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Anatomy and Physiology: Exam 2 > Lecture 9: Muscle Histology and Physiology > Flashcards

Lecture 9: Muscle Histology and Physiology Flashcards

1
Q

Types of Muscle

A

Skeletal,
Cardiac,
Smooth

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2
Q

Skeletal Muscle Brief Definition

A

Moves skin on face and joints,

Voluntary

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3
Q

Cardiac Muscle Brief Definition

A

Allows heart to contract,

Involuntary

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4
Q

Smooth Muscle Brief Definition

A

All over,
Lines body,
Blood pressure, move waste through intestines, etc
Involuntary

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5
Q

Functions of Skeletal Muscles

A 
Produce Joint Movement,
Maintain Posture,
Support Soft Tissue (hold in organs),
Guard Entrances and Exits (eyes/mouth/etc),
Maintain Body Temperature,
Store Nutrient Reserves
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6
Q

Types of Connective Tissue in Skeletal Muscles

A

Epimysium,
Perimysium,
Endomysium

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7
Q

Epimysium Connective Tissue of Skeletal Muscles

A

Covers outside of the muscle,
Separates muscle from muscle,
Most outer layer,
Surrounds each muscle

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8
Q

Perimysium Connective Tissue of Skeletal Muscles

A

Covers muscle fascicles,
Inside of Epimysium,
Separates fascicle from fascicle

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9
Q

Endomysium Connective Tissue of Skeletal Muscles

A

Covers and separates individual muscle cells (fibers) in the muscle fascicle

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10
Q

Where Are Skeletal Muscle Fibers In Cell?

A

Innermost ‘layer’,

Covered with Endomysium

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11
Q

Tendons

A

All three connective tissue layers come together at the end of a muscle to form a tendon,
Dense regular CT proper,
Anchor muscle belly to a bone

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12
Q

Skeletal Muscle Fibers (Cells)

A

Are very long,
Develop through fusion of mesodermal cells,
Become very large,
Contain hundreds of nuclei,
Individual muscle cell inside a fascicle,
Contain microfibrils

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13
Q

How Long Can A Skeletal Muscle Fiber Be?

A

They can run the length of the muscle

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14
Q

Myoblasts

A

Fuse together to create muscle fibers

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15
Q

Sarcolema

A

Cell membrane that surrounds the whole muscle

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16
Q

Sarcoplasmic Reticulum

A

Like smooth reticulum,

Stores calcium

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17
Q

Thick and Thin Filaments

A

Protein filaments (actin and myosin)

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18
Q

Myofibrils

A

Inside skeletal muscle fibers,
Made up of sarcomeres,
Smallest functional units of a skeletal muscle

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19
Q

Sarcoplasm

A

Cytoplasm of a muscle fiber

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20
Q

Sarcomeres

A

Made of protein filaments,
Make up myofibrils,
Connect end to end in myofibrils,
Composed of myosin and actin

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21
Q

Myosin Filament

A

Thick filament with a globular head at one end

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22
Q

Actin Filament

A

Composed of actin, tropomyosin, and troponin,

Attached to a Z disk

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23
Q

Tropomyosin

A

Covers actin active sites to stop myosin from connecting to it

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24
Q

Troponin

A

Calcium binds to it to remove the tropomyosin from the actin filament

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25
Q

Cross-Bridge

A

Actin and myosin bond with one another when actin active sites are exposed

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26
Q

T Tubules

A

Transverse Tubules,

Allow action potentials to quickly spread into cell via tunnels of sarcolemma that network through the sarcoplasm

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27
Q

Action Potentials

A

Happens in excitable cells (nerves/neurons and muscles)

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28
Q

When Do Action Potentials Occur?

A

When a signal causes sodium channels to open in the plasma membrane and a rush of sodium to depolarize the cell membrane

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29
Q

What Are Action Potentials Like?

A

A wave across the surface of a cell,

Quickly and then the cell repolarizes

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30
Q

What Neurotransmitter Is Released at the Synapse?

A

Acetylcholine (ACh)

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31
Q

Neuromuscular Junction (NMJ)

A

Synapse where ACh is released

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32
Q

Motor End Plate

A

Where the ACh binds to receptors on the sarcolemma and triggers an action potential

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33
Q

As The Action Potential Spreads, It Triggers The Release Of…

A

Calcium

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34
Q

Power Stroke

A

Tilt of the myosin head and drag of the actin filaments in the opposite directions

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35
Q

Contraction

A

The pulling of the actin filaments past the myosin filaments results in sarcomere shortening and generation of muscle force

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36
Q

Excitation-Contraction

A

The steps that occur to depolarize the muscle cell and cause contractions together

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37
Q

Triads

A

One T-Tubercle and two terminal cisternae,

Where excitation-contraction coupling occurs

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38
Q

What Happens After The Power Stroke?

