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91 Cards in this Set
- Front
- Back
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What is tissue regeneration?
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The growth of cells and tissues to replace lost structures.
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What is healing?
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The response of tissues to wounds, inflammation, or necrosis that consists of regeneration and scar formation.
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What cells are capable of regeneration?
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Only labile and stabile
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When do labile stells undergo regeneration?
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All the time
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What are the labile cells that continuously regenerate?
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-Epithelial (epidermal)
-GI -Hematopoietic (bone marrow) |
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What stabile tissues are capable of regeneration?
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-Liver
-Kidney |
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What do we call the regeneration of injured hepatic or kidney tissue?
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Compensatory growth
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What is the typical response to an acute wound?
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Wound healing and scar formation
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What is the typical response to a chronic wound?
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Chronic inflammation and fibrosis
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What is the difference between an acute and chronic injury?
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-Acute injury will damage functional cells only
-Chronic injury damages the supporting framework as well |
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What 4 processes govern the size of a cell population?
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-Stem cell input
-Proliferation -Differentiation -Death by apoptosis |
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3 labile cells:
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-Bone marrow
-Epidermal -GI |
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3 stabile cells:
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-Hepatic
-Kidney -Pancreatic |
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3 Permanent cells:
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-Cardiac muscle
-Skeletal muscle -Neurons |
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What cells are nonresponsive to radiation therapy for cancer?
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Permanent cells
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What disease would you not treat with radiation?
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Teratoma
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What type of repication do we see in stem cells?
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Assymetric - one cell remains a stem cell, another differentiates.
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What is required for compensatory growth?
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An intact cellular framework
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So in what type of liver injury can compensatory growth occur?
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Acute, not chronic.
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Where are adult stem cells located in the body?
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In niches
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What does embryonic endoderm differentiate into?
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Epithelial cells of the
-liver -lungs -GI tract |
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What does mesoderm differentiate into?
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1. Mesodermal progenitor cells
2. Hematopoietic progenitor cells |
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What do mesodermal progenitor cells give rise to?
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-Myocytes
-Osteoblasts -Chrondocytes -Adipocytes -Endothelium |
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What do hematopoietic progenitor cells give rise to?
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-Bone marrow cells
-Red blood cells |
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What does ectodermal tissue give rise to?
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-Keratinocyte precursors
-Neurons -Oligodendrocytes -Ependymal cells |
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What is the important factor that induces mesodermal progenitor cells to differentiate into endothelial cells?
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VEGF
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Why is VEGF important?
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It is implicated in the vascularization of tumor tissue
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Where are the stem cells in GI epithelial tissue found?
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Above paneth cells, and below enteroendocrine cells - in the Crypts.
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Where are stem cells for skin found?
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In the hair follicle bulge
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What are quiescent cells?
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Stable cells like hepatocytes, renal cells, and pancreatic cells.
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In what cell cycle phase are quiescent cells?
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G-0
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How do cells know what to do for tissue regeneration or healing?
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By responding to autocrine, paracrine, and endocrine signaling
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What type of signaling is important for hepatic compensatory regrowth?
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Autocrine
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What is another cellular process in which autocrine signaling is important?
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Proliferation of antigen stimulated lymphocytes
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What type of signaling is important for macrophage-fibroblast interaction in wound healing?
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Paracrine
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What are the molecules that act as signals to direct regeneration and healing?
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-Growth factors
-Cytokines |
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What is TGF-beta?
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A growth INHIBITOR
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What specific cell growth is inhibited by TGF-b?
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-Epithelial cells
-Leukocytes |
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What does TGF-b stimulate?
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-Fibrosis
-Smooth muscle cell proliferation |
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How does TGF-b relate to inflammation?
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It is a potent anti-inflammatory
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What are the 4 major signal transduction mechanisms for cell signaling?
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1. 7-transmembrane GPC receptors
2. Receptors with intrinsic tyrosine kinase activity 3. Receptors without it 4. Steroid hormone receptors |
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What are 4 ligands that use the 7-transmembrane GPC receptors?
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1. Epinephrine
2. Norepinephrine 3. Glucagon 4. PTH |
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What type of collagen is found in the basement membrane?
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Type IV
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What disease exhibits thin basement membranes due to abnormal Type IV collagen?
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Alport's syndrome
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What is found in BM with type IV collagen?
