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A&P 223 > Exam #3 Chapter 9 Muscular System (Histology & Physiology) part 2 > Flashcards

Exam #3 Chapter 9 Muscular System (Histology & Physiology) part 2 Flashcards

1
Q

what is the 2nd step of the cross-bridge cycling to occur?

A

1) the myosin head pivots
2) releases ADP
3) pulls the thin filament towards the M line (power stroke) (PULL)

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2
Q

what happens to the calcium ions during muscle relaxation?

A

they are pumped back into the sarcoplasmic retiuclum using ATP

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3
Q

what phases occurs after the stimulus during the muscle twitch in the lab?

A

the short lag phase, contraction phase and a relaxation phase.

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4
Q

during stimulus frequency and muscle contraction in a lab what does higher frequency stimulations produce?

A

incomplete tetanus with higher tension but partial relaxations between stimulations

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5
Q

what type of muscle fiber does treppe occur in?

A

one that has rested for a prolonged period

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6
Q

what type of motor units do muscles that produce delicate movements have?

A

ones with fewer fibers than large postural muscles that produce powerful, less controlled movements

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7
Q

What are all cells and what do they have?

A

polarized and they have a resting membrane potential that can be measured

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8
Q

if there is an increasing stimulus at a low frequency what is there?

A

a gradual increase in tension above the threshold stimulus to a maximal stimulus

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9
Q

during muscle frequency and contraction in a lab how does our nervous system stimulate muscles?

A

at a high frequency producing complete tetanus and recruits enough motor units to accomplish the task

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10
Q

when is the only time myosin heads can generate force?

A

in the area of overlap

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11
Q

while producing a muscle twitch in a lab what does a single stimulus produce?

A

a brief contraction and relaxation generating some tension (force)

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12
Q

what does the force a single fiber generates depends on?

A

the rate of action potential and the fiber length

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13
Q

how is the muscle tone produced?

A

involuntarily when one is awake

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14
Q

why does excitation-contraction coupling occur?

A

because of the anatomical association between the T tubules and the sarcoplasmic reticulum.

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15
Q

what does the membrane cause in and out of the cell?

A

more negative ions in the cell and more positive ions outside the cell

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16
Q

after the steps of excitation-contraction coupling occur what then occurs?

A

the steps of cross-bridge cycling now produce a movement

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17
Q

what does the active tension curve show?

A

the force generated at different muscle lengths

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18
Q

during muscle frequency and muscle contraction in a lab how is an increase in tension achieved?

A

through multiple-wave summation

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19
Q

what does a single motor neuron innervate?

A

multiple muscle fibers that are called a motor unit and function together

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20
Q

what is the relaxation phase?

A

the time during which relaxation occurs

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21
Q

what is excitation-contraction coupling?

A

the steps between an action potential in the sarcolemma and contraction

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22
Q

if a muscle is stimulated with a constant stimulus at a low frequency what is there?

A

a small increase in the tension generated (treppe)

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23
Q

what is the 3rd step of the Excitation-contraction coupling to occur?

A

the action potential n the T Tubule caused a reason of calcium from voltage-regulated channels in the the terminal cisternae

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24
Q

why do sarcomeres generetate little or no force when it is stretched too much?

A

because there is little or no overlap

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25
Q

when do sarcomeres generate maximum force?

A

at an optimal length with maximum overlap

26
Q

what are our muscles generally near?

A

the optimal sarcomere length

27
Q

what is an action potential?

A

a rapid and change to the resting membrane potential

28
Q

during stimulus frequency and muscle contraction in a lab what does low frequency stimulation produce?

A

twitches with little tension

29
Q

what does there need to be in order for the cycle of cross-bridge cycling to occur?

A

Calcium needs to be present and there needs to be available ATP

30
Q

what is occurring during isometric contractions?

A

force is generated but the muscle length does NOT change

31
Q

what does muscle tone prepare the muscle for?

