A&P: Muscular System Flashcards

1
Q

List the 5 functions of the Muscular System

A

MMMSG

  • Movement
  • Maintain posture/body position
  • Maintain body temp
  • Support soft tissue
  • Guard entrances and exits (ex: Sphincters)
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2
Q

Cardiac muscle is composed of ______ cells called ______ that are joined together by _______ ________

A

individual
cardiomyocytes
intercalated disks

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3
Q

What is the main function of intercalated disks in cardiac muscle?

A

they are gap junctions which allow electrical impulses to travel to each cariomyocyte in order to contract in sync

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4
Q

List 3 types of muscle

A

Skeletal Muscle
Cardiac Muscle
Smooth Muscle

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5
Q

Explain why cardiac muscle cells, unlike skeletal muscle cells, do not get fatigued

A

Cardiac muscle cells have more mitochondria compared to skeletal muscle cells, so they rely exclusivley on aerobic respiration to generate energy (aerobic respiration = LOTS ATP MADE)

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6
Q

Compare the 3 muscle types: Skeletal, Cardiac, and Smooth muscle

Include: Cell/Fiber Shape, Number of nuclei, Presence of Striations, Control)

A

Skeletal Muscle:

Cell/Fiber Shape

  • Tubular

Number of nuclei

  • Multinucleated

Presence of Striations

  • Striated

Control

  • Voluntary

Cardiac Muscle:

Cell/Fiber Shape

  • Branches

Number of nuclei

  • Uninucleated

Presence of Striations

  • Striated (intercalated disks)

Control

  • Involuntary

Smooth Muscle:

Cell/Fiber Shape

  • Spindle-shaped

Number of nuclei

  • Uninucleated

Presence of Striations

  • Non-striated

Control

  • Involuntary
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7
Q

List the skeletal muscle organization from largest to smallest. Include which structures are covered by what type of fascia.

A
  • Skeletal Muscle (Epimysium)
    -> Muscle Fascicle (Perimysium)
    Muscle fiber/cell (Endomysium)
    -»> Myofibrils
    -»» Myofilaments - arranged into Sarcomeres
    -»»> Actin (thin filament)
    -»»> Myosin (thick filament)
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8
Q

What type of fascia ties adjacent muscle fibers together?

A

Endomysium

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9
Q

At the end of each muscle, the _____ fibers of all three layers come together to form a bundle called a ______

A

collagen
tendon

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10
Q

Tendons are bands of ____ fibers that attach muscle to the _____ of bone

A

collagen
periosteum

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11
Q

What is defined at the cell membrane of a muscle fiber?

A

sarcolemma

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12
Q

What is defined at the cytoplasms of a muscle fiber?

A

sarcoplasma

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13
Q

What is the sarcoplasmic reticulum?

A

It is the ER of a muscle fiber that stores Calcium during relaxation (also releases Calcium into sarcoplasma when stimulated by an AP)

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14
Q

What is the structural and functional unit of skeletal muscle?

A

sarcomere

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15
Q

What two proteins make up the sarcomere?

A

actin
myosin

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16
Q

What do a narrow network of tubules, T-tubules, allow for?

A

T-tubules allow for an AP to move through the skeletal muscle cell/fiber

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17
Q

How does the distance between Z lines change during muscle contraction?

A

Distance between Z lines/disks are reduced

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18
Q

Does the H zone change during muscle contraction? If yes, how so?

A

Yes, H zone consists of 100% myosin, so when actin gets pulled towards the M line, there is more overlap between myosin and actin. Therefore, the H band will shorten.

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19
Q

Does the A band change during muscle contraction? If yes, how so?

A

No, the A band measures the entire length of mysoin. When muscle contracts, the length of the sarcomere will shorten BUT the length of the filaments (actin and myosin) do NOT change. Therefore, the A band remains the same length during muscle contraction.

20
Q

Be able to draw a complete sarcomere with appropriate disks/bands. Label each disk/band

A

check answer in Muscular System notes

21
Q

Know what each of these bands measure/fxn:

M line
H band
A band
I Band
Z disks

A
  • M line: anchors down myosin
  • H band: measures 100% myosin; NO overlap
  • A band: measures entire length of myosin; varying overlap with actin
  • I band: measures 100% actin; bisected by Z disks
  • Z disks: bisects I band
22
Q

What is the region where the end of a neuron meets a muscle fiber

A

neuromusclular junction

23
Q

Which neurotransmitter triggers contraction?

A

Acetylcholine (ACh)

24
Q

The permeability of ____ ions on the muscles surface at the NMJ changes when ACh is released into the synapse.

A

Sodium (Na+)

25
Q

Explain how a muscle contraction occurs. If it helps, draw it out. Include information about the sliding filament theory.

