Healing/Repair Flashcards
A 56‐year‐old man has experienced severe chest pain for the past 4 hours. On physical examination he is tachycardic. Laboratory studies show a serum troponin I of 9 ng/mL. A coronary angiogram is performed emergently and reveals acute thrombosis of the left anterior descending coronary artery. In this setting, an irreversible injury to myocardial fibers will have occurred when which of the following cellular changes occurs?
A. Blebs form on cell membranes B. Cytoplasmic sodium increases C. Glycogen stores are depleted D. Intracellular pH diminishes E. Nuclei undergo karyorrhexis
E.
What are the two paths of repair in healing?
- Regeneration
- Scar Formation
What is regeneration?
Replacement of damaged cells by replicating cells of the same type
What is scar formation?
Replacement by connective tissue
What is necessary for regeneration to occur?
Residual uninjured cells must have the capacity to divide
What are labile tissues?
Continuously dividing
What are stable tissues?
Low, no level of replication that rapidly divide when stimulated
What are permanent tissues?
Terminally differentiated, nonproliferative in postnatal life
Brain and heart
What is the function of Transforming Growth Factor Alpha (TGF‐alpha)?
Stimulates proliferation of hepatocytes, other epithelial cells
What is the function of Vascular endothelial growth factor (VEGF)?
Stimulates proliferation of endothelial cells; increases vascular permeability
What is the function of Transforming Growth Factor Beta (TGF‐beta)
Chemotactic for leukocytes, fibroblasts; stimulates ECM synthesis; suppresses acute inflammation
When does scar formation occur?
- Injured tissues incapable of regeneration
- Supporting structures severely damaged, stem cells lost
What is angiogenesis?
New blood vessel development from existing vessels
What is the function of VEGF in angiogenesis and what is its inducer?
– Promote angiogenesis
– Increase vascular permeability
It is induced by hypoxia
What is granulation tissue?
Specialized tissue that fills in defects in organs when non‐regenerative cells and/or connective tissue framework is destroyed