Tissue Repair and Wound Healing Flashcards
What does regeneration of tissue require?
intact ECM
note: seen in tissues with high proliferative activity
Repair can be defined as a combination of regeneration and scar formation by ____ deposition
collagen
Tissue is dividing into three groups according to proliferative activity. Differentiate the following three groups and note where they are found:
continously dividing (labile) cells
quiescent (stable) cells
non-dividng (permanent) cells
continously dividing (labile) cells: proliferate throughout life; found in bone marrow, epidermis
quiescent (stable) cells: normally involved in low-level replication but may respond to stimuli by rapid division; found in liver, fibroblasts, kidney, smooth muscle
non-dividng (permanent) cells: do not undergo division in post-natal life; found in neurons, cardiac myocytes
This type of stem cell arises from the inner cell mass of blastocysts and is pluripotent
embryonic stem cells
This type of stem cell is identified in many mature tissues. It is more limited in its ability to differentiate
adult stem cells
The ECM is vital to tissue regeneration, it sequesters ___ and provides ___ to soft tissues and minerals for bone
water; turgor
What are the two fibrous structural proteins of ECM
collagens - tensile strenght
elastins - recoil
This component of the ECM connects components to one another and to cells; mostly transmembrane receptors
ex: Ig family, interns, selecting, cadherins
Adhesive glycoproteins (CAMs)
These components of the ECM are responsible for resilience and lubrication
proteoglycans and glycosaminoglycans
Tissue injury resulting in damage of ____ and ___ elements cannot heal by regeneration, but instead by repairing and scarring
parenchyma; stromal
Describe the sequence of healing
- inflammation
- angiogenesis
- migration and proliferation of fibroblasts
- scar formation
- CT remodeling
Within ___ hours of clot formation, neutrophils appear; use scaffolding of clot to “move in” and clean up the mess
24
Proliferation of fibroblasts and vascular endothelium starts in ____-____ days
1-3
What are histologic features of granulation tissue formation?
small new blood vessels due to angiogenesis, proliferation of fibroblasts, vessels are leaky - tissue is edematous
Granulation tissue peaks around __-__ days
5-7
Neutrophils are largely replaced by ____ by 2-4 days
macrophages
What do macrophages do in the tissue repair process?
clear debris; promote angiogenesis and ECM deposition, main source of growth factors
In regards to scar formation, how long does it take for leukocytes and granulation tissue to have mainly disappeared
2 weeks
In regards to scar formation, describe blanching (occurs after leukocytes and granulation tissue has disappeared)
increased collagen within wound; regression of vascular channels
By the end of the ____ ____, the scar is composed of acellular CT, without inflammation, covered by intact epidermis
first month
What causes wound contraction?
myofibroblasts, formed from tissue fibroblasts though effects of growth factors are similar to smooth muscle cells and contract in the wound tissue
What is the benefit of wound contraction?
helps close gap by decreasing distance between dermal edges
This is the single most important cause of delayed wound healing
infection
This is an inadequate formation of granulation tissue or defective assembly of a scar
wound dehiscence or ulceration
This is excessive formation of components of repair process
keloid or hypertrophic scar
Exuberant granulation which blocks re-epithelization
proud flesh
Exuberant fibroblast proliferation and other CT elements
desmoids or aggressive fibromatoses
