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Honors Anatomy & Physiology > Skeletal Muscle Tissue Part 2 (tension) > Flashcards

Skeletal Muscle Tissue Part 2 (tension) Flashcards

1
Q

Muscle tension

A

Force exerted on a single muscle fiber

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2
Q

Load

A

Opposing force exerted by weight of object

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3
Q

Isometric contractions

Isotonic contractions

A

Isometric- muscle tension does NOT move load

Isotonic- muscle tension moves load & shortens muscle

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4
Q

Example of isometric vs isotonic?

A

Isometric- holding pencil

Isotonic- moving pencil

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5
Q

Example of muscle tension and a load?

A

Muscle tension- gripping pencil

Load-pencil

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6
Q

Motor units

Includes? Avg? Ex?

A

Includes: somatic motor neuron & the skeletal muscle fibers it stimulates
Avg. 150 muscle fibers per motor unit
Ex. Eye 10-20 fibers/motor unit
Biceps 2000-3000 fibers/motor unit

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7
Q

What is the “all or none” rule?

A

All muscle fibers in a motor unit contract & relax together

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8
Q

Total strength of contraction depend on? (2)

A

1) Size of motor units

2) # of motor units activated @ 1 time

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9
Q

Muscle twitch contraction

A

Brief contraction of all muscle fibers in a motor unit from a single action potential
(1 single muscle contraction)

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10
Q

Myogram?

A

Recorded pattern of a twitch

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11
Q

Parts of a muscle twitch (3)

A

Latent period

Contraction period Relaxation period

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12
Q

Latent period

A

2 milliseconds
When action potential is propagated
(No force)

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13
Q

Contraction period

A

10-100 milliseconds
During cross bridging
(Myosin attach to actin and power stroke)

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14
Q

Relaxation period

A

10-100 milliseconds
Calcium 2+ transported back into SR
Contractile force decreasing

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15
Q

Frequency of stimulation and muscle response

Aka? Definition?

A

Increase rate of motor neurons firing creates greater force

-wave summation

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16
Q

What’s wave summation

What does it create?

A

Sum of muscle twitches on muscle fibers
2nd twitch (contraction) begins before end of 1st twitch
2nd twitch is stronger
Creates a greater force bc motor units cannot relax between stimuli

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17
Q

What happens for muscles when there’s constant stimuli?

Decrease? Increase? Leads to?

A 
Relax time decreases 
Ca 2+ concentration increases 
Amount of wave summation increases 
Sustained contractions-tetanus 
Tetanus leads to fatigue
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18
Q

Muscle shapes are affected by what?

A

Fascicles are arranged in patterns which affect function of muscle

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19
Q

6 muscle shapes (patterns) ?

A

1) parallel
2) convergent
3) pennate
4) circular
5) spiral
6) fusiform

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20
Q

Parallel

A

Evenly spaced, attached to a tendon same width as muscle
Strap-like appearance
Ex. Sartorius in thigh (long)

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21
Q

Convergent

A

Broad muscle tapers to a single tendon

Ex. Pectoralis in chest (big & tapers down, traps, lats)

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22
Q

Pennate

A

Muscle resembles a feather
Fascicles attached to tendon @ angle
Types: unipennate, bipennate, multipennate
Ex. Rectus femoris of thigh

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23
Q

Circular

A

Muscle encircles a structure

Ex. Orbicularis oculi of eye

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24
Q

Spiral

A

Muscle wraps around bone or twisted appearance

Ex. Supinator in forearm (tight fit to bone)

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25
Q

Fusiform

A

Muscle thicker in middle, tapered at ends

Ex. Biceps brachii

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26
Q

Functional groups of muscles

Involves? Purpose?

A

Movements at joints involve several muscles

Each muscle has a specific job

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27
Q

List the functional groups of muscles (4)

A

Agonist
Antagonist
Synergists
Fixators

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28
Q

Agonist

A

Provides most force for movement

Usually the largest muscle

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29
Q

Antagonist

A

Lies on opposite side of a joint from agonist

Opposes & slows the motion

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30
Q

Synergists

A

Work w/ agonist

Provides additional support to guide movement

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31
Q

Fixators

A

Hold a bone in place
Makes movement more effective & reduces injury risk
(Not limpy bc this)

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32
Q

What are the diseases/disorders of the muscular system? (4)

A

Carpal tunnel syndrome
Muscular dystrophy
Myasthenia gravis
Fibromyalgia

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33
Q

Carpal tunnel syndrome

Cause? Symptoms?

A

Nerve damage due to irrational of median nerve in wrist

Numbness, tingling in fingers low blood circulation

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34
Q

Carpal tunnel syndrome

Treatment?

A

Surgery

Anti inflammatory drugs

35
Q

Myasthenia gravis

Cause?

