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A&P > CH 8 - The Muscular System > Flashcards

CH 8 - The Muscular System Flashcards

1
Q

Muscular tissue 3 types:

A

Skeletal, cardiac, smooth

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2
Q

Skeletal muscle

A 
Attached to bones
Volunary
Contract/relax by conscious control
Limited capacity of regeneration
Has striations

Elongated cells make up muscle fibers, multinucleated and peripherally placed

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3
Q

Cardiac muscle

A

Found ONLY in the heart
Forms the bulk of the heart wall
Involuntary
Contraction not under conscious control

Fibers are branched,striated, has a single centrally located nucleaus, intercalated discs, gap junctions

Can regenerate under certain conditions

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4
Q

Smooth Muscle

A

Located in walls of hollow internal structures
(Blood vessels, airways, stomach, intestine)
Participates in internal processes such as digestion and regulation of BP

Fibers are spindle shaped, single oval nucleaus, non striated, involuntary, can regenerate

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5
Q

Functions of muscular tisshue

A

Body mmts - walking/running
Body positions - stabilize jnts
Heat - when a muscle contracts it produces heat
Involuntary contraction - shivering
Skeletal muscle contraction - return blood in veins to heart
Storing/moving substances - sphincters
Temporary storage of food - stomach/urine
Cardiac muscle contractions - pump blood through vessels
Smooth muscle contractions - move food/substances through the body

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6
Q

3 layers of connective tissue

Whats the role of connective tissue

A

Protect and strengthen skeletal muscles

Epimysum - wraps entire muscle
Perimysium - surrounds bundles of 10-100 fibers
Endomysium - wraps individual fibers

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7
Q

Tendon

A

Cord of dense connective tissue composed of parallel bundles of collagen fibers

Attach muscle to bone

Achilles tendon

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8
Q

Skeletal muscles are supplied with

A

Nerves and blood vessels

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9
Q

ATP is required for what

A

Muscle contraction

Prolonged muscle action depends of a blood supply to deliver nutrients/oxygen and remove waste products

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10
Q

How do muscles contract

A

The artery and vein that accompany each nerve penetrates a skeletal muscle and the fibers make contact with the terminal portion of the neuron

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11
Q

Muscle action potential is

A

An electric signal when a skeletal muscle fiber is stimulated before it contracts

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12
Q

Motor end plate

A

The region of the sarcolemma near the axon terminal

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13
Q

Motor neuron

A

Nerve cell that delivers the muscle action potential

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14
Q

Motor unit

A

Single neuron along with all the muscle fibers it stimulates

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15
Q

Axon terminals

A

When the axon of a motor neuron enters a skeletal muscle

Divides into branches

Approach but do not touch the sarcolemma of the muscle fiber

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16
Q

Synaptic end bulbs

A

Enlarged swellings at the ends of the axon terminals

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17
Q

Synaptic vesicles

A

In the synaptic bulbs

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18
Q

Synaptic cleft

A

Space bt the axon terminal and sarcolemma

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19
Q

Neurotransmitters

A

Chemicals that fill the synaptic vesicles

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20
Q

Neuromuscular junction (NMJ)

A

The synapse formed between the axon terminals of the motor neuron and the motor end plate of a muscle fiber

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21
Q

Muscle fibers are covered by

A

Sarcolemma - the plasma membrane

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22
Q

Sarcolplasm

A

The cytoplasm of the muscle fiber

Contains many mitochondria

Produce lg amts of ATP

Sarcoplasmic reticulum stores calcium ions required for muscle contraction

Transverse tubules (T Tubles) are tunnels from the surface toward the center of each muscle fiber

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23
Q

How does a motor neuron excite a skeletal muscle fiber

A

Release of acetylcholine
Activation of Ach receptors
Generation of muscle action potential

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24
Q

Release of acetylcholine

A

Arrival of nerve impulse at the synaptic end bulbs as triggers release of the neurotransmitter acetylcholine (Ach)

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25
Q

activation of Ach receptors

A

The binding of Ach to its receptor in the motor end plate opens ion channels that allow sodium ions to flow across the membrane

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26
Q

Generation of muscle action potential

A

Inflow of sodium generates a muscle action potential which travels along the sarcolemma and through the T tubules

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27
Q

In breakdown of Ach, what happens

A

It only lasts breifly because the neurotransmitter is rapidly broken down in the synaptic cleft by an enzyme called acetylcholinesterase (AchE)

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28
Q

Myoglobin are

A

A number of molecules in the sarcoplasm that stores oxygen until it is needed by the mitochondria to generate ATP

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29
Q

Two protein filaments in the myofibrils include

A 
Thin filaments (actin)
Thick filaments (myosin)
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30
Q

