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Anatomy and Physiology > Muscle > Flashcards

Muscle Flashcards

1
Q

describe the main function of muscle

A

contraction, which leads to a lot more functions

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2
Q

list and describe the 4 functional properties of muscle

A
  1. contractility: the ability of muscles to shorten forcefully
  2. excitability: the ability of muscles to respond to a stimulus
  3. extensibility: the ability of muscle to stretch beyond its normal resting point and can still contract
  4. elasticity: the ability of muscle to recoil to its original resting length after being stretched
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3
Q

list the 3 muscle types

A
  1. skeletal muscle
  2. cardiac muscle
  3. smooth muscle
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4
Q

describe skeletal muscle

A

striated, multi-nucleated= much longer cells that run the length of the muscle, voluntary muscle contraction

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5
Q

describe cardiac muscle

A

also striated, found only in the heart, mono-/di/nucleated cells that are connected via intercalated disks, involuntary muscle contraction

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6
Q

describe smooth muscle

A

nonstriated, mononucleated, shorter cells, involuntary muscle contraction

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7
Q

what tissue are the tendons of skeletal muscle made of?

A

dense regular connective tissue

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8
Q

what is the origin and its location in skeletal muscle tendons?

A

the less mobile, fixed attachment, usually on the proximal end of the muscle

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9
Q

what is the insertion and its location in skeletal muscle tendons?

A

the more mobile attachment, usually on the distal end of the muscle

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10
Q

what is the epimysium of skeletal muscle?

A

dense regular connective tissue that surrounds the entire muscle and is continuous with the tendons of that muscle

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11
Q

what is the perimysium of skeletal muscle?

A

dense regular connective tissue that surrounds bundles of muscle fibers

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12
Q

what is the endomysium of skeletal muscle?

A

dense regular connective tissue that surrounds individual muscle fibers, allows for smoother movement and contraction

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13
Q

describe the sarcolemma of skeletal muscle fibers

A

the cell membrane

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14
Q

describe the sarcoplasm of skeletal muscle fibers

A

the cytoplasm

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15
Q

describe the sarcoplasmic reticulum of skeletal muscle fibers

A

specialized endoplasmic reticulum

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16
Q

describe the terminal cisterns of skeletal muscle fibers

A

contained in sarcoplasmic reticulum, have voltage-gated Ca2+ channels

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17
Q

describe transverse (T) tubules of skeletal muscle fibers

A

tubes that run from sarcolemma into cell

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18
Q

describe triads in skeletal muscle fibers

A

one T tubule plus two terminal cisterns

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19
Q

describe myofibrils of skeletal muscle fibers

A

bundles of proteins called myofilaments

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20
Q

list the 2 components of myofilaments of skeletal muscle fibers

A
  1. thick filaments

2. thin filaments

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21
Q

what are thick filaments composed of?

A

myosin

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22
Q

what are the two components of myosin?

A

a tail and a head

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23
Q

what do myosin heads contain? (2)

A

an actin binding site and and ATP binding site

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24
Q

what 3 proteins make up thin filaments?

A
  1. actin
  2. tropomyosin
  3. troponin
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25
Q

describe the structure of actin proteins

A

2 strands spiraled around each other

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26
Q

describe the location and function of tropomyosin

A

spirals around actin, covers myosin head binding sites on actin

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27
Q

describe the location and function of troponin

A

attached to tropomyosin along thin filament, has Ca2+ binding sites

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28
Q

what is a sarcomere? where is it found?

A

the basic unit of contraction, found within myofibrils, runs from one Z disc to another

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29
Q

during a contraction, what moves, what shortens, and what remains the same in the sarcomere?

A

myosin pulls actin toward M-line, and the entire sarcomere shortens, the I band and the H zone also shorten, and the A band remains the same

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30
Q

what is a motor unit?

A

one motor neuron and all the muscle fibers it innervates

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31
Q

how do the muscle fibers of the same motor unit contract?

