Module 8: The Muscular System Flashcards Preview

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Flashcards in Module 8: The Muscular System Deck (70):
1

Fascia

Dense sheet or broad band of irregular connective tissue
Lines the body wall and limbs
Supports and surrounds muscles and other organs

2

Three layers of connective tissue extending from fascia

Epimysium
Perimysium
Endomysium
All three may extend to form a tendon

3

Epimysium

Dense, irregular connective tissue
Encircles entire muscle

4

Perimysium

Dense, irregular connective tissue
Surrounds groups of 10-100+ muscle fibres
Separates fibres into bundles

5

Fascicles

Bundles of 10-100+ muscle fibres separated by perimysium

6

Endomysium

Mostly reticular fibers
Penetrates the interior of each fascicle
Separates individual muscle fibers

7

Sarcolemma

Plasma membrane of muscle fibres

8

Myofibrils

Consist of myofilaments
Make up muscle fibres

9

Sarcoplasmic reticulum (SR)

Encircle each myofibril
Stores calcium
Similar to the endoplasmic reticulum of other cell types

10

Myofilaments

Involved in contraction
Thick and thin

11

Thick filaments

Made of myosin

12

Thin filaments

Made of actin

13

T tubules (transverse tubules)

Infolding of the sarcolemma that carries the
nerve stimulus into the muscle fibre

14

5 levels of organization in skeletal muscle

Skeletal muscle
Fascicle
Muscle fiber (cell)
Myofibril
Myofilaments

15

Terminal cisterns

Dilated end scars of the SR
On both sides of the transverse tubule
Release Ca2+ to trigger muscle contraction

16

Z disc

Narrow, plate-shaped regions of dense protein material
Separate sarcomeres

17

A band

Darker middle part of the sarcomere
Extends entire length of thick filaments

18

I band

Lighter, less dense
Contains thin filaments but no thick
Z disc passes through the center

19

Zone of overlap

At end of A band where thick and thin filaments overlap

20

H zone

Narrow
At centre of A band
Thick filaments but no thin

21

M line

Middle of sarcomere
At centre of H zone
Proteins that hold thick filaments together

22

Three proteins that build myofibrils

Contractile
Regulatory
Structural

23

Two contractile proteins in muscle

Actin and myosin

24

Myosin

Main component of thick filaments
Motor protein in all three types of muscle tissue
Holds thick filaments in alignment at M line

25

Actin

Main component of thin filaments

26

Two regulatory proteins

Tropomyosin and troponin

27

Tropomyosin

Covers myosin-binding sites in actin when muscle is relaxed

28

Troponin

Hold tropomyosin strands in place

29

Titin

Large structural protein
Spans half a sarcomere (connects Z disc to M line)
Elasticity and extensibility

30

α-actinin

Structural protein in Z disc
Bind to actin and titin

31

Myomesin

Structural protein in M line
Bind to titin
Connect adjacent thick filaments

32

Nebulin

Long, nonelastic structural protein
Wrapped around thin filaments to anchor them to Z disc

33

Dystrophin

Structural protein that links thin filaments of sarcomere to integral membrane proteins of sarcolemma

34

Sliding filament theory

Myosin contacts with actin to form cross-bridges
Myosin heads walk along thin filaments
Thin filaments pulled toward M line
Sarcomere shortens

35

Onset of contraction

SR releases Ca2+ into sarcoplasm
Ca2+ binds troponin
Troponin moves tropomyosin away from myosin-binding sites on actin ("frees" them)

36

Steps of contraction cycle

ATP hydrolysis
Myosin heads bind actin to form cross-bridges
Power stroke
Detachment of myosin from actin

37

Isotonic contraction

Muscles shorten and movement occurs

38

Isometric contraction

Muscles do not shorten, no movement

39

Muscle tone

Some muscle fibers are always contracted, muscle is firm

40

Aerobic respiration

Glucose + oxygen → carbon dioxide + water + ATP
38 ATP/glucose

41

Anaerobic respiration

Glucose → lactic acid + ATP
2 ATP/glucose but faster than aerobic
Lactic acid accumulates in the muscle (burning sensation) and diffuses into blood to liver
When there is sufficient oxygen liver converts it to glycogen (storage form of glucose)

42

Metabolism of creatine phosphate

Creatine phosphate + ADP → creatine + ATP

43

Origin

End of the muscle that is attached to the stationary bone

44

Insertion

End of muscle that is attached to the movable bone

45

Deltoid

Shaped like a triangle

46

Latissimus

Wide

47

Orbicularis

Circular

48

Serratus

Serrated

49

Teres

Long and round

50

Trapezlus

Shaped like a trapezoid

51

Brevis

Short

52

Longus

Long

53

Maximus

Large

54

Minimus

Small

55

Minor

Smaller

56

Vastus

Huge

57

Rectus

Straight

58

Transverse

Across

59

Biceps

Two heads

60

Triceps

Three heads

61

Quadriceps

Four heads

62

Fixator

Synergist that immobilizes bone

63

Lever

Rigid structure that can move around a fixed point

64

Fulcrum

Fixed point that levers move around

65

Two different forces acted on levers

Effort - causes movement
Load or resistance - opposes movement

66

Mechanical advantage

Load is closer to fulcrum, effort is farther
Small effort required to move a large load over a small distance

67

Mechanical disadvantage

Load is farther from the fulcrum, effort is applied closer
Larger effort required to move a small load, but at a greater speed

68

First-class lever

Fulcrum is between effort and load
Example: scissors, seesaws, chewing
Mechanical advantage or disadvantage depending or whether effort or load is closer to the fulcrum

69

Second-class lever

Load is between fulcrum and effort
Example: wheelbarrow, standing up on toes
Always produce mechanical advantage because the load is always closer to the fulcrum than the effort (produces the most force)
Uncommon in human body

70

Third-class lever

Effort is between load and fulcrum
Example: forceps
Most common in the body
Always produce mechanical disadvantage because effort is always closer to the fulcrum than the load