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Integrated Physiology > Exam 3: Chapter 12 > Flashcards

Exam 3: Chapter 12 Flashcards

1
Q

how is skeletal muscle attached to the bone?

A

through tendons and connective tissue made of collagen

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2
Q

what is the origin?

A

end of muscle closest to the trunk (bone)
-immobile

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3
Q

what is the insertion?

A

distal attachment site
-mobile

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4
Q

what are muscle fibers?

A

-long, cylindrical
-multi-nucleated
-enclosed in connective tissue
-groups together w/ adjacent muscle fibers called fascicles

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5
Q

what two things make up a muscle?

A

fiber -> fascicle -> muscle

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6
Q

what is the sarcolemma?

A

membrane of muscle fiber

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7
Q

what is the sarcoplasm?

A

cytoplasm of muscle fiber

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8
Q

what is the sarcoplasmic reticulum?

A

modified smooth ER in muscle fiber
-stores Ca2+

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9
Q

what are myofibrils?

A

contractile, elastic proteins
-contains sarcomeres

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10
Q

what is the sarcomere?

A

repeating units, makes muscle striated

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11
Q

what is myosin?

A

thick filament
-contains a heavy chain and light chaing
-ATPase activity
-has an actin binding site

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12
Q

what are the heavy and light chains of myosin?

A

heavy: myosin heads, elastic hinge, tail
light: wraps around heads

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13
Q

what is actin?

A

thin filament
-contains troponin & tropomyosin
-has a myosin binding site

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14
Q

what makes up actin?

A

G-actin -> F-actin -> 2 F-actins wound together

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15
Q

what are T-tubules?

A

cavity inside the sarcolemma, close to SR

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16
Q

what are Z-disks?

A

two of them are present in the sarcomere
-zig-zag shape
-attachment site for actin

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17
Q

what are I-bands?

A

spans into the next sarcomere
-ACTIN ONLY
-where there is no overlap of myosin

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18
Q

what is the A-band?

A

entire length of myosin

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19
Q

what is the H-zone?

A

MYOSIN ONLY
-where there is no overlap of actin

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20
Q

what is the M-line?

A

middle of H-zone
-attachment for myosin

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21
Q

what is titin?

A

elastic stretchy fiber
-Z-disk -> M-line
-stabilizes contractile fibers

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22
Q

what is nebulin?

A

inelastic fiber
-attaches at Z-disk
-stabilizes actin

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23
Q

what are the three main things that happen for muscle contraction?

A

-neuromuscular junction
-excitation-contraction coupling
-contraction-relaxation cycle

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24
Q

what are the steps at the neuromuscular junction?

A
  1. AP goes along a somatic motor neuron
  2. voltage-gated Ca2+ channels open in axon terminal
  3. Ca2+ enters & causes exocytosis of vesicles with ACh
  4. ACh released into neuromuscular junction & binds to nicotinic receptors
  5. cation ion channels open in sarcolemma, leads to Na+ net entry
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25
Q

what are the steps during excitation-contraction coupling?

A
  1. muscle depolarizes & AP travels along sarcolemma
  2. AP enters T-tubule
  3. DHP receptors are activated on T-tubule & changes conformation
  4. opens RyR channels in SR
  5. Ca2+ is released into sarcoplasm
  6. Ca2+ bins troponin
  7. POWERSTROKE
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26
Q

what are the steps during the contraction-relaxation cycle?

A
  1. actin & myosin crossbridge forms due to powerstroke
  2. actin & myosin slide past eachother (I-bands & H-zone get smaller)
  3. overall sarcomere shortens & muscle contracts
  4. Ca2+ ATPase pumps Ca2+ back into SR
  5. tropomyosin covers up myosin binding site
  6. ACh is degraded or diffuses away
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27
Q

what are the powerstroke steps (crossbridge formation)?

A
  1. myosin is bound tightly to actin during rigor state (lots of ATP present)
  2. ATP binds to myosin, myosin releases actin
  3. myosin hydrolyzes ATP (ADP + Pi)
  4. myosin head rotates into the crocked & ready position
  5. Ca2+ signal causes the myosin head to do its powerstroke swivel, Pi is released
  6. ADP is released from myosin head once powerstroke is complete
  7. back to rigor state
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28
Q

what is a twitch?

A

once cycle of contraction-relaxation
-AP from somatic motor neuron -> AP along skeletal muscle fiber -> TWITCH

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29
Q

what is the latent period?

A

delay b/w AP skeletal muscle and twitch
-time it takes for Ca2+ signal to bind troponin, tropomyosin to move, and form a crossbridge

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30
Q

what are the three sources of ATP for skeletal muscle contraction?