A

simultaneously

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32
Q

how many muscle fibers does a typical motor neuron innervate?

A

150

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33
Q

list the first 5 steps of muscle contraction

A
  1. motor neuron releases a neurotransmitter (ACh) at neuromuscular junction
  2. ACh binds to receptor on sarcolemma of muscle fiber
  3. Na+ channels open on sarcolemma, resulting in depolarization, leading to an action potential along sarcolemma
  4. (happening at the same time as 3) excess ACh at neuromuscular junction is broken down by Acetylycholinesterase on sarcolemma
  5. action potential travels along sarcolemma and down the Transverse tubules
34
Q

list steps 6-12 of muscle contraction (beginning after the action potential travels along sarcolemma and down T tubules)

A
  1. when action potential reaches voltage-gated Ca2+ channels on T tubules, those channels are pulled away from Ca2+ release channels on terminal cisterns of sarcoplasmic reticulum
  2. Ca2+ leaves sarcoplasmic reticulum via Ca2+ release channels and enters sarcoplasm
  3. Ca2+ diffuses into myofibrils
  4. Ca2+ binds to troponin on thin filament
  5. a conformation change in the troponin/tropomyosin complex will expose myosin head binding sites on actin
  6. myosin head will bind to ATP and hydrolyze it to ADP and a phosphate group
  7. myosin head orients itself to bind to actin (getting to the ready position)
35
Q

list steps 13-17 of muscle contraction (beginning after the myosin head orients itself to bind to actin)

A
  1. myosin head binds to actin
  2. myosin head pivots toward center of sarcomere and pulls actin toward center of sarcomere with it = power stroke
  3. ADP is released from myosin head and a new ATP binds, and myosin head releases from actin
  4. myosin head will hydrolyze ATP and orient itself to bind to a new myosin head binding site on actin, process repeats
  5. myosin head walks along actin, shortening sarcomere
36
Q

when does muscle relaxation occur?

A

when ACh is no longer released at neuromuscular junction

37
Q

list the 4 steps of muscle relaxation

A
  1. cessation of action potential results in voltage-gated Ca2+ channels covering Ca2+ release channels
  2. Ca2+ that was released returns to sarcoplasmic reticulum via Ca2+ ATPase pump (which requires energy)
  3. Ca2+ diffuses away from troponin, tropomyosin covers myosin head binding sites on actin
  4. sarcomere returns to resting length
38
Q

list the 3 ways muscles can obtain ATP

A
  1. from creatine phosphate
  2. from anaerobic glycolysis
  3. from aerobic respiration
39
Q

when does muscle obtain energy from creatine phosphate and how long does it last?

A

when contraction begins, lasts about 15 seconds

40
Q

in what form can muscle store glucose and how is it released when needed?

A

as glycogen, glucose is released from glycogen during contraction and that glucose is broken down to create ATP

41
Q

where else can muscle get glucose to break down to form ATP?

A

from the bloodstream

42
Q

what are the products of anaerobic respiration?

A

ATP and lactate

43
Q

how long does the energy provided from anaerobic respiration (glycolysis) last?

A

2 minutes

44
Q

where does aerobic respiration occur and what does it require?

A

only in the mitochondria, requires oxygen

45
Q

list 3 substrates that can be used to produce ATP via the Krebs cycle/citric acid cycle in aerobic respiration?

A
  1. pyruvate
  2. fatty acids
  3. amino acids
46
Q

how are the 3 muscle fiber types classified?

A

based on respiration type

47
Q

list the 3 muscle fiber types

A
  1. slow oxidative fibers
  2. fast glycolytic fibers
  3. fast oxidative-glycolytic fibers
48
Q

what are slow oxidative muscle fibers also called?

A

slow twitch fibers/type I

49
Q

how does the myosin head hydrolyze ATP in slow oxidative muscle fibers?

A

slowly

50
Q

why do slow oxidative muscle fibers appear red/dark?

A

they contain a lot of myoglobin, which stores oxygen

51
Q

what type of respiration do slow oxidative muscle fibers perform?

