EX1; Skeletal Muscle Flashcards Preview

AU14 Physiology > EX1; Skeletal Muscle > Flashcards

Flashcards in EX1; Skeletal Muscle Deck (74):
1

What is the organization of the skeletal muscle (7)

whole muscle
fascicle
muscle fiber (cell)
myofibril
sarcomere
filament
protein

2

What is the shape of actin molecules

Two intertwined helical chains of actin molecules (like pearls)

3

These two things are found on the actin chains

troponin
tropomyosin

4

Troponin comprised of what three subunits

TnC (calcium)
TnI (inhibits muscle function)
TnT (binds tropomyosin)

5

Troponin also contains what specific site

Ca binding site

6

A troponin is found every how many actin molecules

7

7

What is the structure of the myosin filament

2 pairs light chains per myosin
2 heavy chains

8

What is the orientation of the cross bridges of the myosin filament

opposite for the left and right
heads away from the center, tails toward

9

This represents the same protein but slightly different amino acid sequence; similar function

isoform

10

True or False
You are born with all your muscle cells, they just undergo isoform changes

True

11

This is the functional unit of the contractile apparatus, which can shorten and generate force

sarcomere

12

What three things compose the sarcomere

thick filaments, thin filaments, and Z-lines (or Z disks)

13

True or False
There is one sarcomere to one muscle cell

False; there are many sarcomeres in every muscle cell

14

This anchors the thin filaments

Z line

15

This large protein extends from Z line to the thick filaments, aiding the thick filaments to remain in the center of the sarcomere

titan

16

This is a thin filament protein; possibly a molecular ruler to determine filament length

nebulin

17

True or False
A major difference between skeletal and cardiac muscle is that cardiac muscle does not contain nebulin

True

18

This is the mechanism by which AP in sarcolemma initiates muscle contraction

excitation-contraction coupling

19

This ion plays a pivotal role in the activation of skeletal muscle

calcium

20

What is the design of the excitation contraction coupling

toward achieving a rapid and very large increase in the free calcium ion concentration inside muscle cells

21

This binds Ca ions in the lateral sacs

calsequestrin

22

Ca is pumped here before it diffuses into the lateral sac

fenestrated collar

23

The lateral sacs and the fenestrated collar are found where

in the sarcoplasmic reticulum

24

Ca ions are released from the lateral sacs of the SR to initiate what

contraction

25

Ca ions re sequestered by the fenestrated collar of the SR to cause what

relaxation

26

What is used to transport Ca in and out of the SR

Ca-ATPase pump

27

This moves deeper into the actin groove upon the introduction of calcium to expose the myosin binding sites on actin

tropomyosin

28

This states that muscles shorten by a relative sliding of thick and thin filaments; the filaments do not change in length

sliding filament theory

29

Using the cross bridge theory; thick and thin filaments are or are not connected at rest

they are NOT

30

These form between the two types of filaments following an increase in free Ca

cross-links (cross-bridges)

31

What two things constitute a cross bridge

actin and myosin

32

Which one, actin or myosin, regulates the cross bridge cycle

myosin
the light chain actin are modulatory

33

What is the first step of the cross bridge theory

cross bridge binds to actin

34

Upon the cross bridge binding to actin, what then happens

the power stroke; cross bridge moves (z-line decrease) release of ADP and P

35

When ADP and P is released during the movement of the power stroke, what happens to the myosin

it undergoes a conformational change

36

What binds to the myosin causing the cross bridge to detach

ATP

37

What energizes the cross bridge

the hydrolysis of ATP

38

The energized cross bridge then does what

bind to actin, and the cycle repeats again and again

39

The amount of force generated is proportional to what

the number of attached cross bridges

40

The rate of the cross bridge cycle determines the rate (velocity) of what

muscle shortening; different types of myosin go through the cycle at different rates

41

True or False
muscle shortening and force generation are energy-consuming events

True

42

The source of energy for force generation and muscle shortening is what

ATP

43

Why is there no change in ATP during muscle contraction

phosocrestine buffering

44

Where in the sarcomere is the creatine kinase found; of which deals with ATP and phosphocreatine

at the M line; right in the center of energy consumption

45

How much ATP is consumed per cross bridge

one cross bridge = one ATP

46

What are the consumers of ATP and how much ATP do they consume

myosin ATPase; contraction (70)
Ca ATPase; relaxation (30)

47

This is a fundamental property of striated muscle that reflects the arrangement and length of thick and thin filaments

length-tension relationship

48

The amount of tension (force) that a muscle can generate when it is activated is dependent upon what

its length

49

This states that a muscle can shorten at a higher velocity when moving a lighter load

load-velocity (force-velocity) relationship

50

What does the load-velocity relationship show us about the cross bridge cycle

the cross bridge cycle to cause shortening since the rate of cycling determines shortening velocity

51

Velocity of skeletal-muscle fiber shortening and lengthening is a function of what

load

52

Generally in mammalian muscles, the amount of ten sun generated by a muscle, per unit of cross-sectional area, is fairly consistent, this shows us what

the difference in the power generated by different muscles is determined mainly by the speed (velocity) of contraction

53

What is different about the latent period when comparing moving a light, intermediate or heavy load

the latent period is longer for heavier loads because you need to build up enough energy to move said load

54

A single muscle is composed of an assembly of this; a single motor neuron and all of the muscle fibers it innervates

motor units

55

True or False
most muscle fibers have one NMJ and are innervated by a single motoneuron

True

56

True or False
Motoneurons can innervate more than one muscle fiber

True

57

How many different muscle fibers can be controlled by a single motor unit

it varies from 100 in muscles controlling fine movement and up to 2,000 muscle fibers in large muscles of the leg

58

What three things can each muscle fiber type be distinguished from other types by

structural, biochemical, and physiological

59

True or False
The types of fibers comprising a muscle are developed from birth and are unchanging

False; they may change during developments, some disease, and in some cases following exercise training

60

What two classifications are used in distinguishing muscle fibers

fast or slow

61

Which fiber, fast or slow has smaller neuromuscular junctions

slow

62

Which fiber, fast or slow are larger in diameter

fast

63

Which fiber, fast or slow contains different sarcomere protein isoforms

slow

64

Which fiber, fast or slow are more fatigue resistant

slow

65

Which fibers, IIA or IIB are smaller

IIA

66

Which fibers, IIA or IIB depends more on an oxidative metabolism

IIA

67

Which fibers, IIA or IIB are less fatigable and contract a little slower

IIA

68

Which fibers, IIA or IIB depends more on glycolytic metabolism

IIB

69

Muscles that are utilized for maintaining posture have a high proportion of what fibers

type I

70

Muscles that are utilized to perform tasks rapidly and with a lot of dexterity contain primarily which fibers

type II

71

This type II fiber are faster and generate more power but are less efficient

IIB

72

Which fibers are most efficient overall (among skeletal fiber types)

type I

73

What are 5 systemic disorders are associated with muscle cramps

dehydration
metabolic; low sodium, magnesium, ca, glucose, potassium
endocrine; thyroid, adrenal insufficiency
pregnancy
drugs and toxins

74

This is a deficiency or defect in dystrophin; links cytoskeletal (structural) proteins to membrane leading to membrane tears and weakness in skeletal and cardiac muscle

muscular dystrophy