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Foundations 2 - Week 3 > Pathology > Flashcards

Flashcards in Pathology Deck (36):
1

What are the 5 types of wounds?

  1. Lacerations
  2. Abrasions
  3. Contusions
  4. Avulsions
  5. Punctures

2

What are the 3 main ways wounds can heal?

  1. Primary Intention - epidermis is brought together (ie-sutures).  Fast healing.  
  2. Secondary Intention - wound is allowed to granulate
  3. Tertiary Intention - wound is debrided and allowed to remain open for a number of days, before closure.  

3

What are the 4 phases of wound healing?

  1. Hemeostasis
  2. Inflammation 
  3. Proliferation
  4. Remodeling 

4

Describe the first phase of wound healing, hemostasis?

What occurs? What is the function? What cells are involved? What growth factors are involved?

Hemostatis is the first phase of wound healing.  It begins with the formation of the fibrin clot.  This serves a number of fuctions, including:

  • Protective barrier to the external environment
  • Scaffolding for cell migration/proliferation
  • Resovior of growth factors that are released during degranulation of platelets. 

Platlets are the main cell involved in hemostasis.  They release growth factors PDGFTGF-beta, and EGF which attact other cells, and start cell proliferation.  

5

Describe the second phase of wound healing, inflammation?

What occurs? What is the function? What cells are involved? What growth factors are involved?

The following events occur during the inflammatory phase of wound healing. 
  • Vasoconstriction and Vasodilation
  • Innate Immune Response
  • Macrophages arrival/activation
  • Neutrophil arrival/activation
  • Decline or Resolution of Inflammatory Phase

Many cells are involved - macrophages, fibroblasts, neutrophils, mast cells, keratinocytes, endothelial cells

Many growth factors are involved - VEGF, FGF, TGF-beta, TNF-alpha, EGF, etc.

6

Describe the third phase of wound healing, proliferation?

What occurs? What is the function? What cells are involved? What growth factors are involved?

The following events take place during the proliferation phase:

  • Angiogenesis
  • Granulation (ECM) of Tissue - fibroblasts, etc.
  • Collagen Deposition - fibroblast
  • Epithelialization - kerakinocytes
  • Contraction - myofibroblasts

Many cells are involved, including: Macrophages, fibroblasts, myofibroblasts, endothelial cells, keratinocytes.  

MMPs are also involved. 

Many growth factors are involved, especially VEGF for angiogenesis 

 

7

Describe the final phase of wound healing, remodeling?

What occurs? What is the function? What cells are involved? What growth factors are involved?

During the remodeling phase of wound healing, following events take place:

  • Type 3 collagen is replaced by type 1.  
  • The disorganized collagen is reorganized along tension lines
  • The collagen is cross-linked to improve tensile strength
  • The scar is flattened

Fibroblasts are the main cell involved in reshaping the wound.  No growth factors are involved.  

8

What is the definition of an infected wound-- how many colony forming units (CFL) per gram of tissue are required?

10^5 (100,000)

9

What is the gold standard for diagnosing infected wounds?

Tissue biopsy

Physicians have a 50:50 chance of diagnosing an infected would by observation alone.  

10

What is biofilm? What is one challenge of biofilms in wound healing?

Biofilm is a group of microorganisms in which cells stick to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS).

Immune cells have difficultly killing pathogens that reside wihitn the biofilm structures.  

11

What are Venous Ulcers? Where do they typically occur?

  • Wounds that occur due to improper functioning venous valves, usually in the legs
  • A full-thickness defect of the skin, most frequently in the ankle region, common over the medial malleolus

12

What are Arterial Ulcers? Where do they typically occur?

  • A full-thickness defect of the skin, most frequently in the ankle region, common over the medial malleolus
  • Most common cause is atherosclerosis

13

What are diabetic Ulcers?

  • Most common foot injuries leading to lower extremity amputation
  • Peripheral neuropathy, peripheral vascular disease, and infection combine to lead to these ulcers and amputation 

14

What are pressure ulcers?

  • Localized injury to skin or underlying tissue, usually over a bony prominence, as a result of unrelieved pressure. 
  • Common among bedridden elderly  

15

What are the 3 cornerstones of wound management?

  1. Moist Wound Healing
  2. Exudate Wounds - remove fluid
  3. Debridement - remove necrotic tissue and foreign materail.  

16

Name some methods of debridement?

  • Mechanical - scrub the wound
    • Hydrotherapy - rinse the wound
    • Wet-to-dry dressing
  • Autolytic – use bodies own moisture and enzymes to liquify wounds
  • Enzymatic- use of topical agens to break down necrotic tissue (collagenase, fibrinogen)
  • Biological such as Maggot therapy
  • Chemical
  • Surgical Sharp Debridement - cut the wound out

17

What are the benefits of using moisture in wound healing?

