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MAMS COT > Lecture: Types of Muscle > Flashcards

Lecture: Types of Muscle Flashcards

1
Q

Myofibroblast

function and appearance

A

MSC-derived fibroblast activated in response to wound healing. Contains a visibly darker cytoplasm due to ribosomes making collagen

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2
Q

Myoepithelial cells

A

epithelium-derived cell found in sweat glands that contracts to release secretion from gland

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2
Q

What do the nuclei of smooth muscles look like?

A

Central, corkscrew-like

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3
Q

Where in the cell are dense bodies found?

A

Intracellular

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4
Q

Where in the cell are dense plaques found?

A

Membrane-bound

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5
Q

What are dense bodies bound to?

A

Actin and Intermediate Filaments (Vimentin/Desmin)

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6
Q

Where is Vimentin found?

A

IF, found in viscera

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7
Q

Where is Desmin found?

A

IF, found in vascular system

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8
Q

Sympathetic nerves release?

A

Norepinephrine

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9
Q

Parasympathetic nerves release?

A

Acetylcholine

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10
Q

How do Caveolae import Ca2+?

A

Caveolin targets parts of the membrane containing lipid rafts, causing it to bend inwards, creating a vesicular structure to import Ca2+, Pinocytosis

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11
Q

Explain Myogenic vs Neurogenic

A

Two differentiations of smooth muscles, allowing the muscle to act either as one unit, or as independent mechanism, allowing for more fine-tuning. aka Unitary vs Multiunit

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12
Q

Myogenic smooth muscle

A

single-unit, visceral, gap junctions, one axon, responsive to hormones

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13
Q

Neurogenic smooth muscle

A

multi-unit, independent action (found in iris, arrector pills, large vessels, lung)

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14
Q

Explain Visceral vs Vascular

A
  • Two differentiations of smooth muscle, similar to myogenic and neurogenic, respectively
  • Visceral found in walls of organs, neurogenic found in walls of vessels
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15
Q

Where would visceral smooth muscle most likely be found?

A

Walls of vessels, such as circular smooth muscle in arteries, longitudinal layer in veins, and pericytes in capillaries

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16
Q

Pericytes

A
  • possibly stem cells for vascular smooth muscle
  • possibly cause capillaries to become leaky/break BBB
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17
Q

Features of cardiac myocytes

A
  • one, sometimes two central nuclei
  • sarcoplasmic cone
  • intercalated disc
  • intermediate size between skeletal and smooth muscle
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18
Q

What is the intercalated disc made out of?

A

Complex of 3 junctions:
1) Fascia (Zona) Adherens: f-actin
2) Gap Junctions
3) Desmosome: Intermediate Filament

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19
Q

Types of striated muscle

A

Skeletal and cardiac

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20
Q

Types of skeletal muscle

A

Ia (Red)
IIa (Intermediate)
IIb (White)

21
Q

Types of cardiac muscle

A

1) Cardiac myocyte (standard)
2) Myocardial endocrine
3) Cardiac conducting

22
Q

Types of contractile single-cells

A
  • Myofibroblasts
  • Myoepithelial cells
23
Q

Myocardial endocrine cells

A
  • located in Atria
  • contain ANP granules
24
Q

ANP granules

A

Release from myocardial endocrine cells in response to atrial wall stretching to reduce body fluid and lower BP via loss of Na+, K+ and H2O in the kidneys

25
Q

Cardiac conducting cells

A
  • cardiac, not nerve cells modified for conducting electrical signals
  • found in anatomical pathways in subendocardium
  • increased size compared to cardiac myocytes
  • more gap junctions
  • increased glycogen
  • fewer myofibrils
26
Q

4 F’s

A

For skeletal muscle:
Fascicle -> Fiber -> Fibril -> Filament

27
Q

Type 1a

A

Red, slow-twitch, oxidative
Capable of repeated contraction without fatigue

28
Q

Type 2a

A

Intermediate, fast-twitch, glycolytic-oxidative
Fatigue-resistant

29
Q

Type 2b

A

White, fast-twitch, glycolytic
Strong and fast, fatigues easily

30
Q

How does the SR differ in fast-twitch muscles?

A

More developed to allow for faster release of calcium

31
Q

Which type of muscle are dyads found in?

A

Cardiac

32
Q

Which type of muscle are triads found in?

A

Skeletal

33
Q

What do the three different types of muscle look like in PAS and cytochrome oxidase staining?

A

PAS: white muscle is darker than red muscle due to the presence of glycogen
CytOxi: stains mitochondria, so red are darker bc oxidative

34
Q

Steps in development of skeletal muscle fibers

A

1) Syncytium of myoblasts
2) Formation of myotube
3) Formation of 2º myotubes -> formation of additional fibers
4) Some myoblasts persist under external membrane -> myosatellite cells

35
Q

Do myocytes exist in a synctium

A

No, only before formation of the syncytium

36
Q

What cells help with skeletal muscle repair?

A

Myosatellite cells

37
Q

Myosatellite cells

A

Multipotent resident stem cell, quiescent, differentiate in response to demands of growth or damage
- Not present in cardiac muscle

38
Q

Does the number of myofibers change?

A

No, only the size can change via a decrease/increase in number of myofibrils

39
Q

Muscle spindle

A

Parallel with muscle and provide info about muscle length

40
Q

Golgi tendon

A

Between muscle and tendon, provides information about force exerted
- associated primarily with reflexes

41
Q

What are the muscle spindle and Golgi tendon important for?

A

1) Proprioception
2) Prevention of overstretching

42
Q

Muscle spindle morphology

A

Bag and chain fibers: sensitive to different ranges of stretch
Capsule: equivalent to perimysium

43
Q

How to bag and chain fibers alter their sensitivity?

A

Innervation by gamma motor neurons

44
Q

List what the A, H and I Bands contain in terms of myosin and actin

A

A - M+A
H - M
I - A

45
Q

How does the M line hold myosin?

A

Using myosin and C-protein

46
Q

How is the Z line connected to Actin

A

Held by alpha-actinin and nebulin

47
Q

What two structures transmit force to the body of the muscle?

A

Desmin and Costameres

48
Q

How does the muscle transmit force to the tendon?

A

Myotendinous junction: actin filaments directly anchored to the cell membrane within anchoring regions parallel to the direction of force

49
Q

Endomysium

A

CT connected to external membrane

50
Q

Perimysium

A

CT surrounding each fascicle

51
Q

Epimysium

A

CT fascia that binds anatomical form of muscle to surrounding tissue

MAMS COT (5 decks)

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