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A&P 1 > Chapter 9: Muscles and Muscle Tissues > Flashcards

Chapter 9: Muscles and Muscle Tissues Flashcards

1
Q

Muscle Fiber

A

skeletal muscle or smooth muscle CELL; but NOT a cardiac muscle cell

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2
Q

What prefixes mean “muscle”?

A

myo, mys, sarco

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3
Q

What are the types of muscle tissue?

A

skeletal, cardiac, smooth

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4
Q

Skeletal Muscle Tissue

A

attached via tendon to bone (most); striated and voluntary

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5
Q

Cardiac Muscle Tissue

A

striated (but not as distinct as skeletal), involuntary and ahs intercalated discs; branched

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6
Q

Smooth Muscle Tissue

A

walls of hollow organs; nonstriated and involuntary

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7
Q

Characteristics of Muscles in General

A

excitability, contractility, extensibility, and elasticity

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8
Q

Excitability

A

aka responsiveness; ability to respond to a stimulus by changing its membrane potential

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9
Q

Contractility

A

ability to shorten forcibly when adequately stimulated

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10
Q

Extensibility

A

ability to stretch when relaxed

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11
Q

Elasticity

A

ability to recoil after stretching

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12
Q

Functions of Muscles

A

produce movement; maintain posture and body position; stabilize joints (muscle tone); generate heat

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13
Q

Structural Hierarchy of Skeletal Muscle

A

biggest to smallest; muscle (a bunch of fascicles) to fascicle (bunch of muscle fibers) to muscle fiber (cell)

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14
Q

What tissues are involved with skeletal muscles?

A

muscle fibers, blood vessels (muscle is well vascularized), connective tissue sheaths, attachments

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15
Q

Nerve and Blood Supply of Skeletal Muscle

A

has 1 nerve, 1 artery and 1 or more veins that supply each muscle; all enter or exit near muscle center

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16
Q

Connective Tissue Sheaths

A

epimysium, perimysium, endomysium

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17
Q

Epimysium

A

dense irregular CT that surrounds the entire muscle

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18
Q

Perimysium

A

dense irregular CT that surrounds a fascicle (bundle of muscle fibers)

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19
Q

Endomysium

A

areolar CT that surrounds each muscle fiber

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20
Q

Attachments of Skeletal Muscles

A

all skeletal muscles have at least 2 points of attachment; an insertion and origin

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21
Q

Insertion

A

end of muscle attached to bone that moves

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22
Q

Origin

A

end of muscle attached to bone that move less

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23
Q

Origins and Insertions may be…

A

direct or indirect

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24
Q

Direct

A

epimysium of muscle fused to periosteum or perchondrium

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25
Q

Indirect

A

tendon or aponeurosis anchors muscle to periosteum, perichondrium or epimysium of another muscle

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26
Q

Deep Fascia

A

what connective tissue sheaths and attachments are collectively referred to as

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27
Q

What does each skeletal muscle fiber have?

A

sarcolemma, sarcoplasm, special structures such as myofibrils, sarcoplasmic reticulum, and T Tubules

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28
Q

Sarcolemma

A

plasma membrane of muscle fibers

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29
Q

Sarcoplasm

A

cytoplasm of muscle fibers; contains large number of mitochondria, glycosomes (glycogen granules), and myoglobin (stores O2)

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30
Q

Myofibrils

A

make up 80% of cell volume; extend entire length or muscle cell; each consists of sarcomeres (repeating units) laid end to end with an internal arrangement of myofilaments

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31
Q

Sarcomeres

A

Smallest contractile units (functional units) or skeletal muscle; contain a dark A band and 1/2 of a light I band

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32
Q

Myofilaments

A

thick filaments: consist of many myosin molecules; head protrude at opposite ends of filaments; thin filaments: consist of 2 strands of actin subunits and 2 types of regulatory proteins (troponin, tropomyosin)

33
Q

Tropomyosin

A

blocks myosin binding sites on think filaments

34
Q

Arrangement of thick and thin filaments…

A

responsible for banding pattern of myofibrils (the A and I bands or dark and light bands)

35
Q

A Band

A

dark region of overlapping thick and thin filaments

36
Q

H Zone

A

region within A band lacking thin filaments

37
Q

M Line

A

region within H zone containing proteins that anchor thick filaments

38
Q

I Band

A

light region of thin filaments only

39
Q

Z Disc

A

region within I band where thick and thin filaments anchor to sarcolemma

40
Q

Elastic Filaments

A

composed of the protein titin; functions to 1) hold thick filaments in place; 2) helps muscle cells spring back into shape; 3) prevent sarcomeres from separating

41
Q

Sarcoplasmic Reticulum

A

SR; interconnecting tubules that encase myofibrils; most tubules run parallel to myofibrils; other tubules form terminal cisterns (large perpendicular cross channels) at A band-I band junctions; functions to store calcium ions

42
Q

T Tubules

A

invaginations of the sacrolemma that run between adjacent terminal cisterns and extend deep into the cells interior; function to conduct electrical impulses which trigger calcium ions to release from the terminal cisterns

43
Q

Contraction of Skeletal Muscle

A

occurs when thick and thin filaments slide past each other as the sarcomeres contract (sliding filament model of contraction); sarcomeres shorten but thick and thin filaments do not; I bands shorten; H zones dissappear; A bands move closer together, but do not shorten

44
Q

All cell membranes are…

A

charged; a difference in electrical charge on either side of membrane; positive on outside and negative on inside; all cells have a negative resting potential

45
Q

Only muscle cells and neuron cells are…

A

excitable; respond to stimuli by altering their membrane potential

46
Q

Chemically Gated Ion Channels

A

closed unless a chemical messenger opens it; ex) acetylcholine (ACh); generate local depolarization (which reverse polarity) called end plate potentials

47
Q

Voltage Gated Ion Channels

A

open/close in reponse to changes in membrane potential; generate large changes in membrane potential called action potential

48
Q

Motor Neurons

A

innervate skeletal muscle cells; exist spinal cord through nerves; branch within muscle forming multiple neuromuscular junction (only one per muscle fiber); motor unit = a motor neurons and all muscle cells it stimulates

49
Q

Contraction of One Muscle Fiber: Phase 1- events at the neuromuscular junction

A

1) action potential arrives at neuromuscular junction; 2) voltage gated calcium ion channels open and calcium ions enter axon terminal; 3) calcium ion entry causes ACh to be realeased from synaptic vesicles in synaptic cleft; 4) ACh binds to ACh receptors on sarcolemma motor end plate; 5) ACh binding opens chemically gated ion channels that allow sodium ions to enter cell and potassium ions to exit cell which generates a local depolarization; 6) ion channels closes when ACh in synaptic cleft is broken down by acetylcholinestrase (AChE)

50
Q

Contraction of One Muscle Fiber Phase 2: Muscle Fiber Excitation

A

1) end plate potential spreads to sarcolemma (if strong enough, it will open voltage gated sodium ion channels); 2) influx of sodium ions reverses membrane polarity (action potential depolarization); 3) efflux of potassium ions restores membrane polarity (action potential repolarization)

51
Q

Contraction of One Muscle Fiber Phase 3: Excitation- Contraction Coupling

A

sequence of events that link the action potential (electrical stimulus) to contraction of the muscle (mechanical action); 1) action potential moves along sarcolemma and down t-tubules; 2) calcium ions released from sarcoplasmic reticulum into sarcoplasm (in relaxed muscle cells, troponin position tropomysin such taht it blocks myosin binding site on actin subunits); 3) released calcium ions binds to troponin causing tropomysin strands to shift, unblocking the myosin binding sites; 4) myosin heads bind to actin forming cross bridges

52
Q

Contraction of One Muscle Fiber Phase 4: Cross Bridge Cycle

A

sequence of events during which myosin heads pull thin filaments toward center of sarcomere; 1) cross bridge formation; 2) power stroke occurs (myosin head bends pulling thin filaments toward m line); 3) corss bridge detachment occurs when ATP binds to myosin head; 4) cocking of the myosin head; cycle continues as long as ATP and calcium ions are available

