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HISTO - Exam 2 > Muscle > Flashcards

Muscle Flashcards

(78 cards)

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1
Q

Covering over an entire muscle.

A

epimysium

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2
Q

Covering over a muscle fascicle.

A

perimysium

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3
Q

Covering over an individual muscle fiber.

A

endomysium

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4
Q

What makes up the endomysium?

A

Basal lamina and reticular fibers

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5
Q

What layers are satellite cells found between?

A

Sarcolemma and basal lamina

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6
Q

What are satellite cells? What is their function?

A

Stem cells, proliferate after trauma to form myoblasts

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7
Q

State the muscle structure hierarchy (from big to small).

A

Muscle (covered by epimysium) > Fascicle (covered by perimysium) > muscle fiber/cell (covered in endomysium) > myofibers > myofilaments

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8
Q

Explain how the A-band, I-band, and Z-line stain with H&E.

A

A-band: dark red, I-band: light red / pink, Z-line: may be seen as dark line that bisects I-band.

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9
Q

Explain the train complex. What muscle type is it common in?

A

T-tuble flanked by sarcoplasmic reticulum on both sides. Most common in skeletal muscle.

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10
Q

What structure do t-tubules align with in muscle cell sarcomeres?

A

A-I band junction

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11
Q

Define teloglia.

A

Axon and Schwann cell at motor end plate. (The basal lamina fuses with the muscle fiber here.)

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12
Q

Define a motor unit.

A

An nerve and the muscles it innervates.

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13
Q

How does botulism toxin block myoneural junction signaling?

A

Blocks Ach release at PRESYNAPTIC membrane.

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14
Q

How does curare block myoneural junction signaling?

A

Blocks association between Ach and its receptor.

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15
Q

How does myasthenia gravis autoantibody block myoneural junction signaling?

A

Blocks association between Ach and its receptor.

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16
Q

Role of the t-tuble.

A

Conduct depolarizing ions (Na+) into the cell quickly uniformly.

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17
Q

Ion released from sarcoplasmic reticulum.

A

Ca2+

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18
Q

What muscle fiber molecule binds Ca2+?

A

troponin

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19
Q

What are the distinguishing characteristics of red fibers?

A

Also known at type 1, slow twitch fibers

  • High myoglobin
  • Numerous mitochondria
  • Fatigue reistant
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20
Q

What are the distinguishing characteristics of white fibers?

A

Also known as type 2, fast twitch fibers

  • Lower myoglobin
  • Lower mitochondria content
  • More stored glycogen
  • Higher myosin-ATPase activity
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21
Q

What are the distinguishing characteristics of intermediate fibers?

A

Characteristics between red and white fibers.

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22
Q

What is the relationship between neuron type and red/white fiber identity?

A

Innervation determines fiber type. Fibers can be converted by removing innervation and replacing with neuron that innervation opposite fiber type.

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23
Q

What is the function of a muscle spindle?

A

Sense changes in muscle length (stretch receptor).

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24
Q

What are the two types of intrafusal fibers?

A

Nuclear bag and nuclear chain

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25
Who is the best super hero?
HistoMan
26
What type of sensory nerve fibers wind around intrafusal fibers?
Annulospiral
27
What factors stimulate proliferation of satellite cells following muscle injury?
MyoD (transcription factor) and HGF (hepatocyte growth factor)
28
Explain rigor mortis.
Death > SR membrane becomes permeable > Ca2+ escape > myosin-actin binding > No ATP to break cross-bridge or allow SERCA to pump Ca2+ back into SR > cross bridge remains until decomposition.
29
What causes muscle atrophy? Hypertrophy?
Atrophy: decrease in muscle fiber size (fewer myofibrils) Hypertrophy: increase in muscle fiber size (more myofibrils)
30
Where did our microsoft fee go?
Turek 2019 Presidential Campaign: "It's a wonderful time to be alive."
31
List the types of myofilaments and state whether each is thick or thin.
Troponin - thin Tropomyosin- thin Actin - thin Myosin - thick
32
What makes up the A band?
Thick filaments (only place where they are found)
33
What makes up the I band?
Thin filaments
34
Elastic protein that connects myosin to Z-disk
titin
35
Inelastic protein that run parallel to actin
nebulin
36
myosin binding protein, holds myosin filaments in register at M-line
myomesin
37
Myosin binding protein with similar function to myomesin
C-protein
38
Bundles actin filaments into parallel arrays and anchors them to Z-disk
alpha-actinin
39
Intermediate filaments that binds myofibirls to each other. Interacts with myofibrils at Z-line/disk
Desmin
40
Holds desmin together
Plectin
41
Actin binding protein, links cytoskeleton (actin) with ECM
Dystrophin
42
H-band
contains myosin (no heads) and creatine kinase
43
Role of creatine kinase?
ADP + phosphocreatine ==creatine kinase==> ATP + creatine
44
Attachement region for thin filaments, contains alpha-actinin
Z-disk
45
What regulates polymerization of actin?
Thymosin beta4 and profilin (cofilin, severin, gelsolin, villin CapZ, and gCAP39 also listed)
46
3 functionally relevant troponin peptides
Tn-T Tn-I Tn-C
47
Role of Tn-C peptide
Binds Ca2+ and releases TnI-tropomyosin inhibition of actin myosin binding.
48
Role of Tn-I peptide
Inhibits myosin head, actin binding (cross bridge formation)
49
Tn-T
binds to Tn complex of tropomyosin
50
Role of sarcoglycans
Maintain association between sacrolemma and ECM
51
Length of myosin thin filament.
15nm
52
What molecules make up a single myosin thick filament?
2 identical heavy chains and 4 lights chains (a pair associated with each heavy chain)
53
List the steps muscle contraction with regard to cross-bridge formation. (Start with ATP hydrolysis. Since this is a repeating cycle, their is no true start.)
1) ATP Hydrolyzed causing myosin head to be "cocked" 2) Myosin head binds actin 3) Pi released, ADP released 4) Head "snaps" back (power-stroke) pulling actin towards M-line (I-band shrinks)
54
How are cardiac muscle cell nuclei different from muscle cell.
One/cell, more round, more centrally located
55
What joins cardiac cells together?
intercalated disks
56
What are the parts of an intercalated disk?
lateral portion | transverse portion
57
What is present in the lateral portion of an intercalated disk?
gap junctions
58
What is present in the transverse portion of an intercalated disk?
fasciae adherens and macula adherens
59
Diad
T-tuble, sarcoplasmic reticulum unit common in cardiac cells
60
Where do T-tubules meet cardiac myofibrils
Z-disk
61
Role of satellite cells in cardiac muscle.
None. Satellite cells not present here. Cardiac muscle cannot regenerate and forms fibrous connective tissue instead.
62
What is the functional physiological effect of phopholamban?
Decrease rate and contractility of heart
63
What is the molecular function of phospholamban?
Inhibit SR Ca2+ ATPase (SERCA)
64
What activates/deactivates phospholamban?
phosphorylation of phospholamban attenuates its inhibitory ability
65
What is the role of SR Ca2+ ATPase (SERCA)
Actively pump Ca2+ back into SR using ATP hydrolysis to drive active transport
66
What hormone controls phospholamban?
Thyroid hormone, reduces phospholamban function (leads to its phosphorylation)
67
What is the effect of MI on cariocyte staining?
Cells have eosinophilic staining and pyknotic nuclei after 24 hours, Inflammatory cells infiltrate tissue after 3 days
68
How long are cardiac muscle cells?
100-150 um
69
How long are smooth muscle cells?
20 um (may be greater than 500 um in gestational uterus, DAMN that's some serious stretching)
70
Alpha-actin containing areas that serve as the insertion points for actin/myosin filaments in smooth muscle?
Dense bodies
71
What is the arrangement of smooth muscle cells?
staggered
72
What is the embryonic origin of single smooth muscle cells?
Ectoderm (ex. salivary, lacrimal, sweat, mammary glands)
73
What is the embryonic origin of smooth muscle located in respiratory, circulatory, digestive, and reproductive tracts?
Mesoderm
74
What is the functional equivalent of smooth muscle dense bodies in skeletal muscle?
Z-disk
75
Where is troponin located in smooth muscle cells?
Smooth muscle cells don't have troponin!
76
What filaments are present in smooth muscle cells?
Actin and tropomyosin - thin Desmin and vimentin - intermediate (serve as links in cytoskeletal network between dense bodies) Myosin - thick
77
Explain the pathway that leads to smooth muscle cell contraction.
Ca2+ released into cytoplasm > Ca2+ - calmodulin complex forms > Ca2+-calmodulin complex activates myosin light chain kinase > Myosin light chain kinase phosphorylates myosin > myosin unfolds and forms filaments > myosin filaments interact with actin > contraction
78
What is the significance of estrogen and progesterone with regard to smooth muscle contraction?
Estrogen increases cAMP levels, Progesterone decreases cAMP. cAMP may also activate myosin light chain kinase

HISTO - Exam 2 (6 decks)

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