves increasing the force of contration of the muscle fibers within the muscle

28
Q

recruitment

A

-refers to increase in the number of muscle fibers contracting

29
Q

multiple-motor unit summation

A

-relationship between increased stimulus strength and increase in the number of contracting motor units

30
Q

treppe (staircase effect)

A
  • occurs in muscles that have been rested for long periods and results in each slow contraction being stronger and stronger for a short period as the muscle warms up
  • it is likely that this happens as more calcium becomes available to sustain the contraction process
31
Q 
Hip
Psoas major (iliopsoas) 1
A

Origin: T12, L1-5 and illiac fossa
Insertion: lesser trochanter of femur
Action: flexes thigh

32
Q

Hip

iliacus (iliopsoas) 2

A

Action: flexes and rotates thigh (medially)

33
Q

Hip

gluteus maximus 3

A

Origin:outer iliac blade, iliac crest, sacrum, coccyx
Insertion: gluteal tuberosity of femur
Action: extends, abducts, rotates thigh laterally

34
Q

Hip

gluteus medius and minimus 4

A

Action: abduct thigh and rotate it medially

35
Q

Hip

tensor fascia latae 9

A

Action: flexes, abducts and rotates thigh

36
Q

Thigh (quad group)

rectus femoris 11a

A

Origin: anterior inferior iliac spine
Insertion: tibial tuberosity by the patellar ligament
Action: flexes thigh

37
Q

Thigh (quad group)

vastus lateralis 11c

A

Action: extend leg at knee

38
Q

Thigh (quad group)

vastus medialis 11b

A

Action: extend leg at knee

39
Q

Thigh (quad group)

vastus intermedius 11d

A

Action: extend leg at knee

40
Q

Thigh

adductor longus 13

A

Action: adducts, flexes and rotates thigh

41
Q

Thigh

sartorius 10

A

Action: flexes, rotates thigh, flexes leg

42
Q

Thigh

gracilis 15

A

Action: adducts thigh; flexes leg

43
Q

Thigh (hamstring group)

biceps femoris 18

A

Origin: ischial tuberosity, linea aspera of femur
Insertion: head of fibula, lateral condyle of tibia
Action: extend thigh; flexes leg

44
Q

Thigh (hamstring group)

semitendinousus 16

A

Action: extend thigh; flexes leg

45
Q

Thigh (hamstring group)

semimembranosus 17

A

Action: extend thigh; flexes leg

46
Q

Leg

tibialis anterior 19

A

Origin: tibia, interosseous membrane
Insertion: metatarsal 1 and cuniform 1
Action: dorsiflexes and inverts foot

47
Q

Leg

extensor digitorum 21

A

Action: extends toes

48
Q

Leg

fibularis longus 22

A

Action: plantar flexes and everts foot

49
Q

Leg

fibularis brevis 23

A

Action: plantar flexes and everts foot

50
Q

Leg

gastrocnemius 24ab

A

Origin: condyles of femur
Insertion:calcaneus by the calcaneal tendon
Action: flexes leg; plantar flexes foot

51
Q

Leg

soleus 24e

A

Action: plantar flexes foot

A/P Lab (8 decks)

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