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BMS 150 Midterm 2 > Skeletal Muscle Physiology 2 > Flashcards

Skeletal Muscle Physiology 2 Flashcards

1
Q

what happen when the calcium binds to troponin C in the muscle fiber cytosol?

A

the troponin complex undergoes a conformational change and Troponin T “pulls” tropomyosin and Troponin I off the myosin-binding site of G-actin subunits

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2
Q

what are the steps of cross-bridge cycle

A
  1. ATP hydrolysis
  2. cross-bridge formation
  3. power stroke
  4. detachment of myosin from actin
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3
Q

prior to myosin being able to bind to actin, it must be ?

A

“energized”

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4
Q

what happens when myosin is bound to ATP

A

it lowers it’s affinity for actin and there is no cross-bridge formation

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5
Q

what hydrolyses ATP -> ADP + Pi in the myosin head?

A

intrinsic ATPase activity

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6
Q

hydrolysis causes what change in the mysoin head?

A

causes the myosin head to pivot, moving down the actin filament so that it lines up with a new actin monomer

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7
Q

calcium binding to troponin, has uncovered what?

A

the mysoin-binding site on actin

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8
Q

the energized myosin head attached to the mysoin-binding site on actin and what is released?

A

Pi

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9
Q

when the myosin head is attached to the myosin-binding site, this creates what?

A

a myosin-actin cross bridge

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10
Q

the cross bridge generates force as what?

A

as myosin neck rotates toward center or sarcomere

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11
Q

what is getting closer together, shortening the sarcomere and generating force?

A

Z lines

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12
Q

what dissociates from myosin and the actin-myosin complex is left in a rigid, “attached” state?

A

ADP

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13
Q

what binds to myosin and myosin detaches from actin

A

ATP

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14
Q

what is isometric contractions?

A

muscle contracts against force transducer without decreasing muscle length

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15
Q

when does isometric contractions occur?

A

occurs when the load is greater than the force of muscle contraction

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16
Q

what is isotonic contractions?

A

muscle shortens against a fixed load

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17
Q

when does isotonic contractions occur?

A

occurs when the force fo the muscle contraction is greater than the load and the tension on the muscle remains constant

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18
Q

what binds to free calcium within the SR

A

calsequestrin and calreticulin

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19
Q

there are 2 main types of muscle fiber types which are?

A

type 1 (slow fibers)
type II (fast fibers)

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20
Q

which fiber type is generally smaller and innervated by smaller nerve fibers?

A

type 1 or slow fibers

21
Q

which fiber type is larger in size and innervated by large nerve fibers

A

type 2 or fast fibers

22
Q

what are the two subtypes of type II fast fibers

A

Type IIA - fast oxidative glycolytic fibers
type IIB - fast glycolytic fibers

23
Q

which type of muscle fiber has more capillaries to supply higher amounts of oxygen

A

type I/ slow fibers

24
Q

which type of muscle fiber has lots of SR for rapid Ca2+ release

A

type II/ fast fibers

25
Q

which type of muscle fiber has lots of myoglobin, giving a reddish appearance

A

type I/slow fibers

26
Q

which type of muscle fiber has lots of mitochondria to support high levels of oxidative metabolism

A

type I/slow fibers

27
Q

proportions of type I and II fibers seems to be partially determined by ?

A

genetic inheritance

28
Q

there are 3 different metabolic systems responsible for recycling AMP and ADP back into ATP to provide a continuous supply of ATP in muscle fibers. what are the 3 metabolic systems?

A
  1. phosphagen system
  2. glycogen lactic acid system
  3. aerobic system
29
Q

T or F: phosphorylated creatine molecule has a low energy phosphate bond

A

false, phosphorylated creatine molecule has a high energy phosphate bond

30
Q

T or F: high energy phosphate bond of phosphocreatine has more energy than the bond of ATP

A

true

31
Q

Both phosphocreatine and ATP together constitute the ?

A

phosphagen system

32
Q

the phosphagen system provide how long of maximal power?

A

8-10 seconds of maximal power

33
Q

what is the initial stage of the glycogen-lactic acid system

A

glycolysis

34
Q

in the case of insufficient oxygen, pyruvate will be converted into what?

A

lactate

35
Q

what happens after the pyruvate converting into lactate

A

it diffuses out of the muscle cells into the interstitial fluid and blood

36
Q

glycogen lactic acid system can sustain maximal muscle contraction for ?

A

1.3-1.6 minutes

37
Q

what is the name of the process of glucose -> pyruvate -> lactate -> glucose

A

cori cycle

38
Q

what is the overall net loss or gain of ATP in the Cori cycle?

A

overall loss of 4 ATP

39
Q

What is the purpose of the cori cycle?

A

providing muscle fibers with 2 ATP, replenishing NAD+ for glycolysis, prevents build-up of lactic acid in skeletal muscle

40
Q

in presence of oxygen, what happens to pyruvate?

A

pyruvate is broken down into carbon dioxide, water, and energy via citric acid cycle and ETC

41
Q

as long as nutrients in the body last, the aerobic system can be used for ?

A

unlimited duration

42
Q

muscle strength is determined mainly by what?

A

its overall size

43
Q

what is muscle power?

A

the measure of the amount of work that the muscle can perform in a given period of time

44
Q

the endurance of muscle depends on

A

the amount of glycogen that has been stored in the muscle prior to the period of exercise and depends on the type and size of muscle fibre

45
Q

what is muscle atrophy

A

muscle no longer receives contractile signals required to maintain normal muscle size

46
Q

what is muscle hypertrophy

A

results from an increase in the number of actin and myosin filaments in each muscle fiber = enlarges individual muscle fibers

47
Q

what is hyperplasia

A

formation of new muscle fibers

48
Q

what is muscle lengthening

A

occurs when muscles are stretched to a greater than normal length which causes new sarcomeres to be added at the ends of the muscle fibers where they attach to the tendons

BMS 150 Midterm 2 (16 decks)

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