A

Myosin heads release actin and ‘recock’ so they can attach to actin again

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39
Q

Recocking of Myosin Head

A

Requires of ATP to detach the head,
ADP is used to recock,
1 ATP per 1 myosin head

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40
Q

Acetyl-Cholinesterase Molecules

A

Breaks down ACh, prevents a prolonged contraction within 1 muscle myofibril

41
Q

Skeletal Muscle Fiber Shortening

A

As many sarcomeres shorten, muscle pulls together (shortens), producing tension

42
Q

Contraction Duration Depends On… (3)

A

Duration of neural stimulus,
Number of free calcium ions in sarcoplasm,
Availability of ATP

43
Q

Relaxation Of Skeletal Muscles

A

Calcium concentrations fall,
Calcium detaches from troponin,
Active sites are re-covered by tropomyosin,
Sarcomeres remain contracted and other forces lengthen them again

44
Q

Rigor Mortis

A

A fixed muscular contraction after death (starts usually 3 hours after death)

45
Q

Causes of Rigor Mortis (3)

A

Ion pumps cease to function (no more ATP made),
Calcium builds up in the sarcoplasm,
Ends in about 3 days (depends on external factors)

46
Q

Lack Of ATP Production In Rigor Mortis Causes..

A

Myosin to never detach,
Cross-bridges do not break,
No shortening,
No lengthening

47
Q

How Many Myosin Filaments Per Muscle Fiber?

A

Millions to billions

48
Q

1 Second Skeletal Muscle Contraction

A

Each myosin filament can breakdown 2500 ATP molecules per second,
Muscles contain only enough ATP to start contraction, then they have to make more

49
Q

ATP + Creatine = ?

A

ADP + Creatine Phosphate (CP)

50
Q

Creatine Phosphate

A

Stores energy in the cell for long-term

51
Q

ADP + Creatine Phosphate = ?

A

ATP + Creatine

52
Q

Creatine Phosphokinase (CPK)

A

Enzyme that makes ATP Resynthesis happen

53
Q

15 Second Skeletal Muscle Contraction

A

ATP + Creatine = ADP + Creatine Phosphate
ADP + Creatine Phosphate = ATP + Creatine
CP is used up in 15 seconds

54
Q

Anaerobic Glycolysis

A

Without Oxygen,
Occurs in Sarcoplasm,
Glucose to Lactic Acid and ATP

55
Q

Aerobic Metabolism

A 
With Oxygen,
More ATP made than anaerobic glycolysis,
Kreb's Cycle/Citric Acid Cycle,
Pyruvate to ATP (glucose, fat, protein)
ATP + H2O + CO2
56
Q

Skeletal Muscle Fatigue

A

When muscles can no longer perform a required activity

57
Q

Causes of Skeletal Muscle Fatigue (4)

A

Depletion of metabolic reserves,
Damage to sarcolemma and sarcoplasmic reticulum,
Low pH (lactic acid),
Muscle damage/exhaustion and pain

58
Q

Skeletal Muscle Recovery Period

A

Time required after exertion for muscles to return to normal (like after exercising),
Oxygen becomes available,
Mitochondrial activity resumes,
Protein fibers heal and may become more numerous

59
Q

Slow-Twitch (ST) Skeletal Muscle Fibers

A

Plenty of oxygen,
High aerobic capacity and fatigue resistance,
Low anaerobic capacity and motor unit strength,
Slow contractile speed (110 ms) and myosin ATPase (slowing ATP splitting),
Low sarcoplasmic reticulum development,
Good at endurance,
More mitochondria = more ATP

60
Q

Example of Slow-Twitch Skeletal Muscle Fibers

A

Core muscles,
Spine muscles,
Eyes,
Fingers

61
Q

Fast-Twitch (Fta) Skeletal Muscle Fibers

A

Faster,
More tension,
Contract for less periods of time,
Moderate aerobic capacity and fatigue resistance,
High anaerobic capacity and motor unit strength,
Fast contractile speed (50 ms),
High sarcoplasmic reticulum development

62
Q

Fast-Twitch (Ftb) Skeletal Muscle Fibers

A 
Fastest muscle fiber,
Fatigue quickly,
Low aerobic capacity, 
Fast contractile speed (50 ms),
High sarcoplasmic reticulum
63
Q

Resistance and Speed of Skeletal Muscle Contraction

A

Heavier the load (resistance) on a muscle the longer it takes for shortening to begin and the less the muscle will shorten

64
Q

Skeletal Muscle Relaxation

A

After a contraction, a muscle fiber returns to resting length by elastic forces, opposing muscle contractions, and gravity

65
Q

Skeletal Muscle Hypertrophy

A

Muscle growth from heavy training,
Increase diameter of muscle fibers too allow for more sarcomeres, no size,
Increases number of myofibrils (actin and myosin),
Increases mitochondria, glycogen reserves

66
Q

Skeletal Muscle Atrophy

A

Lack of muscle activity,

Reduces muscle size, tone, and power

67
Q

Tone

A

Action potential that makes muscle ready/prepared for movement

68
Q

Anaerobic Activities

A

Physical Conditioning,
Use fast fibers to produce more ATP,
Fatigue quickly with strenuous activity,
50 m dash, weight lifting, etc

69
Q

How Is Physical Conditioning Improved With Anaerobic Activities?

