Study Set Content:
often used to describe the deposition of collagen that occurs in the lungs, liver, kidney, and other organs as a consequence of chronic inflammation or in the myocardium after extensive ischemic necrosis (infarction)
Fibrosis
If fibrosis develops in a tissue space occupied by an inflammatory exudate, it is called
organization (as in organizing pneumonia affecting the lung)
driven by growth factors and dependent on the integrity of ECM, and development of mature cells from tissue stem cells
cell proliferation
Cells of these tissues are continuously being lost and replaced by maturation from tissue stem cells and by proliferation of mature cells.
Labile (continuously dividing) tissues
attempt to restore normal structure
Remnants of the injured tissue
create new vessels that provide the nutrients needed for the repair process
Vascular endothelial cells
the source of the fibrous tissue that forms the scar to fill defects that cannot be corrected by regeneration
Fibroblast
Cells of these tissues are quiescent
Stable Tissues
In the G0 of the cell cycle
Quiescent
have only minimal proliferative activity in their normal state.
Stable Tissues
cells are capable of dividing in response to injury or loss of tissue mass; constitute to the parenchyma of most solid tissues such as live, kidney and pancreas
Stable tissues
include hematopoietic cells in the bone marrow and the majority of surface epithelia,
Labile Tissues
The cells of these tissues are considered to be terminally differentiated and nonproliferative in postnatal life.
Permanent Tissues
is driven by signals provided by growth factors and from the ECM.
cell proliferation
The most important sources of these growth factors in cell proliferation are
macrophages
remarkable capacity to regenerate, as demonstrated by its growth after partial hepatectomy
Liver Regeneration
Regeneration of the liver occurs by two major mechanisms:
- proliferation of remaining hepatocytes
- repopulation from progenitor cells
In the second, or growth factor, phase, growth factors, these are produced by many cell types that act on primed hepatocytes to stimulate cell metabolism and entry of the cells into the cell cycle.
Hepatocyte Growth Factor (HGF) or TGF-a
During the phase of hepatocyte replication, numerous genes are activated; these includes:
genes encoding transcription factors, cell cycle regulators, regulators of energy metabolism, and others
The wave of hepatocyte proliferation is followed by replication of nonparenchymal cells such as
Kupffer cells, endothelial cells, and stellate cells