 
  • increase epithelialization, promote dermal matrix synthesis and improve the patient’s comfort.

18

What are the benefits of exudating (removing fluid) a wound?

  • Wound fluid can inhibit the production of certain wound healing cells (keratinocytes, fibroblasts, epithelial cells, etc.)
  • Would fluid contains MMPs, which inhibit wound healing.  

19

What is the growth factor PDGF?

What does it do?

What type of receptors does it act on?

What cells secrete it?

PDGF - Platlet Derived Growth Factor

PDGF is a dimer (homo and hetero)

Functions:

  • Chemotactic for macrophages, fibroblasts
  • Activates macrophages
  • Mitogenic for fibroblasts
  • Stimulates matrix production

Acts on Tyrosine Kinase Receptors 

Secreted mainly by: 

  • Platelets
  • macrophages
  • keratinocytes

20

What is the growth factor VEGF?

What does it do?

What type of receptors does it act on?

What cells secrete it?

VEGF - Vascular Endothelial Growth Factor
 
VEGF Fuctions:
  • Angiogenesis

It works on tyrosine kinase receptors

It is secreted by keratinocytes and macrophages

21

What is the growth factor TGF-Beta?

What does it do?

What type of receptors does it act on?

What cells secrete it?

TGF-Beta - Transforming Growth Factor Beta

TGF-beta functions:

  • Chemotactic for macrophages and fibroblasts
  • Keratinocyte migration
  • Stimulates matrix production by fibroblasts

TGF-beta works on serine-threonine kinase receptors

TGF-beta is secreted by platlets and macrophages

 

 

22

Is TGF-Beta secreted in an active or inactive form?

What type of receptors and signaling does TGF-beta induce?

Inactive.  

It reguires the cleavage of beta-binding proteins and latent associated protein (LAP). 

TGF-beta (isoforms 1 and 2) activates tyrosine kinase receptors which trigges SMAD signlaing proteins which induce gene transcription   

23

What is the growth factor FGF?

What does it do?

What type of receptors does it act on?

What cells secrete it?

FGF - Fibroblast Growth Factor

Function: 

  • Mitogenic for fibroblasts
  • Angeogenic 

FGF acts on tyrosine kinase receptors

FGF is produced by macrophages and damaged endothelial cells

24

What is the growth factor FGF?

What does it do?

What type of receptors does it act on?

What cells secrete it?

EGF -Epidermal Growth Factor

Function: 

  • Migration of Keratinocytes
  • Mitogenic for Keratinocytes

EGF acts on tyrosine kinase receptors

EGF is produced by platlets 

25

What are 5 functions of the Extra Cellular Matrix (ECM)?

  1. Mechanical Support
  2. Embryonic Development
  3. Pathways for cellular migration
  4. Wound Healing
  5. Management of Growth Factors

26

What types of molecules make up the soluble portion of the ECM?

Proteoglycans

27

Proteoglycans are composed of what two molecules?

What is their function in the ECM and Basal Lamina?

 

  • A core proteins + a glycosaminoglycan (GAG)
  • Mechanical Support, Cushion, and limit permeability of ions.  

28

Name 4 glycosamnioglycans? 

  • heparan sulfate
  • chondroitin/dermatan sulfate
  • keratan sulfate
  • hyaluronan (HA).

29

How is Hyaluron differnt from the other glycosaminoglycans (GAGs)?

Unlike the other GAGs, Hyaluron is not linked to a core protein. It is a huge molecule of linked saccharides that acts as a gel and retains water.  

30

What are the 4 insoluble components of the basal membrane and the ECM?

  1. Collagen 
  2. Elastic Fibers (elastin)
  3. Fibronectin
  4. Laminin

31

What are MMPs?

What is their function? 

Name the different types?

What fiber is resistant to MMPs?

MMP - Matrix Metalloproteinases

MMPs breakdown the ECM

Types:

  • collagenases
  • gelatinases,
  • stromelysins
  • matrilysins
  • membrane-type MMPs, and macrophage metalloelastases

Undenatured triple-helix collagen is reistant to MMPs

32

What is fibronectin?

A dimeric protein that bind many different molecules togehter in the ECM and basal membrane

33

What is laminin?

A heterotrimer that associates with integrin and other connective molecules in the basal lamina.  It looks like a cross.  

34

What is entactin?

A monomer that associates with laminin and collagen IV fibers in the basal lamina.

35

What type of collagen fiber is mostly found in the basal lamina?

Type IV

36

What is elastin?

A elastic fiber that resides mostly in the ECM.  It forms cross-linked covalent bonds with it self.  This creates an elastin network.   It is very similar to collagen, except that it is not glycosylated.