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(1) Physiology > S2_L5: Muscle Physiology, Muscle Metabolism, Contraction of Whole Muscle and Motor Units > Flashcards

S2_L5: Muscle Physiology, Muscle Metabolism, Contraction of Whole Muscle and Motor Units Flashcards

1
Q

Strongest muscle because it’s
multi-pennate, and thick cross-sectionally

A

Gluteus maximus

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2
Q

Voluntary, striated muscle that is the strongest because of its size, thickness, and parallel fiber arrangement

A

Skeletal muscle

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3
Q

Involuntary, striated, elastic muscle that is syncytial in form because it forms lumen

A

Cardiac muscle

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4
Q

TRUE OR FALSE: Smooth muscle is involuntary and non-striated.

A

True

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5
Q

Determine the corresponding descriptions of the internal structure of muscle

  1. Weblike structure located on top of the actin and myosin overlap and it is where calcium will be released
  2. Outermost sheath of connective tissue covering each muscle
  3. Perforations where the action potential will travel from sarcolemma towards muscle
  4. Connective tissue that acts as sarcolemma, plasma membrane of the muscle cell
  5. Smaller subunits of muscle fibers covered by perimysium

A. Epimysium
B.
 Muscle fascicle
C. Endomysium
D. Sacroplasmic reticulum
E. T-tubules

A
  1. D
  2. A
  3. E
  4. C
  5. B
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6
Q

What are the three components of the triads of a muscle fiber?

A

1 Transverse tubule (T-tubule) and 2 lateral terminal cisternae

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7
Q

TRUE OR FALSE: Once the action potential travels through the t-tubules, calcium will immediately hit on Troponin C and it does not require diffusion.

A

True

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8
Q

A sarcomere is the functional / contractile unit of the muscle. It starts and ends from?

A

Z-line to z-line OR z-disc to z-disc

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9
Q

Resting membrane potential of muscle

A

-90 mV

It is lower because more protein present and more negative components inside

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10
Q

Determine the corresponding descriptions of the internal structure of muscle

  1. Made up of purely myosin; found between A-Band
  2. Contains a cytoskeletal
    protein (myomesin) that holds the myosin at the midpoint (center of sarcomere)
  3. Isotropic band, made up of purely actin
  4. Dark band made up of actin and myosin
  5. It is the middle of the isotropic band

A. I-band
B. A-band

C. H-zone
D. M-line
E. Z-line

A
  1. C
  2. D
  3. A
  4. B
  5. E
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11
Q

Determine the corresponding descriptions of the molecules found in muscle

  1. Stabilize myosin to the sarcolemma
  2. Protein that attach from z-line will attach to edge of thick filaments and aligns it with the z line
  3. Protein that will align actin filaments to make it straight
  4. Third molecule complex that exposes the binding sites for binding with myosin
  5. Regulatory protein that covers the binding sites on the actin subunits and prevents myosin cross bridge binding

A. Nebulin
B.
 Titin
C. Dystrophin
D. Tropomyosin
E. Troponin

A
  1. C
  2. B
  3. A
  4. E
  5. D
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12
Q

Arrange the organizational levels of skeletal muscle from smallest to largest

Choices: muscle cell (muscle fibers), muscle, myofilaments, fascicle, myofibrils

A
  1. myofilaments
  2. myofibrils
  3. muscle cell (muscle fibers
  4. fascicle
  5. muscle
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13
Q

Theory explaining that during a muscle contraction, the sarcomere shortens and the thin filaments slide past the thick filaments. This results to an overlap of a greater degree.

A

Sliding filament theory

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14
Q

Enumerate the 6 molecular participants in the sliding filament theory of skeletal muscle contraction

A
  1. Myosin
  2. Actin
  3. Tropomyosin
  4. Troponin
  5. ATP
  6. Calcium ions
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15
Q

The ___ movement of the myosin molecule with hinged head pulls the thin filament inward toward the center of the sarcomere and provides the “power stroke” for muscle contraction

A

flexing

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16
Q

After a cross bridge has just finished, energy is needed to remove myosin and separate the cross bridge. The binding of ATP molecule transfers energy to the myosin cross bridge as ATP is hydrolyzed into ___, transforming it into a high energy conformation.

