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Anatomy > Muscle test > Flashcards

Muscle test Flashcards

1
Q

Skeletal muscle tissue

A

Attached to bones and skin
Striated
Voluntary (i.e., conscious control)
Powerful

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2
Q

Cardiac muscle tissue

A

Only in the heart
Striated
Involuntary

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3
Q

Smooth muscle tissue

A

In the walls of hollow organs
Not striated
Involuntary

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4
Q

functions of muscle

A

Movement of bones or fluids
Maintaining posture and body position
Stabilizing joints
Heat generation

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5
Q

skeletal muscle characteristics

A

Excitability
Contractility
Extensibility
Elasticity

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6
Q

excitability

A

responsiveness or irritability: ability to receive and respond to stimuli

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7
Q

Contractility

A

ability to shorten when stimulated

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8
Q

Extensibility

A

ability to be stretched

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9
Q

Elasticity

A

ability to recoil to resting length

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10
Q

Epimysium

A

dense regular connective tissue surrounding entire muscle

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11
Q

Perimysium

A

fibrous connective tissue surrounding fascicles (groups of muscle fibers)

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12
Q

Endomysium

A

fine areolar connective tissue surrounding each muscle fiber

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13
Q

muscle flow chart

A

muscle is covered by epimysium
muscle is made up of fasicles covered by perimysium
fasicles are made of muscle fibers (muscle cells) covered by endomysium
muscle fibers made of myofibrils which are made up of filaments (actin and myosin)

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14
Q

muscles attach directly

A

epimysium of muscle is fused to the periosteum of bone or perichondrium of cartilage

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15
Q

muscles attach indirectly

A

connective tissue wrappings extend beyond the muscle as a ropelike tendon or sheetlike aponeurosis

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16
Q

skeletal muscle cells

A

Cylindrical cell up to 30 cm long
Multiple peripheral nuclei
Many mitochondria
myofibrils, sarcoplasmic reticulum, and T tubules
densely packed rodlike elements (80 percent of cell volume)
striations

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17
Q

glycosomes for

A

glycogen storage

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18
Q

myoglobin for

A

oxygen storage

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19
Q

striations in muscle cells

A

perfectly aligned repeating series of dark A bands and light I bands

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20
Q

Sarcomere

A

Smallest contractile unit (functional unit) of a muscle fiber
The region of a myofibril between two successive Z discs
Composed of thick and thin myofilaments (actin myosin)

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21
Q

thick filaments (myosin)

A

run the entire length of an A band

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22
Q

thin filaments (actin)

A

run the length of the I band and partway into the A band

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23
Q

Z disc/line

A

coin-shaped sheet of proteins that anchors the actin and connects myofibrils to one another

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24
Q

H zone

A

lighter midregion where filaments do not overlap

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25
Q

m line

A

line of protein myomesin that holds adjacent thick filaments together

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26
Q

protein myosin tails contain

A

2 interwoven, heavy polypeptide chains

27
Q

protein myosin heads contain

A

2 smaller, light polypeptide chains that act as cross bridges during contraction
Have binding sites for actin of thin filaments
Also have binding sites for ATP
Has ATPase enzymes

28
Q

Actin contains

A

Twisted double strand of fibrous protein F actin

Tropomyosin and troponin

29
Q

F actin consists of

A

of G (globular) actin subunits

30
Q

G actin consists of

A

active sites for myosin head attachment during contraction

31
Q

tropomyosin

A

block binding site for myosin

32
Q

troponin

A

changes shape when calcium binds to it which moves tropomyosin out of the way

33
Q

thick filament

A

myosin molecules whose heads protrude at opposite ends

34
Q

thin filament

A

two strands of actin subunits twisted into a helix plus troponin and tropomyosin

35
Q

Sarcoplasmic Reticulum

A

network of smooth endoplasmic reticulum surrounding each myofibril
Pairs of terminal cisternae form perpendicular cross channels
Functions in the regulation of intracellular Ca2+ levels

36
Q

T-tubules

A

Continuous with the sarcolemma
Penetrate the cell’s interior at each A band–I band junction
part of triads
conduct impulses deep into muscle fiber

37
Q

triad

A

terminal of cisternae of SR, t tubule, terminal of cisternae of SR

38
Q

t tubule proteins

A

voltage sensors

39
Q

SR foot proteins

A

gated channels that regulate calcium release from the SR cisternae

40
Q

why does generation of force does not necessarily cause shortening of the fiber

A

when the load is greater than the muscle can move, the muscle doesnt shorten
ex trying to pick up a car

