Tissue Repair and Wound Healing Flashcards
Restoration of tissue architecture and function after an injury is called what?
Repair
What is the replacement of the damaged cells and essentially return to a normal state? Occurs by ____ of residual or uninsured cells and by _____ from tissue stem cells. Usual response in what?
Regeneration
Residual cells, replacement
Usual response in rapidly dividing epithelia of the skin, intestines, liver
What is injured tissues that are incapable of regeneration, or supporting structures of the tissue are severely damaged?
Scar formation- repair occurs by the laying down of CT–>scar formation
Scar cannot perform the function of lost parenchyma cells, but provides structural stability that the injured tissue is usually able to function
What is extensive deposition of collagen that occurs as a consequence of chronic inflammation or ischemic necrosis (infarction)?
Fibrosis- if fibrosis develops in a tissue space occupied by an inflammatory exudate, it is called organization (such as PNA in lung)
Cell and tissue regeneration involves cell ____ driven by ____ ______ and is critically dependent on the integrity of the _____ ______.
Proliferation
Growth factors
Extracellular matrix
There are several types of cells that proliferate during tissue repair. What are they?
- remnants of the injured tissue
- vascular endothelial cells
- fibroblasts
Non dividing cells (cell cycle arrest)
G1
Exited the cycle (growth factors stimulate cells to transition from this phase to another phase)
G0
G0 to G1 – S, G2, and M phases
What are hematopoietic cells, surface epithelia, and GI tract epithelium?
Labile (continuously dividing) tissues
These readily regenerate after injury as long as the pool of stem cells is preserved
What tissues are quiescent and have only minimal replicating activity in their nml state but are capable of proliferating in response to injury or loss of tissue mass?
Stable tissues
Liver, kidney, and pancreas
What tissue is terminally differentiated and non-proliferative?
Permanent tissues
Neurons, skeletal muscle, cardiac muscle
Results in a scar
What has self-renewal capacity and asymmetric replication?
Stem cells
The most undifferentiated stem cells
Embryonic stem cells
Inner cell mass of the blastocyst with extensive cell renewal capacity
Tissue stem cells are less undifferentiated and are found among differentiated cells within an organ or tissue with limited self-renewal capacity
Adult stem cells
Hematopoietic stem cells can be isolated from ____ _____ and peripheral blood after mobilization by administration of certain cytokines such as G-CSF.
Bone marrow
Can give rise to all blood cell lineages and continuously replenish the formed elements of the blood
Used for treatment of leukemia and lymphomas
These are proteins that stimulate the survival and proliferation of particular cells and may also promote migration, differentiation, and other cellular responses.
Growth factors
Growth factors induce cell proliferation by binding to specific receptors and affecting the expression of genes whose products typically have what functions?
- Promote entry of cells into the cell cycle
- stimulate the function of growth control genes
Signaling may occur directing in the same cell that produces the factor (____ signaling), between adjacent cells (_____ signaling), or over greater distances (______ signaling).
Autocrine
Paracrine
Endocrine
What is present in the spaces between cells in CT and between epithelium and supportive vascular and smooth muscle structures?
Interstitial matrix
Synthesized by mesenchymal cells (fibroblasts)
What lies beneath the epithelium and is synthesized by overlying epithelium and underlying mesenchymal cells?
Basement membrane
Genetic defect in collagen?
Ehlers-Danlos
Osteogenesis imperfecta
Defect in Elastin?
Marfan syndrome - skeletal abnormalities and weak ended aortic walls
What are hydrated compressible gels conferring resilience and lubrication?
Proteoglycans
What are important constituents of the ECM that binds water?
Hyaluronan
What is involved in cell-to-cell adhesion with linkage of cells to ECM and binding between ECM components?
Adhesive glycoproteins and adhesion receptors
-includes fibronectin (interstitial ECM) and laminitin (basement membrane)
ECM provides mechanical support for cell _____ and cell ______, and maintenance of cell _____. Control of cell _____ by binding and displaying growth factors. Scaffolding for tissue _____.
Anchorage Migration Polarity Proliferation Renewal
What are the steps in scar formation? (3)
- Formation of new blood vessels (angiogenesis)
- Migration and proliferation of fibroblasts and deposition of CT called granulation tissue
- Maturation and reorganization of fibrous tissue (remodeling) to produce stable fibrous scar
Repair beings within ____ hours of injury by the emigration of ____ and the induction of ____ and endothelial cell proliferation.
24
Fibroblasts
Fibroblasts
After ___ to ____ days specialized granulation tissue will appear. Scar remodel will occur over time.
3 to 5 days
What is the most important cause for delay in healing?
Infection
What are the factors that influence tissue repair? (6)
- infection
- nutrition
- glucocorticoids (steroids)
- mechanical variables (increased local pressure or torsion causing wound to pull apart called dehisce)
- poor perfusion (arteriosclerosis and diabetes, obstructed venous drainage)
- foreign bodies (steel, glass, bone)
What is an aberration of cell growth where there is accumulation of exuberant amounts of collagen that can give rise to prominent raised scars?
Keloid- more common in Africa-Americans
Healing wounds may generate exuberant granulation tissue called what?
“Proud flesh”- restoration of epithelial continuity requires cautery or surgical resection of the granulation tissue
Clean,, uninflected surgical incision approximated by surgical sutures.
Healing by first intention
Cell or tissue loss is more extensive at sites of abscess formation, ulceration, and ischemic necrosis in parenchymal organs.
Healing by second intention
