Healing Flashcards
What are the four stages of wound healing
- Haemostasis
- Inflammation
- Proliferation
- Remodelling
When does haemostasis occur?
It occurs as soon as the wound opens
What is a vasospasm?
narrowing of the arteries caused by persistent contraction
What activates the platelets
The platelets are activated by exposed collagen from damaged vessels
What is the consequence of platelets being activated?
- They promote vasoconstriction
- They initiate the formation of a platelet plug
- They start vessel healing
When is acute inflammation fully established?
24 hours after injury
How long can acute inflammation last?
Up to 96 hours if not disrupted
What are some of the cardinal signs of inflammation that can be observed?
- Redness
- Swelling
- Heat
- Pain
- Loss of function
What are some of the functions of neutrophils and macrophages during acute inflammation?
- They establish a microenvironment for the proliferation/granulation stage
- They are essential for wound healing (excessive can reduce healing)
- remove cell debris
- release cytokines for chemotaxis which helps to enhance angiogenesis
What is angiogenesis?
The production of new endothelium
What is epithelialisation?
The generation of new epithelium
What is fibroplasia/ Desmoplasia?
The generation of new connective tissue stroma
What three things make up the proliferation stage?
- Angiogenesis
- Epithelialisation
- Fibroplasia/ Desmoplasia
How long can the remodelling stage last for?
It begins 3-4 weeks after injury if earlier stages are complete
But can last for 2 years
What occurs during the remodelling stage?
- Replacement of new connective tissue
- Removal of damaged connective tissue
to attempt to return the organ back to its function/ functional capacity
Name 4 things that can cause impaired wound healing
- Spontaneous causes
- Wound specific variables
- Systemic variables
- Exogenous variables
What are some examples of spontaneous causes that can cause impaired wound healing
- foreign bodies
- infections
- Neoplasia
What are some examples of wound specific variables that can cause impaired wound healing?
- Body site
- Vascular supply
- Mechanical stress
- Desiccation
What are some examples of systemic variables that cause impaired wound healing
- Nutrition
- Age
- Sex
- Immobility
- Diseases
What are some examples of exogenous variables that cause impaired wound healing?
- Medication
- Radiation
- The environment
What is the function of fibroblasts?
They help synthesise the Extracellular matrix by producing collagen and proteoglycans
This provides an envoronment for other cells to work
What occurs during fibrosis?
Fibroblasts align themselves along the planes of tissue stress during development e.g langers lines
What is the benefit of making surgical incisions along the langers lines?
Reduces the post-surgical scar formation
as the skin is less tight
more tension= more fibrosis= harder to pull the sides together
What kind of fibroblasts are particularly responsive to injury?
Feline
What kind of cells migrate into wounds?
Fibroblasts and endothelial cells
What is the function of the growth factors released during inflammation
They promote proliferation of fibroblasts and endothelial cells
What is granulation tissue?
A distinctive arrangement of connective tissue fibres, fibroblasts and blood vessels (highly vascularised connective tissue)
they run parallel to the wound surface
What is the gross appearance of the granulation tissue
- Red and granular appearance
- New vessels are leaky and they bleed easily
What is proud flesh and in what species is it most common?
Proud flesh is uncontrollable growth of granulation tissue when a wound starts healing
Most common in horses
What are myofibroblasts and what are their function?
Myofibroblasts are specialised fibroblasts with contractile activity
they form in wounds in response to tissue stress
They can then contract to bring the edges of the wound together
What is corneal ulcer healing/ epithelialisation?
Skin and mucus membranes replace superficial epithelial cells
neighbouring epithelial cells separate and migrate to fill the gap and then start to proliferate
In what animal do you get the most fibrostic transformation?
Cats
What do endothelial cell bud formation and migration into tissues under the influence of?
angiogenesis
IGF- alpha and EGF
What is endothelial cell proliferation under the influence of
VEGF
What is secondary cell proliferation under the influence of?
angiopoietin 1
How does angiopoietin 1 work?
stabilises the vessel by recruiting proteocytes and smooth muscle cells and then ECM protein deposition
What is the definition of reepithelialisation?
The process by which skin and mucous membranes replace superficial epithelial cells that are damaged or lost in a wound
