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Anatomy and Physiology 1 > Muscular System Part 3: Muscle Metabolism > Flashcards

Muscular System Part 3: Muscle Metabolism Flashcards

1
Q

What is involved in Substrate level Phosphorylation?

A

A substrate gives one phosphate to Adenosene Diphosphate and it becomes Adenosine Triphosphate

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2
Q

What is Substrate level phosphorylation best for?

A

immediate energy source, made by borrowing from phosphate groups or other molecules to turn ADP into ATP

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3
Q

Transfers P from one ADP to another, converting the latter to ATO

A

Myokinase

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4
Q

Obtains P from a phosphate storage molecule creating creatine phosphate and gives it to ADP

A

Creatine Kinase

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5
Q

What is used to make creatine phosphate and how long does it provide energy for contraction in conjunction with ATP?

A

Excess ATP is used to synthesize creatine phosphate which is a more stable energy storage
energy for 3-15 seconds of muscle contraction depending on intensity

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6
Q

What are the times when each different form of ATP production takes over during exertion

A

Aerobic respiration from 0-8 seconds
Phosphagen system from 8-25 seconds
Glycogen lactate system 30 seconds until heart rate stabilizes and is able to support Aerobic respiration once more.

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7
Q

point at which lactate becomes detectable in the blood

A

Anaerobic threshold or lactate threshold

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8
Q

the pathway from glycogen to lactate

A

Glycogen-lactate system

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9
Q

In the absence of oxygen, glycolysis can generate a net gain of _____ for every glucose molecule consumed

A

2 ATP

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10
Q

Muscles obtain glucose from____ and __________

A

blood and their own stored glycogen

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11
Q

How long does Anaerobic fermentation provide energy?

A

30-40 seconds of maximum activity

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12
Q

Activity that lasts longer than half a minute depends on aerobic respiration
Pyruvic acid entering the mitochondria is completely oxidized generating
ATP
carbon dioxide
Water
Heat

A

Aerobic respiration

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13
Q

How much ATP does a glucose molecule provide during AR

A

36 ATP

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14
Q

What are the two sources of oxygen for muscle tissue

A

Oxygen from hemoglobin in the blood
Oxygen released by myoglobin in the muscle cell

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15
Q

oxygen-binding proteins

A

Myoglobin and hemoglobin

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16
Q

Progressive weakness from prolonged use of muscles

A

Muscle fatigue

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17
Q

What does fatigue in high intensity exercise result from?

A

potassium accumulation in the T tubules reduces excitability
Excess ADP and phosphate slow cross-bridge movements, inhibit calcium release and decrease force production in myofibrils

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18
Q

What does fatigue from low-intensity long duration workouts come from?

A

Fuel depletion as glycogen and glucose levels decline
electrolyte loss through sweat can decrease muscle excitability
Central fatigue when less motor signals are issued from the brain.

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19
Q

Major determinant of one’s ability to maintain high-intensity exercise for more than 4-5 minutes

A

Maximum oxygen uptake or VO2 max

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20
Q

What is VO2 max proportional to and when does it peak

A

Body size
peaks at 20 years of age
greater in males and can be twice as high in a trained athlete

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21
Q

what is Excess Post exercise Oxygen Consumption (EPOC)

A

EPOC meets a metabolic demand also known as oxygen debt
It is the difference between the elevated rate of oxygen consumption following exercise and the usual resting rate

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22
Q

What is EPOC needed for?

A

To aerobically replenish ATP (some of which helps regenerate CP stores)
To replace oxygen reserves on myoglobin
To provide oxygen to liver that is busy disposing of lactate
To provide oxygen to many cells that have elevated metabolic rates after exercise

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23
Q

Have a high myoglobin content
Darker (dark meat in chicken legs and thighs)
Contain more mitochondria
Supplied by more blood capillaries

A

Red Muscle fibers

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24
Q

Have a low content of myoglobin
Lighter (white meat in chicken breasts)

A

White muscle fibers

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25
Q

Muscle fibers contract at different speeds, and vary in how quickly they fatigue
What are the three types

A

1) Slow oxidative fibers/slow twitch
2) Fast oxidative-glycolytic fibers/intermediate fibers
3) Fast glycolytic fibers/fast twitch

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26
Q

Smallest in diameter
Least powerful type of muscle fibers
Appear dark red (more myoglobin)
Generate ATP mainly by aerobic cellular respiration
Have a slow speed of contraction
Twitch contractions last from 100 to 200 msec
Very resistant to fatigue
Capable of prolonged, sustained contractions for many hours
Adapted for maintaining posture and for aerobic, endurance-type activities

A

Slow Oxidative muscle fibers

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27
Q

Intermediate in diameter
Large amounts of myoglobin, many blood capillaries
Have a dark red appearance
Generate considerable ATP by aerobic cellular respiration
Moderately high resistance to fatigue
Generate some ATP by anaerobic glycolysis
Speed of contraction faster
Twitch contractions last less than 100 msec
Contribute to activities such as walking and sprinting

