2: Tissue Renewal and Repair

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2: Tissue Renewal and Repair by Mind Map: 2: Tissue Renewal and Repair

1. Repair

1.1. Regeneration

1.1.1. Labil cells

1.1.1.1. bone marrow hemopoietic cells

1.1.1.2. skin epidermis

1.1.1.3. Gi epithelial cells

1.1.2. Stable cells

1.1.2.1. hepatocytes

1.1.2.2. renal tubular cells

1.1.2.3. pancreatic acinar cells

1.1.2.4. adrenal cortical cells

1.2. Fibrosis (CT repair)

1.2.1. When?

1.2.1.1. Extensive structural damage (framework damaged)

1.2.1.2. Permanent cells

1.2.1.2.1. myocardial muscle cells

1.2.1.2.2. skeletal muscle cells

1.2.1.2.3. ganglion cells (neurones)

1.2.2. Components

1.2.2.1. angiogenesis

1.2.2.2. migration and proliferation of fibroblasts (granulation tissue formation)

1.2.2.2.1. endothelial cells are most common here

1.2.2.3. deposition of ECM, collagen synthesis (scar formation)

1.2.2.4. connective tissue remodelling

1.2.3. Control of cell proliferation

1.2.3.1. balance between:

1.2.3.1.1. fibrogenic agent

1.2.3.1.2. Metallopoteinases

1.2.4. functions of ECM

1.2.4.1. mechanical support of cells

1.2.4.2. control of cell growth

1.2.4.3. maintenance of cell differentiation

1.2.4.4. scaffolding for tissue renewal (basement membrane for liver cells)

1.3. cell proliferation, cell cycle and stem cells

1.3.1. cell cycle is regulated by cyclins

1.3.2. labile cells contain stem cells that differentiate to replace lost cells

1.3.2.1. embryonic stem cells are pluripotent

1.3.2.2. adult stem cells are multi potent

2. Cutanious wound healing

2.1. phases

2.1.1. inflammation

2.1.2. granulation tissue

2.1.3. ECM deposition and remodelling

2.1.4. wound contraction (in large wounds)

2.2. Types

2.2.1. First intention (clean surgical wound)

2.2.1.1. few epithelial cells and focal basement damage

2.2.1.2. epithelial regeneration predominates

2.2.1.3. small scar and minimal wound contraction

2.2.2. Second intention

2.2.2.1. extensive tissue loss

2.2.2.2. large scar and wound contraction by myofibroblasts

2.2.2.3. more intense inflammation and granulation tissue

2.2.2.4. examples

2.2.2.4.1. abscess

2.2.2.4.2. ulceration

2.2.2.4.3. infarction in parenchymal organs

2.2.2.4.4. large wounds

2.3. Wound strength

2.3.1. After surgery: 70% of strength of unwounded skin (because of sutures)

2.3.2. after removing sutures (by one week) only 10% strength

2.3.3. strength increases rapidly over 4 weeks with collagen synthesis

2.3.4. after 3 months 70-80%

3. Pathologic aspects of repair & factors reducing adequate healing

3.1. Infection

3.1.1. prolongs the inflammatory phase

3.1.2. increases local tissue injury

3.2. Nutrition

3.2.1. Vitamin C deficiency -> inhibits collagen synthesis

3.2.2. Glucocorticoids --> anti inflammatory effect

3.3. mechanical pressure causing the wound to pull apart

3.4. poor perfusion (blood supply)

3.4.1. diabetes

3.4.2. atherosclerosis

3.5. foreign bodies

3.5.1. glass

3.5.2. bone fragments

3.6. type of injured tissue, location, & extent of injury

3.7. abnormalities of cell growth and ECM production

3.7.1. excessive collagen accumulation

3.7.2. Keloids (raised scars)