41
Q

Shortening occurs when

A

tension generated by cross bridges on the thin filaments exceeds forces opposing shortening

42
Q

muscle contraction steps with actin and myosin: relaxed state

A

In the relaxed state, thin and thick filaments overlap only slightly

43
Q

muscle contraction steps with actin and myosin: during contraction

A

myosin heads bind to actin, detach, and bind again, to propel the thin filaments toward the M line

44
Q

As H zones shorten and disappear

A

sarcomeres shorten, muscle cells shorten, and the whole muscle shortens

45
Q

steps to contraction

A

activation and excitation

46
Q

activation

A

neural stimulation at a neuromuscular

47
Q

Excitation-contraction coupling

A

Generation and propagation of an action potential along the sarcolemma
Final trigger: a brief rise in intracellular Ca2+ levels

48
Q

skeletal muscle stimulation travel path

A

Skeletal muscles are stimulated by somatic motor neurons
Axons of motor neurons travel from the central nervous system via nerves to skeletal muscles
Each axon forms several branches as it enters a muscle
Each axon ending forms a neuromuscular junction with a single muscle fiber

49
Q

neural muscular junction

A

Situated midway along the length of a muscle fiber
contain synaptic cleft
Synaptic vesicles of axon terminal contain the neurotransmitter acetylcholine (ACh)
Junctional folds of the sarcolemma contain ACh receptors

50
Q

how neural muscular junction works

A

Nerve impulse arrives at axon terminal
ACh is released and binds with receptors on the sarcolemma
Electrical events lead to the generation of an action potential
which travels down t tubule to cause SR to dump calcium which causes troponin to shift and unblock tropomyosin

51
Q

ach affects are terminated by

A

achesterase

52
Q

What does achesterase do

A

which prevents continued muscle fiber contraction in the absence of stimulation

53
Q

steps after ach binds to receptor on sarcolemma when crossing synaptic cleft

A

local depolarization (end plate potential)
generation and propagation of action potential
repolarization

54
Q

local depolarization (end plate potential)

A

ACh binding opens chemically (ligand) gated ion channels
Simultaneous diffusion of Na+ (inward) and K+ (outward)
More Na+ diffuses, so the interior of the sarcolemma becomes less negative
and loses polarity

55
Q

Generation of an action potential

A

End plate potential spreads to adjacent membrane areas
Voltage-gated Na+ channels open
Na+ influx decreases the membrane voltage toward a critical threshold
If threshold is reached, an action potential is generated

56
Q

propagation of an action potential

A

Local depolarization wave continues to spread, changing the permeability of the sarcolemma
Voltage-regulated Na+ channels open in the adjacent patch, causing it to depolarize to threshold

57
Q

repolarization of an action potential

A

Na+ channels close and voltage-gated K+ channels open
K+ efflux rapidly restores the resting polarity
Fiber cannot be stimulated and is in a refractory period until repolarization is complete
Ionic conditions of the resting state are restored by the Na+-K+ pump

58
Q

What maintains polarity

A

3 clacium going out and 2 potassium going in leads to repolarization

59
Q

latent period

A

Time when E-C coupling events occur

Time between AP initiation and the beginning of contraction

60
Q

stopping contraction At low intracellular Ca2+ concentration

A

Tropomyosin blocks the active sites on actin
Myosin heads cannot attach to actin
Muscle fiber relaxes

61
Q

stopping contraction At higher intracellular Ca2+ concentrations

A

Ca2+ binds to troponin
Troponin changes shape and moves tropomyosin away from active sites
Events of the cross bridge cycle occur
When nervous stimulation ceases, Ca2+ is pumped back into the SR and contraction ends
Continues as long as the Ca2+ signal and adequate ATP are present

62
Q

cross bridge cycle

A

Cross bridge formation—high-energy myosin head attaches to thin filament
Working (power) stroke—myosin head pivots and pulls thin filament toward M line
Cross bridge detachment—ATP attaches to myosin head and the cross bridge detaches
“Cocking” of the myosin head—energy from hydrolysis of ATP cocks the myosin head into the high-energy state (pull back to gain another actin)

63
Q

what makes myosin heads let go and cock

A

atp makes it let go, hydrolysis makes it cock

64
Q

why rigamortes people are stiff

A

stiff dead person, no ATP made so cross bridges are stuck. When pumps stop, calcium leaks and causes myosin heads to grab, get stiff, but ATP is gone so cant move

Anatomy (29 decks)

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