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A&P Exam III > Skeletal Muscle > Flashcards

Skeletal Muscle Flashcards

1
Q

Largest contributor to body weight and volume in non-obese people

A

Skeletal muscle

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2
Q

What does the skeletal muscle store for energy

A

Glycogen

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3
Q

How does skeletal muscle absorb glucose

A

GLUT-4

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4
Q

What happens if we are given too much insulin

A

It is absorbed and stored by the skeletal muscle

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5
Q

What is one of the ways the body maintains body temp

A

Basal Resting Tone - Micro contractions by the skeletal muscle. These contractions produce heat to maintain our body temp

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6
Q

Example of fine skeletal muscle control

A

Vocal cords

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7
Q

What do ligaments attach and give an example

A

Bone to bone
Patellar/ACL/MCL

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8
Q

What do tendons attach and give an example

A

Bone to muscle
Achilles

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9
Q

How sturdy are tendons and ligaments

A

Both strong and durable unless overly exerted

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10
Q

List the anatomy of a muscle from largest to smallest

A
  1. Muscle
  2. Fasciculous
  3. Muscle fiber (cell)
  4. Myofibril
  5. Sarcomere
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11
Q

What is the fasciculous composed of

A

A group of muscle fibers (cells)

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12
Q

What is a motor unit comprised of

A
  1. Collection of muscle fibers
  2. Motor neuron
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13
Q

What is graded movements

A

The ability to provide different amounts of force utilizing smaller MU’s and larger MU’s

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14
Q

Are smaller MU’s or larger MU’s easier to excite

A

smaller

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15
Q

What does myoglobin do

A

Takes O2 from hemoglobin and helps load it into muscle cells

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16
Q

Difference between Type 1 and Type 2 skeletal muscle

A
  1. Type 1 - “Red” “Slow”, lots of myoglobin, lots of mitochondria due to needing energy over a long period of time (Duck meat) Red due to high amounts of iron
  2. Type 2 - “White” “Fast Twitch”, very little myoglobin, fewer mitochondria. Not as efficient at using energy. (Chicken breast, wings)
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17
Q

Why should we eat red meat in moderation

A

Lots of iron, which is an oxidizer and increases incidences of cancers

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18
Q

Difference between mens and womens multivitamins

A

Mens usually do not have iron

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19
Q

What does the blue line represent

A

Duration of depolarization

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20
Q

What is the sarcolemma

A

Outer membrane of skeletal muscle

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21
Q

What is the sarcoplasm

A

Fluid under the cell wall (sarcolemma)

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22
Q

What is the sarcoplasmic reticulum

A

Where calcium is stored, also produces lipids and proteins. (ER of the sarcomere)

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23
Q

What are the transverse tubules

A

A channel that helps an action potential to run through the muscle fibers

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24
Q

Functional unit of the skeletal muscle

A

Sarcomere

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25
Q

Thick part of the sarcomere

A

Myosin filament

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26
Q

Thin part of the sarcomere

A

Actin filament

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27
Q

What makes parts of the sarcomere lighter or darker

A

The presence of myosin makes sections darker

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28
Q

What does the Z disk signify

A

The end of the sarcomere

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29
Q

What is the I band composed of

A

Only actin

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30
Q

What is the A band composed of

A

Actin and myosin

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31
Q

What is the H band composed of

A

Only myosin

32
Q

What is the M line

A

Middle of the H band

33
Q

On a basic level, what is a skeletal muscle contraction

A

Myosin will use its head to pull the I band towards the A band
I band gets smaller, A band stays the same length

34
Q

What happens to each part during contraction

  1. A band
  2. I band
  3. H band
  4. Z disks
A
  1. Usually doesn’t change width during contraction
  2. Shrinks
  3. Move closer together
35
Q

How are skeletal muscle nuclei different from other nuclei

A

There are multiple nuclei in each cell. This is due to the length of the cells themselves and the density, making it difficult for nuclei to travel to areas that need repair.
Compared to neuronal nuclei that can move more freely.

36
Q

What do myosin heads bind to

A

F-actin

37
Q

How many myosin light chains for every heavy chain

A

2

38
Q

What are myosin thick filaments composed of

A

2 heavy myosin chains wrapped around eachother, both with 2 myosin light chains (4 in total)

39
Q

Where do myosin heads bind on actin

A

Active sites

40
Q

What is F-actin entwined with

A

Tropomyosin

41
Q

What does tropomyosin do

A

Blocks active sites on F-actin

42
Q

How are F-actin active sites exposed

A

Ca++ bathes the actin filament, which binds Troponin C.
Troponin T (which is bound to tropomyosin) and Troponin I (which is bound to F-actin), then move away from eachother causing F-actin and tropomyosin to unwind enough to expose the active site