A

Frequent, brief, intensive workouts, strength training,

Hypertrophy

70
Q

Aerobic Activities

A 
Physical Conditioning,
Supported by mitochondria,
Require oxygen and nutrients,
Prolonged activity (long distance runs),
Rely more on slow-twitch muscle fibers to keep up with physical demands,
Able to provide enough oxygen and blood
71
Q

How Is Physical Conditioning Improved With Aerobic Activities?

A 
Repetitive training (neural responses),
Cardiovascular training/endurance training
72
Q

What Couple Replace Muscle Fibers During Prolonged Inactivity?

A

Fibrous Tissue (scar tissue)

73
Q

Motor Unit

A

One motor neuron and muscle fiber it innervates,
Uses fine control with slow-twitch muscle fibers,
Strength control

74
Q

Length-Tension Relationship

A

Tension generated depends on length of muscle

75
Q

Tension Production

A

Three phases:
Latent period,
Contraction phase,
Relaxation phase

76
Q

Latent Period Before A Skeletal Muscle Contraction

A

Action potential moves through a sarcolemma that causes calcium release,
Action potential spreads over the muscle and t tubules

77
Q

Contraction Phase Of A Skeletal Muscle Twitch

A

Calcium ions bind,
Tension begins to peak,
Interaction of actin and myosin

78
Q

Relaxation Phase Of A Skeletal Muscle Twitch

A

Calcium levels fall after the optimum number of interactions occur,
Active sites are covered,
Tension falls to resting levels,

79
Q

Higher Stimulus Frequency = ?

A

An increase in tension production

80
Q

Treppe Skeletal Muscle Stimulation

A 
Low frequency (up to 10/sec),
Stimulating right after a twitch makes it stronger because less of a latent period and calcium is already available,
Stronger each time until constant twitch strength
81
Q

Wave Summation Skeletal Muscle Stimulation

A

Stimulus before the end of relaxation phase,

Results in incomplete Tetanus Stimulation

82
Q

Complete Tetanus Skeletal Muscle Stimulation

A

Stimulating before relaxation phase even starts,

Allows for smooth body movements

83
Q

Structure of Cardiac Muscle Tissue

A 
Striated,
Found only in heart,
Sarcomeres,
Smaller than skeletal muscles,
Single nuclei
84
Q

Cardiac Muscle Cells Are Called

A

Cardiocytes

85
Q

Characteristics of Cardiocytes (7)

A 
Small,
Single nucleus,
Short, wide T tubules,
No triads,
SR with no terminal cisternae,
Aerobic (high myoglobin and mitochondria),
Intercalated discs
86
Q

Intercalated Discs of Cardiac Muscles

A

Specialized contact points between cardiocytes,
Join cell membranes of adjacent cardiocytes with gap junctions and desmosomes,
Able to depolarize
Allow ions to spread from 1 cardiac muscle cell to another

87
Q

Functions of Intercalated Discs of Cardiac Muscles

A

Maintain structure of cardiac muscles,
Enhance molecular and electrical connections,
Conduct action potentials

88
Q

Automaticity of Cardiac Muscles

A

Self depolarizing,
Contraction without neural stimulation,
Controlled by pacemaker cells (leakiest cells)

89
Q

Extended Contraction Time of Cardiac Muscles

A

To be able to push blood along/through arteries thoroughly,

10 times as long as skeletal muscle

90
Q

Prevention of Wave Summation in Cardiac Muscles

A

Long refractory period,

Want long contraction/long relaxation because there is no need for seizing or long term contraction of cardiac muscles

91
Q

Smooth Muscle Tissue in Body Systems

A 
Forms around other tissues,
Blood vessels,
Reproductive and Glandular systems,
Digestive and Urinary systems,
Integumentary system
92
Q

Smooth Muscle Tissue Function in Blood Vessels

A

Regulates blood pressure and flow

93
Q

Smooth Muscle Tissue Function in Reproductive and Glandular Systems

A

Produces movement

94
Q

Smooth Muscle Tissue Function in Digestive and Urinary Systems

A

Forms sphincters,

Produces contractions

95
Q

Smooth Muscle Tissue Function in Integumentary System

A

Arrector pili muscles cause goose bumps

96
Q

Structure of Smooth Muscle Tissue

A

Nonstriated tissue (no sarcomeres),
Scattered actin and myosin filaments,
Whole cell shrinks during a contraction

97
Q

Characteristics of Smooth Muscle Tissue (4)

A

Long, slender, spindle shaped,
Single, central nucleus,
No T tubules, myofibrils, or sarcomeres,
No tendons

98
Q

Smooth Muscle Tissue Contractions Are Caused By…

A

Neurons, hormones, or other local chemical factors

Anatomy and Physiology: Exam 2 (5 decks)

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