Muscle System Flashcards

1
Q

sarco-

A

flesh

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2
Q

myo-

A

muscle

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3
Q

mys-

A

muscle

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4
Q

functions of muscle system

A
  • movement
  • maintain posture
  • stabilizes joints
  • generates heat
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5
Q

types of tissue

A
  • skeletal
  • cardiac
  • smooth
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6
Q

anatomy of skeletal muscle

A
  • fibers are enclosed by endomysium
  • many endomysii are wrapped together by the perimysium
  • one group of fibers wrapped in perimysium is called a fascicle
  • all fascicles are wrapped together in epimysium
  • blended into tendons or aponeuroses
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7
Q

aponeuroses

A

layers of flat, broad tendons

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8
Q

sarcolemma

A

plasma membrane of skeletal muscle

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9
Q

myofibrils

A

long, ribbon-like organelles filling majority of cytoplasm

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10
Q

sarcomere

A

basic unit of muscle (I and A bands)

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11
Q

I and A bands

A

myofilaments

-give the appearance of striation

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12
Q

2 types of myofilaments

A
  • thick

- thin

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13
Q

thick filaments

A

composed of myosin and ATP enzymes

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14
Q

thin filaments

A

composed of actin and regulatory proteins

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15
Q

sarcoplasmic reticulum

A
  • surrounds each myofibril

- plays a role in storing and releasing calcium during contraction

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16
Q

2 main functions of muscles

A

-irritability and contractility

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17
Q

irritability

A

-receive and respond to stimuli

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18
Q

contractility

A

shorten when stimuli is applied

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19
Q

nerve stimulis

A
  • muscle cells must be stimulated by nerve impulses to contract
  • cells join at neuromuscular junctions
  • gap b/w is called synaptic cleft
  • when impulse reaches neuromuscular junction, a neurotransmitter is released
  • neurotransmitter travels across synaptic cleft and attaches to sarcolemma
  • if enough neurotransmitter reaches the sarcolemma, then Na ions rush into muscle cell and generate electrical current called action potential
  • causes contraction
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20
Q

neuromuscular junctions

A
  • where muscle cells join

- don’t touch, but very close

21
Q

synaptic cleft

A

gap between neuromuscular junctions

-filled w/ fluid

22
Q

motor unit

A

1 neuron and all skeletal muscles that it stimulates

23
Q

muscle contraction mechanism(sliding filament theory)

A
  • when muscle fibers are activated by the nervous system, cross bridges attach and detach to myosin on the thin filaments and sliding begins
  • powered by ATP
  • contraction requires Ca until action potential ends, then Ca is stored into sarcoplasmic reticulum
24
Q

contraction of skeletal muscle

A
  • skeletal muscles consist of thousands of muscle cells
  • react with graded responses
  • produced by changing frequency of muscle stimulation or changing # of muscle cells being stimulated
25
Q

graded responses

A

different degree of shortenings

26
Q

muscle twitches

A

single, brief, jerky contractions

27
Q

fused tetanus(complete tetanus)

A

muscles move through an accumulation of nerve impulsed

28
Q

unfused tetanus(incomplete)

A

steps leading to fused tetanus

29
Q

of stimuli in contraction

A

force of muscle contraction depends on how many cells are stimulated

  • when only a few cells are stimulated, contraction as a whole will be slight
  • when all motor units are active, contraction is very strong
30
Q

ATP for contraction

A
  • as muscles contract, the bonds of ATP are hydrolyzed to release needed energy
  • muscles store only 4-6 seconds worth, so ATP must be regenerated
31
Q

3 pathways for ATP regeneration

A
  • direct phosphorylation of ADP by creatine phosphate
  • aerobic respiration
  • anaerobic respiration
32
Q

direct phosphorylation of ADP by creatine phosphate

A
  • CP transfers high energy phosphate to ADP molecule, resulting in ATP (yields 1 ATP per CP)
  • anaerobic
  • muscles store 5x as much CP as ATP; however, CP supplies are exhausted in about 15-20 seconds
33
Q

aerobic respiration

A
  • glucose is broken down into CO2, H2O, and up to 36 ATP (per 1 glucose model)
  • requires O2, amino acids, fatty acids
  • slow process but allows muscles to contract for hours
34
Q

anaerobic glycolysis and lactic acid formation

A
  • glycolysis breaks glucose into pyruvic acid and 2 ATP (per 1 glucose molecule)
  • if O2 is not present then pyruvic acid is broken into lactic acid (yields 5% of ATP for aerobic respiration) (faster process and provides ATP for 30-60 seconds of strenuous muscle activity)
35
Q

muscle fatigue

A

inability of a muscle to contract even though it is being stimulated

  • occurs bc of O2 debt
  • depending on blood supply, lactic acid accumulation and low ATP, causes muscle to contract less and less effectively, then stop
36
Q

o2 debt

A

-person can’t take up enough o2 fast enough to keep muscle supplied

37
Q

types of muscle contractions

A

isotonic

-isometric

38
Q

isotonic contraction

A
  • myofilaments slide, causing muscle to shorten and movement occurs
  • ex: bending knee, rotating arm, smiling
39
Q

isometric contractions

A
  • myofilaments attempt to slide but are unable to due to immovable object and tension builds up
  • ex: attempting to move 400 lbs alone or pushing against a wall
40
Q

adduction

A

movement of a limb toward the body midline

41
Q

circumduction

A

combination of flexion, extension, abduction, and adduction, where proximal end of limb is stationary and its distal end moves in a circle

42
Q

dorsiflexion

A

standing on heels

43
Q

plantar flexion

A

pointing the toe

44
Q

inversion

A

-turning the sole of the foot medially

45
Q

eversion

A

-turning the sole laterally

46
Q

opposition

A

movement of the thumb to touch the tips of the other fingers

47
Q

supination

A

rotating the forearm laterally so the palm faces anteriorly (anatomical position)

48
Q

pronation

A

rotating the forearm medially so the palm faces posteriorly