A

Autoimmune disease

-immune system mistakenly produces antibodies that destroy ACh receptors

36
Q

Myasthenia gravis

Symptoms ?

A

Weakness eyelid, face, neck, and extremity muscles

Droopy eyelids, double vision

37
Q

Myasthenia gravis

Treatment?

A

Drugs to inhibit the enzyme that digest ACh

38
Q

Fibromyalgia

Cause? Symptoms?

A

Cause- not precisely known
Pain, tenderness, & stiffness of muscles (all the time)
Inflammation of muscles

39
Q

Common muscular conditions (5)

A 
Spasm
Cramp
Facial tics
Strain
Sprain
40
Q

Spasm

A

Sudden & involuntary muscle contraction
Seizure or convulsion
-multiple spasms of skeletal muscles

41
Q

Cramp

A

Strong, painful spasms of leg & foot

42
Q

Facial tics

A

Periodic spasms

43
Q

Strain

A

Stretching or tearing of muscle

44
Q

Sprain

A

Twisting of a joint- damaging muscles, tendons, ligaments, blood vessels

45
Q

Example of antagonist and agonist on body

A

Biceps moves (agonist) and tricep slows it down (antagonist)

46
Q

Example of functional groups of muscles on an object (cup)

A

Agonist-movement of cup to mouth
Antagonist- cup to mouth w/o being jerky
Synergists- directs cup to mouth
Fixators- holds movement in place

47
Q

Threshold stimuli

A

Amount of stimulus that will cause muscle contraction

Not enough stimulus -> no muscle contraction

48
Q

Recruitment of motor units

A

Process where the number of active motor units increases

-as intensity of stimulation increases, more motor units in a muscle are activated (ex. Picking up stapler vs book)

49
Q

What’s a motor unit?

Where is it located?

A

Neuron and muscle fiber it innovates
(Neuron & all axon terminals that attach to muscle fibers)
IN A MUSCLE

50
Q

Muscle recruitment
Which contract first?
Strong vs weak contractions?
Contract how?

A

Smallest muscle fibers contract 1st
Larger muscle fibers contract 2nd
-weak contractions: posture muscles (like holding your head up)
-strong contractions: running
NOT ALL MOTOR UNITS OF A MUSCLE ARE CONTRACTING AT THE SAME TIME (ALTERNATE)

51
Q

Force of muscle contractions?
Depend on?
Affected by?

A 
Force depends on # of cross bridges activated (power stroke)
Affected by:
-# of fibers stimulated 
-size of fibers 
-frequency of stimulation
-degree of stretch
52
Q

Velocity & duration of muscle contraction

Depends on?

A

Type of muscle fibers contracting
What type of ATP production used
-aerobic respiration
-anaerobic respiration

53
Q

Muscle tone

Purpose? Leads to?

A

Small amount of tension in muscle due to weak, involuntary contractions of motor units
-established by neurons in brain & spinal cord
-keeps body posture
Flaccid- state of limpness where muscle tone is lost (weak)

54
Q

How many Types of muscle fibers are involved in muscle contraction?

A

2

55
Q

Characteristics of 2 types of muscle fibers involved in muscle contraction
Similarities? Differences?

A

-vary in myoglobin content
•white muscle fibers-white muscle
•red muscle fibers-dark muscle
•most muscles are a combination of both
-contract & relax at different speeds
-vary in the source of ATP production & fatigue rate

56
Q

Type 1 of muscle fibers involved in muscle contraction

A

Slow oxidative fibers (SO)

57
Q

Characteristics of type 1 (SO)

Fatigue? ATP? Location? Measure? Contraction?

A

Smallest diameter
Dark red muscle- large amounts of myoglobin & capillaries
ATP produced by aerobic respiration
Slow rate of contraction
Produce less force for a longer period of time
*very resistant to fatigue
Adapted for: maintaining posture & aerobic endurance activities
(Think turkey, dark on our body legs & arms) (last to fatigue)

58
Q

Type 2 muscle fibers (3)

A 
Fast oxidative glycolytic (FOG)
Fast oxidative (FO) 
Fast glycolytic (FG)
59
Q

Characteristics of type 2 muscle fibers

Example? Fatigue? Measure? Classified?

A 
Categorized by energy production method
Less myoglobin & blood supply (white muscle)
Fast twitch fibers 
Larger diameter fiber 
*fatigue quickly 
Ex. Eye muscles
60
Q

Fast oxidative glycolytic fibers (FOG)

Fatigue? Contraction? Adapted for?

A
  • moderate resistance to fatigue
  • fast rate of contraction
  • adapted for: walking, jogging
61
Q

Fast glycolytic (FG)

A 
Fatigue quickly (first to fatigue) 
Contract strongly & quickly (most force) 
Adapted for: intense movements of short duration like weight lifting, throwing a baseball
62
Q

Recruitment of the muscle fibers

Definition? Which forces are what fibers?

