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BIOL 446 Physiological Ecology > Exam 2: Movement and Muscle Physiology > Flashcards

Exam 2: Movement and Muscle Physiology Flashcards

1
Q

In vertebral skeletal muscle, how many neurons code for one motor unit?

A

one

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2
Q

In invertebrate skeletal muscle, how many neurons code for one motor unit?

A

multiple

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3
Q

What is the result of having multiple motor neurons controlling one motor unit?

A

Results in signal crossing

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4
Q

What are central pattern generators (CPG)?

A

A repeating pattern of rhythmic movement caused by a closed negative feed backlook

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5
Q

What is a cellular oscillator?

A

An individual neuron that generates a temporally patterned activated

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6
Q

What is a network oscillator?

A

When multiple neurons interact to generate a patterned activity

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7
Q

What is a closed-loop model?

A

When a negative feedback loop maintains a stable cyclic pattern of activity

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8
Q

How does network oscillation occur?

A

An activate neuron inhibits the following neuron; the next neuron is turned on when the previous neuron is inactivated

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9
Q

Is the CNS involved in central pattern generation?

A

No, but it modulates CPG output based on sensory information

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10
Q

How are muscle cells structure within a skeletal muscle fiber?

A

muscle cells are long and multinucleated

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11
Q

Why is excitation-contraction coupling considered “coupled?”

A

Because two membrane systems are involved in excitation

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12
Q

What are the two membrane systems involved in excitation?

A

Transverse tubule membrane and sarcoplasmic reticulum membrane

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13
Q

What is the function of transverse tubules (T-tubules)?

A

continuation of sarcolemma that extends into interior of muscle fiber

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14
Q

What is the sarcolemma?

A

The membrane of a skeletal muscle cell

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15
Q

What is the sarcoplasmic reticulum?

A

An organelle in skeletal muscle used to store Ca2+

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16
Q

What is sliding-filament theory?

A

Muscle contraction is caused by sliding myosin and actin filaments within sarcomeres

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17
Q

What are sarcomeres?

A

A segment of a muscle fiber extending between Z-discs

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18
Q

How are action potentials in skeletal muscle cells generated

A

Cholinergic neurotransmitters are expressed by the motor neuron and depolarize the sarcolemma

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19
Q

What happens once an action potential is generated in a skeletal muscle cell?

A

The action potential travels down the T-tubule and activates dihydropyridine receptors in the sarcolemma

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20
Q

What occurs once dihydropyridine receptors in the sarcolemma are activated by an action potential?

A

dihydropyridine open ryanodine receptors in the sarcolemma which release Ca2+ into the sarcoplasm?

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21
Q

Why do dihydropyridine receptors open ryanodine receptors?

A

Because they are attached

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22
Q

What is the function of troponin?

A

To bind pull on tropomyosin when Ca2+ is present and reveal action binding sites?

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23
Q

What is the function of tropomyosin?

A

To block actin binding sites when muscle cells are relaxes

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24
Q

What does Ca2+ do once release from the sarcoplasmic reticulum?

A

Binds to troponin to pull tropomyosin away from actin binding sites

25
Q

What causes myosin heads to bind to actin?

A

Hydrolysis of ATP cocks the myosin head in position to form a cross bridge with a FREE actin binding site?

26
Q

What are cross bridges in reference to sliding filament theory?

A

The connection between a myosin head and actin binding site

27
Q

Which muscle filament is considered the thick filament?

A

Myosin

28
Q

Which muscle filament is considered the thin filament?

A

actin

29
Q

What causes filaments to physically slide?

A

Release of inorganic phosphate by the myosin head causes a power stroke that cocks the myosin head

30
Q

How is ADP removed from a myosin head?

A

It is released when the myosin head is cocked by release of inorganic phosphate

31
Q

How is the position of a myosin head reset?

A

ATP binds to the head and separates it from actin

32
Q

What is polyneural intevation?

A

When multiple motor neurons are responsible for one muscle unit

33
Q

Why can’t arthropods use action potentials for their nervous systems?

A

Polyneural intervation causes too much overlap for action potentials to be successful at propagating coherent signals

34
Q

What triggers levels of muscle tension in arthropods?

A

Degree of depolarization increases muscle tension

35
Q

What neurotransmitter is used to excite arthropod muscular tissue?

A

glutamate

36
Q

What function does glutamate perform in arthropod neurons?

A

Opens Na+ channels and increase degree of depolarization

37
Q

What neurotransmitter is used to inhibit depolarization of an invertebrate neuron?

A

GABA

38
Q

How does GABA inibit depolarization?

A

Opens Cl- channels to hyperpolarize the membrane

39
Q

What are octopamine and tyramine and what do they do?

A

Neurotransmitters that tell skeletal muscle to source energy from glycogen

40
Q

How are octopamine and tyramine affected during migration?

A

Inhibited to increase sourcing energy from lipids

41
Q

What is a benefit of having only one neuron control each motor unit and one neuron able to control multiple motor units?

A

Allows fine tuned control

42
Q

How is muscle tension increased in a vertebrate?

A

Frequency of action potentials and number of motor units recruited

43
Q

What is isometric contraction?

A

the ability of muscle tissue to replace tired units with unused ones to maintain endurance

44
Q

How does muscle growth (hypertrophy) occur?

A

More blood flow and nutrients
Larger myosin and actin filaments
More nuclei

45
Q

Do muscle cells increase in number to increase muscle size?

A

no

46
Q

What kind of respiration does endurance exercise employ? Why?

A

Aerobic; has the highest metabolic output

47
Q

What kind of muscle fibers does endurance exercise mostly use?

A

Type I/slow twitch muscle fibers

48
Q

What neural pattern is commonly involved in endurance exercise?

A

Central pattern generators

49
Q

What kind of respiration does resistance exercise employ? Why?

A

Anaerobic; faster

50
Q

How do type II muscle fibers compare to type I in endurance?

A

They are sensitive to fatigue

51
Q

What kind of muscle fibers does resistance exercise employ?

A

Type II/fast twitch

52
Q

How are type IIa and IIx muscle fibers different in structure/properties?

A

IIx has fastest Ca2+ reuptake, cross bridge cycling, and fatigues the fastest
IIa is like an intermediate of I and II

53
Q

How does endurance training affect muscle fiber composition?

A

Increase mitochondria concentration and turns IIx fibers in IIa

54
Q

What is PGC-1α1?

A

A transcription factor that regulates genes that affect muscle fiber endurance

55
Q

How does resistance training affect muscle fiber composition?

A

Changes IIx fibers to IIa and increases nuclei number and myosin/actin filament size

56
Q

What is PGC-1α4?

A

a transcription factor that upregulates growth factors and protein syntheis

57
Q

How did PGC-1α1 and PGC-1α4 relate?

A

They are different isoforms of the same gene

58
Q

How does an exercise taper affect muscle composition?

A

Brings back some lost IIx fiber

59
Q

Why is an exercise taper beneficial?

A

IIx fibers can be employed when bursts of energy are needed

BIOL 446 Physiological Ecology (8 decks)

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