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CELL 302 > Lecture A7, A8 > Flashcards

Lecture A7, A8 Flashcards

1
Q

Muscles are formed from this type of cell?

A

myoblasts

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2
Q

Myoblasts (def.)

A

embryonic precursors of myocytes

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3
Q

myocytes (a.k.a ____ )

A

muscle cells

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4
Q

Differentiation of myoblasts into muscle cells is called ______

A

-myogenesis

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5
Q

During myogenesis of skeletal muscle, myoblasts do what?

A

-fuse into multinucleated myotubes, which are combined into muscle fibers

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6
Q

Myoblasts arise from ______ called _____

A

-blocks of mesodermal cells
-somites

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7
Q

Somites are found where?

A

-lateral to the neural tube in the embryo that is derived from the neural crest.

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8
Q

Somites also give rise to tissues other than muscle like: ______

A

-skeletal tissue and CT in skin

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9
Q

where myoblasts will form in developing somite is determined by ______

A

specific signals from surrounding tissue including neural tube and the lateral ectoderm

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10
Q

early somite differentiates into ______

A

dermomyotosome & sclerotome

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11
Q

dermomyotosome differentiates into ______

A

dermotome & myotome

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12
Q

sclerotome gives rise to ____

A

skeletal structure

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13
Q

dermotome gives rise to ______

A

connective tissue of skin

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14
Q

____ induce myogenesis

A

Wnt, Hh and BMP

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15
Q

In myogenesis, there are multiple types of ______

A

Wnt proteins and Frizzled receptors

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16
Q

BMPs act similarly to _____ and act as _____

A

-TGFB proteins
-morphogens

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17
Q

BMPs organize what?

A

several parts of human body including bones

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18
Q

In myogenesis, Wnt 1/3a from ____ , Wnt6/7a from _____ , BMP4 from _____ and HH act on early somite

A

-neural tube
-surface ectoderm
-lateral mesoderm plates

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19
Q

Like other progenitor cells, myoblasts ______ to increase cell number.

A

-proliferate

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20
Q

In the correct environment, (signalling proteins), myoblasts will further ______

A

differentiate into muscles

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21
Q

Myoblasts also migrate via cell movement through ______ to the sites where muscles will form (aka _____)

A

-the developing embryo
-premuscle masses

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22
Q

_____ are transcription factors that direct myoblast
differentiation

A

-MEFs and MRFs

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23
Q

MRF stands for _____

A

muscle regulator factor proteins

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24
Q

MRF is expressed where?

A

-only in muscle

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25
Q

Types of MRF: _____

A

MyoD, Myf5, Myogenin (MyoG) and Mrf4 (in order of activation)

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26
Q

MRF is ____ (type of TF) that does what? (2)

A

-a bHLH TF
-binds a DNA motif called the E-box, interacts with MEFs

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27
Q

MRF binds to ____ as co-factors

A

E-proteins

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28
Q

MEF stands for _____

A

muscle enhancer factor proteins

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29
Q

MEF is expressed where?

A

-in several cell linages

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30
Q

MEF does what?

A

-interacts with MRFs
-binds DNA motif called MADS box (MEF-box)

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31
Q

MEF often binds DNA as _____

A

a dimer

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32
Q

The myogenic program is split into two parts: _____

A

-determination
-differentiation

33
Q

Determination of myogenic program has two parts: ____

A

-induction
-maintenance

34
Q

Maintenance of myogenic program involves _____

A

steady state of MRFs and MEFs

35
Q

Differentiation of myogenic program involves _____

A

muscle differentiation genes

36
Q

Expressing MyoD (a MRF) does what in cell?

A

-turns cell into a myoblast cell

37
Q

MyoD expression induces muscle cell fate in this lineage?

A

-mesodermal

38
Q

MyoD expression does not induce muscle cell fate in these lineages?

A

-endodermal + ectodermal

39
Q

MRFs are required at ______ of the myogenic lineage

A

-multiple stages

40
Q

MRF transcription factors directly regulate _____ in myoblasts and are degraded after _____

A

-the cell cycle
-associated phase

41
Q

MRF associated with G1

A

-MyoD

42
Q

MRF associated with M

A

-Myf5

43
Q

Myocytic stem cell (aka ____)

A

satellite cell

44
Q

Myoblasts fusion (uninucleated) form ___ which differentiate to form _____

A

-myotubes (multinucleated)
-muscle fiber/myofiber (multinucleated)

45
Q

committed satellite cell does this to contribute to muscle regeneration and repair?

A

symmetric division (horizontal plane)

46
Q

satellite stem cell does this to contribute to muscle regeneration and repair?

