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Pathology > IIT 1 > Flashcards

IIT 1 Flashcards

1
Q

How long does it take fibrin to form a scaffold for cell migration?

A

Minutes

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2
Q

How long does it take for necrotic tissue to be removed by phagocytosis and proteases and what molecules do this?

A

Days. Macrophages and neutrophils

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3
Q

How long does it take for macrophages and platelets to secrete chemical mediators that direct tissue repair?

A

Hours

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4
Q

How long does it take for new blood vessels and fibroblasts to invade the wound along the fibrin scaffold?

A

Begins at 2-3 days

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5
Q

How long does it take for fibroblasts to secrete collagen?

A

Begins at 4-5 days

That is ideal but this may be delayed if things interfere.

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6
Q

How long does remodelling and contraction take?

A

Weeks to months

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7
Q

What are the three phases of wound healing?

A

Inflammatory phase
Proliferative Phase
Remodeling

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8
Q

Whats are the steps in the inflammatory phase?

A
  1. Formation of the fibrin scaffold
  2. Removal of necrotic tissue
  3. Macrophages and platelets secrete chemical mediators that direct tissue repair
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9
Q

What happens during formation of the fibrin scaffold?

A

Fibrin is formed from fibrinogen, which makes a matrix that cells can crawl on.
Fibrinogen leaks from incised blood vessels and inflamed leaky vessels.

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10
Q

What does fibrin formation look like histologially?

A

Eosinophilia as fibrin fills the defect.

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11
Q

What happens during the removal of necrotic tissue?

A

Necrotic tissue must be removed prior to wound repair.

  • phagocytosis of debris
  • secretion of proteases (macrophages/neutrophils)
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12
Q

What is the process by which macrophages and platelets secrete chemical mediators that direct tissue repair?

A

Macrophages and platelets produce growth factors that allow for new vessel formation (angiogenesis) fibroblast recruitment, synthesis of collagen.

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13
Q

What occurs during the proliferative phase?

A

New blood vessels and fibroblasts invade the wound along the fibrin scaffold. These provide nutrients.
At this point, there still isn’t much strength.

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14
Q

What are the steps in the proloferative phase of wound healing?

A

New blood vessels and fibroblasts invade the wound.

Fibroblasts secrete ECM.

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15
Q

What is secreted by fibroblasts in the proloferative phase?

A

ECM (collagen). This starts at 4-5 days.

Granulation tissue is produced.

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16
Q

Is granulation tissue the same as granulomatous inflammation?

A

No, very different. Granulation tissue involves new blood vessels, fibroblasts produce collagen.
New collagen starts to be produced 4-5 days after injury.
Granulomatous inflammation is chronic inflammation with macrophages surrounded by lymphocytes.

17
Q

What does granulation tissue look like grossly?

A

Pebbley granular appearance. The new blood vessels give this look.

18
Q

How strong is the wound in the prolifative phase before remodeling?

A

Not very. There isn’t much collagen, not super strong at 10 days.

19
Q

What are the key occurrences in the remodeling phase?

A

Maturation of collagen, wound contraction

20
Q

What is involved in the maturation of collagen?

A

Type 1 gets replaced to type 3, which is stronger.

Collagen bundles also get cross linked.

21
Q

What is the strength of the wound in the remodeling phase at 3 weeks, 6 weeks and 6 months?

A

20%, 70%, 80%

22
Q

What is formed during wound contraction in the remodling phase?

A

Myofibroblasts. These cause contraction to shrink the wound.

This takes 4-14 days (but a wound does not regain normal strength by 4 days).

23
Q

What is the difference between fibrin and fibrous tissue?

A

Fibrin is protein, no cells. It is a sticky matrix for binding/clots.
Fibrous tissue includes fibroblasts, fibrin and blood vessels

24
Q

What are the events in epithelial tissue healing?

A

-rapid sliding of epithelium
-delayed hyperplasia and migration of epithelium
Connective tissue and basement membrane stay intact, surviving epithelial cells spread on basement membrane to cover defect. They turn from cuboidal flat to squamous in order to cover the defect.

25
Q

What are the 3 requirements for epithelial tissue healing?

A
  • intact connective tissue framework (virus kills epithelial structure)
  • adequate vascular supply (for nutrients)
  • mitotically active epithelium (eg no drugs that prevent mitosis, need mitosis for reparation - hyperplasia and proloferation)
26
Q

How long does epithelial repair take?

A

24-48 hours

27
Q

What is the scientific name for a scab?

A

Eschar

28
Q

How does an incision heal?

A

Repair CT first, lay down BM, fibrin, necrotic debris. Epithelial cells can’t migrate across fibrin tissue, need bm matrix. Granulation tissue forms.

29
Q

What is healing with first intention?

A

Wound edges close together, don’t really see wound contraction. Small amount of granulation tissue. Can suture.

30
Q

What is 2nd intention?

A

Wound edges not opposed, larger amount of granulation tissue. Don’t suture.

Pathology (12 decks)

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