Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
36 Cards in this Set
- Front
- Back
|
Regeneration
|
a. Complete regeneration of lost tissue
b. Requires intact ECM c. Seen in tissues with high proliferative activity |
|
|
Repair
|
a. Combination of regeneration and scar formation by collagen deposition
b. Dominant process where ECM is damaged c. Partial or complete restoration of function (usually partial) |
|
|
Liver regeneration
|
a. Requires an intact extracellular matrix
|
|
|
Liver repair by scarring
|
a. Matrix is damaged
b. Injury is repaired by fibrous tissue deposition and scar formation |
|
|
Continuously dividing cells
|
i. Labile
ii. Proliferate throughout life iii. Bone marrow, epidermis |
|
|
Quiescent cells
|
i. Stable
ii. Normally involved in low-level replication iii. May not respond to stimuli by rapid division iv. Liver, fibroblasts, kidney, smooth mucle |
|
|
Non-dividing cells
|
i. Permanent
ii. Do not undergo division in post-natal life iii. Neurons, cardiac myocytes |
|
|
Pluripotent embryonic stem cells
|
1. Capacity for self renewal
2. Capacity to generate all cell lineages 3. Give rise to multipotent stem cells |
|
|
Multipotent stem cells
|
1. More restricted development potential
2. Eventually produce differentiated cells |
|
|
Somatic stem cells
|
i. Identified in many mature tissues (bone marrow, skin, GI, liver, pancreas and fat)
ii. More limited capacity to differentiate iii. Give rise to rapidly proliferating cells that become progenitor cells which have more limited developmental potential |
|
|
Niche
|
1. Somatic cell microenvironment
2. Composed of mesenchyman, endothelial, and other cell types |
|
|
Niche cells
|
1. Generate or transmit stimuli that regulate stem cell self-renewal and the generation of progeny cells
|
|
|
Transdifferentiation
|
1. Cells differentiate from one type to another
2. “Developmental plasticity” 3. Mature cells do not do this 4. Hematopoietic stem cells may be induced to differentiate into other cell types |
|
|
Repair and wound healing ECM/cell matrix
|
1. ECM regulates growth, proliferation, movement and differentiation of cells living within it
2. Constantly remodeling 3. Integral to morphogenesis, regeneration, wound healing, chronic fibrotic processes, tumor invasion and metastasis 4. Sequesters water, provides turgor to soft tissues and minerals for bone |
|
|
ECM functions
|
1. Provides mechanical support and structure
2. Controls cell growth 3. Maintains cell differentiation 4. Provides scaffolding for tissue renewal 5. Establishes specialized microenvironments for various tissues 6. Provides storage and presentation of regulatory molecules |
|
|
Collagens
|
Tensile strength
|
|
|
Elastins
|
Recoil
|
|
|
Adhesive glycoproteins
|
1. Connect components to one another and to cells
2. Mostly transmembrane receptors 3. Ig family, integrins, selectins, cadherins |
|
|
Proteoglycans and glycosaminoglycans
|
1. Resilience and lubrication
|
|
|
Healing by repair, scar formation, and fibrosis
|
i. Tissue injury resulting in damage of parenchyma and stromal elements cannot heal by regeneration, but instead by repair and scarring
|
|
|
Healing by repair, scar formation and fibrosis is affected by....
|
1. Proliferative capacity of damaged tissue
2. Integrity of ECM 3. Degree and chronicity of inflammation |
|
|
Sequence of healing
|
a. Inflammation
b. Angiogenesis c. Migration and proliferation of fibroblasts d. Scar formation e. Connective tissue remodeling |
|
|
Clot formation
|
a. Wounding causes activation of platelets and coagulation pathways resulting in blood clot
b. Stops bleeding and acts as scaffold for cells attracted to area by chemokines, cytokines, and growth factors c. Within 24 hours, neutrophils appear, use scaffolding to move in and clean up mess |
|
|
Granulation tissue formation
|
a. Proliferation of fibroblasts and vascular endothelium starts in 1-3 days
b. Peaks around 5-7 days c. Forms a framework for scar formation |
|
|
Characteristic histologic features of granulation tissue formation
|
i. Small new blood vessels due to angiogenesis
ii. Proliferation of fibroblasts iii. Vessels are leaky→ tissue is edematous |
|
|
Neutrophils
|
i. Largely replaced by macrophages by 2-4 days
|
|
|
Macrophages
|
i. Clear extracellular debris, fibrin, foreign material
ii. Promote angiogenesis and ECM deposition iii. Main source of many growth factors in healing wounds that drive fibroblast migration, proliferation, and ECM production |
|
|
Re-epithelialization
|
i. 2-4 days, well underway
ii. Takes much longer to fill in larger wounds |
|
|
Scar formation
|
a. By 2nd week, leukocytes and granulation tissue have mainly disappeared
b. Blanching begins with increased collagen around wound area c. Regression of vascular channels d. Dermal appendages are lost e. End of 1st month, scar composed of acellular connective tissue w/o inflammation, covered by intact epidermis |
|
|
Granulation tissue conversion
|
i. Avascular scar composed of→
ii. Fibroblasts, collagen, fragments of elastic tissue, other ECM components |
|
|
Wound contraction
|
a. Generally occurs in large wounds (2nd intention)
b. Myofibroblasts contract in wound tissue c. Helps close gap by decreasing the distance between the dermal edges and reducing wound surface area |
|
|
Characteristics of healing by 2nd intention vs. primary intention
|
a. More debris to remove
b. More intense inflammation c. Larger amounts of granulation tissue are formed d. Edges of wound on surface do not join e. During the scarring process, the wound contracts |
|
|
Keloid
|
a. Excess collagen deposition in the skin
b. Raised scar |
|
|
Wound dehiscence
|
a. Inadequate formation of granulation tissue or assembly of a scar
b. Can also lead to ulceration c. Most common after abdominal surgery |
|
|
Ulceration
|
a. Wounds can ulcerate because of inadequate vascularization during healing
|
|
|
Fibromatoses
|
a. Lie in interface between benign proliferations and malignant tumors
|
