Repair and Regeneration Flashcards
What are the 2 forms of healing?
Regeneration and repair
What is healing by regeneration?
Cells replaced by like cells and tissue regains function
What is healing by repair?
Cells cannot be replaced by like cells and so fibrosis and scarring occur. There is a loss of specialised function.
What are the characteristics of labile cell populations?
High turnover
Active stem cell population
Excellent regenerative capacity
Name a location where labile cell populations are found
Epithelia
What are the characteristics of quiescent cell populations?
Low turnover
Good regenerative capacity
Turnover can massively increase if required
Name two locations where quiescent cell populations are found
Liver
Renal tubules
What are the characteristics of permanent cell populations?
Zero turnover
Zero regenerative capacity
Long life span
Which condition observes a collapse of reticular framework in the liver?
Cirrhosis
What are the characteristics of stem cells
A prolonged self renewal
An asymmetric replication
Crucial to regeneration
When does repair occur?
When the normal structure cannot be replaced
What are the consequences of healing by repair?
Functional
What are the characteristics of healing by repair?
Basic stereotyped pathological process
Repair of specialised tissue by formation of fibrous scar
Granulation tissue in abundance
What are the three components of granulation tissues?
New capillary loops
Phagocytic cells (Neutrophils and macrophages)
Myofibroblasts
What are the steps of new vessel formation?
Endothelial cell proliferation
Buds
Canalisation
New vessels
What is the function of phagocytes in granulation tissue?
Remove dead/damaged tissue
What is the function of myofibriblasts in granulation tissue?
Synthesis collagen and ECM
What 3 categories can oesophageal peptic ulcers be grouped into?
Intrinsic diseases
Extrinsic diseases
Functional
What is the pathophysiology of intrinsic forms of oesophageal peptic ulcers?
Narrow the lumen through inflammation, fibrosis or neoplasia
What is the pathophysiology of extrinsic forms of oesophageal peptic ulcers?
Compromise the lumen by direct invasion or lymph node enlargement
What is the pathophysiology of functional forms of oesophageal peptic ulcers?
Disrupt oesophageal peristalsis
Lower oesophageal sphincter function
Both via affects on smooth muscle and it’s innervation
What are some causes of oesophageal peptic ulcers?
Acid Infectious Congenital Drug induced Autoimmune Iatrogenic Radiation
As vascularity and cellularity of granulation tissue decrease, what increases?
Collagen
ECM
Wound strength
What are some local factors inhibiting healing?
Infection Haematoma Foreign bodies Mechanical stress Blood supply
What are some systemic factors inhibiting healing?
Age Drugs Anaemia Diabetes Malnutrition Catabolic states Vitamin C deficiency Trace metal deficiency
What are the predisposing factors to healing by first intention?
Clean, uninfected surgical wound
Good homeostasis
Edges opposed with sutures or staples
What are the predisposing factors to healing by second intention?
Wound edges unopposed
Greater extensive scarring
What are the steps to fracture healing?
Removal of necrotic fragments
Osteoblasts lay down woven bone
Remodelling according to mechanical stress
Replacement by lamellar bone
What causes non-union of fractures?
Misalignment Infection Movement Pre-existing bone pathology Interposed soft tissue
What is different about healing in the brain compared to healing in other tissues?
Supporting tissue is giant cells rather than collagen and fibroblasts, hence damaged tissue is removed often leaving a cyst
Gliosis rather than scarring
Generally, is EGF secreted from and what is its function?
Secreted from: macrophages and platelets
Function: Stimulates granulation tissue formation
Generally, where is TGF secret from and what is its function?
Secreted from: Macrophages and platelets
Function: Chemotactic agent and inhibits production of MMPs
Generally, where is platelet derived growth factor secreted from and what is its function?
Macrophages and platelets
Chemotactic agent and stimulates angiogenesis
Where is TNF secreted from and what is its function?
Macrophages, mast cells and T Lymphocytes
Activates macrophages and regulates other cytokines
