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Flashcards in Muscle Physiology Deck (78):
1

functions of the muscular system

movement, posture, stabilizing joints, generate heat, store nutrients, contractile (tissue shortens), excitable (irritability), extensible (stretched to an extent), elasticity

2

what is the organization of a muscle (outside to inside)?

epimysium, fasicles, perimysium, muscle fibers (aka cells), endomysium, myofibrils, sarcomeres,actin/myosin

3

dense CT surrounding an entire muscle

epimysium

4

surrounds individual muscle cells (muscle fibers)

endomysium

5

___ divides muscle into bundles of muscle fibers (fasicles)

perimysium

6

elongated multinucleate cells; banded appearance

muscle fiber

7

bundle of muscle fibers

fasicle

8

rodlike contractile unit

myofibril

9

contractile elements of the cells that contain thick and thin filaments called

myofilament
actin (thin) mysoin (thick)

10

contractile unit composed of myofilaments

sarcomere

11

embryonic mesodermal cells that forms each muscle fiber

myoblasts

12

what happens when myoblasts fuse?

it creates a mature muscle cell

13

a tannish cell that remains in the embryonic state and doesnt fuse

satellite cell

14

what are satellite cells?

stem cells that can become active under certain circumstances

15

Whats an example when would a satellite cell become active? their function when active?

when the muscle fiber becomes damaged
they help reduce injured tissue and repair it

16

plasma membrane of a muscle fiber

sarcolemma

17

cytoplasm of a muscle fiber

sarcoplasm

18

endoplasmic reticulum of a muscle fiber
what does it do?

sarcoplasmic reticulum
concentrates and stores Calcium ions

19

what does the sarcoplasm contain?

glycogen or myoglobin (stores O2)

20

what structure contains the myofibrils?

sarcoplasm

21

structure of a cell that only contains thin myofilaments

I- band

22

structure of a cell that contains the Z-line

I-band

23

which determines the end/start of a new sarcomere?

Z-line

24

structure of a cell that contains mostly thick myofilaments

A-band

25

structure of a call that contains the H-zone (only thick myofilament)

A-band

26

elastic filament composed of a hugh protein

titin

27

subunits of actin (looks like little balls) that contain the active sites

G actin

28

G actin forms long filaments of actin called

F- actin strand

29

the molecule ___ stabilizes their structure like strings

nebulin

30

protein that has 2 strands that spiral around the strand and block myosin binding sites while relaxed

tropomyosin

31

protein on the actin that has 3 polypeptides

troponin

32

what do the 3 polypeptides of troponin do?
TnI

TnI is inhibitory (suppress or restrain)

33

what do the 3 polypeptides of troponin do?
TnT binds to

TnT binds to tropomyosin

34

what do the 3 polypeptides of troponin do?
TnC binds to

TnC binds to calcium ions

35

what 2 things help during muscle relaxation and contraction?

troponin and tropomyosin
they control the interaction

36

what is the "go" signal of muscle contraction?

the release of calcium

37

A & I band form into englarged forming channels

terminal cisternae (in pairs)

38

T-tubule joins the terminal cisternae of the SR forming a

triad

39

what does the triad do?

sends electrical impulse for releasing Ca ions

40

what is the process of making the muscle contract?

an axon is released and enters the muscle and gives off short branches when it stops at the neuromuscular junction. myofilaments slide past one another resulting in muscle contraction

41

what is the contraction process called?

excitation-contraction coupling

42

region where 2 excitable cell make an electrical/chemical contact with each other

synapse

43

the synapse between nerve and muscle

neuromuscular junction

44

membrane sacs or vesicles of a chemical neurotransmitter junction in the axon terminal

ACh- acetylcholine

45

specialized part of the sarcolemma that is highly folded to increase surface for ACh receptors

motor end plate

46

release of ACh into synaptic cleft due to an influx in calcium

exocytosis

47

what happens to the ACh after released into the cleft

binds to its receptors that are on the motor end plate

48

what happens when the ACh is at the motor end plate?
what is the name of this?

sodium and potassium channels open. more sodium is flowing in than potassium going out. sarcolemma is then negative
depolarization

49

what role does calcium have in the cross bridge formation?

calcium makes the active sites available

50

what happens when the active sites are available?
what is this called?

the release of P (phosphate) causes the myosin head to move so it can reach for the active site on the F strand
power stroke

51

what works together so the muscle fibers shorten?

all of the sarcomeres of the myofibril

52

what is the amount of tension (force) produced by the muscle?

number of cross bridges formed by the sarcomere

53

what happens to the A band and the Hzone during contraction?

the A bands move closer together and the Hzone decreases

54

what happens to the I band and the Z line during contraction?

I bands shorten and distance between Z lines shorten

55

the end of the muscle that is in a fixed position

origin

56

end of the muscle that moves towards the fixed end

insertion

57

force exerted by a contracting muscle on an object

muscle tension

58

opposing force exerted on the muscle by weight of an object to be moved

load

59

motor neuron and all the muscle fibers it innervates

motor unit

60

what structure tones the muscle?

motor units, the more the stronger contraction

61

response of a motor unit to a single action potential of its motor neuron

twitch
(they contract quickly then go back to relax)

62

what are the three phases of a twitch in order from start to finish?

latent period, contraction phase, relaxation phase

63

"step wise" increase in tension

treppe

64

phenomenon when strength of stimulus stays the same but theres an increase in frequency of stimulation

wave summation

65

what happens to the muscle during wave summation?

there is not enough time for all the Ca to leave the SR before the next contraction, therefore the Ca levels are high in the sarcoplasm causing more cross bridges

66

continued summation with tension getting greater until sustained but quivering contraction is reached

unfused/incomplete tetanus

67

when the relaxtion phase of a twitch is eliminated and the contractions fuse into 1 smooth sustained plateau of contraction

fused/complete tetanus

68

continuous contraction (Ca levels are so high because none can return to SR)

maximal tension

69

a muscle working a maximal or near maximal tension (or vigorous exercise)

fatigue

70

how is too much contraction controlled or brought back to normal?

more motor units are recruited

71

stimulus at which the first observable contraction occurs

threshold stimuli

72

strongest stimulus that produces increased contractile force (all muscles motor units are recruited)

maximal stimuli

73

equal tension, tension rises and muscle length changes

isotonic

74

lifting an object, walking, running
isotonic or isometric?

isotonic

75

eqyal measure, tension produced doesnt exceed resistance (important for overcoming gravity and posture)

isometric

76

carrying a bag of groceries, holding your head up
isotonic or isometric?

isometric

77

muscle tension exceeds the resistance

concentric contraction (flexion) ; 1/2 isotonic contraction

78

peak tension is less than the load and muscle elongates because other muscles are contracting

eccentric contraction (extension) ; 2/2 isotonic contraction