Chapter 11: Muscular System Flashcards Preview

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Flashcards in Chapter 11: Muscular System Deck (123)
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1
Q

3 types of muscular tissue

A
  • skeletal
  • cardiac
  • smooth
2
Q

Characteristics of Muscles (5)

A
  • responsiveness
  • conductivity
  • contractility
  • extensibility
  • elasticity

(elaine received constant contractions extensively)

3
Q

responsiveness to what? (3)

A

excitable

-to chemical signals, stretch, & electrical charges

4
Q

conductivity

A

electrical change triggers a wave of excitation

5
Q

contractility

A

shortens when stimulated

6
Q

extensibility

A

capable of being stretched

7
Q

elasticity

A

returns to original length after being stretched

8
Q

skeletal muscle

A

striated VOLUNTARY muscle attached to one or more bones

9
Q

Muscle cell =______

A

muscle fiber

10
Q

striations

A

alternating light and dark transverse bands

11
Q

What do tendons attach specifically?

A

muscle to bone matrix

12
Q

endomysium

A

connective tissue around muscle cells

13
Q

perimysium

A

connective tissue around muscle fascicles

14
Q

epimysium

A

connective tissue surrounding entire muscle

15
Q

what is the purpose of collagen? (3)

A

returns muscle to resting length
protects muscles from excessive stretching
contributes to power output & muscle efficiency

16
Q

sarcolemma

A

plasma membrane of a muscle fiber

17
Q

sarcoplasma

A

cytoplasm of a muscle fiber

18
Q

myofibrils

A

long protein bundles that occupy the main portion of the sarcoplasma

19
Q

what are the components of myofibrils?what do they store?

A

glycogen (provide energy for heightened exercise) & myoglobin (stores oxygen)

20
Q

where are mitochondria packed in muscle fibers?

A

in spaces between myofibrils

21
Q

myoblast

A

stem cells that fuse to form each muscle fiber

22
Q

sarcoplasmic reticulum (SR)

A

smooth ER that forms a network around each myofibril

23
Q

what is the sarcoplasmic reticulum a reservoir for?

A

calcium

24
Q

what activates the muscle contraction process?

A

calcium

25
Q

terminal cisternae

A

dilated end sacs of SR which cross the muscle fiber from one side to the other

26
Q

T tubules

A

tubular infoldings of the sarcolemma that penetrate through the cell & emerge on the other side

27
Q

triad

A

a T tubule & two terminal cisterns

28
Q

thick filaments

A

made of several hundred myosin (golf club)

29
Q

thin filaments

A

fibrous actin of 2 intertwined stands

30
Q

What portion of the actin subunit can bind the head of the myosin molecule?

A

gobular (G) actin

31
Q

tropomyosin

A

blocks the active sites of G actin & prevents myosin from binding when muscles are relaxed

32
Q

troponin

A

small calcium binding protein on each tropomyosin molecule

33
Q

contractile proteins?

A

myosin & actin

34
Q

regulatory proteins?

A

tropomyosin & troponin

35
Q

what happens when calcium is released into the sacroplasm?

A

Ca binds to troponin which then changes shape and moves tropomyosin from the active site of actin

36
Q

sarcomere

A

Z disc to Z disc

functional contractile of muscle fiber

37
Q

Which myofilament is free floating?

A

myosin, it is not anchored like actin

38
Q

A band

A

dark; overlapping of thick and thin filaments

39
Q

H band

A

middle of A band (thick filaments ONLY)= bare zone

40
Q

M line

A

middle of H band

41
Q

I band

A

light; crosses over 2 sacromeres

42
Q

Z disc

A

provides anchorage for thin filaments and elastic filaments

43
Q

what myofilaments do muscle fibers contain? (3)

A

thin, thick, and elastic

44
Q

which band shortens during contraction

A

H band

45
Q

Why do muscle cells shorten?

A

because their individual sarcomeres shorten (Z disc pulled closer together)

46
Q

a skeletal muscle never contracts unless stimulated by ______? what happens if this is severed?

A

a nerve; muscle is paralyzed

47
Q

somatic motor neurons

A

nerve cells whose cell bodies are in the brainstem & spinal cord that serve skeletal muscles

48
Q

what portion of somatic motor fibers lead to the skeletal muscle?

A

their axons

49
Q

1 nerve fibers= ______ muscle fiber

A

several

50
Q

what does an effective contraction require?