A

Phosphocreatine
Oxidative Phosphorylation
Anaerobic glycolysis

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31
Q

how does phosphocreatine make ATP?

A

donates its phosphate to ADP to make ATP (reversible)
-limited supply but makes ATP the quickest

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32
Q

how does oxidative phosphorylation make ATP?

A

steps of aerobic respiration (glycolysis, CAC, ETC)
-gives the most ATP (1 glucose = 30 ATP)

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33
Q

how does anaerobic glycolysis make ATP?

A

when O2 is low, 1 glucose = 2 ATP
-unable to exercise long

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34
Q

what is fatigue?

A

muscle is no longer able to generate or sustain expected power output (not due to lack of ATP)
-Central and Peripheral

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35
Q

what is central fatigue?

A

psychological (motor cortex) & feeling of wanting to give up
-protective reflexes
-occurs before physiological fatigue

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36
Q

what is peripheral fatigue?

A

changes that occur from the neuromuscular junction -> myofibrils

37
Q

what are the speeds Ca2+ ATPase activity and ATP hydrolysis of type 1, 2A, & 2X muscle fibers?

A

slow-twitch (1): slowest!
oxidative-glycolytic (2A): fast
glycolytic (2X): fast

38
Q

what are the diameters of type 1, 2A, & 2X muscle fibers?

A

slow twitch (1): smallest
oxidative-glycolytic (2A): medium
glycolytic (2X): large

39
Q

what is the duration of time for contraction in type 1, 2A, & 2X muscle fibers?

A

slow twitch (1): long
oxidative-glycolytic (2A): short
glycolytic (2X): short

40
Q

what are the levels of capillaries, mitochondria, and myoglobin (O2 storage) for type 1, 2A, & 2X muscle fibers?

A

slow twitch (1): highest level (dark red)
oxidative-glycolytic (2A): intermediate level (red)
glycolytic (2X): lowest level (pale)

41
Q

what is the development of tension of type 1, 2A, & 2X muscle fibers?

A

slow twitch (1): slow
oxidative-glycolytic (2A): intermediate
glycolytic (2X): fast

42
Q

are type 1, 2A, & 2X muscle fibers fatigue resistant?

A

slow twitch (1): fatigue resistant
oxidative-glycolytic (2A): fatigue resistant
glycolytic (2X): easily fatigued

43
Q

what type of metabolism do type 1, 2A, & 2X muscle fibers have?

A

slow twitch (1): aerobic
oxidative-glycolytic (2A): both aerobic and anaerobic
glycolytic (2X): anaerobic

44
Q

what are examples of each of the type 1, 2A, & 2X muscle fibers?

A

slow twitch (1): posture (most used)
oxidative-glycolytic (2A): standing, walking
glycolytic (2X): jumping, sprinting (least used)

45
Q

what are three things that can impact tension?

A

sarcomere length
motor unit recruitment
AP frequency

46
Q

how does sarcomere length impact tension?

A

must be optimal length (too short or long = little tension)
-resting length is optimal to generate optimal tension

47
Q

how does motor unit recruitment impact tension?

A

depends on amount of units activated & type
-more units = more tension
-body regulates!!

48
Q

what are the motor units for fine movements?

A

more units with fewer fibers per neuron

49
Q

what are the motor units for gross movements?

A

fewer units with more fibers per neuron

50
Q

do fast units or slow units have more tension?

A

fast units

51
Q

what is recruitment of motor units?

A

process of activating motor units

52
Q

what is asynchronous recruitment of motor units?

A

activating different motor units at different times
-allows for longer tension and lessen fatigue

53
Q

how does AP frequency impact tension?

A

twitches summate due to increased AP frequency
-releases more Ca2+ = more crossbridges = more tension
-doesn’t allow the muscle to fully relax

54
Q

what is tetanus?

A

when maximal tension is reached
-unfused & fused

55
Q

what is unfused / incomplete tetanus?

A

little bit of relaxation b/w AP’s

56
Q

what is fused / complete tetanus?

A

no relaxation, highest level of summation

57
Q

what is an isotonic contraction?

A

creates force & moves a load (movement)
-concentric = muscle shortens (flexion)
-eccentric = muscle lengthens (extension)

58
Q

what is an isometric contraction?

A

creates force w/o movement
-muscle remains same length
-EX: plank, holding weights stationary

59
Q

what is a lever?

A

rigid rod that pivots around a fulcrum
-BONE

60
Q

what is a fulcrum?

