Topic 11: Muscular System Flashcards

1
Q

Muscular System

A

— refers to skeletal muscle system
— primarily attached to bone
— produce movement by contracting – byproduct = heat

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2
Q

Skeletal Muscle

A

cells called fibers

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3
Q

fascicle

A

group fibers

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4
Q

whole muscle

A

= group of fascicles

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5
Q

List the CT component of skeletal muscle

A

1) Fascia

2) Tendons + Aponeuroses

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6
Q

Fascia

A

= CT

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7
Q

Epimysium

A

– surrounds entire muscle

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8
Q

Perimysium

A

– surrounds fascicles

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9
Q

Endomysium

A

– surrounds each muscle fiber

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10
Q

Tendons + Aponeuroses

A

— extensions of epi-, peri-, + endomysium

— anchors to bone (periosteum), cartilage, skin, or fascia

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11
Q

tendon

A

= rope-like
o e.g. Achilles tendon

connect muscle to bone

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12
Q

aponeurosis

A

e. g. galea aponeurotica = epicranial aponeurosi

- sheet like

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13
Q

Describe the structure of Skeletal Muscle Fiber

A
— large multinucleate cells
— parts:
1) Sarcolemma = cell membrane
2) Sarcoplasm = cytoplasm
3) Myofibrils (intracellular
4) T-tubules structures)
5) Sarcoplasmic Reticulum
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14
Q

Myofibrils

A

— within each fibre there are several hundreds to thousands

— composed of sarcomeres:

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15
Q

Describe the structure of sarcomeres

A

(composed of proteins):
o made of 2 types of myofilaments:
a) thin filaments:
thick filaments

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16
Q

thin filaments

A

— composed of:
i. actin – functions in contraction

2
ii. tropomyosin + iii. troponin – regulate
contraction (regulatory proteins)

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17
Q

thick filaments

A

— composed of:
i. myosin – functions in contraction
— attached to Z discs by titin
— has rod-like tail with 2 globular heads
o head extends toward actin and attaches to it
– forming a crossbridge

18
Q

A band

A

dark = length of thick filament – myosin + actin

with troponin + tropomysosin

19
Q

H zone

A

lighter band at center of A band – myosin only

20
Q

I band

A

— light = actin (with troponin + tropomyosin) + titin

21
Q

Z discs

A

(in center of I band)
— actin + titin attach
— connect sarcomeres: between 2 z-discs = 1 sarcomere

22
Q

M line

A
where myosin tails (thick myofilaments) attach to
each other (center of sarcomere
23
Q

T-tubules

A

— continuations of sarcolemma that extend deep into fiber (cell)
— directly encircle myofilaments of myofibrils at junction of A & I bands
(2/sarcomere)

24
Q

Sarcoplasmic Reticulum

A

— = smooth ER

— triad = 2 enlarged areas of SR (terminal cisternae) & T-tubule

25
How do muscles produce movement?
1) Pulling on bones when they contract 2) Using group action 3) Lever systems
26
origin
attachment of tendon to stationary bone
27
insertion
attachment of tendon to movable bone
28
agonist
major muscle producing the movement
29
synergists
help the agonist action and prevent undesirable motions caused by the agonist
30
antagonist
produces opposite action of agonist (contraction inhibited when agonist contracts)
31
Lever systems
bone/muscle interaction at a joint parts: a) levers = bone b) fulcrum = joint
32
effort
contraction of agonist
33
resistance
opposes movement
34
effort must be greater than resistance to get movement
35
flexion of forearm
o agonist = biceps brachii o antagonist = triceps brachii o synergists = brachialis, brachioradialis o lever = radius (insertion of agonist) o fulcrum = elbow joint o effort = muscle contraction o resistance = weight of object plus forearm
36
extension of forearm
o agonist = triceps brachii | o antagonist = biceps brachii
37
Flexors
— decrease angle between 2 bones | — e.g. biceps brachii
38
Extensors
— increase angle (back to anatomical position after flexion) | — e.g. triceps brachii
39
Abductors
move limb away from midline
40
Adductors
move limb toward midline
41
Naming of skeletal muscles
1. action 2. shape 3. size 4. origin insertion 5. number of origins 6. shape of fibres 7. location