A

aerobic respiration

52
Q

what type of movements are slow oxidative muscle fibers good for?

A

movements that happen over a long period of time, like posture maintenance and endurance

53
Q

where can slow oxidative muscle fibers be found in chicken, and in what type of horse are these most predominant?

A

dark meat in chicken, Arabian horses

54
Q

what are fast glycolytic muscle fibers also called?

A

fast twitch/type IIA

55
Q

how does the myosin head hydrolyze ATP in fast glycolytic muscle fibers?

A

quickly

56
Q

what do fast glycolytic muscle fibers lack and what does this mean for their color and respiration type?

A

they lack myoglobin = no oxygen = rely on anaerobic respiration = appear white

57
Q

what are fast glycolytic muscle fibers good for?

A

short bursts of activity

58
Q

what are fast oxidative-glycolytic muscle fibers also called?

A

fast twitch/type IIB

59
Q

do fast oxidative-glycolytic muscle fibers have any myoglobin? what does this mean?

A

they have SOME myoglobin, which means they can utilize some aerobic respiration

60
Q

where are fast oxidative-glycolytic muscle fibers found in chickens and in what type of horse are they predominant?

A

chicken breasts, white meat, in Quarter Horses

61
Q

what color are fast oxidative-glycolytic muscle fibers?

A

slightly pink

62
Q

what is summation? what does it determine?

A

adding things together, determines contraction strength

63
Q

list the 2 types of summation

A
  1. motor unit summation

2. temporal summation

64
Q

describe motor unit summation

A

when multiple motor units contract at the same time, the contraction is stronger

65
Q

describe temporal summation

A

when the frequency of the stimulus to contract increases, the contraction is stronger

66
Q

what is tetany?

A

when further increases in the frequency of the stimulus to contract will not result in a stronger contraction, the contraction has reached a steady state

67
Q

does tetany always occur as a result of pathology?

A

no not always

68
Q

what is tetanus?

A

when clostridium tetani produces a neurotoxin that results in tetany of muscles, prevents inhibitory signals, so only activating signals are released, neurotoxin can get through blood-brain barrier

69
Q

what is fatigue?

A

decrease in work capacity caused by work itself

70
Q

what causes muscular fatigue?

A

caused by decrease in available ATP and a buildup of metabolites in muscle such as lactate or phosphate

71
Q

what is muscle rigor?

A

when ATP is depleted, the myosin head cannot detach from actin and stays in a painful contracted state

72
Q

what is rigor mortis? how does is affect meat?

A

muscle rigor that occurs after death, has a negative effect on meat tenderness after slaughter

73
Q

what is Hyperkalemic Periodic Paralysis (HYPP)

A

high blood potassium (K+), caused by defective Na+ channels in muscle that randomly open, leading to depolarization, causing random muscle contraction, can be mild or severe, linked to Impressive’s genes

74
Q

list 3 drugs that effect muscle contraction

A
  1. anticholinesterase
  2. curariform
  3. botulinum toxin
75
Q

how does anticholinesterase effect muscle contraction?

A

inhibits acetylcholinesterase so acetylcholine will not be broken down, prolonging muscle contraction due to no removal of stimulus to contract

76
Q

what is anticholinesterase used in and why is that bad?

A

insecticides, if animals get into it can lead to asphyxiation and death

77
Q

how does curariform effect muscle contraction?

A

binds to acetylcholine receptors, keeping acetylcholine from binding, inhibiting contraction, leading to asphyxiation

78
Q

how is curariform used in a good way?

A

in small doses during surgery to prevent certain muscles from contracting and fucking things up

79
Q

what is botulinum toxin produced by and where is it found?

A

clostridium botulinum, found in some soils

80
Q

how does botulinum toxin effect muscle contraction?

A

inhibits release of acetylcholine from motor neuron, inhibiting contractions and can lead to asphyxiation

Anatomy and Physiology (18 decks)

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