A

symmetric division (horizontal plane)
asymmetric division (vertical plane)

47
Q

3 types of muscle cells

A

1) Skeletal muscle
2) Cardiac muscle
3) Smooth muscle

48
Q

Multiple myoblasts fuse together to form _______

A

skeletal muscle

49
Q

The dermomyotome (DM) is derived from the ______

A

-dorsal part of the somite

50
Q

A myotome is ____ (def.)

A
  • the group of muscles innervated by a single spinal nerve
51
Q

Primary myogenesis (def.) + happens at what stage?

A

-cell fusion (somitic stem cell -> fetal stem cell)
-embryonic

52
Q

Secondary myogenesis (def.) + happens at what stage?

A

-basal lamina assembly + innervation/NMJ formation (fetal stem cell -> myocytes)
-fetal

53
Q

General structure of skeletal muscle

A
  • myofiber (muscle cell) has multiple myofibrils which has sarcomere units
54
Q

Sarcomere: I band

A

thin filaments

55
Q

Sarcomere: A band

A

-thin and thick filaments
-doesn’t change length during contraction

56
Q

Sarcomere: H zone

A

-thick filaments only
-shortens during contraction

57
Q

Sarcomere: Z disk

A

-border between two sacromeres

58
Q

General structure of smooth muscle cells

A

-thick and thin filaments
-dense bodies + attachment plaques

59
Q

dense bodies + attachment plaques in smooth muscle cells are analogous to _____ of skeletal and cardiac muscle fibers

A

Z-discs

60
Q

Parts of skeletal myofibrils + function

A

-actin (filamentous and globular)- thin filament
-myosin - thick filament
-tropomyosin - covers myosin-binding site on actin
-troponin - attaches to tropomyosin with Ca++ binding site

61
Q

Sliding-filament Contraction is dependent on ____

A

ATP, Ca++

62
Q

The sarcoplasmic reticulum does what?

A

-release Ca++ upon depolarization with nerve signals through Ca++ release channel

63
Q

Ca++ recovery in sarcoplasmic reticulum

A

-Ca++ renters SR through Ca++ ATPase

64
Q

T tubules are found in what type of cells?

A

striated muscle cells (cardiac and skeletal )

65
Q

Transverse tubules do what?

A

permit rapid transmission of the action potential into the cell

66
Q

Nerve that synapses on neuromuscular junction releases _____

A

acetylcholine (ach)

67
Q

neuromuscular junction (def.)

A

chemical synapse between a motor neuron and a muscle fiber

68
Q

ACh (def.)

A

neurotransmitter secreted from parasympathetic neurons

69
Q

Skeletal muscle contraction steps

A

1) nerve triggers release of ach from synaptic knob into cleft
2) ach binds to ach receptors on NMJ (starts impulse in sarcolemma of muscle fiber)
3)impulse spread through T tubules
4) Ca++ ions released from terminal cisternae into sarcoplasm
5) Ca binds to troponin which changes shape, moving tropomyosin = open active sites
6)myosin heads of thick filament attaches to open sites = crossbridges
7) myosin moves thin fila. toward center then ATP binds myosin heads
8) ATP broken into ADP & P
9) repeating movement until Ca++ removed (active transport)
10) tropomyosin covers active sites = relaxation of filaments

70
Q

smooth muscle cells have this characteristics: ____

A

single nuclei (mononuclear), not organized myofibrils

71
Q

adjacent smooth muscle cells were physically couplied at ____

A

dense bodies

72
Q

caveolae function

A

regulate cell signaling and uptake and release of Ca2+ from sarcoplasmic reticulum

73
Q

characteristics of cardiac muscle

A

-mononuclear
-gap junctions + desmosomes
-intercalated discs

74
Q

Cardiomyocyte lineage from ____

A

cardiac mesoderm (further differentiation activates/repressed by Wnt)

75
Q

Myoepithelial cells are _____ to muscle cells

A

-similar

76
Q

Myoepithelium are part of secretory glands: _____

A
  • Sweat
  • Mammary
  • Lacrimal (tear)
  • Salivary
77
Q

Myoepithelial cells lineage

A

stem cell -> luminal progenitor + basal progenitor
luminal progenitor -> ductal luminal + alveolar
basal progenitor -> myoepithelial

78
Q

Mammary gland epithelium cell lineages

A

ectoderm => mesenchymal stem cell => endothelial precursor cell => ductal precursor cells (puberty) + alveolar precursors cells (pregnancy) => (both produce) myoepithelial cells + luminal cell

CELL 302 (18 decks)

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