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T1 Physiology > Myology > Flashcards

Myology Flashcards

1
Q

All types of muscle tissue share these 4 characteristics:

A

1) Electrical Excitability
2) Contractility
3) Extensibility
4) Elasticity

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2
Q

Another word for striated muscle

A

Skeletal muscle

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3
Q

Alternating light and dark bands that are characteristic of this Skeletal muscle

A

Striations

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4
Q

If a muscle is a pack of spaghetti, these are like individual servings.

A

Fascicle

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5
Q

If a muscle is a pack of spaghetti, these are like single piece of spaghetti.

A

Muscle fibres (cells)

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6
Q

the cell (plasma) membrane of the muscle cell

A

sarcolemma

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7
Q

tiny invaginations tunnel in from the sarcolemma towards the centre of the muscle fibre

A

transverse tubules

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8
Q

the cytoplasm of the muscle fibres – contains lots of glycogen

A

sarcoplasm

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9
Q

a protein that binds oxygen that has diffused into the muscle fibre and delivers it to the mitochondria

A

myoglobin

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10
Q

specialized contractile organelles of the muscle cell

A

myofibrils

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11
Q

fluid filled tubes and sacs running along and surrounding each myofibril– they store and release calcium into the cell (when it’s needed)

A

sarcoplasmic reticulum

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12
Q

the functional unit of a myofibril (of contraction)

A

sarcomeres

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13
Q

makes up the thin filaments of a sarcomere

A

actin

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14
Q

the thick filaments of a sarcomere

A

myosin

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15
Q

What gives gives skeletal muscle its striated

appearance?

A

Thick and thin myofilaments overlapping during contraction.

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16
Q

What do skeletal muscle cells need to generate tension?

A

Stimulated by a nerve signal from a motor neuron

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17
Q

What is the name for the junction between the axon terminal of a motor neuron and the sarcolemma of muscle cells?

A

Neuromuscular junction (NMJ)

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18
Q

What is the name for the gap between an axon terminal and a motor neuron?

A

A synaptic cleft

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19
Q

Which neurotransmitter is released

across the synaptic cleft when the signal reaches the NMJ?

A

acetylcholine (ACh)

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20
Q

True or false: muscles can create their own action potentials.

A

False: they must come from the nervous system

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21
Q

When the signal crosses the synaptic cleft it stimulates the _____________

A

Sarcolemma

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22
Q

The ability to respond to certain stimuli by producing electrical signals is called _____________

A

Electrical excitability

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23
Q

When an action potential travels down the transverse tubules and stimulates the sarcoplasmic reticulum, it releases ___________

A

Calcium

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24
Q

What is the effect of the release of calcium within a muscle fibre?

A

It allows the myosin (of the thick filament) to connect with the actin (of the thin filament)

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25
Q

What is the result of repeated ‘ratcheting’ of the muscle filament?

A

shortening of the sarcomere, the myofibril, the muscle fibre, the muscle

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26
Q

What causes the thick filaments to stop ratcheting of the thin filaments, resulting in a stoppage of tension generation?

A

Insufficient calcium

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27
Q

True or false: skeletal muscle fibres consume ATP at the same rate

A

False: skeletal muscle fibres need to vary the levels at which they consume ATP

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28
Q

Muscle fibres store enough ATP to last for what duration of activity?

A

Three seconds

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29
Q

______________ is a molecule that stores high amounts of energy in its chemical bonds

A

Creatine Phosphate (PCr_

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30
Q

How is the energy from PCr released used to reform ATP?

A

It’s split by an enzyme

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31
Q

Why is PCr is first source of energy used when muscle

contraction begins?

A

It releases energy very quickly

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32
Q

The breakdown of PCr provides energy for - seconds.

A

3-15

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33
Q

What does it mean that the process of breaking down PCr into ATP is anaerobic and alactic

A

no oxygen is needed and no lactic acid is produced

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34
Q

In the context of muscles: when muscle activity continues and PCr is depleted, ___________ is used to make ATP

A

Glucose

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35
Q

Where do cells store the glucose used to make ATP?

A

glycogen stored in their cytoplasm/sarcoplasm or glucose from the blood

36
Q

the process of making ATP from glucose occurs in the cell cytoplasm and is called __________

A

glycosis

37
Q

through glycolysis, a molecule of glucose is broken into _ molecules of pyruvic acid and -
ATP

A

2 molecules of pyruvic acid

2-3 ATP

38
Q

normally, pyruvic acid enters the mitochondria where it undergoes and series of reactions
(that require oxygen) called ________________

A

Aerobic cellular respiration

39
Q

n the absence of oxygen, as during heavy excercise/demand, pyruvic acid does not go into the mitochondria – it is converted into ___________

A

lactic acid/lactate

40
Q

What happens to the lactic acid when glucose is broken down into ATP?

A

It diffuses out of the cell into the blood

41
Q

Anaerobic glycolysis supplies energy for how long?

A

30-40 seconds

42
Q

How is lactic acid converted back into to glucose/glycogen in the liver?

A

Via the Cori cycle

43
Q

How does the body stop lactic acid from accumulating?

A

It is consumed by other muscle fibres, less

active nearby muscles, and the heart

44
Q

Lactic acid has a 1⁄2 life of _________.

A

15-25 minutes (usually cleared in a matter of hours)

45
Q

When is Aerobic Cellular Respiration the body’s active pathway for ATP regeneration?

