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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
Where in the sacromere do we have the ability to produce force?
Overlap of actin and myosin A-zone
26
Define a motor unit
1 or more muscle cell/fibers that are controlled by ONE motor neuron
27
How many skeletal muscles can a motor neuron control?
1 - many
28
T/F: Small motor units activate 2nd
F 1st
29
Describe the difference between small muscles and large muscles
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
30
How many myofibrils are in ONE regular muscle cell/fiber?
200
31
For stronger muscle cells, how many myofibrils can you have?
1000s
32
Muscles that have fewer myofibrils are normally used for what?
Fine motor skills More precise movements
33
What gives Type 1 muscle its red color? Why?
Myoglobin The iron in myoglobin gives off a red color
34
What is myoglobin?
Iron containing protein helps O2 unload from blood to muscle to be used by mitochondria to make ATP
35
Describe type 1 muscle. Ex)
Produce slow, strong contractions that can be sustained a long time. Red -Lots of myoglobin and mitochondria Ex) Geese breast
36
Describe type 2 muscle. Ex)
Can produce fast, strong contractions, but doesnt last long White (lacks alots of myoglobin) -very little myoblin/mitochondria Ex) chicken breast
37
What type of muscle is the Ocular Muscles?
Type 2
38
What is the Soleus? What type of muslce is this?
Type 1 Cap muscle in the lower leg-helps with standing all day
39
What is the Gastrocnemius? What type of muscle is this?
**Mixed Type 1 & 2 -- Type 2 dominates** Located in leg next to soleus.
40
What type of muscles are mostly in our body?
Mixed Type 1&2
41
Define: Sarcolemna
Cell wall of skeletal muscle
42
Define: Sacroplasma
Fluid inside the muscle cell
43
Where is the sacroplasmic reticulum located? Why?
Near the cell wall and Transverse tubules (T-tubules) Close to the DHP voltage sensors used to open the Ca++ channel.
44
What does the SR store?
Ca++
45
What is striation? What are the muscles called?
Alternating color pattern when skeletal and cardiac muscle are stretched out. Striad muscle
46
What is thin filament?
Actin
47
What is thick filament?
Myosin
48
Contraction depends on the ______ of the sacromere
Shortening
49
Anatomy: Sacromere
Z disc - z disc
50
Anatomy: Z disc
End of the sacromere Bundled up actin around each other
51
Anatomy: I band
Only actin light in color
52
Anatomy: A band
Actin + Myosin Darkest of bands (appears as a line) Thin
53
Anatomy: H band
Myosin only Dark
54
Anatomy: Titin
Elastic connective tissue protein Anchors actin + myosin Holds sacromere together and allows movement
55
H =
myosin
56
I =
actin
57
A =
actin + myosin
58
Which band needs space in order to produce a contraction?
I band
59
What happens to the I band during a contraction?
Disappears
60
T/F: A band allows actin/myosin to pull on each other closing the space in the I zone
T
61
What happens to the H band during a contraction?
Disappears
62
T/F: Myosin is very stretchable
F Myosin has a fixed width
63
What is the Sliding filament mechanism?
The processes of the lengthening and shortening of the sacromere resulting in reducing overall length of the muscle resulting in a muscle contraction
64
Skeletal muscles can be very long. How do we repair damage and handle mechanisms down the cell?
The skeletal muscle cells are multinucleated to handle this.
65
How do you identify the nuclei in skeletal muscles?
They are little purple dots under the microscope
66
Describe how proteins get down a motor neuron?
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
There are _____ myosin molecules in a myosin filament
200
68
Each myosin molecule has ___ chains
6
69
What are the 6 chains in a myosin molecule?
2 heavy chains in the tail 2 regulatory light chains 2 essential light chains
70
What are the myosin heads?
The 2 essential light chains
71
What are myosin filaments?
long strings of myosin molecules wrapped together at the tail
72
Describe the tail of the myosin filament
2 heavy chains wrapped around each other used to fasten to other myosin molecules
73
Describe the regulatory light chain
Influences activity of the "head" More active in smooth muscle than skeletal muscle Things get phosphorylated here
74
Where are the essential and regulatory light chains located?
essential is more towards the outside regulatory is more inside
75
What does the myosin head do?
"essential light chain" -Posses ATP activity - has binding site for F-actin When it contracts -> pulls on actin inward -> shortens sacromere
76
What does actin filaments consist of?
2 protein strands: - F-actin -Tropomyosin
77
Describe the F-actin strand
Has the binding sites for the myosin heads
78
Describe the tropomyosin strand
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
What is a troponin complex?
3 proteins stuck together that when activated by Ca++, allows tropomyosin to unravel a bit and reveal the binding sites on F-actin
80
What are the 3 proteins on the troponin complex?
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
What is the binding site for Ca++ in skeletal muscle?
Troponin C
82
Describe a high energy myosin head
Resting state ADP + Pi attached to head loose spring (uncocked) -- relaxed
83
Describe a low energy myosin head
contraction ATP will bind tight spring (cocked) -- tension
84
What is required for a myosin head to be released from F-actin?
ATP
85
What is Excitation-Contraction Coupling?
Turning an electrical event into an event that generates force EPP --> AP
86
What is the Ca++ channel called in the SR called?
Ryanodine receptor
87
What is rigor mortis?
Stiffening of the muscles ATP deficiency where myosin head cannot leave F-actin
88
What happens within the sacromere if you run out of ATP?
Ability to produce force is limited myosin head wont be released from F-actin
89
Describe the Cross-bridge cycling process.
90
What is passive tension?
"stretch" outside force used to over/under stretch a sacromere
91
What is active tension?
Muscle contraction from an AP
92
What is total tension?
Passive + active tension
93
The cardiac sacromere is naturally _________ specifically in the ventricular wall to pump blood
understretched
94
_____ is the optimal stretch length for a sacromere
2 micrometers
95
Over/under stretched sacromere =
less force in contraction
96
What happens in the heart when the sacromere gets overstretched?
Less force produced in L ventricle --> Heart failure
97
T/F: If there is no overlap in actin and myosin then there is no force produced?
T
98
Where is your achilles tendon?
Back of heel
99
Why is your gait not the same after an achilles tendon injury?
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 (33 decks)

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