Brainscape's Knowledge GenomeTM

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


See full index

KES 344 Musculoskeletal Physiology > Exam #3 first part > Flashcards

Exam #3 first part Flashcards

1
Q

What are muscle fibers?

A

Highly specialized cylindrical cells

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

What determines the strength of muscle fibers?

A

The diameter of the fibers

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

What determines the length of muscle fibers?

A

Length is highly variable and depends on functional architecture (demands)

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

What are the different fiber organizations?

A

Longitudinal: Run in straight lines (biceps)
Pennate: Run diagonally (vastus lateralis)
Multipennate: Run diagonally in different directions (gluteus medius)

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

Where do skeletal muscles attach and how?

A

Skeletal muscles attach to bones via tendons

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

What is basal lamina?

A

The scaffolding that surrounds muscle cell

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

What is endomysium?

A

The collagenous mesh-like tissue that surrounds fiber and basal lamina

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

What is the perimysium?

A

The membrane that surrounds organized bunches of muscle fibers called fascicles

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

What is the epimysium?

A

The membrane that surrounds bundles of fascicles for actual muscles

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

What part of them muscle feels pain?

A

Pain receptors are located in the membrane, the membrane and connective tissue feels the pain, not the muscle fibers

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

What organelles are responsible for the day-to-day needs of the muscle cells?

A

Nuclei (multiple nuclei per muscle cells)

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

What is the purpose of the many nuclei in muscle cells?

A

To regulate protein synthesis (up regulate under stress and use, down regulate under immobilization or lack of use)

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

What does the endoplasmic reticulum do for muscle cells?

A

It is responsible for transporting cellular materials outside the cell
Since the muscle manufactures components for its local use, the ER is not well developed
The Ribosomes are associated with the ER

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

What do the ribosomes do for the muscle cells?

A

They synthesize muscle proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do mitochondria do for the muscles?

A

Source for aerobic energy (production of ATP)

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

How are mitochondria distributed in the muscle cells?

A

Type I: >20%

Type II: <20%

17
Q

What is a neuromuscular junction?

A

Comprised of a motor end-plate
A chemical neurotransmitter is used to convey information from the nerve (presynaptic) to the junctional receptors of the muscle (postsynaptic) across a synaptic cleft

18
Q

What are junctional receptors?

A

Specific proteins that integrate themselves into the sarcolemma

19
Q

How are neuromuscular junctions formed?

A

During development, the nerve contracts the muscle fiber. Due to the contact, ACh receptors are attracted to the site of contact and become trapped by the nerve.
The result in decreasing the number of ACh receptors along the rest of the fiber, only having receptors at the location of contact.

20
Q

How do the mechanism of the down regulation and supercompensation occur?

A

Down regulation: due to lack of use, the number of ACh receptors at the NMJ are reduced
Supercomprensation: due to repeated use and stimulation, the number of ACh receptors at theNML are increased

21
Q

What are myofibrils?

A

Small filaments (1 micrometer) that are bound together to form a muscle fiber. Arranged in parallel.

22
Q

What is a sarcomere?

A

Subunits of myofibrils (means muscle segment)
Arranged in series.
The interdigitation pattern gives skeletal muscle its striated appearance

23
Q

What is a motor unit?

A

Comprised of one motor neuron and all the muscle fiber that it innervates
The number of fibers the neuron innervate varies

24
Q

How are the movements generated by the motor units determined?

A

Fewer muscle fibers innervated by the motor neuron = finer but weaker movement
More muscle fiber innervated by the motor neuron = stronger but lesser coordinated movements

25
Q

What defines a sarcomere length?

A

The area between the two Z-disks

26
Q

What is the average sarcomere length at rest?

A

2.2 micrometers long

27
Q

What compound within the myofibrils enables the stretch-shortening property of muscle?

A

Titin protein

28
Q

What allows the mechanism of hypertrophy?

A

Increase in number of myofibrils leads to an increase in size of the muscle fibers, causing larger muscle belly. Muscle fibers do not increase in number.

29
Q

What allows the mechanism of hypertrophy?

A

Increase in number of myofibrils leads to an increase in size of the muscle fibers, causing larger muscle belly. Muscle fibers do not increase in number.

30
Q

What is myosin filament?

A

A polymer of myosin molecules

31
Q

What is a myosin molecule?

A

Highly asymmetric molecules
One end is globular “motor” domain (head) which powers muscle contraction: HMM
Other end is rod-like “tail” permitting multiple molecules to assemble into the thick filament: LMM

32
Q

What are HMM made up of?

A

HMM (the heavy chain) is made up of 2 subfragments (S-1 and S-2)
S-1 is the globular head (cross bridge)

33
Q

How is actin structured?

A

Long alpha-helical arrangement of actin monomers with no middle section
In has a + and - end based on the direction of polymerization

34
Q

How is actin structured?

A

Long alpha-helical arrangement of actin monomers with no middle section
In has a + and - end based on the direction of polymerization

35
Q

What is special about the helical shape of Actin?

A

A groove is created by the groove, and the regulatory protein tropomyosin fits nicely in the groove

36
Q

What is troponin?

A 
A protein along the tropomyosin string
Comprised of three subunits
Tn-T: Binds troponin to tropomyosin
Tn-C: Binds calcium during contraction
Tn-I: Exerts an inhibitory influence on tropomyosin when calcium is not present
37
Q

What are the steps in the power stroke contraction?

A
  1. Binding: myosin cross bridge binds to actin molecule
  2. Power stroke: Cross bridge bends, pulling thin myofilament inwards
  3. Detachment: Cross bridge detaches at the end of the power stroke and returns to original conformation
  4. Binding: Cross bridge binds to more distal actin molecule; cycle repeats

KES 344 Musculoskeletal Physiology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions