Healing and Repair Flashcards
What is regeneration?
Regeneration is the growth of cells and tissue to replace the lost structure
What is Organisation?
Organisation is Fibrous tissue formation
What is resolution?
Resolution is the complete disappearance of Inflammatory exudate and debris in the process of healing
What is Fibrosis
Fibrosis is a process in which there is excessive accumulation of fibrous tissue in response to complication in healing
Role of macrophage in Healing and repair?
- Clear inflammatory site of cellular debris
- Play important role in chronic inflammation healing and repair
- Macrophages secrete cytokines for ECM synthesis
What is extracellular matrix made of?
ECM is made of Collagen, proteoglycans, hyaluronic acid
Cellular processes involved in healing?
- Cell migration
- Cell proliferation
- Angiogenesis
- Inflammatory cell clear out infectious stimuli
- ECM synthesis and remodalling
Growth factors that stimulate ECM synthesis
- Macrophage derived growth factor (MDGF)
- Platelet derived growth factor (PDGF)
- Epidermal growth factor (EGF)
- Fibroblast growth factor (FGF)
- Transforming growth factor (TGF)
Which organs can undergo regeneration?
- Liver
- Skin
- GIT epithelium
- Bone marrow
Prototypical organs cannot undergo regeneration
- Kidney
- Heart
- Brain
Types of dividing and non-dividing cells
- Labile cells (constantly undergoes replication)
- Stable cells (normally does not undergo replication but can be induced to undergo replication)
- Permanent cells (cannot undergo replication)
Side effects of cancer chemotherapy tends to affect what type of dividing cells the most and what are the side effects of chemotherapy?
Affects Labile cells the most
Side effects of chemotherapy are, Weight loss, Loss of appetite, Hair loss, Anaemia, infection, Bruising and bleeding
Process involved in fibrous repair
- Granulation tissue formation
- Angiogenesis
- Fibroblastic and myofibroblastic proliferation
- Wound contraction (myofibroblast)
- Collagen synthesis and maturation
- Scar remodelling
What is granulation tissue and which phase of healing is it found in and what processes occur?
It is found in the early phase of healing
It is a highly vascularised tissue composed of fibroblasts, myofibroblast and inflammatory cells
Angiogenesis, fibroblastic proliferation and deposition of new immature collagen occurs at this stage of healing
Myofibroblast migration and proliferation is driven by what cytokines
TNF
PDGF
TGF Beta
FGF
Collagen synthesis requires what vitamin?
Explain collagen maturation?
Collagen synthesis requires Vitamin C
Collagen maturation is replacement of Type 3 collagen by type 1 collagen and formation of cross linkages
Steps in scar maturation and remodelling
- As repair progresses, collagen synthesis exceeds degradation
- Accumulation of collagen occurs
- Tensile strength of collagen increases due to development of cross linkages
- Vascular involution occurs resulting in pale avascular scar formation
Factors affecting wound healing
- Incision vs laceration (clean cut vs rough edges)
- Depth of cut
- Blood supply to wounded area
- Secondary infection (results in poor growth)
- Movement
- Age of patient
- Nutrient
- Metabolic status (Diabetes, Hypothyroidism = poor healing)
- Hormones (corticosteroid = poor healing, thyroxine, androgens, estrogens, GH increases wound healing)
Complication of wound healing
- Defective scar formation resulting in wound dishiscence and incisional hernia
- Excessive scar formation, Keloid formation
- Excessive contraction
Ulcer implies damage to which layers of the skin?
What does this say about the type of healing?
Ulcer represents damage to the epidermis, dermis, +/- subcutaneous tissue
Once dermis and deeper tissues are involved healing occurs via fibrosis
Complications of peptic ulcers in the stomach?
- GI bleeding
- perforation followed by peritonitis causing septic shock
- fistula formation
- Fibrosis leading to obstruction
Complications of post myocardial infarction?
- Aneurism
- Thromboembolism
- Haemopericardium
- Arrhythmia
Lung healing post pneumonia if basement membrane is damaged vs if basement membrane is not damaged
If basement membrane is not damaged, type 2 pneumocytes re-epithelialise into mature pneumocytes and complete resolution is possible
If basement membrane is damaged, there will be intra-alveolar as well as interstitial scarring resulting in decreased vital capacity
Distinguishing gross and microscopic feature of liver cirrhosis is?
Regenerating hepatocyte nodule surrounded by dense bands of collagenous fibres
Complications of chronic persistent liver injury and causes of chronic persistent liver injury
- Portal hypertension leading to GI varices causing heamoptysis, splenomegaly
- Hypoalbunemia leading to oedema and heart failure
Causes likely to be viral hepatitis or alcohol disease
Steps of healing of a fracture
- Fracture of bone initially bridged by heamotoma
- Heamotoma gets replaced by granulation tissue which gets replaced by collagenous fibrous tissue
- Proliferation of osteoblast from endosteum and periosteum to form woven bone
- Bone remodelling by osteoclast to form Laminar bone
Complications of healing of a fracture
Non-union, Fibrous union and osteomyelitis
