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Module 1 vetmed > Skeletal muscle > Flashcards

Skeletal muscle Flashcards

1
Q

Features of skeletal muscle

A

Striated
Attached by bones
Support and movement of skeleton
Voluntary- somatic nervous system
Have multiple nuclei formed by fusion of mononuclear myoblasts in utero
All normal organelles and myofibrils

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2
Q

Transverse section looks like

A

Nuclei moved to the outside
Myofibrils- pink in histology

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3
Q

Longitudal section looks like

A

Peripheral nuclei
Striated
Long fibres
Limited CT between fibres

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4
Q

What are myofibrils made up of

A

Repeated sacromeres- made up of thin and thick filaments

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5
Q

What are thick filaments made up of

A

6 Myosin molecules

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6
Q

What is the structure of myosin

A

Two long proteins twist to form tail of myosin molecule and two globular proteins

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7
Q

How is myosin arranged

A

Tails together with heads popping out at right angles which fixes them in place

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8
Q

Is a structural protein in different orientation

A

Yes

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9
Q

What is M line

A

Where base of muscle is

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10
Q

What is A band

A

Total length covered by two of our thick filaments

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11
Q

What are thin filaments made out of

A

Actin molecules

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12
Q

How are thin filaments structured

A

Arranged in long chain
Wrap them around each other to form a helix
Wrapped around actin molecule is tropmyosin molecule and holding tropomysoin is troponin molecule

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13
Q

What molecule determines the set length

A

Actin

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14
Q

What is Z line

A

When actin molecule is attached to structural protein

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15
Q

Where is the myosin binding site

A

In the actin molecule.
The binding site is covered in troponin molecule attached to structural protein which leads to Z line.

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16
Q

What causes the stripy appearance of muscle

A

The rise of Z line as thick and thin filaments overlap

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17
Q

Where do repeated sacromeres run

A

Along the Longitudal axis

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18
Q

How do we contract the muscle

A

Change amount of overlapping by moving thick and thin filaments relative to each other

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19
Q

What decreases M and Z line distance

A

Contracting of the muscle

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20
Q

What is A band

A

Overall length of thick filaments- not going to change

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21
Q

What is H zone

A

Where there are only thick filaments and no thin filaments

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22
Q

Does H zone decrease when muscles are contracting

A

Yes because greater degree of overlap is occurring

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23
Q

What is I band

A

Where there is only thin filaments and no thick filaments

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24
Q

What is the sacromere

A

Difference between two Z lines
When you contract muscle it only shortens in one direction

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25
What does Cross bridge cycling require
Requires use of myosin head and thin filament
26
What is in the myosin head
Actin binding site ATP binding site ATPase activity
27
What happens to myosin head in resting state
ATP will bind to myosin and activate the myosin. Splits ATP to ADP
28
What happens when the myosin is activated
A cross bridge will be formed
29
What is a cross bridge
Physical link between the mysoin head and thin filament
30
What happens when actin binds to myosin head
Change in shape of myosin head and releases ADP and phosphate but also changes orientation of myosin head relative to the tail and causes it to bend.
31
How can ATP bind to myosin heads
Open binding site for ATP to bind to myosin head as ADP has moved across. So this causes cross bridges to break and will revert back to vertical position.
32
Pathway of cross bridge cycling
ATP binds Forms cross bridge Bends ATP binds again Breaks cross bridge Back to vertical position Forms New Cross bridge Binds again
33
What causes rigamortous
No ATP to break cross bridges, so muscle becomes rigid as thick and thin filaments are held relative to each other
34
What causes falccidity
Eventually the body will use up ATP and cross bridging will break causing flaccidity
35
Why does the myosin binding site need to be inhibited
ATP is always present so constant binding and rigidity would occur
36
There are three troponin binding sites, what are they?
Tropmyosin molecule Actin binding site Calcium binding site
37
At resting is the calcium binding site in troponin occupied
No it is not
38
What happens if we increase amount of intracellular calcium
Calcium will bind to that binding site and will change shape of the troponin molecule and cause the tropomyosin to swing away from the myosin binding site. So this forms ability to make cross bridges
39
What can we regulate the contraction of the muscle with
Concentration of intracellular calcium levels
40
What is a sacroplasmic reticulum
A bag like structure Contains vast quantities of calcium- calcium store Has voltage gated calcium channels on the surface
41
What happens when an AP passes along the sacroplasmic reticulum
Opening of calcium voltage gated channel and calcium will flow out out of sacroplasmic reticulum and into the cell cytoplasm
42
Why does calcium need reuptake
So there isn’t consistent contraction
43
How do we bring about calcium reuptake
Calcium ATPase pump If there is a defect in this pump then there is constant rigidity
44
Lag time
When it takes a while for calcium to be released and be repackaged.
45
Isotonic contraction
Tension within muscle does not change- shorten the muscle due to cross bridge cycling
46
Isometric contraction
Muscle is held in position were it can’t physically shorten, creating more cross bridges- no movement of filaments- more tension
47
Tetanic contraction
Lots of twitches summed together
48
Length tension relationship
Amount of tension we can generate in the muscle changes with the length of the muscle when we send an electrical signal to it
49
Maximum tension
Maximum overlap of thick and thin filaments- optimal length
50
What happens if we stretch the muscle to the point were our thin filament are no longer in contact with our thick filament
Generate no tension No cross bridge cycling occurs
51
Resting length is
The optimal length
52
How do we get ATP
Free ATP Create ATP- Creatine phosphate and ADP Break down food stuff by aerobic glycolysis
53
What is myoglobin
Oxygen store in muscle cells
54
What are the three types of skeletal muscle
Slow oxidative Fast oxidative Fast glycolysis
55
Tension developed by each fibre is formed by
Action potiential frequency Fibre length Fibre diameter Fatigue
56
If you induce more fibres to contract what happens
Bigger twitch
57
What fibres is small tension related to
Slow oxidative
58
What fibres is medium tension related to
Fast oxidative
59
What fibres is large tension related to
Fast glycolysis
60
If you want a fine movement
One motor unit

Module 1 vetmed (22 decks)

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