Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HUBS191 > Skeletal Muscle > Flashcards

Skeletal Muscle Flashcards

Lecture 9

1
Q

A myofilament is primarily composed of

A

actin and myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Actin forms..

A

the thin filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Actin forms the thin filament, a …

A

structural scaffold that runs along the myofilament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Myosin forms the..

A

thick filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Function of myosin

A

Acts a motor molecule, attaching to actin and generating force to pull

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When does actin and myosin bind together

A

when calcium is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when calcium is present,

A

myosin and actin bind together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When actin and myosin bind together in the presence of calcium,

A

they form cross bridges and allow contraction to occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

1st step of cross bridge cycling

A

The myofilament has just finished a power stroke which is pulling on actin. Actin/myosin cross bridges are still present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

2nd part of cross bridge cycling

A

A molecule of ATP binds to the myosin, in preparation for releasing some energy to prime the myosin head.
The binding of ATP causes the myosin head to release actin… no more cross bridge!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

3rd part of cross bridge cycling

A

The myosin head burns the ATP to make energy (and some ADP waste). It stores the energy by changing the shape o the myosin, getting it ready to pull on actin again.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

4th part of cross bridge cycling

A

If calcium is present and bound to the myofilament, then it’s time for the next contraction. The energized myosin head can now bind to actin, forming a cross bridge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

last part of cross brideg cycling

A

There is now an energised myosin head attached to actin. The myosin uses its stored energy to pull, causing the actin filament to slide. The sacromere shortens,.. contraction has occurred.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Muscle tensions depends on what two things

A
  • The number of muscle fibres recruited
  • The rate at which the muscle is stimulated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Muscle tension: The number of fibres activated is regulated by..

A

how many neurons are active at one time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A small number of active neurons tends to produce low force from the muscle,

A

with the amount of force generally increasing as more neurons are activated.

17
Q

The process of activating more fibres to make more force is called…

A

recruitment

18
Q

Muscle tension - recruitment

A

The process of activating more fibres to make more force

19
Q

Many action potential fired in a rapid sequence results in…

A

a sustained release of calcium from the sarcoplasmic reticulum, a sustained period of actin-myosin interaction and a sustained period of contraction.

19
Q

Twitch

A

When a single action potential will result in a pulse of calcium release into the cytoplasm and a short period of tension development

20
Q

Tetanus

A

Happens when we reach maximal signalling and contraction capability of the muscle, at which point the force will platueau.

21
Q

Each muscle has an optimal length where…

A

it will be the strongest

22
Q

What happens when the muscle is either shorter or longer than its optimal length

A

It will be weaker

23
Q

What is the result of the changing overlap between the actin and myosin filaments

A

The length tension relationship where a muscle will have an optimal length where it is the strongest

24
Q

What happens when there is not enough and too much overlap between the actin and myosin filaments

A

There won’t be a lot of cross bridges. Too much and there would be no space left to contract.

25
Q

Fast fibres are mighty but…

A

fatigue quickly

26
Q

Slow fibres supply…

A

steady force and are slow to tire

27
Q

Fibre diameter of fast and slow fibres

A

Fast - large
Slow - small

28
Q

capillary supply of fast and slow fibres

A

Fast - few
Slow - many

29
Q

Mitochondria supply of fast and slow fibres

A

Fast - few
Slow - many

30
Q

colour of fast and slow fibres

A

Fast - white
Slow.- Red

31
Q

Fatigue resistance of fast and slow fibres

A

Fast - low
Slow - high

32
Q

time to peak tension of fast and slow fibres

A

Fast - fast
Slow - slow

33
Q

Explain how a contraction is produced

A

The myofilament proteins actin and myosin bind together when cellular calcium is high, creating cross bridges. Myosin then uses the energy liberated from ATP to pull on the actin filament, causing a contraction.

34
Q

Skeletal muscle force generation depends on…

A

the number of fibres that contract (recruitment) and the frequency of stimulation, up to a maximum possible force (tetanus)

35
Q

Muscles rich in fast fibres produce..

A

lots of force quickly thanks to their energy reserves, but they tire out quickly

36
Q

Slow fibres are able to generate a lot of energy even while working..

A

so they are difficult to fatigue.

HUBS191 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions