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A/P > Lecture 10/9: Skeletal Muscle AP > Flashcards

Lecture 10/9: Skeletal Muscle AP Flashcards

Test 3

1
Q

Skeletal Muscle is ___% of our body mass

A

40%

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2
Q

Where is Glycogen stored?

A

Liver
Skeletal muscle

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3
Q

How is the skeletal muscle useful is defense?

A

Defense against cold temperatures. Acts an an insulator

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4
Q

What does the skeletal muscles store to use for energy?

A

Glycogen

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5
Q

What happens when the skeletal muscles need to use energy?

A

Stored glycogen is broken down into glucose

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6
Q

Describe glycogen

A

starch compound

glucose molecules stuck together in a chain

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7
Q

Skeletal muscles are ________ of the central nervous system

A

Effectors

Neutral targets

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8
Q

T/F: the skeletal muscle stores ions

A

T

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9
Q

What is a bone-bone connection?

A

Ligament

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10
Q

What are examples of liagments?

A

Patella
MCL
ACL

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11
Q

What is a muscle-bone connection?

A

Tendon

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12
Q

What is an example of a tendon?

A

Achilles

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13
Q

What is a muscle-muscle (“tendon bridge”) connection?

A

tendon

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14
Q

Another name for a skeletal muscle fiber is _____

A

Cell

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15
Q

What is a group of skeletal muscle cells?

A

Fasciculous

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16
Q

What is Fasciculous separated by?

A

Connective tissues

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17
Q

What is a group of Fasciculi?

A

Muscle

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18
Q

Fill in the blank:
Muscle -> _____ -> ______ -> ______ -> Sacromere

A

Fasciculous
Muscle cell
Myofibril

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19
Q

Where is actin and myosin located?

A

Inside the myofibiril

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20
Q

What is a myofibril?

A

Cylinder inside muscle fiber that contains actin and myosin

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21
Q

What is a sacromere?

A

functional/contractile unit of myofibril where actin/myosin overlap

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22
Q

What are the color differences when looking at a skeletal muscle under a microscope?

A

Thin (actin) and thick (myosin) filaments

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23
Q

What color is a thin filament?

A

Lighter color

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24
Q

What color is a thick filament?

A

darker color

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25
Q

Where in the sacromere do we have the ability to produce force?

A

Overlap of actin and myosin

A-zone

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26
Q

Define a motor unit

A

1 or more muscle cell/fibers that are controlled by ONE motor neuron

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27
Q

How many skeletal muscles can a motor neuron control?

A

1 - many

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28
Q

T/F: Small motor units activate 2nd

A

F

1st

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29
Q

Describe the difference between small muscles and large muscles

A

Small muscles: Easier to excite
– require less electrical activity
– activated 1st
– helps with fine motor skills

Large muscles: Activated 2nd if you need to produce more force
– requires more electrical activity
– harder to excite

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30
Q

How many myofibrils are in ONE regular muscle cell/fiber?

A

200

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31
Q

For stronger muscle cells, how many myofibrils can you have?

A

1000s

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32
Q

Muscles that have fewer myofibrils are normally used for what?

A

Fine motor skills
More precise movements

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33
Q

What gives Type 1 muscle its red color? Why?

A

Myoglobin

The iron in myoglobin gives off a red color

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34
Q

What is myoglobin?

A

Iron containing protein

helps O2 unload from blood to muscle to be used by mitochondria to make ATP

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35
Q

Describe type 1 muscle. Ex)

A

Produce slow, strong contractions that can be sustained a long time.

Red

-Lots of myoglobin and mitochondria

Ex) Geese breast

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36
Q

Describe type 2 muscle. Ex)

A

Can produce fast, strong contractions, but doesnt last long

White (lacks alots of myoglobin)

-very little myoblin/mitochondria

Ex) chicken breast

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37
Q

What type of muscle is the Ocular Muscles?

A

Type 2

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38
Q

What is the Soleus? What type of muslce is this?

A

Type 1

Cap muscle in the lower leg-helps with standing all day

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39
Q

What is the Gastrocnemius? What type of muscle is this?

A

Mixed Type 1 & 2 – Type 2 dominates

Located in leg next to soleus.

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40
Q

What type of muscles are mostly in our body?

A

Mixed Type 1&2

41
Q

Define: Sarcolemna

A

Cell wall of skeletal muscle

42
Q

Define: Sacroplasma

A

Fluid inside the muscle cell

43
Q

Where is the sacroplasmic reticulum located? Why?

A

Near the cell wall and Transverse tubules (T-tubules)

Close to the DHP voltage sensors used to open the Ca++ channel.

44
Q

What does the SR store?

A

Ca++

45
Q

What is striation? What are the muscles called?

A

Alternating color pattern when skeletal and cardiac muscle are stretched out.

Striad muscle

46
Q

What is thin filament?

A

Actin

47
Q

What is thick filament?

A

Myosin

48
Q

Contraction depends on the ______ of the sacromere

A

Shortening

49
Q

Anatomy: Sacromere

A

Z disc - z disc

50
Q

Anatomy: Z disc

A

End of the sacromere

Bundled up actin around each other

51
Q

Anatomy: I band

A

Only actin

light in color

52
Q

Anatomy: A band

A

Actin + Myosin

Darkest of bands (appears as a line)

Thin

53
Q

Anatomy: H band

A

Myosin only

Dark

54
Q

Anatomy: Titin

A

Elastic connective tissue protein

Anchors actin + myosin

Holds sacromere together and allows movement

55
Q

H =

A

myosin

56
Q

I =

A

actin

57
Q

A =

A

actin + myosin

58
Q

Which band needs space in order to produce a contraction?

A

I band

59
Q

What happens to the I band during a contraction?

A

Disappears

60
Q

T/F: A band allows actin/myosin to pull on each other closing the space in the I zone

A

T

61
Q

What happens to the H band during a contraction?

A

Disappears

62
Q

T/F: Myosin is very stretchable

A

F

Myosin has a fixed width

63
Q

What is the Sliding filament mechanism?

A

The processes of the lengthening and shortening of the sacromere resulting in reducing overall length of the muscle resulting in a muscle contraction

64
Q

Skeletal muscles can be very long. How do we repair damage and handle mechanisms down the cell?

A

The skeletal muscle cells are multinucleated to handle this.

65
Q

How do you identify the nuclei in skeletal muscles?

A

They are little purple dots under the microscope

66
Q

Describe how proteins get down a motor neuron?

A

There are some tracks

There is a cart

Load the proteins up in the cart. and roll them down the axon in the cart…….

67
Q

There are _____ myosin molecules in a myosin filament

A

200

68
Q

Each myosin molecule has ___ chains

A

6

69
Q

What are the 6 chains in a myosin molecule?

A

2 heavy chains in the tail
2 regulatory light chains
2 essential light chains

70
Q

What are the myosin heads?

A

The 2 essential light chains

71
Q

What are myosin filaments?

A

long strings of myosin molecules wrapped together at the tail

72
Q

Describe the tail of the myosin filament

A

2 heavy chains wrapped around each other

used to fasten to other myosin molecules

73
Q

Describe the regulatory light chain

A

Influences activity of the “head”

More active in smooth muscle than skeletal muscle

Things get phosphorylated here

74
Q

Where are the essential and regulatory light chains located?

A

essential is more towards the outside
regulatory is more inside

75
Q

What does the myosin head do?

A

“essential light chain”

-Posses ATP activity
- has binding site for F-actin

When it contracts -> pulls on actin inward -> shortens sacromere

76
Q

What does actin filaments consist of?

A

2 protein strands:
- F-actin
-Tropomyosin

77
Q

Describe the F-actin strand

A

Has the binding sites for the myosin heads

78
Q

Describe the tropomyosin strand

A

Functions as a shield

oriented in a way that myosin heads cannot see binding sites on F-actin strand

Has a troponin complex that allows the binding sites to be revealed

79
Q

What is a troponin complex?

A

3 proteins stuck together that when activated by Ca++, allows tropomyosin to unravel a bit and reveal the binding sites on F-actin

80
Q

What are the 3 proteins on the troponin complex?

A

Troponin I: binds to actin

Troponin T: binds to tropomyosin

Troponin C: has 4 Ca++ binding sites
– fastens I & T together
– twists to unravel tropomyosin

81
Q

What is the binding site for Ca++ in skeletal muscle?

A

Troponin C

82
Q

Describe a high energy myosin head

A

Resting state

ADP + Pi attached to head

loose spring (uncocked) – relaxed

83
Q

Describe a low energy myosin head

A

contraction

ATP will bind

tight spring (cocked) – tension

84
Q

What is required for a myosin head to be released from F-actin?

A

ATP

85
Q

What is Excitation-Contraction Coupling?

A

Turning an electrical event into an event that generates force

EPP –> AP

86
Q

What is the Ca++ channel called in the SR called?

A

Ryanodine receptor

87
Q

What is rigor mortis?

A

Stiffening of the muscles

ATP deficiency where myosin head cannot leave F-actin

88
Q

What happens within the sacromere if you run out of ATP?

A

Ability to produce force is limited

myosin head wont be released from F-actin

89
Q

Describe the Cross-bridge cycling process.

A
90
Q

What is passive tension?

A

“stretch”

outside force used to over/under stretch a sacromere

91
Q

What is active tension?

A

Muscle contraction from an AP

92
Q

What is total tension?

A

Passive + active tension

93
Q

The cardiac sacromere is naturally _________ specifically in the ventricular wall to pump blood

A

understretched

94
Q

_____ is the optimal stretch length for a sacromere

A

2 micrometers

95
Q

Over/under stretched sacromere =

A

less force in contraction

96
Q

What happens in the heart when the sacromere gets overstretched?

A

Less force produced in L ventricle –> Heart failure

97
Q

T/F: If there is no overlap in actin and myosin then there is no force produced?

A

T

98
Q

Where is your achilles tendon?

A

Back of heel

99
Q

Why is your gait not the same after an achilles tendon injury?

A

The Sx required cutting the and sewing the tendon. It will be shorter and not in the optimal stretch position.

Can use a cadavier to try to help prevent the shortening of tendon

A/P (26 decks)

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