A band

A

Dark area

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31
Q

I band

A

Light area

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32
Q

Sarcomere

A

Functional unit of striated muscle fibers

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33
Q

Z discs

A

Zig zagging zones of dense protein material that separates the sarcomeres from one another

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34
Q

H zone contains

A

Only thick filaments

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35
Q

Actin is the protein component in

A

Thin filament

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36
Q

Myosin is

A

The binding site in each actin molecule is where the myosin head attaches

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37
Q

Tropomyosin and troponin are

A

2 other proteins in thin filaments

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38
Q

Myosin is the protein in

A

Thick filaments

Shaped like 2 golf clubs twisted together

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39
Q

Myosin tails are arranged

A

Parallel to each other

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40
Q

Myosin heads are

A

The projecting ends from outward from the surface of the shaft

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41
Q

Sliding filament theory

A

Myosin heads of thick filaments pull on thin filaments causing the thin filaments to slide toward the center of a sarcomere

This leads to muscle contraction

Only occurs when the level of calcium ions is high enough and ATP is available

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42
Q

Whats needed for muscle contraction

A

Calcium ions and energy in the form of ATP

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43
Q

Contraction cycle is

A

The repeating sequence of events

1) splitting ATP into ADP
2) forming cross-bridges
3) power stroke
4) binding ATP

44
Q

Relaxation from contraction has 2 changes

A

Acetylcholine is broken down by acetylcholinerase (AChE)

Calcium ions are rapidly transported from the sarcoplasm into the sarcoplasmic reticulum and tropomyosis slikds over myosis binding sites on actin, then the thin filaments slip back to their relaxed positions

45
Q

Muscle tone

A

A process when a whole muscle is not contracting, a small number of its motor units are involuntarily activated to produce a sustained contraction

46
Q

Flaccid

A

When muscle tone is lost and neurons are damaged/cut

47
Q

Creatine

A

A small AA that is made in the liver, kidneys, & pancreas derived from (milk, red meat, fish)

48
Q

Muscle fibers have 3 sources of ATP production

A

1) creatine phosphate
2) anaerobic glycolysis
3) aerobic respiration

49
Q

Creatine phosphate is what

A

An energy rich molecule that is unique to muscle fibers

50
Q

Anaerobic glycolysis is a process when

A

Oxygen levels are low

Vigorous muscle activity

Pyruvic acid converted to lactic acid

Occurs w/o using oxygen

51
Q

Aerobic cellular respiration is a

A

Series of oxygen requiring rxns that produce ATP in the mitochondria and muscle activity that lasts longer than half a min

52
Q

Muscle fibers have 2 scs of oxygen

A

1) oxygen that diffuses into them from the blood

2) oxygen released by myoglobin in the sarcoplasm

53
Q

Myoglobin is

A

An oxygen binding protein found only in muscle fibers

Binds oxygen when oxygen is plentiful and releases it when its less

54
Q

Muscle fatigue

A

Inability of the muscle to contract forcefully after prolonged activity

Caused by lowered release of calcium ions from sarcoplasmic reticulum resulting in decline of calcium level in sarcoplasm

55
Q

Oxygen debt

A

The added oxygen over and above the oxygen consumed at rest that is taken into the body after exercise

56
Q

3 ways the extra oxygen is used to restore metabolic conditions

A

1) convert lactic acid back into glycogen stores in the liver
2) resynthesize creatine phosphate and ATP
3) to replace the oxygen removed from myoglobin

57
Q

Recovery oxygen uptake

A

The elevated use of oxygen after exercise

58
Q

Control of muscle tension results from

A

1) single muscle action potential

2) a muscle twitch has a smaller force than a maximum force or tension

59
Q

The total tension of a muscle fiber depends on

A

The rate at which nerve impulses arrive at its neuromuscular junction

60
Q

Twitch contraction is a

A

Brief contraction of all the muscle fibers in a motor unit in response to a single action potential in its motor neuron

61
Q

Myogram

A

Recording of a muscle contraction

62
Q

Latent period

A

A brief delay between the application of the stimulus and the beginning of the contraction

63
Q

Contraction period

A

The second phase
Upward tracing
Repetitive power strokes

64
Q

Relaxation period

A

Third phase
Downward tracing
Power strokes cease

65
Q

Frequency of stimulation

A

If a second stimulus arrives before a muscle fiber has completely relaxed the second stimulation will be stronger than the first because the second contraction begins when the fiber is at a higher level of tension already

66
Q

Wave stimulation

A

A larger contraction

67
Q

Unfused (incomplete) tetanus

A

Wavering contraction when a skeletal muscle fiver is stimulated at a rate of 20-30x/sec

