Muscular System Flashcards

1
Q

all or nothing principle

A

when a muscle contractions it must contract with all possible force or none at all.

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2
Q

isometric contraction

A

muscle length remains the same but tension increases; they work but do not produce movement.

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3
Q

isotonic contraction

A

the tone or tension within the muscle remains the same; occurs usually when there is little or no resistance

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4
Q

motor unit

A

functional unit of skeletal muscle; composed of motor neuron and the attached muscle fibers

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5
Q

myofibril

A

fine fibers closely packed together

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6
Q

myofilament

A

proteins in the myofibers that are arranged into groups that cause striations to appear (bands)

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7
Q

neuromuscular junction

A

motor neurons attaching to a motor endplate,

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8
Q

sarcolemma

A

surrounds each muscle fiber; located in the plasma membrane.

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9
Q

sacromere

A

segment between 2 successive Z lines or discs.
ex. between thick and thin myofilaments

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10
Q

sarcoplasm

A

the cytoplasm of striated muscle cells

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11
Q

sarcoplasmic reticulum

A

a modified ER system for pumping Ca++ ions

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12
Q

t tubules

A

allow electrical signals to travel deeper into the cell
* a sandwiched t tubules is a triad.

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13
Q

tetanus

A

muscle that does not have enough time between contractions to completely relax; displayed by skeletal muscle

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14
Q

threshold stimulus

A

minimal level of stimulation needed to cause contraction

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15
Q

excitability

A

the ability to respond to a stimulus, which may be delivered from a motor neuron or a hormone.

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16
Q

contractility

A

the ability of muscle cells to forcefully shorten.

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17
Q

extensibility

A

the ability of a muscle to be stretched or extended.

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18
Q

motor neuron

A

neuronal cells located in the central nervous system (CNS) controlling a variety of downstream targets.

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19
Q

cross bridges

A

the “heads” of myosin

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20
Q

acetylcholine

A

neurotransmitter diffuses into the synapse in order to initiate an impulse. (contraction)

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21
Q

relaxation

A

occurs after Ca++ is released the SR begins to pump it back into sacs. when Ca++ is removed, it frees up the troponin molecules and shuts down the contraction.

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22
Q

grades strength principle

A

muscles get stronger when they are constantlly challanged.

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23
Q

visceral

A

(single-unit) form continuous sheets, is found in digestive, urinary and reproductive tracts, and exhibits peristalsis, autorhythmicity

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24
Q

peristalsis

A

a series of wave-like muscle contractions that move food through the digestive tract.

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25
Q

antagonist

A

muscles that directly oppose a movement

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26
Q

fixator

A

joint stabilizers that help maintain posture

27
Q

synergist

A

muscles that assist prime movers

28
Q

insertion

A

distal; the site where bone and muscle are attached and move during contraction.

29
Q

lever

A

force weight, level balance.
includes 4 parts…
1) rigid rod or bar (bone) lever
2) fixed pivot (joint) fulcrum
3)weight or resistance that is moved load
4) force or pull (the contraction) effort

30
Q

prime mover

A

muscle/group that performs specific movement.

31
Q

endomysium

A

connective tissue membrane that covers individual muscle fibers. (inner)

32
Q

perimycium

A

a tougher connective tissue membrane that holds fascicles together (middle)

33
Q

tendon

A

strong tough cord that attaches muscle to bone

34
Q

tendon sheath

A

tube shaped fibrous connective tissue

35
Q

aponeurosis

A

broad flat sheet of connective tissue

36
Q

fascicle

A

sheet/broad band of connective tissue.

37
Q

origin

A

the site where bone and muscle are attached, but do not move during contraction

38
Q

treppe

A

also known as the staircase phenomenon. shows that muscles contract more forcefully after they have been contracted a few times.

39
Q

what are the basic functions of muscle?

A

1) contraction
2) heat production from movement
3) maintaining posture (standing, sitting, etc)
4) storing and moving substances throughout
the body.

40
Q

what are the 3 types of muscle?

A

cardiac, smooth, and skeletal

41
Q

how does each type of muscle differ structurally?

A

cardiac - involuntary, branched, stiriated.
smooth - involuntary
skeletal - voluntary, striated.

42
Q

what are the three stages of a muscle contraction?

A

1) latent period
2) contraction phase
3) relaxation phase

43
Q

what are the 3 types of levers?

A

1st class lever, 2nd class lever, 3rd class lever

44
Q

how does the first class lever work?

A

joint is in the middle of the force and pull. like seesaw
ex. atlas of spine and skull

45
Q

how does the second class lever work?

A

weight lies between fulcrum and joint. like wheelbarrow.
ex. standing on tippy toes.

46
Q

how does the third class lever work?

A

pull exerted between fulcrum and weight. like lifting a shovel
ex. flexing biceps.

47
Q

how are muscles named? provide an example

A

1) location- arm, brachialis
2) function- move towards, adductor
3) shape- triangle, deltoid
4) direction of fibers- straight, rectus
5) # of heads or divisions- two, biceps
6) points of attachment- sternocleidomastoid

48
Q

what are the two types of tetanus?

A

fused and unfused

49
Q

what is the difference between the two different types of tetanus?

A

fused - smooth, stiriated muscle contractions
unfused - sustained but wavering contraction

50
Q

what is the graded strength principle influenced by?

A

1) metabolic condition of muscle fibers
2) # of muscle fibers contracting
3) # of motor units recruited
4) intensity and frequency of stimulation

51
Q

what are the four types of proteins that make up myofilaments

A

myosin, acting, tropomyosin, troponin.

52
Q

myosin

A

make up most of thick filament

53
Q

actin

A

globular proteins; make bulk of thin filaments.

54
Q

tropomyosin

A

blocks active sites of actin

55
Q

troponin

A

holds tropomyosin in place at finding site

56
Q

titin

A

accounts for most of the myofilaments elasticity and extensibility bc it can stretch to four times its initial length and return unharmed.

57
Q

dysrophin

A

cytoskeletal protein that links thin filaments to the sarcolemma; help transmit tension.

58
Q

tonic contraction

A

continued partial contractions

59
Q

flaccid

A

muscles with less than normal tone are
considered

60
Q

spastic

A

muscles with more than normal tone are
considered

61
Q

concentric / eccentric

A

reduces the angle of the joint / increasing the angle and lengthening the muscle

62
Q

stretch reflex

A

The amount of a load on muscles can also
influence contraction.

63
Q

what is a length-tension relationship

A

the max strength a muscle can supply is
directly related to the initial length of its fibers.

64
Q

intercalated discs

A

strong electrically coupled junctions