A

the contraction of several motor units (one nerve fiber + muscle fibers) at once

51
Q

average motor unit?

A

200 muscle fibers for each motor unit

52
Q

small motor units are used for what?

A

fine degree of control

ex. eye & hand muscles

53
Q

large motor units are used for what?

A

more strength than control

54
Q

synapse

A

point where a nerve fiber meets its target cell

55
Q

neuromuscular junction

A

when target cell is a muscle fiber

56
Q

synaptic knob

A

swollen end of nerve fiber

57
Q

synaptic cleft

A

tiny gap between synaptic knob & muscle sarcolemma

58
Q

What is the purpose of Schwann cells?

A

to isolate & insulate all of the NMJ from surrounding tissue fluid

59
Q

synaptic vesicles undergo ______ releasing ACh into ______

A

exocytosis; synaptic cleft

60
Q

Lack of ACh receptors leads to?

A

paralysis in disease

61
Q

What separates the Schwann cells & the entire muscle cell from surrounding tissue?

A

basal lamina

62
Q

What does the basal lamina contain?

A

acetylcholinesterase (AChE) to break down ACh after contraction causing relaxation

63
Q

What helps hold the synaptic knob in place?

A

Schwann cells & basal lamina

64
Q

voltage=______ def?

A

electrical potential; a dif in electrical charge from one point to another

65
Q

What is the resting membrane potential?How is it maintained?

A

about -90mV; Na-K pumps

66
Q

What is happening in an unstimulated resting cell? (3)

A
  • more anions on the inside of the plasma membrane
  • plasma membrane is polarized
  • excess Na (ECF) and excess K (ICF)
67
Q

What else is inside the ICF?

A

proteins, nucleic acids, and phosphates (all which cant penetrate the membrane)

68
Q

What is happening in a stimulated muscle fiber?

A
  • ion gates open in the plasma membrane
  • Na moves inside (down concentration gradient)
  • cations override negative charge of ICF (depolarization)
  • Na gates close/ K open
69
Q

What turns the membrane back into its negative state?

A

loss of positive K ions (repolarization)

70
Q

action potential

A

quick up & down

polarized(resting)-> depolarization-> repolarization

71
Q

what type of paralysis is tetanus?

A

spastic paralysis caused by C. tetani

72
Q

flaccid paralysis

A

state in which the muscles are limp & cannot contract

73
Q

botulism

A

type of food poisoning caused by neuromuscular toxin secreted by C. botulinum (prevent contraction)

74
Q

What does the RMP shift to when Na is moved into the cell?

A

-90mV to +75mV

75
Q

length tension relationship

A

amount of tension generated by a muscle & the force of contraction depends on how stretched/contracted it was before stimulated

76
Q

What does the optimum resting length produce?

A

greatest force when muscle contracts

77
Q

muscle tone

A

monitored by the nervous system that adjusts the length of the resting muscle & maintains a state of partial contraction

78
Q

What does overly contraction cause?

A

crick in your neck

79
Q

What does overly stretched cause?

A

actin filament have no myosin heads to attach to

80
Q

rigor mortis

A

hardening of muscles & stiffening of body beginning 3 to 4 hours after death

81
Q

muscle relaxation requires _____, which is no longer produced after death

A

ATP

82
Q

myogram

A

chart of the timing & strength of a muscle contraction

83
Q

_____, subthreshold electrical stimulus cause ___ contraction

A

weak; no

84
Q

threshold

A

min voltage necessary to generate an action potential in the muscle fiber & produce contraction

85
Q

twitch

A

quick cycle of contraction when stimulus is at threshold or higher

86
Q

Twitches vary depending on?

A
  • stimulus frequency
  • concentration of Ca in sarcoplasma
  • how stretched the muscle was
  • temp of muscle
87
Q

If the pH of the sarcoplasma is lower than normal, what happens?

A

fatigue

88
Q

When stimulus intensity remains _____ twitch strength_____?

