Chapter 10 - Muscular Tissue Flashcards Preview

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Flashcards in Chapter 10 - Muscular Tissue Deck (193)
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31

Darker middle part of sarcomere that extends entire length of thick filaments & includes parts of thin filaments that overlap thick filaments

A band

32

Zone of Overlap

toward each end of A band where thin & thick filaments lie side by side

33

lighter, less dense area of sarcomere that contains thin but no thick filaments

Z discs passes through center of each

I band

34

center of each A band which contains thick but no thin filaments

H zone

35

M line

supporting proteins that hold thick filaments together in H zone

36

 Myofibrils are built from (3) kinds of proteins 

1) contractile

2) regulatory

3) structural 

37

Contractile proteins (2) 

1) Myosin

2) Actin

38

Myosin

thick filaments

Functions as a motor protein (can achieve motion)

 Convert ATP to energy of motion

 Projections of each myosin molecule protrude outward (myosin head

39

Actin

Thin filaments

actin molecules provide a site where a myosin head can attach

 

40

Myosin

head vs tail.

head - shaped like 2 golf clubs & protrude outward towards thin filaments

tail - point toward M line in center of sarcomere

41

Other parts of thin filaments other than actin

 Tropomyosin and troponin are also part of the thin filament 

 

42

 In relaxed muscle 

 Myosin is blocked from binding to actin. Why?

How do can muscle contractions occur?

 

 

WHY?  -  because trands of tropomyosin cover the myosin-binding sites (held in place by troponin) 

Calcium ion binding to troponin moves tropomyosin away from myosin- binding sites 

 Allows muscle contraction to begin as myosin binds to actin

 

43

Structural Proteins (2) 

1) Titin

2) Dystrophin

44

1) Titin

 

stabilize position of myosin 

accounts for much of the elasticity & extensibilituy of myofibrils

45

2) Dystrophin

links thin filaments to sarcolemma

46

Sliding Filament Mechanism

myosin heads attach to and “walk” along thin filaments at both ends of sarcomere 

pulling thin filaments toward center of sarcomere 

Z discs come closer together & sarcomere shortens leading to shortening of entire muscle

47

 Length–Tension Relationship 

___ of muscle contraction depends on __ of ___

forcefulness of muscle contraction depends on length of sarcomeres

48

When muscle fiber is stretched, 

what happens to overlap and tension (forcefulness) ?

LESS overlap between thick & thin filaments 

tension is diminished

49

When a muscle fiber is shortened, 

what happens to filaments and tension?

filaments are compressed (thick filaments crumple as they are compressed against Z discs) 

fewer myosin heads make contact with thin filaments 

tension is diminished

50

Neuromuscular Junction

synapse between a somatic motor neuron & a skeletal muscle fiber

51

Where communication occurs between a somatic motor neuron and a muscle fiber 

synapse

52

Gap that separates the two cells 

synaptic cleft

53

 Chemical released by the initial cell communicating with the second cell 

neurotransmitters 

54

sacs  suspended within the synaptic end bulb containing molecules of the neurotransmitter ______

Synaptic Vesicles

contain ​acetylcholine (Ach) 

55

 The region of the muscle cell membrane opposite the synaptic end bulbs that contains Acetylcholine receptors

Motor End Plate

56

The tension or force of muscle cell contraction varies and is dependant on (4) 

1) The rate at which nerve impulses arrive  (impulses/sec) - frequency of stimulation

2)The amount of stretch before contraction

3) The nutrient and oxygen availability

4) The size of the motor unit 

57

Motor Units consists of a __ ___ and the __ __ it stimulates

motor neuron 

muscle fibers

58

The axon of a motor neuron branches out forming __ ___ with different muscular fibers (about 150) 

neuromuscular junctions

59

Control of precise movements consist of many small motor units 

How many muscle fibers per motor unit for:

1) voice production muscles

2) muscle controlling eye movement

3) muscles in arm & leg

1) 2-3

2) 10-20

3) 2000-3000

60

The total ____________of a contraction depends on the size of the motor units and the number that are activated 

strength