43
Q

What are troponin complexes

A

Troponin C
Troponin T
Troponin I

44
Q

Explain cross bridge cycling

A
  1. The myosin head is bound by phosphate and ADP. It is “cocked” and in its resting state
  2. Ca++ causes the active site to be exposed and the myosin head attaches itself (weak corrs bridge state)
  3. The phosphate then leaves the myosin head causing a stronger bond of the myosin head to the active site (strong cross bridge state)
  4. ADP then leaves the myosin head causing it to pull the actin filament (post powerstroke state)
  5. At this point the myosin head is in an (attached state) until ATP comes and binds to the myosin head causing it to release
  6. The ATP is hydrolized to ADP and phosphate which reprimes the myosin head to its cocked state
45
Q

What is rigamortus caused by (not just death)

A

Depletion of ATP, myosin heads can’t release from actin

46
Q

Another name for terminal schwann cells

A

Teloglial cell

47
Q

How many muscle cells can a single motor neuron connect to

A

One or many

48
Q

What is the purpose of subneural clefts

A

Allows more surface area for ion channels on the post synaptic cell

49
Q

How do the pre and post synaptic cells deal with high energy consumption

A

A lot of mitochrondria on both ends

50
Q

What type of channels are deep inside the subneural cleft

A

V-G Na+ channels

51
Q

What are some safety mechanisms in the motor unit and what are they for

A
  1. Excess AcH is released, much more than needed
  2. Typically only 10% of V-G Na+ channels are activated, the other 90% are in reserve
  3. These ensure that the muscle cell is being activated
52
Q

Name the subunits of a “mature” nicotinic ACh receptor

A

2 Alpha subunits
1 Beta subunit
1 Delta subunit
1 Epsilon subunit

53
Q

What ions move through Nicotinic ACh receptors

A

Primary - Na+
Ca++ not as easily (larger)
K+ moves out of cell (not a significant amount)

54
Q

Why do negative ions not move through nicotinic ACh receptors

A

Negatively charged amino acids in the wall of the channel that repel negatively charged ions

55
Q

Smooth/cardiac muscle vs skeletal muscle on calcium

A

Smooth muscle and cardiac muscle are more dependent on blood calcium
Skeletal muscle produces its own calcium through SR

56
Q

Name for calcium release channels

A

Ryanodine receptors (RyR1)

57
Q

What is a DHP receptor

A

Receptor in cleft that will sense an action potential and signal the SR to release calcium.

58
Q

How is calcium reabsorbed into the SR

A

SR endoplasmic reticulum calcium ATPase (SERCA)

59
Q

What stores and binds calcium in the SR

A

Calsequestrin

60
Q

Why is calcequestrin important

A

More Ca++ bound to it means more Ca++ out of SR solution which allows more Ca++ to enter the SR at a time

61
Q

Explain E-C Coupling

A
  1. Motor neuron depolarizes
  2. Ca++ influx into motor neuron
  3. ACh vessicles fuse to presynaptic membrane
  4. ACh secreted by presynaptic neuron
  5. ACh interacts with nACh receptors
  6. Na+ comes in (1st) Ca++ comes in (2nd)
  7. Na+ and Ca++ influx generates end plate potential
  8. Local depolarization
  9. AP spreads down muscle fibers in both directions
  10. Action potential spreads via V-G Na+ channels, including down T-tubules
  11. Muscle depolarization sensed by DHP receptors
  12. DHP pulls on ryanodine receptors
  13. Ca++ influx into SR
62
Q

List AChesterase inhibitors

A

Neostigmine, pyridostigmine, physostigmine

63
Q

What is an important component of tension

A

An optimal amount of stretch

64
Q

What do A, B, C, and D tell us

A

A. No room to shorten
B. Optimal
C. Optimal
D. Too stretched out

65
Q

Give an example of how an injury affects muscles ability to contract

A

Achiles tendon rupture
Gastrocnemius rolls up and loses all stretch. So no ability to contract.
Even after repair the tendon will be shortened which will have a chronic affect on function

66
Q

Explain Frank-Starling mechanism

A

Force of contraction is directly dependent on stretch of heart muscle
or
CO directly proportional to venous return

67
Q

Passive tension =

A

Stretch

68
Q

Active tension =

A

Muscle contraction

69
Q

Total tension =

A

Active tension + passive tension

70
Q

Where does passive tension come from

A

Tendons

71
Q

How do load and contraction velocity correlate

A

Increased load = decreased muscle contraction speed

72
Q

What is tettany

A

Constant strong contractions

73
Q

Atrophy

A

Loss of skeletal muscle cells. Hard to regenerate muscle cells

74
Q

Hypertrophy

A

Increased myofibrils over time

75
Q

In hypertrophy what differs between myofibrils and skeletal muscle cells

A

Skeletal muscle cells do not typically duplicate or do so very slowly

Myofibril duplication is what adds muscle mass

76
Q

What is hyperplasia

A

Replication of actual muscle cells (usually requires specific drugs)

A&P Exam III (3 decks)

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