53
Q

ATP is needed for…

A

muscles to relax NOT to contract

54
Q

Rigor Mortis

A

basically when all the muscles in a dead body start to contract because there is no ATP to cause the muscles to relax; begins 3-4 hours after death and peaks at 12 hours; after 12 hours muscles start to relax because they start to decompose

55
Q

Contraction of a Whole Muscle

A

each muscles is served by at least one nerve; each nerve contains axons; each muscle cell has only one neuromuscular joints

56
Q

Motor Unit

A

consits of one neuron and all muscle fibers it innervates; number of muscle fibers per motor unit varies (4- hundreds); fibers of large motor units spread throughout muscle

57
Q

A Muscle Twitch

A

response of a whole muscle to a single stimulus; recorded on a myogram (graph showing the amount of tension a muscle develops when its length is heald constant as it contracts); muscle develops tension when stimulated but does not shorten

58
Q

Each Muscle Twitch has Three Phases which are…

A

latent period: no reponse by cross bridges begin to cycle; period of contraction: cross bridges are cycling and tension increases; period of relaxation: tension decreases and then to zero (longer than contractile period)

59
Q

Graded Muscle Contractions

A

variations in the degree of muscle contraction by altering either the frequency or the strength of a stimulus

60
Q

FOR ALTERaTING STIMULUS FREQUENCY KNOW THE PICS AND DESCRIPTIONS OR MAKE A QUIZIZZ OF IT

A
61
Q

Altering Stimulus Strength

A

an increase in stimulus strength result in recruitment (which is the activation of more motor units)

62
Q

Subthreshold Stimuli

A

produce no observable contraction

63
Q

Threshold Stimulus

A

smallest stimulus to initiate a contraction

64
Q

Maximal Stimulus

A

smallest stimulus needed for a maximal contraction; or all motor units have been recruited

65
Q

Smallest Fiber Units Recruited

A

controlled by highly excitable neurons (lowest threshold)

66
Q

Large Fiber Motor Units Recruited

A

controlled by least excitable neurons (highest threshold); activated only when maximal contraction is necessary

67
Q

Isotonic Contractions

A

muscle tension overcomes load and muscle length changes

68
Q

Concentric Contractions

A

muscle generates tensions as it shortens

69
Q

Eccentric Contractions

A

muscle generates tension as it lengthens

70
Q

Isometric Contraction

A

muscle tensions does NOT overcome load; muscle length remains the same

71
Q

ATP Roles in Muscle Contraction

A

provides energy for movement of cross bridges; required for muscle cell relaxation; provides energy for sarcoplasmic reticulum to reclaim dumped calcium ions; provides energy for Na/K pump to maintain membrane potential

72
Q

What are the three mechanisms of ATP regeneration?

A

direct phosphorylation; anaerobic pathway; aerobic pathway

73
Q

Direct Phosphorylation

A

phosphate tranferred from stored creative phosphate (CP) to ADP to form ATP; very rapid; first source muscles use; provides ~15 secs of ATP

74
Q

Anaerobic Pathway

A

glycolysis and lactic acid formation; inefficient but fast; ~40 seconds of ATP; accumulation of lactic acid in muscles is partly responsible for muscle soreness

75
Q

Aerobic Pathway

A

glucose broken down completely to CO2 and H2O; slow but efficient; hours of energy; 30 ATP’s generated per glucose; prefers to use glucose/carbs; will use lipids second; and will use proteins but at that point your kinda dying of starvation

76
Q

ATP and Creatine Phosphate fuel activities….

A

requiring a surge of power for only a few seconds; weight lifting, diving, sprinting

77
Q

Glycolysis and Lactic Acid Formation fuel activities…

A

requiring slightly longer bursts of activity; tennis, soccer, 100m dash, or swim

78
Q

Aerobic Respiration fuels activities….

A

all light to moderate activities and prolonged activites that focus on endurance; running a marathon, competing in a triatholon

79
Q
A

A&P 1 (16 decks)

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