A

ADP and P (inorganic phosphate)

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17
Q

This condition occurs when dystrophin is lacking in the muscle

A

Duchenne’s muscular dystrophy (muscle weakness)

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18
Q

Determine the corresponding descriptions of the types of troponin

  1. Calcium ions bind to this to expose the binding sites
  2. Binds to tropomyosin; for relaxation
  3. Inhibits binding

A. Troponin T
B. Troponin I

C. Troponin C

A
  1. C
  2. A
  3. B
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19
Q

TRUE OR FALSE: In a single cross bridge cycle, only 1 myosin head is at high action potential and only 1 ATP is needed.

A

True

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20
Q

Arrange the events in the cross bridge cycle in order

Choices:
1 = binding of myosin to actin
2 = hydrolysis of ATP, which leads to the re-energizing
and repositioning of the cross bridge
3 = power stroke of the cross bridge that causes the sliding of the thin filaments
4 = transport of calcium ions to the sarcoplasmic
reticulum
5 = binding of ATP to the cross bridge, which
results in the cross bridge disconnecting myosin from
actin
6 = influx of calcium

A

613524

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21
Q

Each power stroke of a myosin head, shortens the
muscles by _%

A

1% (a single cross bridge cycle)

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22
Q

TRUE OR FALSE: During a muscle contraction, all cross bridges are neither bound nor disconnected at the same time

A

True

Multiple cross bridge cycling is coordinated
sequentially to prevent all cross bridges from either
being connected or disconnected at the same time

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23
Q

Although the sarcomere shortens, the length of each
myofilament does not change, however, the width of
the ___ changes. The Z line goes toward the M-line during contraction and the A-band does not change in width.

A

H-Zone and I band

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24
Q

Between myosin and actin, it’s ___ that shortens the muscles

A

Myosin

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25
Q

TRUE OR FALSE: Fast-twitch oxidative muscles are fatigue-resistant

A

True

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26
Q

ATP is composed of the ___ with two additional phosphate groups attached by high-energy
phosphate bonds

A

adenine nucleotide

27
Q

Rebuilding ADP into ATP requires a synthetic enzyme
to carry out ___ and a source of energy to “rebuild” the high-energy bond.

A

dehydration synthesis

28
Q

When ATP supplies are low, muscle cells use three
processes to synthesize additional ATP. Enumerate these.

A
  1. Hydrolysis of creatine phosphate
  2. Glycolysis
  3. Krebs cycle (citric acid cycle) and oxidative
    phosphorylation
29
Q

The immediate source of energy for rebuilding ATP

A

Creatine phosphate

30
Q

A hydrolytic process that transfers energy and a phosphate group from creatine phosphate to ADP, forming ATP

A

Substrate phosphorylation

31
Q

Glucose is a major source of energy for synthesizing
ATP. Glucose is available to muscles from two
different sources, enumerate both.

A
  1. It enters the muscle cell directly from the blood
  2. It is produced by hydrolysis of glycogen stored in the muscle cell
32
Q

Stored glucose / sugar that is found everywhere (e.g. in muscle liver cells)

A

Glycogen

33
Q

When glucose is used as a source of energy for synthesizing ATP, how many moles of ATP are produced?

A

2 ATP

-Converting glycogen to glucose produces 3 moles of ATP, but it has to be converted to glucose 6 phosphate and uses up 1 ATP for this process

34
Q

The byproduct of glycolysis is ___

A

pyruvic acid

35
Q

Without the presence of oxygen, pyruvic acid will become ___, which is a competitor for calcium. Once it builds up, it binds to troponin C and this leads to muscle fatigue and causes DOMS (delayed onset muscle soreness).

A

lactic acid

36
Q

What are the end products of the aerobic pathway

A
37
Q

Determine the corresponding descriptions of the energy systems

  1. 2-3 minutes of explosive activity
  2. Net products are 2 ATP molecules, 2 pyruvic acid molecules
  3. 3-15 secs all out muscular contraction (explosive, burst)
  4. Submaximal muscle contraction
  5. End products are 36 moles of ATP, water, and CO2

A. ATP-PC
B. Glycolytic pathway

C. Aerobic pathway

A
  1. B
  2. B
  3. A
  4. C
  5. C
38
Q

Excess lactic acid quickly brings about ___

A

muscle fatigue

39
Q

If oxygen is available, the cells can carry out aerobic
respiration and instead of conversion to lactic acid, pyruvic acid enter the mitochondria, where it is converted to (1)___ in the Krebs cycle and energy is
transferred to ATP in (2)___

A
  1. acetyl CoA
  2. oxidative phosphorylation
40
Q

Holds / carries oxygen to muscle

A

Myoglobin

41
Q

White muscle fibers mainly use (1)___ to synthesize
ATP and are light in color due to reduced (2)___

A
  1. glycolysis
  2. myoglobin
42
Q

Red muscle fibers mainly use the what 2 processes to synthesize ATP?

