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Physiology > Lab 3 - Muscle > Flashcards

Lab 3 - Muscle Flashcards

1
Q

Which program is used to examine the contraction properties of skeletal (striated) muscle?

A

The SimMuscle program. It simulates the frog muscle-nerve preparation.

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2
Q

SimMuscle program:

  1. Transducer
  2. Channel 1
  3. Channel 2
A
  1. Converts the changes in muscle length and muscle tension into electrical signals. Should be connected to the oscilloscope through a cable.
  2. Connects oscilloscope to the stimulator
  3. Recieves signals from the transducer
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3
Q

SimMuscle program: steps on how to use

A
  1. Turn on the apparatus (On/Off).
  2. Drag preparation into the rack (the nerve is placed
    automatically on the stimulator electrodes).
  3. Connect transducer to the oscilloscope (“Length” socket).
  4. Calibrate the experimental setup (“Zero Adjust”).
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4
Q

What is muscle contraction based on?

A

Sliding of contractile elements, actin and myosin.

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5
Q

What is spatial (or quantal) summation?

A

As the stimulus strength is increased, more and more fibres contract. Finally all the fibres are activated and the muscle reaches its maximal contraction level.

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6
Q

How does the muscle contract?

A
  1. AP incr. myoplasmic Ca conc.
  2. Ca binds to troponin-C, shifting the tropomyosin-troponin complex to the groove of the actin filament.
  3. The myosin binding sites on the actin filament are freed to react with myosin.
  4. Activated myosin heads (09 degrees) bind to actins active sites
  5. Binding allows myosin heads to reach resting state
  6. Myosin bend first 40 degree and release ADP and Pi. Then at 45 degrees, the filaments are sliding –> muscle contracts
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7
Q

Latency period

A

The time between the stimulation and the start of the contraction (electro-mechanical coupling=

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8
Q

Dissociation of muscle contraction

A

If ATP is available, it binds to myosin, which dissociates from the actin and myosin head turn to original activated position (90 degree).

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9
Q

Cross bridge cycle

A

The complete cycle of formation of actomyosin complex, sliding of filaments and dissociation.

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10
Q

How can muscle contraction be increased?

A
  1. Spatial or quantal summation

2. Incr. the frequency of triggering of the contraction fibers.

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11
Q

Superposition

  1. What is it?
  2. Why?
  3. How is it examined?
A
  1. Temporal summation. If a fibre is stimulated repeatedly before the previous ca transient has finished, the new stimulus elicits additional ca release –> contraction increases.
  2. IC ca has no time to be removed
  3. Muscle is stimulated with twin stimuli.
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12
Q

Tetany

A

Muscle spasms, caused by deficiency of ca.
Happens when we incr. the frequency. The time lapse betw. stimuli is shorter than contraction time and the contraction gets stronger. The muscle dont´t relax but shows continious spams –> complete tetany

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13
Q

Muscle fatigue:

  1. What causes it?
  2. What does it lead to?
  3. Diff. betw the two muscle types
A
  1. Incr. conc. of metabolic br-prod. Lack of E leads to form. of lactic acid which directly inhibits the muscle function.
  2. Lack of neurotransmitters. Contraction decr. and contraction time incr.
  3. White (glycolytic) containing fast-twitch fibers exhaust faster. Red (oxidative) with slow-twitch fibrers exhaust slower.
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14
Q

Length tension diagram - consist of?

A

1.A passive stretch curve, an isotonic max. curve and an isometric max. curve.

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15
Q

How can a isotonic max. curve be obtained on a length tension diagram?

A

The muscle is passively stretched with diff. loads and stimulated with supramax. stimuli, under isotonic conditions.

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16
Q

How can a isometric max. curve be obtained on a length tension diagram?

A

The muscle is passively stretched with diff. loads and stimulated with supramax. stimuli, under isometric conditions.

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17
Q

What is the optimal work range for the striated muscle?

A

Medium tension (preload). Most are slightly contracted under phys.conditions.

18
Q

How can the velocity of a contraction be measured?

A

The quotient of the change in muscle length and the contraction time: v = s (mm) / t (ms)

19
Q

Electromyography

A

Recording of the el.activity of muscle tissue, using electrodes attached to the surface of the skin.

20
Q

Electromyogram

A

Recording of el.activity as a function of time.

21
Q

Hematocrit value (venous)

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 0.35-0.45 l/l
b) 0.35-0.45 l/l
c) 0.35-0.45 l/l
d) 0.35-0.45 l/l
e) 0.35-0.45 l/l

22
Q

Blood clotting (37 degrees)

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 20-25 min
b) 5-15 min
c) -
d) -
e) 5-6 min

23
Q

RBC sedimentation rate

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 60-90 mm/hour
b) 0-2 mm/hour
c) 0 mm/hour
d) 0 mm/hour
e) 1-14 mm/hour

24
Q

WBC: lymphocytes

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 35 (15-45) %
b) 60 (55-75) %
c) 60 (55-75) %
d) 60 (55-75) %
e) 60 (55-75) %

25
Q

WBC: neutrophils granulocytes

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 60 (55-75) %
b) 35 (15-45) %
c) 35 (15-45) %
d) 35 (15-45) %
e) 35 (15-45) %

26
Q

Blood glucose

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 5 (3-5.5) mmol/l
b) 3 (2-4) mmol/l
c) 3 (2-4) mmol/l
d) 3 (2-4) mmol/l
e) 5 (3-5.5) mmol/l

27
Q

RBC count

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 6-12 x 10^12/l
b) 6-12 x 10^12/l
c) 6-12 x 10^12/l
d) 6-12 x 10^12/l
e) 6-12 x 10^12/l

28
Q

Retikulocytes

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 0 %
b) 0 %
c) 0 %
d) 0%
e) 0-5 %

29
Q

WBC count

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 5-15 x 10^9/l
b) 5-15 x 10^9/l
c) 5-15 x 10^9/l
d) 5-15 x 10^9/l
e) 5-15 x 10^9/l

30
Q

RBC lifespan

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 120 days
b) 120 days
c) 120 days
d) 120 days
e) 60 days

31
Q

Heart rate

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 30-40 /min
b) 60-80 /min
c) 60-80 /min
d) 60-80 /min
e) 60-80 /min

32
Q

Respiratory rate

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 10-15 /min
b) 10-30 /min
c) 15-30 /min
d) 15-30 /min
e) 12-20 / min

33
Q

Body temp.

a) horse
b) cattle
c) sheep
d) goat
e) swine

A

a) 37-5-38.0
b) 38.0-39.0
c) 38.5-39.5
d) 38.5-39.5
e) 38.5-39.5

34
Q

Maximal stimuli/Minimal stimuli

A

Max: a stimulus strong enough to evoke a maximal response.
Min: the weakest stimuli that just causes complete contraction

35
Q

Steps for measuring a muscles passive stretch curve

A

Relative length determined by diff. weights

36
Q

What happens when Ca binds to TnC

A

Shift tropomyosin-troponin complex to the groove of the actin filament

37
Q

Which nerve and which muscle is used in the classical frog experiment?

A

M.gastrocnemicus og n.ishiadicus

38
Q

Explain the importance of the muscle reacting to diff. threshold potentials

A

The “All or none” law of muscle fibers

39
Q

What is the “All or none” law?

A

Contracting maximally

40
Q

What is temporal summation?

A

Superposition

41
Q

How do we find the minimal stimulus for a muscle?

A

Incr. stimulus strength gradually by betw. 0 and 500 mV.

Physiology (20 decks)

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