A

Fast Oxidative-Glycolytic fibers

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28
Q

Largest in diameter
Generate the most powerful contractions
Have low myoglobin content
Relatively few blood capillaries
Few mitochondria
Appear white in color
Generate ATP mainly by glycolysis
Fibers contract strongly and quickly
Fatigue quickly
Adapted for intense anaerobic movements of short duration

A

Fast glycolytic fibers

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29
Q

Muscles that have a high proportion of SO fibers

A

Postural muscles of the neck, back, and legs

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30
Q

Muscles that have a high proportion of FG fibers

A

Muscles of the shoulders and arms

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31
Q

Muscles that have a high proportion of FOG and SO fibers

A

Leg muscles

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32
Q

What are ratios of FG and SO fibers determined by

A

genetics

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33
Q

Individuals with a higher proportion of ______ excel in intense activity (weight lifting, sprinting)

A

FG fibers

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34
Q

Individuals with higher percentages of _______ excel in endurance activities (long-distance running)

A

SO fibers

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35
Q

_______ transforms some FG fibers into FOG fibers

A

Aerobic exercise
Endurance exercises do not increase muscle mass

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36
Q

Exercises that require short bursts of strength produce an increase in the ______

A

size of the FG fibers
Muscle enlargement (hypertrophy) due to increased synthesis of thick and thin filaments

37
Q

Contraction of a muscle against a load that resists movement
A few minutes of resistance exercise a few times a week is enough to stimulate muscle growth
Growth is from cellular enlargement
Muscle fibers synthesize more myofilaments and myofibrils and grow thicker

A

Resistance training (example: weightlifting)

38
Q

Improves fatigue-resistant muscles
Slow twitch fibers produce more mitochondria, glycogen, and acquire a greater density of blood capillaries
Improves skeletal strength
Increases the red blood cell count and oxygen transport capacity of the blood
Enhances the function of the cardiovascular, respiratory, and nervous systems

A

Endurance training (aerobic exercise)

39
Q

_____ produce(s) a single muscle action potential.

A

Single nerve impulses

40
Q

Action potentials are _____ size(s)

A

the same
only the force of contraction varies

41
Q

Maximum Tension (force) is dependent on

A

The rate at which nerve impulses arrive
The amount of stretch before contraction
The nutrient and oxygen availability
The size of the motor unit

42
Q

A motor neuron and the muscle fibers it stimulates
The axon of a motor neuron branches out forming neuromuscular junctions with different muscle fibers

A

Motor Units

43
Q

2 - 3 muscle fibers/motor unit

A

Voice production

44
Q

10 - 20 muscle fibers/unit

A

Eye movements

45
Q

200 - 1000 muscle fibers/ unit

A

Leg muscles

46
Q

depends on the size of the motor units and the number that are activated

A

Total strength of contraction depends on

47
Q

The brief contraction of the muscle fibers in a motor unit in response to an action potential

A

Twitch contraction

48
Q

How long do twitch contractions last?

A

20-200 miliseconds

49
Q

A brief delay between the stimulus and muscular contraction
The action potential sweeps over the sarcolemma and Ca++ is released from the SR

A

Latent period 2ms

50
Q

Ca++ binds to troponin
Myosin-binding sites on actin are exposed
Cross-bridges form

A

Contraction Period 10-100ms

51
Q

Ca++ is transported into the SR
Myosin-binding sites are covered by tropomyosin
Myosin heads detach from actin
Muscle fibers that move the eyes have contraction periods lasting 10 msec
Muscle fibers that move the legs have contraction periods lasting 100 msec

A

Relaxation period 10-100ms

52
Q

keeps skeletal muscles firm
Maintains posture
Loss of nerve input results in flaccidity

A

Muscle Tone

53
Q

The tension developed remains constant while the muscle changes its length
Used for body movements and for moving objects
Picking a book up off a table

A

Isotonic Contractions

54
Q

Muscle shortens

A

Concentric

55
Q

muscle lengthens

A

eccentric

56
Q

The tension generated is not enough for the object to be moved and the muscle does not change its length
Holding a book steady using an outstretched arm

A

Isometric Contraction

57
Q

refers to problems at somatic neurons, neuromuscular junctions, or muscle fibers.

A

Neuromuscular disease

58
Q

disease of the skeletal muscle

A

Myopathy

59
Q

Chronic progressive degeneration of neuromuscular junction
Autoimmune, antibodies block some acetylcholine receptors - muscles become increasingly weaker.
Affects ~1/10,000 people in US
Initially affects eye, throat muscles, may extend to limbs, in severe cases respiratory paralysis.
Associated with thyroid dysfunction
More common in women, onset 20-40 (males 50-60).

A

Myasthenia gravis

60
Q

technique to remove harmful antibodies from blood plasma

A

Plasmapheresis (Myasthenia Gravis treatment option)

61
Q

retard breakdown of ACh allowing it to stimulate the muscle longer

A

cholinesterase inhibitors (Myasthenia Gravis treatment option)

62
Q

helps to dampen the overactive immune response that causes myasthenia gravis

A

Thymus removal or thymectomy (Myasthenia Gravis treatment option)

63
Q

Group of genetic muscle-destroying diseases (many versions)

A

Muscular dystrophy

64
Q

most common form.
X-linked, 1/3,500 male births
Mutation in dystrophin gene - sarcolemma tears easily when muscles contract
Most die from respiratory or cardiac failure prior to age 20.

