[P] Week 2: Inflammation and Repair - Part 3 Flashcards
TISSUE REPAIR
What is repair in the context of tissue?
Repair, also called healing, refers to the restoration of tissue architecture and function after an injury.
TISSUE REPAIR
What initiates the healing process after tissue injury?
Injury to cells and tissues sets in motion a series of events that contain the damage and initiate the healing process.
TISSUE REPAIR
What are the two processes involved in the repair of damaged tissues?
regeneration, which restores normal cells, and scarring, the deposition of connective tissue.
TISSUE REPAIR
What factors influence the repair process?
The repair process depends on type of wound, inflammatory process, matrix damage, and organ.
CELL AND TISSUE REGENERATIO
What is complete healing of an organ?
It is a complete healing of the organ (ex. wound, injury)
Example: Healing of a cut on the skin.
CELL AND TISSUE REGENERATIO
What does regeneration involve?
Involves proliferation of cells and tissues.
CELL AND TISSUE REGENERATIO
What is replaced during regeneration?
Replacement of structure and function.
CELL AND TISSUE REGENERATIO
Which organs in the body may regenerate?
Liver, kidney, epithelia of skin and GIT.
TISSUE PROLIFERATIVE ACTIVITY
Tissue of the body are divided into 3 groups on the basis of proliferative activity of their cells, enumerate
- Labile tissues (continuously dividing)
- Quiescent tissues (stable)
- Permanent tissues (non-dividing)
TISSUE PROLIFERATIVE ACTIVITY
continuously dividing cells that proliferate throughout life, replacing those that are destroyed.
Labile tissues (continuously dividing
Examples include surface epithelia, squamous cells (skin, oral cavity, vagina, cervix), lining of excretory ducts, columnar epithelium (GIT, endometrium), and transitional epithelium (GUT).
TISSUE PROLIFERATIVE ACTIVITY
Where are labile cells found?
Labile cells can be found in bone marrow and in hematopoietic tissues.
TISSUE PROLIFERATIVE ACTIVITY
low level of replication but can undergo rapid division in response to stimuli, allowing them to reconstitute the tissue of origin.
Quiescent tissues (stable)
Examples include parenchymal cells (liver, kidneys, pancreas), fibroblasts, smooth muscle cells, chondrocytes, osteocytes, and endothelial cells.
TISSUE PROLIFERATIVE ACTIVITY
lining epithelium of a blood vessel but are not labile cells; they proliferate only when there is an injury.
Endothelial cells
TISSUE PROLIFERATIVE ACTIVITY
consist of cells that have left the cell cycle and cannot undergo mitotic division in postnatal life.
Permanent tissues (non-dividing
Examples include cardiac muscle, skeletal muscle, and neurons.
MECHANISMS OF TISSUE & ORGAN REGENERATION
Mammals cannot regenerate whole tissues or organs because of the following reasons, enumerat
- No blastema formation
- Rapid fibroproliferative response after injury
- Wnt/β-catenin is highly conservative
LIVER REGENERATION
TOF
The human liver has a remarkable capacity to explode.
F - regenerate
LIVER REGENERATION
How is liver mass restored after resection?
Restoration of liver mass is achieved without the regrowth of the lost lobes that were resected.
more of a compensatory growth
LIVER REGENERATION
What are the two major mechanisms of liver regeneration?
Regeneration of the liver occurs by:
- proliferation of remaining hepatocytes
- repopulation from progenitor cells
LIVER REGENERATION
What triggers hepatocyte proliferation in the regenerating liver?
Hepatocyte proliferation is triggered by the combined actions of cytokines and polypeptide growth factors.
Do all hepatocytes replicate during liver regeneration?
Almost all hepatocytes replicate during liver regeneration after partial hepatectomy.
What happens if repair cannot be accomplished by regeneration alone?
Repair occurs by replacement of the injured cells with connective tissue, leading to the formation of a scar, or by a combination of regeneration of some residual cells and scar formation.
Steps in repair
- Scar formation and fibrosis
o First, there is injury in the area. There may be bleeding and scab formation, followed by inflammation. - Inflammation
- Angiogenesis
- Migration and Proliferation of Fibroblasts
- Scar Formation
- Connective Tissue Remodeling
process of new blood vessel development from existing vessels
ANGIOGENESIS
what are the types of Angiogenesis
- Vasculogenesis
- Angiogenesis or Neovasculrization
ANGIOGENESIS
It is the formation of new blood vessels assembled during embryonic development.
Vasculogenesis
They may start from cells like angioblasts or hemangioblasts.
ANGIOGENESIS
Vasculogenesis may start from?
angioblasts or
hemangioblasts
ANGIOGENESIS
It is the formation of new vessels in adults; these are already coming from a well-formed vessel and may appear as branching or extending.
Angiogenesis or Neovascularization
ANGIOGENESIS
stable cells; once they are needed, they can proliferate.
Endothelial cells
Initially, endothelial cells are on a low level of replication, however, once needed, they will undergo replication.