68
Q

Fused (complete) tetanus

A

Sustained contraction

80-100x/second

69
Q

Motor unit recruitment

A

The process in which the number of contracting motor units is increased

70
Q

3 types of skeletal muscle fibers

A 
Slow oxidative fibers (SO)
- postural muscles of neck, back, leg 
-lg amt of myoglobin and mitochondria
- resistant to fatigue
-prolonged sustained contractions 
(Long distance walking)
Fast oxidative-glycolytic fibers (FOG)
-leg muscles
-high resistance to fatigue
-lg amt of myoglobin and glycogen
-anaerobic glycolysis
(Running, swimming)
Fast glycolytic fibers (FG)
-shoulder/arm
-fatigue quickly
-anaerobic glycolysis
-low myoglobin
-lg amt of glycogen
(Wt lifting, sprinting)
71
Q

Cardiac muscle tissue is found only where

A 
In the heart
Single centrally located nucleus
Involuntary
Contraction is not under conscious control 
Can regenerate under certain conditions
72
Q

Intercalated discs are what

A

Irregular transverse thickenings of carcolemma

73
Q

Gap junctions allow muscle action potentials to do what?

A

Spread quickly from one cardiac muscle fiber to another

Has endomysium, perimysium but lacks epimysium

74
Q

The heart beats because some of the cardiac muscle fibers act as a

A

Pacemaker to initiate each cardiac contraction

75
Q

What increases and decreases the heart rate?

A

Several hormones and neurotransmitters

76
Q

Under resting conditions what should the BPM be

A

75x/min

77
Q

Mitochondria in the cardiac muscle fibers do what?

A

Produce most of the needed ATP via aerobic cellular respiration

78
Q

Cardiac muscle fibers can use lactic acid to do what

A

Make ATP

79
Q

Smooth muscle tissue is found where?

A

Internal organs and blood vessels
Involuntary
Not under conscious control
Contains thick, thin, and intermediate filaments

80
Q

2 types of smooth muscle:

A

Visceral

Multi-unit

81
Q

Visceral (single unit) are found where

A

Walls of blood vessels, stomach, intestine, uterus, urinary bladder

82
Q

Multi unit smooth muscle fibers consist of

Where are they found?

A

Individual fibers w/ motor nerve endings

Found in walls of lg arteries, lg airways to lungs, arrector pili muscle of skin, and internal eyemuscles

83
Q

Dense bodies are similar to what

Where are they found in

A

Similar to Z discs in striated muscle to where the thin filaments are attached

Found in sarcoplasm and sarcolemma

84
Q

Most smooth muscle fibers contract and relax in response to nerve impulses from what?

A

ANS

85
Q

Hormone epinephrine is released by what and causes what?

A

Released by adrenal medulla

Causes relaxation of smooth muscle in the airways and blood vessels walls

86
Q

Around 30 yrs old what happens

A

Humans undergo a slow progressive loss of skeletal muscle mass which is replaced by fibrous and adipose tissue

87
Q

Origin

A

Attachment of a muscle by means of a tendon to the stationary bone

88
Q

Insertion is

A

The other end of the muscle attached by means of a tendon to the movable bone at a point

89
Q

Group actions

A

When muscles are moving and acting in groups

90
Q

Prime mover or agonist

A

This is the leader muscle that causes an action

91
Q

Antagonist

A

Is a muscle that relaxes while the prime mover contracts

92
Q

Synergists are

A

Muscles that help the prime mover function

93
Q

Fixaters are

A

Groups of muscles that stabilize the origin of the prime mover

94
Q

Myopathy

A

Disease/disorder of the skeletal muscle

95
Q

Neuromuscular dz

A

Disease/disorder of the skeletal musle to any of the components of a motor unit

96
Q

Myasthenia gravis

A

Autoimmune dz that causes chronic progressive damage of the neuromuscular junction (face and neck)

97
Q

Muscular dystrophy refers to a group of what

A

Inherited muscle - destroying dz that cause progressive degeneration of skeletal muscle fibers

DMA - duchenne muscular dystrophy

98
Q

Fibromyalgia

A

Non articular rheumatic d/o that usually appears bt ages 25-30

Severe fatigue, poor sleep, headaches, depression

99
Q

Electromyography (EMG)

A

Study of electrical changes that occur in musculature tissue

100
Q

Hypertonia

A

Increased muscle tone - muscle stiffness

101
Q

Hypotonia

A

Decreased/lost muscle tone

102
Q

Myalgia

A

Pain in associated muscles

103
Q

Myoma

A

Tumor consisting of muscular tissue

104
Q

Myomalacia

A

Softening of muscle tissue

105
Q

Myositis

A

Inflammation of muscle fibers (cells)

106
Q

Myotonia

A

Increased muscular excitability and contractility

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