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73 Cards in this Set
- Front
- Back
Define 'healing'
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The replacement of dead and damaged cells by healthy tissue
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The replacement of dead and damaged cells by healthy tissue
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Healing
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What are the two ways healing is achieved?
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Regeneration
Repair |
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What precedes healing?
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Haemostasis and acute inflammation
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Haemostasis must be achieved before _______ can occur
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Healing
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What is haemostasis? How does it occur?
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A complex process which causes the bleeding process to stop.
Occurs via formation of a blood clot in the would |
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During acute inflammation, what do neutrophils and macrophages do? (3)
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They phagocytose debris, secrete growth factors and other chemical mediators
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What produces growth factors? (4)
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Fibroblasts, platelets, macrophages and endothelial cells
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Give an example of growth factors (3)
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Epidermal growth factor
Cytokines Platelet-derived growth factor |
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What is contact inhibition?
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The natural process of arresting cell growth when two or more cells come into contact with each other
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injured cells are replaced by ___________ cells of the same type
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parenchymal
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What are parenchymal cells?
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A cell that replaces injured cells of the same type
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What are the three types of cell responsible for regeneration?
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Stable (quiescent) cells
Permanent cells Labile cells |
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Cells that constantly divide during life to replace like cells that are being lost
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Labile cells
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Give three examples of labile cells
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Skin epithelial cells, gut epithelial cells, bone marrow cells
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Cells that have a low level of replication under normal circumstances
Can switch to rapid levels of replication with the correct stimulus |
Stable (quiescent) cells
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Give examples of stable (quiescent) cells (3)
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Epithelial cells of kidney, liver, etc.
Fibroblasts Smooth muscle |
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Cells either incapable of mitosis or organised replication
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Permanent cells
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Give three examples of permanent cells. Think!
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Neurones
Skeletal and Cardiac Muscle |
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What is necessary for regeneration to work?
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The supporting architectural framework (i.e. the basement membrane) need to be in tact
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Pure regeneration after injury is common/rare. Why?
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Rare. For regeneration to take place, basement membrane needs to be in tact --> Not usual after injury
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Progresses centrally over time
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Regeneration
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The replacement of injured cells by fibrous connective tissue
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Repair
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Repair is less common than regeneration T/F
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F
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Often occurs when supporting framework of labile, permanent or stable tissue cells is destroyed
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Repair
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How does repair occur?
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Via granulation tissue formation
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What is granulation tissue?
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The perfused (Supplied with a fluid), fibrous connective tissue that replaces a fibrin clot in healing wounds. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals.
It is composed of: extracellular matrix, immune system cells vascularisation components |
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The perfused (Supplied with a fluid), fibrous connective tissue that replaces a fibrin clot in healing wounds. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals.
It is composed of: extracellular matrix, immune system cells vascularisation components |
Granulation tissue
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What cells does granulation tissue contain?
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Fibroblasts and macrophages
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Involved in angiogenesis
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Granulation tissue
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What is VEGF?
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Vascular endothelial growth factor - the most important stimulator of angiogenesis
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The most important stimulator of angiogenesis
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VEGF
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Macrophages secrete growth factors T/F
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T
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Migrate and proliferate rapidly
Replace cell debris Produce collagen and other important components of ECM |
Fibroblasts
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Repair begins in the first 48 hours after injury T/F
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F, it begins in the first 24 hours
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How long does it take for a scar to form?
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4-7 weeks
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Collagen increases during repair, cellularity decreases over time in granulation tissue. T/F
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T
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What does 'intention' mean in regard to wounds?
