Lecture 3 Flashcards
What 3 factors does the healing process depend on?
The type of tissue damaged
The extent of the injury
Underlying host factors
Disease
Deviation or interruption of normal structure and/or function
Healing and Tissue Repair
Attempt to return to normal structure and function
Parenchymal vs Stromal
Parenchymal tissue refers to the functioning cells of a body part, such as a hepatocyte or nephron.
Stromal tissue refers to the structural cells of a body part such as connective tissue or the ECM.
What are the 3 cell types?
Labile, Stable, and Permanent
Where do I find labile cells?
They are cells that continually reproduce/divide. They are often found in epithelial tissue, such as the skin, oropharynx, bone marrow and GI/GU tract.
Where do I find stable cells?
Stable cells normally stop dividing once growth ceases, but can regenerate.
Usually found as hepatocytes or smooth muscle cells.
They require a stromal framework for regeneration.
Where do I find permanent cells?
Fixed cells that rarely regenerate or divide.
Examples include ocular, neurons, heart, skeletal muscle cells, and RBCs.
What 4 categories make up the ECM?
Fibrous Structural Proteins, Water-hydrated gels, Adhesive glycoproteins, and ground substance.
What is another name for ECM?
interstitial matrix
What are the fibrous structural proteins of the ECM?
Collagen and elastin
What are the water-hydrated gels of the ECM?
Hyaluronan and proteoglycans
What are the adhesive glycoproteins of the ECM?
Fibronectin and laminin
What is ground substance?
It refers to the ECM except for fibrous proteins.
What is a basement membrane?
It is the underlying epithelial, endothelial, and smooth muscle cells; separating the lining from the connective tissue.
What is the interstitial matrix?
It is the gel-like substance found between cells.
What are integrins and what are they used for?
They are integral/transmembrane proteins that allow for attachment to the ECM and communication between the intracellular and extracellular environment.
What is granulation tissue?
It is the precursor to scar tissue. It develops when there is a wound that can’t be resolved with regeneration alone. It is a highly vascularized tissue that is typically reddish, moist, soft, bumpy, and granular in appearance. It is very fragile and bleeds easily.
What is angiogenesis and what triggers it?
It is the generation of new blood vessels from existing blood vessels, triggered by the release of VEGF from hypoxic cells.
What are the 4 steps of angiogenesis?
- Proteolytic degradation of parent vessel basement membrane by VEGF, leading to a sprout.
- Migration of endothelial cells from parent vessel towards an angiogenic stimulus.
- Proliferation of endothelial behind the leading edge of migrating cells.
- Maturation of endothelial cells and vessel walls.
What are examples of conditions that cause angiogenesis?
Damaged or disrupted tissue
Cancerous lesions
Diabetic Retinopathy
What makes scar tissue?
Fibroblasts
What are the initial ECM components secreted by fibroblasts?
Fibronectin, collagen, hyaluronan, and proteoglycans
What happens to scar tissue over time as it is constructed?
Increased collagen synthesis, diminished fibroblast proliferation, and diminishing new blood vessels.
Involves loss of vascularization and becomes a dense collagen matrix.