Exam 1: Healing and Repair Flashcards
when does repair start
pretty soon after inflammation does; and continues during and beyond inflammatory phase
perfect restoration of function is dependent on
regeneration of lost cells by similar cells; and the orderly arrangement of these new cells in relation to preexisting cells (repair by regeneration)
if the original cells cannot be replaced by their own kind then they are rpelaced by
other cell types (repair by replacement) usually by fibrous connective tissue
if necrosis is extensive, even tissues that are capable of regenration are repalced by
fibrous connective tissue
what are the steps in scar formation
angiongenesis
formation of granulation tissue
remodeling of connective tissue to produce stable fibrous scar
angiogenesis
formation of new blood vessels, which supply nutrients and oxygen needed to support the repair process
formation of granulation tissue
proliferation of fibroblasts and new thin-walled, delicate capillaries in a loose extracellular matrix, often with admixed inflammatory cells, mainly macrophages
scar comprises
a cellular CT largely devoid of inflammatory cells and covered by an esentially normal epidermis
dermal appendages destroyed in the line of the incision are
permanently lost
granulation tissue
part of the repair process and consits of inflamed proliferating fibrous tissue
granulomatous
inflammatory infiltrates characterized by macrophages
major cytokine involved in fibrosis is
TGF-B
platelet derived growth factor (PDGF) sources
platelets, macrophages, endothelium
PDGF function
chemotactic for fibroblasts, macrophags, smooth muscle, mitogenic for fibroblasts
transforming growth factor beta (TGFB) sources
platelets, t cells, macrophages
TGFB function
chemotactic for fibroblasts, leukocytes, stimulates proliferation of fibroblasts, extracellular matrix
fibroblast growth factor (FGF) sources
many cell types
FGF function
stiulates angiogenesis, mitogenic for endothelium, smooth muscle, fibroblasts
epidermal growth factor (EGF) sources
platelets, macrophages
EGFf function
induces proliferation of epithelium, endothelium, fibroblasts, increases production of glycosaminoglycans
insulin-like growth factors (igf) sources
fibroblasts, hepatocytes
IGF function
mitogenic for fibroblasts
IL-1 source
macrophages, endothelium
IL-1 function
chemotacti for leukocytes, stimulates proliferatio of keratinocytes, fibroblasts, endothelium
TNFa sources
macrophages
TNFa funciton
mitogenic for fibroblasts; angiogenic
IFNy source
lymphocytes
IFNy function
inhibits fibrobast proliferation; inhibits collagen synthesis
fibrosis most often refers to
abnormal deposition of collagen that occurs in internal organs in chronic diseases
fibrosis is typically associated with
loss of tissue and may be responsible for substancial organ dysfunction and even organ failure, such a s in a cirrhotic liver or end-stage kidney
when a fracture occurs, growth factors are released by macrophages and plateltes in the blood clot (hematoma) and start the
proliferation of cartilage and granulation tissue
callus
refers to an unorganized meshwork of woven bone
after months, there is modeling of the woven bone into
lamellar bone
what are the most common complicationsof fracture healing
inadequate blood supply, instability, and infection
what are the steps in bone healing
- fragments displaced, soft tissue traumatized, bleeding, hematoma
- proliferation of cartilage and granulation tissue
- callus
- modeling of woven bone into laellar bone
why is repair in CNS very limited
because mature neurons do not divide (neurons and processes are lost forever)
after nervous tissue is gone, replacement by
glial cells (astrocytes) forming a glial scar
in PNS injury to nerves may be followed by
regeneration if the nerve cell body remains
myocardial cells are
permanent
repair can only take place in myocardium by
fibrosis; which decreases myocardial contractility