A

1) AP reaches axon terminal of motor neuron
2) ACh released into NMJ
3) ACh binds to receptor on sarcolemma of skeletal muscle cell
4) Na+ diffuses into skeletal muscle cell -> more Na+ diffuses in = skeletal muscle cell AP STARTS
5) AP travels along sarcolemma down to the T tubules
6) AP activated receptors on T tubules and extracellular Ca2+ diffuses in -> intracellular Ca2+ increases
7) Coupled receptor on SR membrane stimulated to release Ca2+
8) Ca2+ diffuses out of SR and into sarcoplasma (process known as Ca2+ induced Ca2+ released mechanism)
9) Ca2+ that was released from the SR (intracellular) will bind to troponin and initiates contraction (sliding filament theory)

CA2+ USED FOR CONTRACTION COMES FROM SR NOT EXTRACELLULARLY

10) Ca2+ binds to troponin (which sits on top of tropomyosin)
11) Triggers shift in position of tropomyosin to expose myosin binding sites on actin
12) ADP + Pi = will attach to actin -> Pi falls off from myosin head = power stroke = muscle contraction

26
Q

What enzyme will be present in the NMJ when a signal from a motor neuron ends? (Hint: What would stop a muscle contraction)

A

Acetylcholinesterase, so that it can degrade/break down ACh in the synapse to stop muscle contraction

27
Q

Define a motor unit

A

all of the muscle fiber controlled by a single motor neuron

28
Q

Describe the relationship between the size of a motor neuron and control of movement

A

If a motor neuron controls a SMALL amount of muscle fibers = precise movement
Ex: eye movement

If a motor neuron control a LARGE amount of muscle fibers = movement does not need to be as precise
Ex: leg muscles

29
Q

Define muscle tone

A

resting tension of skeletal muscle (contractions dont cause enough for movement)

30
Q

Define: Atrophy

A

Decrease in muscles mass, size, and strength that occurs when they arent used

31
Q

What are isotonic contractions?

A

Muscular contraction that changes muscle length

32
Q

What are the two types of isotonic contractions? How do they differ? Include example

A

Concentric: contraction that shortens a muscle (Ex: lifting object off the desk/bicep curl)

Eccentric: contration where the muscle length increases (Ex: lower bicep curl)

33
Q

What is isometric contraction?
Include example

A

Muscle tension increases by the muscle does not change length
(Ex: Plank)

34
Q

What type of contraction is important for maintaining posture, standing, sitting?

A

Isometric contraction

35
Q

Compare and Contrast the differece between fast fibers and slow fibers. Include: Time for contraction, number of mitrochondria, endurance.

A

Fast Fibers

Time For Contraction:
- Contract VERY quickly

Number of Mitochondria
- Fewer mitochondria

Endurance:
- Fatigue

Slow Fibers

Time For Contraction:
- Contract VERY slowly

Number of Mitochondria
- More mitochondria

Endurance:
- DO NOT fatigue

36
Q

Compare origin from insertion

A

Origin = attachment site that does NOT move during contraction

Insertion = attachment site that moves during contraction

37
Q

Define: Agonist (Prime Mover)
Include example

A

muscle whose contraction is mainly responsible for producing a particular movement
Ex: biceps are agonist during a bicep curl

38
Q

Define: Antagonist
Include example

A

muscle whose action oppose the movement produced by another muscle
Ex: triceps are antagonist to the bicep during a bicep curl

39
Q

Define: Synergist

Include example

A

a muscle that contract to help the prime mover
Ex: brachialis during bicep curl

40
Q

Define: Fixator

Include example

A

synergist that stabilize the origin of a prime mover by preventing the movement of another joint

ex: shoulder muscles stabalize the shoulder joint during a bicep curl

41
Q

Be able to label the most important muscles on a diagram. Refer to notes

A

For answers, refer to Muscular System notes

42
Q

What are the three processes that muscles use to obtain energy?

A

aerobic CR
anaeorbic CR
Creatine phosphate breakdown

43
Q

Describe: Aerobic CR.

Include: What is broken down, What is produced, What is required, Where in the cell does it take place/end?

A
  • Glucose is broken down into LOTS of ATP
  • Process requires Oxygen and produces CO2 and Water
  • Begins in cytoplasm and ends in mitochondria
44
Q

Describe: Anaerobic CR.

Include: What is broken down, What is produced, Where in the cell does it take place/end?

A
  • Glucose is broken down in few ATP (AKA glycolysis) and byproduct include lactic acid
  • Glucose is broken down in the cytoplasm
  • Oxygen is NOT used

glc -> lactic acid + ATP (few)

45
Q

What causes muscle pain when exercising?

A

When the body moves to anaerobic CR for energy, it produces lactic acid as a by product. This increase in lactic acid causes muscle pain.

46
Q

How does Creatine Phosphate relate to the muscular system?

A

It generates ATP by donating Phosphate group (from Creatine Phosphate) to ADP to form ATP