Skeletal Muscle Tissue Part 2 (tension) Flashcards Preview

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Flashcards in Skeletal Muscle Tissue Part 2 (tension) Deck (84):
1

Muscle tension

Force exerted on a single muscle fiber

2

Load

Opposing force exerted by weight of object

3

Isometric contractions
Isotonic contractions

Isometric- muscle tension does NOT move load
Isotonic- muscle tension moves load & shortens muscle

4

Example of isometric vs isotonic?

Isometric- holding pencil
Isotonic- moving pencil

5

Example of muscle tension and a load?

Muscle tension- gripping pencil
Load-pencil

6

Motor units
Includes? Avg? Ex?

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

7

What is the "all or none" rule?

All muscle fibers in a motor unit contract & relax together

8

Total strength of contraction depend on? (2)

1) Size of motor units
2) # of motor units activated @ 1 time

9

Muscle twitch contraction

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

10

Myogram?

Recorded pattern of a twitch

11

Parts of a muscle twitch (3)

Latent period
Contraction period Relaxation period

12

Latent period

2 milliseconds
When action potential is propagated
(No force)

13

Contraction period

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

14

Relaxation period

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

15

Frequency of stimulation and muscle response
Aka? Definition?

Increase rate of motor neurons firing creates greater force
-wave summation

16

What's wave summation
What does it create?

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

17

What happens for muscles when there's constant stimuli?
Decrease? Increase? Leads to?

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

18

Muscle shapes are affected by what?

Fascicles are arranged in patterns which affect function of muscle

19

6 muscle shapes (patterns) ?

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

20

Parallel

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

21

Convergent

Broad muscle tapers to a single tendon
Ex. Pectoralis in chest (big & tapers down, traps, lats)

22

Pennate

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

23

Circular

Muscle encircles a structure
Ex. Orbicularis oculi of eye

24

Spiral

Muscle wraps around bone or twisted appearance
Ex. Supinator in forearm (tight fit to bone)

25

Fusiform

Muscle thicker in middle, tapered at ends
Ex. Biceps brachii

26

Functional groups of muscles
Involves? Purpose?

Movements at joints involve several muscles
Each muscle has a specific job

27

List the functional groups of muscles (4)

Agonist
Antagonist
Synergists
Fixators

28

Agonist

Provides most force for movement
Usually the largest muscle

29

Antagonist

Lies on opposite side of a joint from agonist
Opposes & slows the motion

30

Synergists

Work w/ agonist
Provides additional support to guide movement

31

Fixators

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

32

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

Carpal tunnel syndrome
Muscular dystrophy
Myasthenia gravis
Fibromyalgia

33

Carpal tunnel syndrome
Cause? Symptoms?

Nerve damage due to irrational of median nerve in wrist
Numbness, tingling in fingers low blood circulation

34

Carpal tunnel syndrome
Treatment?

Surgery
Anti inflammatory drugs

35

Myasthenia gravis
Cause?

Autoimmune disease
-immune system mistakenly produces antibodies that destroy ACh receptors

36

Myasthenia gravis
Symptoms ?

Weakness eyelid, face, neck, and extremity muscles
Droopy eyelids, double vision

37

Myasthenia gravis
Treatment?

Drugs to inhibit the enzyme that digest ACh

38

Fibromyalgia
Cause? Symptoms?

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

39

Common muscular conditions (5)

Spasm
Cramp
Facial tics
Strain
Sprain

40

Spasm

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

41

Cramp

Strong, painful spasms of leg & foot

42

Facial tics

Periodic spasms

43

Strain

Stretching or tearing of muscle

44

Sprain

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

45

Example of antagonist and agonist on body

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

46

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

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

Threshold stimuli

Amount of stimulus that will cause muscle contraction
(Not enough stimulus -> no muscle contraction)

48

Recruitment of motor units

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

What's a motor unit?
Where is it located?

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

50

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

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

Force of muscle contractions?
Depend on?
Affected by?

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

52

Velocity & duration of muscle contraction
Depends on?

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

53

Muscle tone
Purpose? Leads to?

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

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

2

55

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

-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

Type 1 of muscle fibers involved in muscle contraction

Slow oxidative fibers (SO)

57

Characteristics of type 1 (SO)
Fatigue? ATP? Location? Measure? Contraction?

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

Type 2 muscle fibers (3)

Fast oxidative glycolytic (FOG)
Fast oxidative (FO)
Fast glycolytic (FG)

59

Characteristics of type 2 muscle fibers
Example? Fatigue? Measure? Classified?

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

60

Fast oxidative glycolytic fibers (FOG)
Fatigue? Contraction? Adapted for?

-moderate resistance to fatigue
-fast rate of contraction
-adapted for: walking, jogging

61

Fast glycolytic (FG)

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

62

Recruitment of the muscle fibers
Definition? Which forces are what fibers?

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

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

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

64

In skeletal muscle, ATP is required to...

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

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

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

What's the main immediate energy during muscle contraction?

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

67

Creatine phosphate

(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

Glycolysis

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

What does glycolysis use?

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

Anaerobic catabolism
Leads to what?

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

Aerobic catabolism

Aka oxidative catabolism which requires oxygen directly
Allows for longer lasting muscle contractions bc these reactions produce many MORE ATP than glycolysis

72

Oxidative catabolism
ATP production depends on?

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

73

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

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

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

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

3 sources of energy for ATP are?

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

76

First class lever

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

Fulcrum

Pivot, or hinge point

78

Load

Weight you're trying to move

79

Force

Effort applied to lever

80

Second class lever

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

Third class lever

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

Ex of all levers

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

83

What does lack of ATP cause?

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

Muscular dystrophy cause and treatment?

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