Pathoma - Chapter 2 - Wound Healing

Front 1

When is healing initiated?

Back 1

When inflammation begins.

Front 2

Healing occurs via two processes. What are they?

Back 2

(1) Regeneration
(2) Repair

Front 3

What is regeneration?

Back 3

Replacement of tissue with native tissue.

Front 4

Regeneration is dependent on some property of the tissue. What is it?

Back 4

The regenerative capacity of the tissue.

Front 5

Tissues can be divided into three types based on their regenerative capacity. What are they?

Back 5

(1) Labile tissues. Tissue stem cells are constantly cycling to regenerate the tissue.
(2) Stabile tissues. They are quiescent, but can reenter the cell cycle.
(3) Permanent tissues. Lack significant regenerative potential.

Front 6

Where do we have labile tissues?

Back 6

(1) Small and large bowel.
(2) Skin (basal layer stem cells)
(3) Marrow

Front 7

The marker of hematopoietic stem cells is ____?

Back 7

CD34+

Front 8

What is the stem cell of the lung?

Back 8

Type II pneumocyte

Front 9

Where would regenerative cells be located on this histograph?

Back 9

Front 10

Give two examples of a stable tissue.

Back 10

(1) Liver. If you resect the liver, it can regenerate by compensatory hyperplasia. Each hepatocyte can reenter cell cycle and divide and produce additional cells.
(2) Proximal renal tubule. In ATN, cells die, but they can regenerate.

Front 11

How would permanent tissues heal?

Back 11

By repair, not regeneration.

Front 12

Repair replaces damaged tissues with a ______.

Back 12

scar

Front 13

When does repair occur?

Back 13

(1) When regenerative stem cells are lost.
(2) When tissue lacks regenerative capacity.

Front 14

The initial phase of repair is called?

Back 14

Granulation tissue.

Front 15

Granulation tissue consists of what? What do each of them do?

Back 15

(1) Fibroblasts (deposit type III collagen)
(2) Capillaries (nutrients)
(3) Myofibroblasts (contract wound)

Front 16

What do you see?

Back 16

Granulation tissue.

Front 17

Eventually, granulation tissue will produce a __________.

Back 17

scar

Front 18

In scar formation, what change in collagen happens? What enzyme performs this?

Back 18

Type III collagen is replaced with type I collagen

Collagenase

Front 19

Collagenase requires _______ as a cofactor.

Back 19

zink

Front 20

Type I collagen is abundant in ________?

Back 20

Bone (bONE = ONE = I)

Front 21

Type II collagen is primarily seen in ________?

Back 21

Cartilage (CarTWOlage = TWO = II)

Front 22

Type III collagen is a very __________ (strong/pliable) type of collagen. Where do we see type III collagen?

Back 22

pliable

Blood vessels/lymphatics (need for stretch), granulation tissue (it needs to be able to stretch and mold into a final scar), embryonic tissue (baby is growing and needs to be able to stretch)

Front 23

Type IV collagen is seen where?

Back 23

Basement membrane

Front 24

What is the mechanism of regeneration and repair?

Back 24

It is mediated by paracrine signaling via growth factors. Interaction of GFs with receptors result in gene expression and cellular growth.

Front 25

TGF-alpha is an important ___________ and _____________ growth factor.

Back 25

epithelial; fibroblast growth factor

Front 26

TGF-beta is an important ________________ and it inhibits _________.

Back 26

fibroblast growth factor; inflammation

Front 27

PDGF is an important ________, _________ and ____________ growth factor.

Back 27

endothelium; smooth muscle; fibroblast

PLTs release it to aid in healing when there is damage.

Front 28

Fibroblast growth factor is a strong ____________ factor and is important for _________ development.

Back 28

angiogenetic; skeletal

Front 29

Vascular endothelial growth factor is important for ___________.

Back 29

angiogenesis

Front 30

Cutaneous healing can occur via one of two ways. What are they?

Back 30

(1) Primary intention. You get a wound, brought into the ER and wound edges are brought together. Results in minimal scar formation.
(2) Secondary intention. We don't let the edges be approximated. Tissue remains open and the granulation tissue fills in the defect.

Front 31

Delayed wound healing can be caused by [...]

Back 31

(1) Infection (MCC). Continued inflammation impairs healing.
(2) Vitamin C deficiency (hydroxylation; proline and lysine residues of procollagen must be cross-linked)
(3) Copper deficiency (lysyl oxidase)
(4) Zinc (collagenase)
(5) Other: Foreign body (chronic inflammation), ischemia (no nutrients), diabetes, malnutrition.

Front 32

The normal amino acid structure of collagen is?

Back 32

-Gly-X-Y-

X = proline or lysine (usually proline)
Y = proline or lysine (gets hydroxylated)... Vitamin C is needed to -OH the Y amino acids.

Front 33

What is dehiscence? It is most commonly seen after __________ surgery.

Back 33

When the wound opens/ruptures.

Abdominal surgery.

Front 34

What is a hypertrophic scar?

Back 34

Aberrant healing process: Excess production of scar tissue that is localized to the wound (type I collagen)

Front 35

What is a keloid?

Back 35

Aberrant healing process: Excess production of scar tissue that is waaay out of proportion to the wound.

Front 36

A keloid is characterized by excess ____________?

Back 36

type III collagen

Front 37

There is a genetic predisposition to keloids and it is MC seen in ____________.

Back 37

african-americans

Front 38

The classic location of a keloid is in the _________.

Back 38

earlobe

Also face and upper extremities.