A

contraction and steadies the body

32
Q

what is the first step in contraction?

A

when a muscle fiber is stiumulated to produce an action potential in the sarcolemma at the neuromuscular junction

33
Q

what happens at the neuromuscular junction?

A

a muscle fiber is stimulated to produce an action potential in the sarcolemma

34
Q

after death do cells have a membrane potential that can be measured?

A

no

35
Q

what happens when no more action potentials come down the somatic motor neuron axon?

A

all the ACH is degraded, stopping action potentials in the sarcolemma.

36
Q

what happens to the tropomyosin during muscle relaxatoin?

A

it’s rolled back on the myosin binding sites of actin and contraction ceases

37
Q

what are the two types of isotonic contractions?

A

1) concentric isotonic contractions

2) eccentric isotonic contractions

38
Q

what is the lag (latent) phase?

A

the gap between the time of the stimulus application to the motor neuron and the beginning of the contraction

39
Q

what is the 3rd step of the cross-bridge cycling?

A

An ATP binds to the myosin head and it detaches from the action (RELEASE)

40
Q

why does the voltage read as a negative number?

A

because the inside is negative compared to the outside

41
Q

what is multiple-wave summation?

A

the adding of calcium releases together

42
Q

why is little or no force generated in a sarcomere when it is compressed too much?

A

since the thin filaments overlap or the thick filaments hit the Z disc

43
Q

what are eccentric isotonic contractions?

A

the muscle lengthens

44
Q

what is muscle tone?

A

the contraction of a few motor units when the muscle is not contracting

45
Q

what is the 2nd step of the Excitation-contraction coupling to occur?

A

next to the T Tubules are 2 large sections of the sarcoplasmic reticulum called terminal cisternae that form a triad with the T Tubule

46
Q

what is the contraction phase?

A

the time during which contraction occurs

47
Q

what is the fourth and last step of the Excitation-contraction coupling to occur?

A

the calcium binds to troponin and moves trypomyosin off the actin active sites to which myosin heads can now bind

48
Q

what is the first step of the Excitation-contraction coupling to occur?

A

the action potential in the sarcolemma travels down the T Tubules

49
Q

what is the 4th step of the cross-bridge cycling?

A

the myosin head hyrolyzes ATP into ADP and (P) which remain attached and the head recocks (EXTEND)

50
Q

what type of force does a sarcomere generate when it is compressed too much?

A

little or no force

51
Q

during cross-bridge cycling what happens when tropomyosin is moved?

A

when tropomyosin is moved the myosin head has an attached ADP and an attached inorganic phosphate (P)

52
Q

in neurons and muscle fibers what are actions potentials always?

A

the same

53
Q

during stimulus frequency and muscle contraction in a lab at higher frequency stimulations how is complete tentanus achieved?

A

with high, steady tension generated by high calcium levels obtained

54
Q

what is the first step of the cross-bridge cycling to occur?

A

the myosin head, with an ADP and (P) attached, binds to the myosin binding sites of actin, for a cross bridge and releases the (P) (GRAB)

55
Q

when can a sarcomere generate little or no force?

A

when it is stretched too much

56
Q

what speeds is calcium diffused out down the steep concentration gradiant and pumped back into the sarcoplasmic retiuclum?

A

it is released at a quick rate and pumped back in slowly

57
Q

what is occurring during isotonic contractions?

A

force is generated and muscle length changes

58
Q

what is the action potential caused by?

A

ions moving through the membrane in ion channels

59
Q

what is the force related to during the muscle twitch?

A

the amount of calcium

60
Q

what are concentric isotonic contractions?

A

the muscle shortens

61
Q

when there is an increasing stimulus at a low frequency that occur during stimulus strength and motor unit response that causes a gradual increase in tension above stimulus to a maximal stimulus, what is this due to?

A

stimulating more motor units (graded response)

62
Q

what needs to be present in order for myosin binding sites to be available?

A

calcium

A&P 223 (50 decks)

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