Regeneration And Repair Flashcards
What processes are involved in wound healing
Homeostasis (Prevention of bleeding)
Inflammation
Regeneration OR Repair
What is Regeneration and when is it possible
Regrowth of cells, so that there is minimal evidence of injury
Only possible with minor injuries as an intact collage framework is needed
Compare the types of tissue in regards to proliferative ability
What cell cycle stage are each of them in
Labile: Continuously replicating, In cell cycle
Stable: Normally low level of replication, but can undergo rapid replication if needed, In G0 but can enter G1
Permanent: No replication, have left cell cycle and can’t re-enter
Give 2 examples of each of Labile, Stable, Permanent tissue
Labile: Haematopoietic tissue, Marrow cells
Stable: Bone, Kidneys
Permanent: Cardiac/ Skeletal muscle, Neurons
Define fibrous repair
Replacement of functioning tissue with a scar
What are the steps involved in Scar Formation, how soon do they start
What happens in the first and second one
- Bleeding and Homeostasis (Secs-mins)
- Severed vessels contract, clot formed
- Scab formation - Inflammation (Mins-days)
- Neutrophils appear
- Acute then chronic inflammation - Proliferation (Days-weeks)
- Remodelling (Weeks-years)
What happens in the 3rd step of scar formation (Proliferation)
Granulation tissue invades;
- New capillaries formed by angiogenesis
- Proliferation of Fibro+Myofibroblasts and ECM
What are 3 functions of granulation tissue
Fills the gap
New capillaries supply O2 and nutrients
Contracts to close the gap
What happens in the final step of scar formation (Remodelling)
Maturation of the scar;
- Reduced cell population
- More collagen
- Myofibroblasts contract
- Capillaries disappear
Name the 5 cells involved in Fibrous Repair along with their functions
Neutrophil/ Macrophage: Phagocytosis+ Mediator release
Lymphocyte: Co-ordinate other cells
Endothelial cell: Proliferation + Angiogenesis
Fibroblast: Secrete collagen/ elastin-> ECM
Myofibroblast: Wound contraction
Describe the structure of a fibroblast and myofibroblast
Where can a myofibroblast be found
Spindle shaped nucleus Cytoplasmic extensions (Hard to see, as they interdigitate)
Myofibroblast: Similar to fibroblast, between a fibroblast and smooth muscle
Name 1 acquired and 3 inherited diseases of defective collagen
Acquired- Scurvy
Inherited;
- Alport Syndrome
- Osteogenesis Imperfecta
- Ehlers-Danlos Syndrome
What is Ehlers-Danlos Syndrome
What are 4 signs
Inherited disorder where collagen fibres lack adequate strength
- Hypermobile joints
- Hyperextensible, Fragile skin
- Poor wound healing
- Colon rupture
What is Alport Syndrome
What are 3 signs
Abnormal type 4 collagen
- Impaired glomerular filtration
- Dysfunction of lens and ear
- Blood in urine as kids/ teens
Name 3 methods of controlling regeneration and repair by cell communication
Direct cell to cell/ stroma contact
Growth factors (Or other local mediators)
Hormones
What are Growth Factors, how do they work
Name 4
Polypeptides that act on specific cell surface receptors. They cause the cell enter cell cycle and proliferate
- Epidermal growth factor
- Platelet derived growth factor
- TNF
- Vascular Endothelial growth factor
Describe contact-inhibition
Suggest a condition where this mechanism is defective
Isolated cells replicate until they are in contact with other cells.
This is done via CADHERINS between cells which inhibit further proliferation
Cancer
In 4 steps, explain healing of skin by Primary Intention
- There is a small wound with apposed edges
- Minimal clotting and granulation tissue formation
- Epidermis regenerates, Dermis repairs (fibrous)
- A small scar remains
In 4 steps, explain healing of skin by Secondary Intention
- There is significant tissue loss, with unapposed edges (Abscess may force edges apart)
- Abdundant clotting/ inflammation/ granulation tissue formation
- Considerable wound contraction is needed
- Epidermis regenerates from edges, Dermis needs significant repair
Compare the 2 classifications of factors affecting wound healing
Local: Relating to wound
Systemic: Relating to individual
Identify 6 LOCAL factors that affect wound healing
Identify 5 SYSTEMIC factors that affect wound healing
Local;
- Size and location of wound
- Blood supply available
- Mechanical stress
- Local infection
- Foreign body presence
- Haematoma
Systemic;
- Age
- Drugs
- Malnutrition
- Anaemia/ Hypoxia/ Hypovolaemia
- Obesity
Name 6 Complications of Fibrous Repair
- Insufficient fibrosis (Dehiscence)
- Excessive fibrosis
- Fibrous adhesions may be formed
- Loss of function
- Architecture disrupted
- Excessive contraction
Name 4 times Insufficient Fibrosis can occur
Name the scar from excessive fibrosis, who’s at more risk of this
Why are Fibrous Adhesions bad
Why is excessive scar contraction bad
Obesity
Elderly
Malnutrition
Steroid use (Thinner skin)
A Keloid scar (Made of collagen and elastin); Afro-Caribbeans
Adhesions can cause tube obstruction
Tubes can be constricted
Why does cartilage not heal well
Lacks blood supply, lymphatic drainage and innervation