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-Laminin
-Proteoglycan |
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What holds epithelial cells to the basement membrane?
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Integrins
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What cells are found floating within the interstitial matrix?
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Fibroblasts
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What do fibroblasts secrete?
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ECM components
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What is the interstitial matrix made up of?
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-Fibrillar collagens
-Elastin -Proteoglycans -Hyaluronate |
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What holds the interstitial matrix together?
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Cell adhesion proteins
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What is the most common protein in the animal world?
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Collagen
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What disease results from vit C deficiency? Why?
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Scurvy - because there is poor hydroxylation of procollagen
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What are the fibrillar collagens?
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Types I, II, III, V, and XI
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What types of collagen are defect in Osteogenesis imperfecta and Ehlers Danlos syndromes?
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1-3 and 5
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What is the nonfibrillar collagen?
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IV
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What 3 molecules interact to give tissues elasticity?
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-Elastin
-Fibrillin -Elastic fibers |
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What disease results in abnormal elastic fiber formation?
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Marfan's syndrome
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What is Marfan's syndrome?
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An inherited defect in fibrillin
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What is the classic symptom of Marfan's syndrome?
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Acute aortic dissection
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List the 4 types of CAM's:
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-IgG family CAMs
-Cadherins -Integrins -Selectins |
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What is the structure of proteoglycans?
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-Core protein
-Numerous GAGs |
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What is the general goal of tissue repair?
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To restore tissue
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What type of repair is better at fully reconstituting damaged tissue?
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-Regeneration
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What type of repair generally results in some scar formation?
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-Wound healing
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What is fibrosis?
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Any abnormal deposition of connective tissue
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What is the hallmark of healing?
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Granulation tissue
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What will mature granulation tissue on a trichrome show?
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Much blue color due to the staining of collagen
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What is a very important process that occurs in healing and allows for granulation tissue to develop?
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Angiogenesis
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What is the important angiogenic growth factor?
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VEGf
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What are 2 pathways by which angiogenesis can occur?
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1. Mobilization of endothelial precursor cells EPCs from BM
2. Branching from pre-existing vessels |
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What is VEGf secreted by? (2 cells)
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-Mesenchymal cells
-Stromal cells |
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What molecules stabilize newly formed vessels?
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-Angiopoietins 1 and 2
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What other cells need to be recruited during angiogenesis?
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-Pericytes
-Smooth muscle cells |
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In what 3 pathologic conditions is VEGF implicated?
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-Chronic inflammation
-Tumors -Diabetic retinopathy |
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What important factor triggers scar formation?
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TGF-beta - to cause fibrosis
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What are the 3 basic phases in cutaneous wound healing?
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1. Inflammation
2. Granulation tissue formation 3. Wound contraction |
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What wounds heal by first intention?
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Those with opposed edges - like surgical incisions
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What happens within the first 24 hours of healing by first intention?
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PMNs move towards a central fibrin clot.
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What happens by day 3 of healing by first intention?
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Macrophages replace the PMNs to form granulation tissue
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What happens by day 5 of healing by first intention?
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The incisional space is filled with granulation tissue and the epidermis recovers.
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What happens during the 2nd week of healing by first intention?
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Collagen continues to accumulate and fibroblasts continue to proliferate
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What happens by the end of the 1st month of healing by first intention?
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The scar is devoid of inflammatory infiltrate
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How is healing by 2nd intention different from by 1st intention?
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The incision or wound is not opposed, but larger with separated edges.
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How is the inflammatory response different in 2nd intention healing?
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It is much more dramatic and intense
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How is the epidermal repair in 2nd intention compared to 1st?
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The epidermis is thinner
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What is the effect of infiltration of myofibroblasts in 2nd intention healing?
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The wound contracts in the weeks following repair
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What gives the wounded area strength after repair?
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Collagen deposition
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What are 3 causes of deficient scar formation?
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-Wound dehiscence
-Inadequate vascularization (PVD) -Nonhealing wounds due to peripheral neuropathy |
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What are 3 examples of excessive repair formations?
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-Keloid scars
-Proud flesh exuberant granulatn -Desmoids |
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When does fibrosis occur?
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When tissue damage is persistant and chronic
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What are 3 examples of fibrotic diseases?
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-Cirrhosis of the liver
-Chronic pancreatitis -Pulmonary fibrosis |
