Chronic Inflammation and Healing and Tissue Repair Flashcards
Define disease
A deviation or interruption of normal structure and/or function
What is healing and tissue repair?
An attempt to return to normal structure and function
What does the healing process vary on?
The type of tissue damaged, the extent of injury, and the underlying host factors
What is parenchymal tissue?
Functioning cells of a body part
What is stromal tissue?
Connective, supportive framework that promotes or helps to enable the function of parenchymal tissue
What are labile cells?
Cells that continually divide and replicate
What is an example of labile cell
Bone marrow, epithelial cells
What are stable cells?
Cells that normally stop dividing when growth stops, but can regenerate when stimulated
What is required for stable cells to regenerate properly?
A stromal framework
What are permanent cells?
Cells that rarely or never regenerate or divide
What is extracellular matrix?
Material secreted by local cells through the body that surrounds and supports the cells. Made up of fibrous structural proteins, water-hydrated gels, adhesive glycoproteins, and ground substance
What are the 2 types of fibrous structural protein?
Collagen, elastin
What are types of water-hydrated gels?
hyaluronan, proteoglycans
What are 2 examples of adhesive glycoproteins?
fibronectin, laminin
What does ground substance refer to?
all extracellular matrix except the fibrous proteins
What is a basement membrane?
A membrane underneath epithelial, endothelial, and smooth muscle cells. Separates lining from connective tissue
What must be present before re-epithelization can occur?
Basement membrane
What is interstitial matrix?
Gel-like substance between body cells
What are integrins?
Transmembrane proteins in cells that allow for attachment to extracellular matrix and communication between extracellular and intracellular
When does granulation tissue develop?
When there is a wound that cannot be resolved just by regeneration as a precursor to scar tissue
What does granulation tissue look like?
Reddish, moist, soft, and “bumpy” or granular. It is fragile and bleeds easily
What is the production of new capillaries called?
Angiogenesis
What is in granulation tissue?
New capillaries, proliferating fibroblasts, and residual inflammatory cells
What is the generation of new blood vessels from existing blood vessels?
Angiogenesis
What is a chemical signaling molecule for angiogenesis and what cells produce it
vascular endothelial growth factor, cells deficient in oxygen
What are the 4 steps in angiogenesis?
1) Degradation of parent vessel basement membrane, 2) Migration of endothelial cells from parent vessel toward angiogenic stimulus, 3) Proliferation of endothelial cells behind leading edge of migrating cells, 4) Maturation of endothelial cells and vessel walls
What tissue does scar tissue build on?
Granulation tissue framework of new vessels and loose ECM
What do fibroblasts do for scar tissue formation?
Fibroblasts move to area of injury and proliferate. They secrete ECM components (fibronectin, hyaluronan, proteoglycans, collage). These components are degraded over time by proteases and replaced
What happens after fibroblasts proliferate and secrete ECM in scar tissue formation?
Increased collagen synthesis and decreased fibroblast proliferation. Decreased new blood cells. Granulation tissue transitions to dense collagen fiber matrix. Loss of vascularization
What are the chemical mediators involved in the healing process?
Interleukins, interferons, prostaglandins, and leukotrienes
What do chemical mediators do for regulation of the healing process?
They promote chemotaxis of leukocytes and fibroblasts and mediate inflammatory response
What are the growth factors to know for regulation of the healing process?
Vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, epithelial growth factor
What are the functions of growth factors in the healing process?
-proliferation, differentiation, and cell metabolism
-mediate inflammatory response
-promote chemotaxis of leukocytes and fibroblasts
-stimulate angiogenesis
-contribute to generation of ECM
What are the 4 stages of healing and tissue repair?
Hemostasis. inflammation, proliferation, and remodeling
What are the three stages of wound intention?
primary intention, secondary intention, and tertiary intention
What is primary intention?
small incision-like wounds with well-approximated edges
What is secondary intention?
large, crater-like wounds with greater loss of tissue
What is tertiary intention?
large wound that is intentionally left open and then closed at a later date. Usually done when there is drainage or an infection
What occurs in hemostasis?
Blood vessels initially constrict. There is increased platelet attraction and aggregation. Then, thrombus forms to promote hemostasis and prevent entry of foreign agents. After the vessel injury, the capillary dilates and increases permeability
What do leukocytes do in inflammation?
Neutralize foreign bodies and pathogens introduced into the tissue