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The healing process of a wound
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Occurs when uninfected wound without tissue loss is closed promptly by sutures
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Healing of skin by primary intention
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Blood from cut vessels fills gap
Fibrin forms blood clot which binds cut surfaces Clot at surface dehydrates to form scab Would now sealed from further damage |
Immediate healing action by primary intention
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Neutrophils migrate from incision margin
Phagocytose any debris Epidermis thickens at edge of wound via cell proliferation Spurs of cells migrate across gap Fuse at centre to form continuous layer (i.e. epithelial cell regeneration |
Healing of skin by primary intention 24-48 hours on
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Macrophages replace neutrophils
COntinue phagocytosis Granulation tissue forms at incision margin COllagen fibres present at edge of wound but verticlal orientated Would red - 'livid' - macroscopically Continued epithelial regeneration Stratification of epithelium |
Healing of skin by primary intention by day 3
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Granulation tissue fills wound space
Collagen more abundant and bridging gap Epidermis normally stratified and keratinised |
Healing of skin by primary intention by day 5
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Granulation tissue matures
Continued accumulation of collagen Vascularity and macrophages reduce Scar becomes paler macroscopically - 'blanching' |
Healing of skin by primary intention during second week
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Collagen at maximum
Scar complete Tensile strength _____ Collagen remodels Cross-linking and thickening of fibrils Fibrils organise along lines of stress Tensile strength increased to 80% of original tissue |
Healing of skin by primary intention by the end of 1 month, and the following few months
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Occurs in an open wound with excessive tissue lost
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Skin healing by secondary intention
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Would defect larger
Process slower Larger area of necrotic debris leads to more intense inflammation Larger would leads to larger area of granulation tissue Granulation tissue present at surface as epithelial regeneration slower Would contraction occurs |
Differences between secondary and primary intention wound healing
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Healing of bone fractures - capable of complete regeneration T/F
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T, unless adverse factors are present
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Bleeding from ruptured vessels
Clot formation fills wound gap and surrounds area |
Immediate action from bone fracture healing
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Neutrophils and macrophages migrate from incision margin
Phagocytose any debris |
Healing of bone fractures within 24-48 hours
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Formation of granulation tissue
Proliferation of cartilage cells from edge of wound Cartilage and granulation tissue fill wound site Known as 'provisional callus' or 'procallus' |
Healing of bone fractures by day 4
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Cartilage begins to calcify
Osteoblasts lay down osteoid Forming firstly a 'fibrocartilaginous callus' Then a 'bony callus' Weak as composed of woven (disorganised) bone |
Healing of bone fractures during second weak
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Remodelling of bony callus
Osteoclastic and osteoblastic activity Lamellar (organised) bone replaces woven bone Marrow cavity restored Bone strength returns to normal No macroscopic or microscopic evidence of injury |
Healing of bone fractures during weeks 2-7
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Healing is impaired by two different factors, name them
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Local and systemic factors
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What are local factors that can affect healing? (4)
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Infection (most common)
Mechanical factors (early movement) Foreign material (can't be phagocytosed and can cause infection) Size, location and type of wound |
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What are the systemic factors that can affect healing? (5)
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Nutrition
Diabetes Mellitus Circulation Glucocorticoid (steroid) drugs [Can have anti-inflammatory effect] Immune suppression |
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Which nutrients are especially important in healing?
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Protein, Vitamin C and Zinc
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What are the complications of wound healing?
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Would ulceration (often due to poor vascularity)
Wound dehiscence Stretching of scar Excessive growth of scar elements Keloid/hypertrophic scar Exuberant granulation tissue (proud flesh) |
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Bleeding from ruptured vessels
Clot formation fills wound gap and surrounds area |
Immediate action from bone fracture healing
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Neutrophils and macrophages migrate from incision margin
Phagocytose any debris |
Healing of bone fractures within 24-48 hours
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Formation of granulation tissue
Proliferation of cartilage cells from edge of wound Cartilage and granulation tissue fill wound site Known as 'provisional callus' or 'procallus' |
Healing of bone fractures by day 4
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Cartilage begins to calcify
Osteoblasts lay down osteoid Forming firstly a 'fibrocartilaginous callus' Then a 'bony callus' Weak as composed of woven (disorganised) bone |
Healing of bone fractures during second weak
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Remodelling of bony callus
Osteoclastic and osteoblastic activity Lamellar (organised) bone replaces woven bone Marrow cavity restored Bone strength returns to normal No macroscopic or microscopic evidence of injury |
Healing of bone fractures during weeks 2-7
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Healing is impaired by two different factors, name them
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Local and systemic factors
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What are local factors that can affect healing? (4)
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Infection (most common)
Mechanical factors (early movement) Foreign material (can't be phagocytosed and can cause infection) Size, location and type of wound |
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What are the systemic factors that can affect healing? (5)
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Nutrition
Diabetes Mellitus Circulation Glucocorticoid (steroid) drugs [Can have anti-inflammatory effect] Immune suppression |
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Which nutrients are especially important in healing?
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Protein, Vitamin C and Zinc
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What are the complications of wound healing?
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Would ulceration (often due to poor vascularity)
Wound dehiscence Stretching of scar Excessive growth of scar elements Keloid/hypertrophic scar Exuberant granulation tissue (proud flesh) Contracture Persistent cavity |
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What causes a keloid/hypertrophic scar?
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Excess collagen leading to a 'tumour like' outgrowth
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What is exuberant granulation tissue (or 'proud flesh')?
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Formation of excess granulation tissue
Blocks regeneration of epithelium |
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Blocks regeneration of epithelium
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Proud flesh
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Exaggeration of normal wound contraction
Distorts surrounding structures May impair movement or function |
Contracture
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Failure of healing process due to presence of factor inhibiting healing
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Persistent cavity - non-union
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