A

constant; vary with the stimulus frequency

89
Q

10-20 stimuli per second produces what type of twitch? (staircase) describe

A

treppe; the muscle still recovers fully between twitches, but each twitch develops more tension than the one before

90
Q

20-40 stimuli per second produces what? describe

A

incomplete tetanus (piggy back); each new stimulus arrived before the previous twitch is over

91
Q

40-50 stimuli per second produces what? describe

A

complete tetanus; muscle has no time to relax between stimuli

92
Q

isometric contraction

A

producing internal tension; but external resistance causes it to stay at the same length or become longer (NO MOVEMENT)

93
Q

concentric contraction

A

muscle shortens as it maintains tension

94
Q

eccentric contraction

A

muscle lengthens as it maintains tension

95
Q

ATP supply depends on availability of: (2)

A

oxygen

organic energy sources (glucose & fatty acids)

96
Q

2 pathways of ATP synthesis? which yields the most ATP?

A

aerobic respiration (use oxygen) yields more ATP (36 per molecule) anaerobic fermentation (without the presence of oxygen)

97
Q

For short intense exercises how is oxygen supplied?

A

via myoglobin for limited aerobic respiration

98
Q

What enzymes are used by muscles for transfer of phosphate? (2)

A
myokinase (makes cyclic AMP)
creatine kinase (uses creatine phosphate)
99
Q

What system is used for nearly all energy used for short bursts of intense activity?

A

phosphagen system

100
Q

After the phosphagen system-> a muscle enters ___ ____ which uses ___ to produce _____. How many ATPs are gained?

A

Anaerobic fermentation; glucose ; lactic acid

2 ATPs per molecule

101
Q

long term energy uses which synthesis pathway?

A

aerobic respiration

102
Q

What happens during fatigue? (4)

A
  • ATP synthesis decline as glycogen consumed
  • ATP shortage; slows down Na-K pumps
  • lactic acid lowers pH of sarcoplasm
  • motor nerve fibers use up ACh
103
Q

endurance? how is it determined?

A

ability to maintain high intensity exercise for more than 4-5 minutes; by one’s max oxygen uptake

104
Q

How can you “beat” fatigue? (2)

A
  • taking oral creatine (increases level of creatine phosphate in tissue: increase speed of ATP regeneration)
  • carbohydrate overload (extra glycogen packed in)
105
Q

slow oxidative muscle fibers (3)

A
  • slow twitch, red, type I fibers
  • abundant in mitochondria, myoglobin
  • adapted for aerobic respiration & fatigue resistance
106
Q

fast glycolytic muscle fiber

A
  • fast twitch, white, type II fiber

- quick response, but not fatigue resistance

107
Q

properties of cardiac muscle? (5)

A
  • contraction w/ regular rhythm
  • must contract in unison
  • contractions must last long to expel blood
  • must work in sleep
  • tightly resistant to fatigue
108
Q

Cardiac muscles are _____ and contain _____

A

striated; myocytes

109
Q

in cardiac muscle, myocytes are joined at notched linkages called what?

A

intercalated disc

110
Q

Cardiac muscles contain _____, so they can contract without need for nervous stimulation

A

built in pacemaker

111
Q

How are damaged cardiac muscle cells repaired?

A

via fibrosis (not capable of mitosis-very little)

112
Q

which synthesis is used almost exclusively by cardiac muscle?

A

aerobic respiration

113
Q

Smooth muscle does not contain?

A

t-tubule or sarcomere structure

114
Q

characteristics of smooth muscle (3)

A
  • capable of mitosis & hyperplasia
  • injured muscle can regenerate well
  • some lack nerve supply
115
Q

Describe myocyte structure in smooth muscle?

A
  • fusiform shape
  • no visible striations
  • Z discs are replaced by dense bodies
116
Q

Which type of smooth muscle is more widespread? does it require a nerve supply?what does it use

A

single unit smooth muscle; NO; gap junctions

117
Q

Smooth muscle can contract in response to ____. Such as (3)

A
  • chemicals

- hormones, CO2, stretch, oxygen deficiency

118
Q

Does stimulation mean contraction in smooth muscle?

A

NO; relax arteries or contract bronchiles

119
Q

What do the smooth single units contain?

A

autonomic nerve fibers varicosities

120
Q

What are varicosities?

A

beadlike swellings that contain synaptic vesicles & few mitochondria

121
Q

How is contraction different in smooth vs skeletal muscle?

A
  • calcium binds calmodulin on thick filaments
  • calcium enters from the cell EC
  • very slow due to arrangement (Ca must be actively removed)
  • smooth contract forcefully when greatly stretched
122
Q

the ______ ______ is resistant to fatigue

A

latch bridge mechanism

123
Q

stress relaxation response

A

helps hollow organs gradually fill (bladder)