Case 1 - cutaneous wound healing Flashcards
what are the 4 stages of healing?
1)Haemostasis
2)Inflammation – occurs after a few hours up until a few days
3)Proliferation – we lost tissue so we need to get the tissue back
4)Remodelling
when does haemostasis occur post injury?
immediately after injury
when does inflammation occur post injury?
Begins within minutes, typically within the first hour, and becomes fully active in the first 24–48 hours
when does proliferation occur post injury?
generally begins around day 3 to day 5 post-injury and can last up to 2 weeks, depending on the severity and type of injury.
when does remodelling occur post injury?
Remodeling after an injury typically occurs in the later stages of the healing process. It is part of the healing phase known as the maturation and remodeling phase. This phase follows the initial inflammatory and proliferative stages and can last anywhere from several weeks to months, or even years, depending on the severity of the injury
what cells are involved in haemostasis?
Platelets
what cells are involved in inflammation?
Neutrophils,
Macrophages
what cells are involved in proliferation?
Macrophages,
Lymphocytes,
Fibroblasts
what cells are involved in remodelling?
Fibrocytes
what is the function/activity of haemostasis?
Clotting
what is the function/activity of inflammation?
Phagocytosis
what is the function/activity of proliferation?
- Fill defect
- Re-establish
skin function - Closure
what is the function/activity of remodelling?
Develop
tensile
strength
what happens in the vascular stage of haemostasis?
▪ Cellular damage causes endothelial cells to
release cytokines and endothelin, which
stimulate smooth muscle contraction, bringing
about vasoconstriction.
▪ Cytokines additionally stimulate the division of
endothelial cells, smooth muscle cells, and
fibroblasts.
▪ The endothelial plasma membranes become
“sticky”
what are the 3 principal components of haemostasis?
- The vessel wall (vascular phase)
- Platelets (primary hemostasis; platelet phase)
- Fibrin (secondary hemostasis; coagulation phase)
what are platelets
▪ Are disc-shaped anucleate cell fragments that are shed from megakaryocytes in the bone marrow into the bloodstream.
[▪ Their function depends on several glycoprotein
receptors:
▪ Platelet Gplb receptors to vWF
▪ GPIIb/IIIa receptors on activated
platelets form bridging cross-links with
fibrinogen, leading to platelet
aggregation.
▪ A contractile cytoskeleton]
what are the inhibitors that regulate the size of the primary hemostatic plug or soft clot?
Prostacyclin – this is released by endothelial cells
Circulating enzymes – these break down ADP
ADMTS13: a plasma metalloprotease that proteolyses vWF and thereby helps limit further platelet adhesion
what is fibrin?
Fibrin is a protein polymer, which has a high tensile strength and reinforces, anchors and stabilises the primary hemostatic plug
what are macrophages?
Macrophages are large, irregular shaped, agranulated cells with a
large bean-shaped nucleus
what are the primary roles of macrophages?
Primary
roles of macrophages:
▪ Phagocytosis of neutrophils
▪ Phagocytosis of fragments of ECM
what do you know about macrophages and MMP’s?
▪ Macrophages secrete extracellular enzymes, called Matrix Metallo Proteases (MMPs), to degrade necrotic tissue at the wound site.
▪ MMPs require Calcium to form a functional shape & Zinc for the active site.
▪ Uncontrolled MMPs can degrade newly formed tissue or destroy growth factors.
▪ MMPs are balanced by tissue inhibitors of metalloproteases (TIMPs), which are released locally by cells and inactivate MMPs by reversibly binding to them.
what’s the difference between what M1 macrophages are for and what M2 macrophages are for?
M1 Macrophages - macrophages involved in the initial inflammation response and
removal of dead tissue and debris
M2 Macrophages - macrophages involved in tissue repair
what is granulation tissue?
Granulation tissue is a new connective tissue with microscopic blood vessels and myofibroblasts that develop at the wound site in the process of healing. It’s made up of fibroblasts, collagen type III fibres, blood vessels
what does epethelialisation require?
Epithelialization requires the migration of epithelial cells across the granulation tissue, to close the epidermal defect.
