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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
relative strength
-maximum force exerted in relation to body weight or muscle size
26
muscle cross-sectional area (MSCA)
-measure by taking the girth of the forearm
27
summation
-involves increasing the force of contration of the muscle fibers within the muscle
28
recruitment
-refers to increase in the number of muscle fibers contracting
29
multiple-motor unit summation
-relationship between increased stimulus strength and increase in the number of contracting motor units
30
treppe (staircase effect)
- 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
``` Hip Psoas major (iliopsoas) 1 ```
Origin: T12, L1-5 and illiac fossa Insertion: lesser trochanter of femur Action: flexes thigh
32
Hip | iliacus (iliopsoas) 2
Action: flexes and rotates thigh (medially)
33
Hip | gluteus maximus 3
Origin:outer iliac blade, iliac crest, sacrum, coccyx Insertion: gluteal tuberosity of femur Action: extends, abducts, rotates thigh laterally
34
Hip | gluteus medius and minimus 4
Action: abduct thigh and rotate it medially
35
Hip | tensor fascia latae 9
Action: flexes, abducts and rotates thigh
36
Thigh (quad group) | rectus femoris 11a
Origin: anterior inferior iliac spine Insertion: tibial tuberosity by the patellar ligament Action: flexes thigh
37
Thigh (quad group) | vastus lateralis 11c
Action: extend leg at knee
38
Thigh (quad group) | vastus medialis 11b
Action: extend leg at knee
39
Thigh (quad group) | vastus intermedius 11d
Action: extend leg at knee
40
Thigh | adductor longus 13
Action: adducts, flexes and rotates thigh
41
Thigh | sartorius 10
Action: flexes, rotates thigh, flexes leg
42
Thigh | gracilis 15
Action: adducts thigh; flexes leg
43
Thigh (hamstring group) | biceps femoris 18
Origin: ischial tuberosity, linea aspera of femur Insertion: head of fibula, lateral condyle of tibia Action: extend thigh; flexes leg
44
Thigh (hamstring group) | semitendinousus 16
Action: extend thigh; flexes leg
45
Thigh (hamstring group) | semimembranosus 17
Action: extend thigh; flexes leg
46
Leg | tibialis anterior 19
Origin: tibia, interosseous membrane Insertion: metatarsal 1 and cuniform 1 Action: dorsiflexes and inverts foot
47
Leg | extensor digitorum 21
Action: extends toes
48
Leg | fibularis longus 22
Action: plantar flexes and everts foot
49
Leg | fibularis brevis 23
Action: plantar flexes and everts foot
50
Leg | gastrocnemius 24ab
Origin: condyles of femur Insertion:calcaneus by the calcaneal tendon Action: flexes leg; plantar flexes foot
51
Leg | soleus 24e
Action: plantar flexes foot

A/P Lab (8 decks)

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