A

Duchenne Muscular dystrophy

65
Q

Major signs of Duchenne’s muscular dystrophy

A

Progressive muscular wasting
Poor balance/Frequent falls
Walking difficulty/Waddling gait
Limited range of motion
Calf deformation
Scoliosis
Respiratory difficulty
Droopy eyelids
Loss of bladder control

66
Q

Result from inadequate blood flow, low electrolytes, overuse, dehydration

A

Cramps

67
Q

Involuntary spasmodic contractions of normally voluntary muscles

A

tics

68
Q

Brief twitch of an entire motor unit - often associated with multiple sclerosis or amyotrophic lateral sclerosis

A

Fasciculation

69
Q

Spontaneous contraction of a single muscle fiber - may signal destruction of motor neurons.

A

Fibrilation

70
Q

Pain associated with fibrous connective tissue components of muscles, tendons, ligaments
Pain, tenderness, stiffness,General fatigue, headaches, depression
Affects ~ 3 million in US
Onset ages 25-50
15 X more common in women

A

Fibromyalgia

71
Q

Contracts with regular rhythm
Contract in unison
Contraction lasts long enough to expel blood
Must function during wake and sleep (autonomic)
Must be resistant to fatigue (uses aerobic cellular respiration)

A

Features of cardiac muscle

72
Q

Visceral layer of serous pericardium
Smooth, slippery texture to outermost surface

A

Epicardium (single layer)

73
Q

95% of heart is cardiac muscle

A

Myocardium

74
Q

Smooth lining for chambers of heart, valves and continuous with lining of large blood vessels

A

Endocardium (inner layer)

75
Q

Same arrangement of actin and myosin
Shorter fibers 50-100µ long, branched
Usually one centrally located nucleus
Numerous large mitochondria (~25% cell volume)
Very aerobic, can use lactate
Ends of fibers connected by intercalated discs
Discs contain gap junctions (allow action potential conduction between fibers) - act as a unit.

A

Cardiac muscle tissue

76
Q

Specialized cardiac muscle fibers
Self-excitable
Repeatedly generate action potentials that trigger heart contractions
100 beats/min, modified by autonomic nervous system
-Autonomic nervous system can increase or decrease heart rate and contraction strength
Very slow twitches; does not exhibit quick twitches like skeletal muscle
- Maintains tension for about 200 to 250 ms- Gives the heart time to expel blood

A

Autorhythmic fibers

77
Q

2 Important functions of Autorhythmic fibera

A

Acts as a pacemaker
Forms a conduction system

78
Q

_______ is named for its lack of striations
Some _______ lack nerve supply; others receive input from autonomic fibers with many varicosities containing synaptic vesicles
Capable of mitosis and hyperplasia
Injured _________ regenerates well
________ is slower than skeletal and cardiac muscle
Takes longer to contract but can remain contracted for a long time without fatigue

A

Smooth muscle

79
Q

It can propel contents of an organ (e.g., food in GI tract)
It can modify pressure and flow of blood in the circulatory system and air in the respiratory system

A

Smooth muscle

80
Q

Provides fine control in areas like iris and piloerectors in hair

A

smooth muscle

81
Q

One nucleus near the middle of the cell
thick and thin filaments are present but not aligned with each other, smooth not striated

A

Myocytes of smooth muscle cells

82
Q

Occurs in some of the largest arteries and pulmonary air passages, in piloerector muscles of hair follicle, and in the iris of the eye

A

Multiunit smooth muscle

83
Q

Autonomic innervation similar to skeletal muscle
Terminal branches of a nerve fiber synapse with individual myocytes and form a motor unit
Each motor unit contracts independently of the others

A

Multiunit smooth muscle

84
Q

More widespread
Occurs in most blood vessels, in the digestive, respiratory, urinary, and reproductive tracts
Often in two layers: inner circular and outer longitudinal
Myocytes of this cell type are electrically coupled to each other by gap junctions
They directly stimulate each other and a large number of cells contract as a single unit

A

Single-unit smooth muscle or Visceral muscle

85
Q

Smooth muscles can contract or relax due to a variety of stimuli, what are those stimuli?

A

Autonomic activity
Parasympathetic nerves secrete acetylcholine stimulating GI tract smooth muscle
Sympathetic nerves secrete norepinephrine relaxing smooth muscle in bronchioles (dilating them)
Hormones, carbon dioxide, oxygen, and pH
Hormone oxytocin stimulates uterine contractions
Temperature
Cold excites piloerector muscles
Warmth relaxes muscle in skin blood vessels
Stretch
Stomach contracts when stretched by food
Autorhythmicity
Some single-unit smooth muscle cells in GI tract depolarize at regular intervals

86
Q

Smooth muscles get most of their C++ from ____

A

ECF or extracellular fluid

87
Q

Pockets on teh sarcolemma that concentrate calcium channels

A

caveolae

88
Q

Calcium binds to ________ on thick filaments

A

calmodulin

Anatomy and Physiology 1 (14 decks)

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