Tissues Responses to Injury Flashcards
What is the primary goal of tissue repair?
Restoration of tissue architecture and function after an injury.
What are the two main outcomes of tissue repair?
- Regeneration
- Fibrosis
What factors influence the outcome of tissue repair?
- Regenerative capacity of tissues
- Nature of the injury
- Severity of the injury
- Duration of the injury
Define granulation tissue.
- New, growing blood vessels
- Proliferating fibroblasts
- New matrix synthesis
- Inflammatory cells
What are the three groups of tissues based on regenerative capacity?
- Continuously dividing (labile) tissues
- Stable tissues
- Permanent tissues
What characterizes continuously dividing (labile) tissues?
- Cells are continuously proliferating
- Can easily regenerate after injury
- Contain a pool of stem cells
Which tissues are classified as stable tissues?
- Liver
- Kidney
- Pancreas
What defines permanent tissues?
- Cells can’t proliferate
- Can’t regenerate, leading to scarring
What is the first step in the tissue repair process?
Inflammation
What occurs during the organization step of tissue repair?
- Fibroblasts secrete collagen
- New capillaries bud
- Microphages remove clot
- Granulation tissue develops
What is the difference between healing by first intention and second intention?
- First intention: occurs in small wounds, epithelial regeneration predominates
- Second intention: occurs in larger wounds, fibrosis predominates
What is the healing timeline for first intention healing at 24 hours?
- Clot forms
- Neutrophils arrive
- Epithelium begins to regenerate
What is a keloid scar?
Excess deposition of collagen that develops late in the healing process.
What is proud flesh?
Granulation tissue in excess.
What is the typical strength of a wound at suture removal?
10%
How does the strength of a wound change over time?
Rapid increase over the next 4 weeks, reaching 70-80% by the third month.
What are the defining properties of stem cells?
- Ability to differentiate into other cells
- Ability to self-regenerate
What are the types of stem cell differentiation potential?
- Totipotential
- Pluripotential
- Multipotential
- Quadripotential
- Unipotential
- Nullipotential
What are some sources of stem cells?
- 3-Day Embryo
- 5-7 Day Embryo
- Fetal tissue
- Adult stem cells
- Cord blood stem cells
What are some problems associated with embryonic stem cells (ESCs)?
- Ethical and political barriers
- Low survival rate after injection
- Potential dangers like tumor development
- Immune rejection