A

Krebs cycle and oxidative phosphorylation

43
Q

Principle of training specifically for an activity, the muscle adapts to that particular sport or activity

A

Principle of specificity

44
Q

It is a motor neuron and all of the muscle cells it
stimulates (innervations)

A

Motor unit

45
Q

Small motor units are used for (1)___ movements, while large motor units are used for (2)___ movements

A
  1. precise
  2. gross
46
Q

Is maintained by asynchronous stimulation of random motor units

A

Muscle tone

47
Q

Enumerate the 3 Factors Affecting Muscle Tension

A
  1. Frequency of stimulation
  2. Number of motor units recruited
  3. Degree of muscle stretch
48
Q

A muscle contraction in response to a single stimulus
of adequate strength

A

Muscle twitch

49
Q

Determine the corresponding descriptions of the muscle twitch phases

  1. Ca2+ actively transported back into terminal cisternae
  2. The point where stimulator is activated and the time it took for AP to travel to sarcolemma
  3. Sarcomeres shorten as a result of myosin cross bridge cycling
  4. Sarcolemma and T-tubules depolarize, Ca2+ released into cytosol
  5. Tension is reduced, muscle returns to original
    length

A. Latent period
B.
 Contraction
C. Relaxation

A
  1. C
  2. A
  3. B
  4. A
  5. C
50
Q

Determine the corresponding descriptions of the muscle morphology

  1. Poorly developed sarcoplasmic reticulum
  2. Have Intercalated disks
  3. Have dense bodies instead of Z lines
  4. T – system is located at Z lines
  5. Have tropomyosin but absent troponin

A. Cardiac muscle
B. Smooth muscle

A
  1. B
  2. A
  3. B
  4. A
  5. B
51
Q

Smooth muscle characterized by large sheets, low resistance bridges, and have gap junctions. It is syncytial in function and located in the intestines, uterus, and ureters.

A

Visceral smooth muscle

52
Q

TRUE OR FALSE: Multi-unit smooth muscle has no interconnecting bridges.

A

True

53
Q

A mechanism that produces sustained contraction where dephosphorylated myosin cross-bridges remain attached to actin.

A

Latch bridge mechanism

54
Q

These are small invaginations at the sarcolemma that act as the rudimentary analog T – system.

A

Caveoli

55
Q

Determine whether cardiac or smooth muscle is described

  1. Tonic response
  2. Latch bridge mechanism, cAMP relaxes
  3. Increase cAMP and force of contraction
  4. Phasic response
  5. Inhibits phosphorylation of the myosin light chain
    kinase

A. Cardiac muscle
B. Smooth muscle

A
  1. B
  2. B
  3. A
  4. A
  5. B
56
Q

Stimulus is applied before completion of relaxation and results in higher tension and a higher muscle twitch response. Additional influx of Ca2+ promotes a second contraction, which is added to the first contraction.

A

Temporal summation

57
Q

A series of maximal stimuli is delivered to muscle at a frequency just below tetanizing frequency. An increase in tension developed during each twitch.

A

Treppe (Staircase Effect)

58
Q

With increased frequency of stimulation, the muscle exhibits a shorter contraction-relaxation cycle.

A

Incomplete Tetanus / Unfused Tetanus

59
Q

With rapid multiple stimulation, contractions fuse into
a smooth, continuous, total contraction without
evidence of any cyclical relaxation. Abundant intracellular calcium provides continual availability of binding sites on actin for cross bridge cycling.

A

Complete Tetanus / Fused Tetanus

60
Q

With continuous rapid stimulation, muscle is no longer
able to sustain its level of tension but gradually
elongates. It is due to build-up of acidic compounds which affect protein functioning, a relative lack of ATP, and ionic imbalances resulting from membrane activities.

A

Fatigue

61
Q

When this kind of stimulus is given, the muscle does not respond, it has no visible response.

A

Subthreshold stimulus

62
Q

Muscle tension is very high at ___ length because there is optimal overlap between actin and myosin filaments.

A

Midrange / Resting

63
Q

Arrange the following contractions from highest to lowest tension produced

Choices:
Isometric, fast concentric, slow eccentric, fast eccentric, slow concentric

A
  1. Fast eccentric
  2. Slow eccentric
  3. Isometric
  4. Slow concentric
  5. Fast concentric

(1) Physiology (16 decks)

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