A

pivoting point
-JOINT

61
Q

what is the load-velocity relationship?

A

speed of contraction (velocity) decreases as load increases

62
Q

what are the six locations of smooth muscle?

A

vascular, GI, urinary, respiratory, reproductive, ocular

63
Q

what are the two contraction patterns of smooth muscle?

A

Phasic: no contraction -> contraction-relaxation pattern
Tonic: always some level of contraction / tension

64
Q

what is single-unit communication?

A

gap junctions, electrical signal, contract as a unit
-majority!

65
Q

what is multi-unit contraction?

A

each unit functions independently, no gap junctions

66
Q

do smooth muscles contract and relax slower or faster than skeletal muscle?

A

slower
-slowest twitch time

67
Q

what does actin attach to instead of Z-disks in smooth muscle?

A

dense bodies

68
Q

what is the contraction pathway for smooth muscle?

A
  1. AP is generated from autonomic NS, a hormone, a paracrine, or stretch in the plasma MB
  2. Ca2+ channels open, Ca2+ enters from ECF
  3. causes Ca2+ release from SR
  4. Ca2+ binds calmodulin
  5. Ca2+ / calmodulin complex activates myosin light chain kinase
  6. MLCK phosphorylates myosin light chains
  7. crossbridge forms & powerstroke cycle occurs (moves dense bodies)
  8. smooth muscle contracts
69
Q

what is the relaxation pathway for smooth muscle?

A
  1. Ca2+ ATPase pumps Ca2+ back into ECF and SR
  2. Myosin light chain phosphatase (MLCP) dephosphorylates myosin heads
70
Q

what happens to contraction when there is high amounts of MLCP in the cell

A

takes more of Ca2+ to get same force of contraction
-decreased sensitivity to Ca2+

71
Q

what happens to contraction when there is low amounts of MLCP in the cell?

A

takes less Ca2+ to get same force of contraction
-increases sensitivity to Ca2+

72
Q

what is pharmacomechanical coupling?

A

initiates Ca2+ release to contract the smooth muscle w/o changing MB potential
-uses a chemical signal (hormones, paracrines, NTs)
-no AP generated

73
Q

what are the two ways Ca2+ is released from the SR?

A

Ca2+ induced Ca2+ release
-Ca2+ from ECF opens RyR channels on SR

IP3 mediated Ca2+ release
-IP3 opens RyR channels

74
Q

what are the three ways ECF Ca2+ entry is initiated?

A

Voltage-gated Ca2+ channels in MB
-opens due to depolarization

Ligand Ca2+ channels (NT, hormone, paracrine)

Stretch activated Ca2+ channels
-as vessels stretch, they do myogenic contraction
-causes a mechanical release of Ca2+

75
Q

what are two types of unstable MB potentials in smooth muscles?

A

slow wave potentials
-resting MB varies, can depolarize & repolarize but doesn’t always reach threshold

pacemaker potentials
-autorhythmic, always reaches threshold

76
Q

how do alpha receptors impact smooth muscle?

A

contraction!
-IP3 pathways (GPCR)
-sympathetic

77
Q

how do beta receptors impact smooth muscle?

A

relaxes!
-cAMP pathways
-bronchioles & cardiac tissue
-sympathetic

78
Q

how does histamine impact smooth muscle?

A

constricts bronchioles

79
Q

how does NO impact smooth muscle?

A

relaxes vascular smooth muscle

80
Q

which of the three types of muscle, lacks sacromeres?

A

smooth muscle

81
Q

which of the three types of muscle, is striated?

A

skeletal & cardiac

82
Q

what is the tissue morphology of the three types of muscles?

A

skeletal: multinucleate, long & cylindrical
smooth: uninucleate, spindle shaped
cardiac: uninucleate, branching

83
Q

which of the three types of muscle only contains tropomyosin and lacks troponin?

A

smooth muscle

84
Q

what does Ca2+ for each of the three types of muscle bind to?

A

skeletal: troponin
smooth: calmodulin
cardiac: troponin

85
Q

where does Ca2+ come from for each of the three types of muscles?

A

skeletal: SR
smooth: ECF & SR
cardiac: ECF & SR

86
Q

what is the contraction speed for each of the three types of muscles?

A

skeletal: fast
smooth: slow
cardiac: intermediate

87
Q

what initiates contractions for each of the three types of muscles?

A

skeletal: ACh
smooth: stretch, chemical, autorhythmic
cardiac: autorhythmic

88
Q

what hormones influence each of the three types of muscles?

A

skeletal: none
smooth: multiple hormones
cardiac: epinephrine

Integrated Physiology (23 decks)

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