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Flashcards in The Muscle System Deck (99):
2

Musculoskeletal system

Comprised of muscles and skeltons

3

Muscles and skeletons are ____ that produce movment

effectors

4

3 types of vertebret muscle

skeletal, cardiac, smooth

5

Skeletal muscle involves

voluntary movement, breathing

6

Cardiac involves

beating of the heart

7

Smooth muscle

involuntary, movement of internal organs

8

What does it mean when skeletal muscles are "striated"

they have "strips" of muscle cells

9

skeletal muscle cells are called

muscle fibers

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Muscle fibers are extremely ____, _____ cells

large - multinucleated

11

Skeletal muscles form by _____ of _____

fusion of embryonic myoblasts

12

One muscle consists of many _____ bundled together by connective tissue

muscle fibers

13

Each muscle fiber has several ______

myofibrils

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Myofibrils consist of

bundles of actin and myosin filaments

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The contractile proteins

Actin and myosin

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Actin are ____ filaments

thin

17

Myosin are ____ filaments

thick

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Sarcomere

overlapping actin and myosin filaments

19

Each myofibril consists of repeating units called

Sarcomeres

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Titin and what does it do?

the largest protein in the body that holds bundles of myosin filaments in place

21

Describe the "sliding filament mechanism"

myosin heads bind to specific sites on actin molecules to form cross bridges, then change conformation to cause the actin filments to slide 5-10 nm

22

During the sliding filament mechanism mysoin heads _____ to specific sites on ____ to form ______

bind; actin; crossbridges

23

Muscle contration is initiated by ______ from a ____ neuron at the ______

action potentials, motor neruon, neuromuscular junction

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A motor unit

all the muscle fibers that are activated by one motor neuron

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Muscle cells are inhibited or excited?

excited

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the plasma membrane of the muscle cells can ____ action potentials

conduct

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____ is released by the motor neuron at the ______ and opens _____ in the _______

ACH; neuromuscular junction; ion channels; motor end plate

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The chemical synapse between a motor neuron and a muscle cell is

the neuromuscular junction

29

Action potentials move through fibers via

T-tubules (transverse tubules)

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T-tubules descend into the

sarcoplasm (muscle fiber cytoplasm)

31

The sarcoplasm is

the muscle fiber cytoplasm

32

T-tubules run close to the

sarcoplasmic reticulum

33

The sarcoplasmic reticulum (SR) is

a closed compartment that surrounds every myofibril, the ER of muscle cells

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the SR has ____ pumps

Ca2+

35

At rest here is a ____ concentration of Ca in the _____ of the SR

high concentration; lumen

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An action potential will ____ Ca channels and Ca flows ______ of the SR and triggers the interaction of

open; out; action and myosin

37

Actin filaments also include

tropomyosin and troponin

38

3 subunits of troponin bind to ___,__,___

actin, tropomyosin, and Ca2+

39

At rest, _____ blocks binding sites on actin

tropomyosin

40

Troponin changes conformation when

Ca2+ is released and binds to it

41

Tropomyosin is bound to _____ and the twisting of it exposes ___ on actin

troponin; binding sites

42

When ___ pumps remove Ca2+ from the sarcoplasm, ____ stops

Ca2+; contraction

43

The cardiac muscle is also striated

True

44

The cardiac muscle cells are ____ than skeletal muscle cells and have how many nuclei?

smaller; just one nucleus

45

Cardiac muscle cells can withstand high pressures due to

branching and interdigitating

46

What initiates and coordinates heart contractions?

pacemaker and conducting cells

47

The heartbeat is generated by the heart muscle itself which means that it is

myogenic

48

Heart transplantations are possible because

the autonomic NS modifies the rate of pacemaker cells, but isnt nescessary

49

Cardiac and smooth muscle cells are arranged in

sheets

50

cells in cardiac sheets are in electrical contact vi

gap junctions

51

the cell sheets allow an action potential to ___ to all others in the sheet, so the heart can _____ contractions

spread; sync

52

what connects the cytoplasm of two neighboring cells and allow electrical communication?

