Healing & Repair Flashcards
Regeneration types
- replacement w/ original cell type
- replacement w/ CT
Labile cells
- proliferate & continually replace destroyed cells
- found in: epithelium, hematopoietic cells of spleen, lymphoid organs, bone marrow
Stable cells
- low replication rate, but rapid division can be stimulated
- found in: parenchymal cells of glandular organs, vasc. endothelial cells, fibroblasts, smooth m., osteoblasts, chondroblasts
Permanent cells
- don’t replicate at all or its insignificant
- usually replaced by CT
- found in: nerves, skeletal m., cardiac m.
Injuries in organs mostly made of labile or stable cells are replaced by
Regeneration or regen./CT replacement
If an injury is severe and damages the stroma or basement membrane, then ______ replacement more likely
CT
Repair by CT replacement
1) fibroblastic cells
2) granulation tissue
3) scar formation
24 hrs after injury you see…
Fibroblast and vascular endothelial cell proliferation
3-5 days post-injury, you see…
Granulation tissue
Components of granulation tissue
Fibroblasts and newly formed BV
Angiogenesis/neovascularization
New BV formed from budding of pre-existing BV
4 steps of angiogenesis/neovascularization
- enzymatic degrad. of basement membrane
- endothelial cell migration-> angiogenic stim.
- endothelial cell prolif.
- maturation of endothelial cells & organization-> capillary tubes
T or F: granulation tissue has tight gap junctions
False, they’re leaky and cause the tissue to be edematous
Myofibroblasts
- fibroblasts of granulation tissue
- characteristics: indented nuclei, prominent cytoplasmic fibril bundles, increased contractile proteins
Microscopic features of granulation tissue
- lg. amts of macrophages
- various amts of eosinoph., neutrop., lymph.
Function of macrophages in granulation tissue
- eliminate injurious agent
- remove extracellular debris
- blanching of wound
Blanching definition
collagen fibers accumulate, excess. Vasc. Channels regress, area becomes lighter
First intention healing definition
- occurs w/o wound contamination
- wound edges approx. & close wound
- ex. Surgical incisions that are sutured closed
When suturing a wound, this occurs…
- incision space filled w/ blood and fibrin
- clot formation
- clot gets dehydrated -> scab
24 hrs after suturing sx incision….
- neutroph. @ edges
- epith. edges prolif.-> migrate under sceb -> forms thin, continuous epith. layer
72 hrs after suturing sx incision…
- predominant cell-> macrophages
-granulation tissue dev. starts
- presence of collagen fibers (don’t bridge the incision)
- epithelial cells grow
- epidermal covering over incision gets thick
Day 5 after suturing sx incision…
- granulation tissue and collagen fibers bridge incision
- epidermis thickness= normal
- keratinized epithelium
Second week of first intention healing
- collagen acc.
- fibroblast prolif.
- inflamm. Cells & edema disappear
- blanching starts
End of month 1 of first intentional healing
- CT scar
- no inflamm. Cells
- epidermis intact
- damaged adexnal struct.
- decr. Tensile strength
Second intention healing definition
- regeneration minimal
- wound filled w/ granulation tissue
- occurs in more extensive tissue loss (infarction, lg surface wounds, inflammation ulcers)
Exuberant Granulation
- aka: equine “Proud Flesh”
- so much granulation tissue that a mass is formed & lacks epith.
Keloid formation
- Lg bulging scars due to collagen
- happens in darker skinned ppl more frequently