A

Different motor units recruited in specific order

  • weak force needed: SO motor units activated
  • more force needed: SO & FOG
  • max force required: SO FOG & FG
63
Q

What’s is the way to remember what forces are which fibers?

A

Weak forces last longer than max, therefore, SO fatigue last

64
Q

In skeletal muscle, ATP is required to…

A

POWER the NA+/K+ pumps involved in action potentials
RELEASE the myosin heads from actin active sites & RECOCK the heads in preparation for another power stroke
PUMP Ca2+ back into SR during relaxation

65
Q

How is ATP generated/created? (3) depends on? Carried out how?

A

Immediate cytosolic reactions (ATP) (digestion, breaking down carbs)
Glycolytic catabolism in the cytosol (Glycolysis, Anaerobic)
Oxidative catabolism in the mitochondria (aerobic)
All 3 processes may occur simultaneously in muscle fibers during contractions, but used in DIFFERENT proportions, depending on the resources & needs of the cell

66
Q

What’s the main immediate energy during muscle contraction?

A

Stored ATP in the muscle fiber which is tepidly consumed during muscle contraction

67
Q

Creatine phosphate

A

(In our blood) Concentration in the cytosol 5-6 times higher than ATP
Can immediately regenerate enough ATP for about 10 secs of max muscle activity

68
Q

Glycolysis

A

Series of reactions that occur in all cells’ cytosol to break glucose down into pyruvate; it provides energy for muscle contraction once immediate source of energy are depleted

69
Q

What does glycolysis use?

A

Glucose found in the blood & stored in muscle (or liver) cells as glycogen
It can replenish ATP for 30-40 secs of sustained contraction

70
Q

Anaerobic catabolism

Leads to what?

A

Aka glycolysis which does not require oxygen directly but the amount of oxygen present leads to 2 possible outcomes

1) if oxygen abundant, pyruvate formed by glucose catabolism enters mitochondria for oxidative catabolism which then occur simulate royalty w/ glycolysis as long as glucose is available
2) if not abundant, pyruvate converts into 2 molecules of lactic acid which is either converted back into glucose by liver or taken up by mito. For oxidative catabolism

71
Q

Aerobic catabolism

A

Aka oxidative catabolism which requires oxygen directly

Allows for longer lasting muscle contractions bc these reactions produce many MORE ATP than glycolysis

72
Q

Oxidative catabolism

ATP production depends on?

A

Amount of ATP produced depends on the TYPE of fuel used by the fiber

73
Q

What do muscle fibers prefer to use for oxidative energy sources?

A

Prefer to use glucose, but as it becomes unavailable, they will catabolism fatty acids & amino acids (protein, muscle itself)
(Glucose is easier to break down & use)

74
Q

What is the predominant energy source after 1 minute of contraction? Why?

A

Oxidative catabolism
Provides nearly 100% of the necessary ATP after several minutes
Can provide ATP for hours, as long as oxygen and fuels are available

75
Q

3 sources of energy for ATP are?

A 
Digestion 
Glycolysis immediate  (anaerobic catabolism) - no oxygen
Oxidative catabolism (aerobic catabolism) - oxygen
76
Q

First class lever

A

Fulcrum is located btwn applied force & load to be moved
Force applied & load moved are in opposite directions (see saw)
Lever works @ mechanical advantage or disadvantage, depending on location of fulcrum

77
Q

Fulcrum

A

Pivot, or hinge point

78
Q

Load

A

Weight you’re trying to move

79
Q

Force

A

Effort applied to lever

80
Q

Second class lever

A

Fulcrum is located farther from applied force
Load moved is btwn fulcrum & force applied, & moves in same direction as force
Lever works at mechanical advantage to move large loads at short distance w/ little effort

81
Q

Third class lever

A

Fulcrum is located closer to applied force
Force applied between fulcrum & load moved, & moves in same direction as force
Lever works at mechanical disadvantage to move small loads a greater distance w/ greater speed

82
Q

Ex of all levers

A

First - dribbling basketball
Second- rising on tiptoe
Third- pulling up on a fishing rod

83
Q

What does lack of ATP cause?

A

Causes the muscles to bc ridged bc no ATP causes muscle tension.
Power stroke wouldn’t be able to occur as a result of the lack of ATP, which makes the muscle stay tense

84
Q

Muscular dystrophy cause and treatment?

A

Progressive degeneration & weakening of muscles
Muscle fibers die & replaced by fat & connective tissue
Can be genetically inherited
Duchenne muscular dystrophy- don’t produce protein dystrophin
Inject muscles w/ immature muscle cells that produce dystrophin

Honors Anatomy & Physiology (45 decks)

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