gap junctions

53

Gap junctions in cell sheets allow ___ and ____ muscle cells to contract simultaneously

cardiac and smooth

54

The simplest muscle cells

smooth muscle cells

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smooth muscle cell contains just

one cell/nucleus

56

They are "smooth" muscle cells because

actin/myosin are not as regularly arranged

57

Smooth muscle cells are under ____ control

Autonomic NS control

58

What is a twitch

minimum unit of contraction by skeletal muscle

59

Twitch is measured in terms of

tension

60

A _____ generates a twtich

a single action potential

61

If action potentials are close together the twitches add up.

True

62

How do twitches build up?

calcium pumps can't clear out all the Ca from the sarcoplasm before the next one comes and it piles up

63

Tetanus is

when APs are so frequent that this is always calcium in the sarcoplasm

64

How long a muscle fiber can sustain tetanic contraciton depends on ____ supply

ATP

65

What is needed to break actin/mysoin bonds and "re-cock" the heads?

ATP

66

To maintain contraction...

actin-myosin bonds have to keep cycling

67

3 systems for muscles to obtain ATP

Immediate, glycolytic, oxidative

68

Immediate system

uses pre-formed ATP and creatine-phosphate

69

Glycolytic system

metabolizes carbs to pyruvate and lactic acid; anaerobic

70

Oxidative system

carbs and fatty acids to H2O and CO2 (aerobic)

71

Creatine phosphate (CP) ___ energy in a ____ bond that can transfer to ADP

stores energy in a phosphate bond

72

ATP+CP is the ____ system

immediate

73

The ATP from the ____ immediate system is exhusted within seconds; ___ yield of ATP

immediate; low yield of ATP

74

In the glycolytic system, enzymes are in the _______

sarcoplasm/cytoplasm

75

ATP generated during glycotic system is not directly available to myosin

False, its FAST!

76

Is glycotic system aerobic or anaerobic?

Anerobic

77

Glycotic system has a ___ ATP yild

Low as well

78

Immidate and glycolytic systems provide energy for _____

less than one minute

79

Oxidative phosphorylation occurs in the

Mitochondria

80

Oxidative method makes _____ of ATP and is ____

a lot of; aerobic (CO2) is created

81

ATP must ____ from the mitochondria to the ____ in the cytoplasm, therefore it is ____ than the other two systems

diffuse; mysoin; slower

82

Two main types of skeletal muscle fibers

slow and fast twitch

83

The slow twitch muscle fibers are the _____ or ___ muscle

oxiative or red

84

ST fibers contain ____ which is the oxygen binding protein

myoglovin

85

ST fibers contain many _____ and _____

Mitochondria and blood-vessels

86

In ST fibers, max tension develops ____ and is _____ to fagitue

slowly; highly resistant

87

ST fibers have reserves of what?

Glycoghen and fat

88

ST fibers and produce ATP as long as ____ is avaialble

oxygen

89

ST fibers are good to use with ____ excercise

aerobic exercise

90

Fast-twitch muscle fibers are ____ or ___ muscles

glycolytic/white

91

Complete opposite of ST fibers - _____ mitochonrdria, blood vessels, myoglobin

LITTLE

92

FT fibers develop max tension ____ and fatigue ______-

faster and faster

93

FT fibers can replenish ATP for prolonged contraction

FALSE

94

What determines muscle strength and endurance?

The proportion of ST and FT fibers

95

Genetic heritage plays a role in determining

Proportion of ST and FT fibers

96

Training a muscle can alter muscle properties

True (to an extent)

97

Anerobic exercise increases muscle _____.

Strength

98

What happens when a muscle gets stronger?

new actin/myosin filaments form, muscle gets JACKED

99

Aerobic exercise increases muscle _____

Endurance

100

What happens when muscle gains endurance?

oxidative capacity is enhanced due to the increase in mitochondria, blood vessels, myoglobin, and enzymes