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BIO 152 > Muscle Physiology > Flashcards

Muscle Physiology Flashcards

1
Q

Events at the NEUROMUSCULAR JUCTION: Part one - In the SYNANPTIC KNOB of SOMATIC MOTOR NEURON

A
  • AP opens voltage-gated Ca2+ channels
  • Ca2+ influx triggers exocytosis of SYNAPTIC VESICLES
  • Ach diffuses across SYNAPTIC CLEFT
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2
Q

Events at the NEUROMUSCULAR JUNCTION: Part two - At the motor end plate of SKELETAL MUSCLE FIBER

A
  • Ach binds ligand-gated channels
  • Na+ influx depol. MUSCLE FIBER to threshold
  • AP generated along SARCOLEMMA
  • AchE removes Ach and stops signal
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3
Q

What does the ā€œEā€ is AchE stand for?

A

AcetylcholinESTERASE

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4
Q

After travelling along the SARCOLEMMA, where does AP go?

A

Down the TRANSVERSE TUBULES

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5
Q

What kind of channels does AP open in the TERMINAL CISTERNAE of SR?

A

Voltage-gated Ca2+ channels

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6
Q

Where is Ca2+ released into?

A

The CYTOSOL

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7
Q

What does Ca2+ bind to?

A

TROPONIN

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8
Q

When TROPONIN changes shape, what effect does it have on TROPOMYOSIN?

A

It moves TROPOMYOSIN to expose the MYOSIN binding sites on ACTIN

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9
Q

How does Ca2+ get back into the SR?

A

A PUMP

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10
Q

What would happen if Ca2+ pumps stop working?

A

Ca2+ will build up and the MUSCLE will stay contracted, no relaxation

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11
Q

What is it called when MYOSIN HEADS bind to ACTIN?

A

The CROSS BRIDGE

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12
Q

What happens during a POWERSTROKE?

A

MYOSIN pulls ACTIN, shortening the SARCOMERE and causing CONTRACTION

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13
Q

What releases MYOSIN from ACTIN?

A

ATP

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14
Q

What provides energy for the MYOSIN HEAD to re-cock for another POWERSTROKE?

A

ATP splitting

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15
Q

How many times does the CROSS BRIDGE CYCLE repeat?

A

Many times

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16
Q

ISOTONIC, CONCENTRIC CONTRACTION = ?

A

Muscle shortens e.g. lift object

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17
Q

ISOTONIC, ECCENTRIC CONTRACTION = ?

A

MUSCLE lengthens e.g put down object

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18
Q

ISOMETRIC CONTRACTION = ?

A

MUSCLE stays the same length e.g. holding object, maintaining body position

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19
Q

CONTRACTION of many SACROMERES leads to

A

CONTRACTION of many MYOFIBRILS

20
Q

CONTRACTION of many MYOFIBRILS leads to

A

CONTRACTION of MUSCLE FIBERS + pull on ENDOMYSIUM

21
Q

CONTRACTION of MUSCLE FIBERS leads to

A

CONTRACTION of MUSCLE FASCICLE + pull on PERIMYSIUM

22
Q

CONTRACTION of MUSCLE FASCICLE leads to

A

CONTRACTION of whole MUSCLE + pull on EPIMYSIUM

23
Q

CONTRACTION of whole MUSCLE pulls on TENDON which pulls on

A

PERIOSTEUM/BONE

24
Q

T or F: Do MUSCLES push

A

F, they pull

25
How many MUSCLE groups are required for action?
At least 2
26
What are the 4 functional MUSCLE groups?
1) PRIME MOVERS 2) ANTAGONISTS 3) SYNERGISTS 4) FIXATORS
27
PRIME MOVER =
a force for specific movement, aka AGONIST e.g. BRACHIALIS for arm FLEXION
28
ANTAGONIST =
Reverse, slow, stop movement e.g. TRICEPS BRACHII for arm FLEXION
29
SYNERGISTS =
Stabilize joints, aids PRIME MOVER movement e.g. BICEPS BRACHII
30
FIXATORS =
Holds BONES in place e.g. rotator cuff MUSCLES
31
How long does AP last?
1-2 msec
32
How long does CONTRACTION last?
7-100 msec
33
What leads to TETANUS
Many consecutive APs
34
1 MOTOR UNIT =
1 MOTOR NEURON + all MUSCLE FIBERS it innervates
35
What factors effect CONTRACTION?
1) Freq. of STIM. 2) Number of MUSCLE FIBERS contracting 3) Type of MUSCLE FIBER
36
How many MUSCLE FIBERS/MOTOR UNITS for precise movement?
About 10
37
How many MUSCLE FIBERS/MOTOR UNITS for powerful movement?
About 1000
38
What is the benefit of MOTOR UNITS recruited in shifts?
Allows sustained CONTRACTION without fatigue
39
An immediate source of energy:
One step transfer of E and PHOSPHATE from CREATINE PHOSPHATE (CREATINE PHOSPHATE + ADP = CREATINE + ATP)
40
Sustained E sources:
AEROBIC and ANAEROBIC RESPIRATION
41
AEROBIC RESP. =
Requires O2, makes 32 ATP/GLUCOSE, many steps = slooow
42
ANAEROBIC RESP. =
No O2, makes 2 ATP/GLUCOSE, few steps, makes LACTIC ACID = changes pH
43
Slow-oxidative fibers =
Slow to contract/fatigue, uses AEROBIC, mitochondria, many caps, hi myoglobin, appear red e.g. MUSCLES of leg, back, marathon, endurance
44
Intermediate fibers =
intermediate resistance to fatigue, AEROBIC, some mitochondria, some caps, lo myoglobin, appears pink
45
Fast-glycolytic =
fast to contract/fatigue, fast/powerful, but not for long, ANAEROBIC, more MYOSIN, ACTIN = larger diameter fibers, appears white
46
MUSCLE fatigue is caused by
1) Dec. E reserves 2) Damage to MUSCLE FIBER 3) Dec. pH leading to dec. Ca2+ binding to TROPONIN 4) Central fatigue: mental, pain, dec. motor recruitment
47
O2 debt =
Amount of O2 required to restore levels of ATP, CREATINE PHOSPHATE, GLYCOGEN, remove lactic acid, power sweat gland activity

BIO 152 (26 decks)

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