Flashcards in Healing/Repair Deck (31)
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
What are the two paths of repair in healing?
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?
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
What is organization?
Process of transforming granulation tissue into a dense scar. With time blood vessels become less prominent, collagen matures.
What is the function of macrophages in wound healing?
Remove debris and secrete cytokines
What is the function of fibroblasts in wound healing?
Produce extracellular connective tissue matrix
What is the function of myofibroblasts in wound healing?
Contract the wound
What is 1st intention?
Clean, uninfected surgical incision with edges approximated by surgical sutures that results in a small scar
What is 2nd intention?
Large wound where the edges are not approximated and the wound granulates without closing the gap with sutures
A 68‐year‐old man with diabetes mellitus, type 2 undergoes a below‐knee amputation for wet gangrene. The patient's postoperative course is complicated by severe depression and anorexia. The healthcare team is concerned that dietary deficiencies will result in impaired wound healing. Supplementation of which of the following would be most appropriate?
A. Copper and Vitamin D
B. Folate and Zinc
C. Iodine and vitamin E
D. Vitamin C and Vitamin E
E. Vitamin C and Zinc
What is the function of Vitamin C in repair?
Needed for collagen cross-linking
What is the function of Cu in repair?
Lysyl oxidase activity to cross-link lysine and hydroxylysine
What is the function of zinc in repair?
Zn is a cofactor for collagenase
What is the effect of steroids on repair?
They inhibit inflammation and wound healing
What is a hypertrophic scar?
Excess production of scar tissue
What is a keloid?
Accumulation of excess collagen
A 31‐year old firefighter suffers extensive third‐degree burns over his arms and hands. This patient is a high risk for the development of which of the following complications of wound healing?
D. Squamous cell carcinoma
What is dehiscence?
Reopening up of a wound