A

When the body is able to get oxygen in to the cells (e.g. at rest or at low-moderate intensity exercise)

46
Q

How is oxygen delivered to the cells during Aerobic Cellular Respiration?

A

By myoglobin or from oxygen diffusing from the blood

47
Q

How is ATP produced during Aerobic Cellular Respiration?

A

Pyruvic acid enters the mitochondria and in a series of reactions that require oxygen are able to occur

48
Q

Which three energy substrates can be used to make ATP during Aerobic Cellular Respiration, and rank them from most to least effective in ATP production.

A
  1. Fats
  2. Carbohydrates
  3. Proteins
49
Q

What are three main differences found in skeletal muscle fibres?

A

▪ the speed at which they generate tension
▪ how they use different energy substrates
▪ how they fatigue

50
Q

This type of muscle fibre is also called slow-twitch fibres or type 1 because they’re recruited first

A

Slow Oxidative (SO) Fibres

51
Q

What makes Slow Oxidative (SO) Fibres so fatigue resistant and used in endurance-type functions (e.g. maintaining posture, running a marathon)?

A

They have lots of mitochondria, myoglobin, capillaries, and they generate ATP via aerobic cellular respiration (i.e. oxygen is available)

52
Q

True or false, SO fibres are also resistant to atrophy with immobilization.

A

False, with immobilization, they atrophy faster (than type II fibres)

53
Q

This type of muscle fibre is also called type IIa because they’re recruited second

A

Fast Oxidative-Glycolytic (FOG) Fibres

54
Q

What makes Fast Oxidative-Glycolytic (FOG) Fibres slightly less fatigue resistant and used in endurance (e.g. walking) and shorter-duration functions (e.g. sprinting)?

A

They have intermediate amounts of mitochondria, myoglobin, capillaries, and generate ATP via aerobic and anaerobic energy pathways

55
Q

This type of muscle fibre is also called type IIx and is recruited third

A

Fast Glycolytic (FG) Fibres

56
Q

Which type of muscle fibre is used in high intensity, short duration activities (e.g. weight lifting, slap shot) and shorter-duration functions (e.g. sprinting)?

A

Fast Glycolytic (FG) Fibres

57
Q

True or false: within a motor unit, there is usually a mix of are a mix of SO, FOG, FG fibres

A

False: although most muscles are a mix of SO, FOG, FG fibres, within a given motor unit, all fibre types are the same type.

58
Q

Since precise movements require small changes in muscle contraction, muscles that perform fine movements will be made up of ______ motor units.

A

small motor units (few m. fibres/motor unit)

59
Q

:arge (imprecise) movements don’t require small changes in muscle contraction – they typically
require large amounts of tension. Therefore, muscles that perform gross movements will be made up of __________

A

large motor units (many m. fibres/motor unit)

60
Q

What are two ways for a muscle to increase the amount of force generated?

A

1) increase the number of motor units recruited

2) increase the frequency of neuronal AP firing (wave summation)

61
Q

the forcefulness of contraction (the ability to generate force) depends on the _____________ within a muscle before the contraction begins

A

length of the sarcomeres

62
Q

Between optimal overlap, minimal overlap, and excessive overlap, which has the best ability to generate tension?

A

Optimal overlap (resting length)

63
Q

muscle contraction through a range against a resistance that is not changing is called ___________

A

isotonic

64
Q

a shortening contraction is called ____________

A

concentric

65
Q

a lengthening contraction is called __________

A

eccentric

66
Q

a muscle contraction in which the length of the muscle does not visibly change

A

isometric

67
Q

muscle contraction through a range in which the equipment varies the resistance to match the strength curve

A

variable resistance

68
Q

muscle contraction through a range in which the equipment keeps the velocity of movement constant

A

isokinetic

69
Q

a small amount of tension being generated in the muscle

not strong enough to produce movement

A

muscle resting tone

70
Q

a brief contraction of all the muscle fibres in a motor unit in response to a single AP in its motor neuron

A

twitch contraction

71
Q

a lack of tone from the nerve being damaged or cut

A

flacidity

72
Q

increase in muscle size

A

hypertrophy

73
Q

decrease in muscle size

A

atrophy

74
Q

the inability of a muscle to function at the required level due to energy substrate depletion, metabolic by-products, neurological fatigue, or central nervous system fatigue

A

fatigue

75
Q

CT that surrounds the entire muscle

A

epimysium

76
Q

CT that surrounds the fascicles

A

perimysium

77
Q

CT that surrounds the muscle fibres

A

endomysium

78
Q

Place where the epimysium, perimysium, and endomysium extend beyond the muscle fibres to connect the muscle to the periosteum

A

tendon

79
Q

the transition from muscle tissue to tendon

A

musculotendinous junction

80
Q

the transition from tendon to periosteum

A

tendoperiosteal junction

81
Q

a broad, flat, tendon

A

aponeurosis

82
Q

a tube that surrounds a tendon to protect it

A

tendon sheath

83
Q

undifferentiated muscle cells actively involved in muscle repair and regeneration

A

satellite cells

84
Q

specialized cells within the heart that can generate their own electrical signals (they act as a pacemaker)

A

Autorhythmicity

85
Q

What type of muscle does this describe: found in the walls of hollow tubes, spindle shaped, have gap junctions, involuntary, contractions start slowly and last longer

A

smooth muscle

86
Q

capacity for skeletal strength progressively decreases after approximately age ____

A

25

87
Q

a greater proportion is lost after approximately age ___

A

50

T1 Physiology (6 decks)

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