Week 7- Wound Heeling Flashcards
Name the 4 phases of wound healing
-haemostatsis
-inflammation
-proliferation
-remodelling
What is the function of inflammation
-limit spread of injury
-prevent further damage
-dilute or remove harmful agents e.g. bacteria, toxins etc
-removed damaged cells, tissues and debris ready for TISSUE REPAIR
-Name cardinal signs of inflammation
-swelling
-redness
-heat
-pain
-losss of function
What occurs in the vascular phase of inflammation
-capillary bed vasodilation (increased blood flow)
-capillary and venule have increased permeability (become leaky)
-tissue fluid from blood taken into connective tissue. Taken up by proteoglycans.
What stimulates the vascular response
Cytokinesis
How long does the vascular phase last
Secs-mins
How long till the cellular phase occurs
3-5days
When do mast cells burst, what do they release?
When tissue is damaged, release histamine, serotonin
When do platelets cells burst, what do they release?
Blood vessel damage. Release histamine, serotonin
Describe vascular phase (4)
1)Histamines cause vasodilation. Blood vessels widen, increasing blood flow (redness and heat) serotonin and prostoglandins prolong the duration
2) histamines stimulate endothelial cells to loose their tight junctions and blood vessels become-permeable (more leaky)
3) proteins and plasma move into the intracellular spaces by osmosis. Fluid moves into interstitial fluid/ taken up by proteoglycans and cause Odema (swelling)
4) pain receptors (nociceptors) are sensitised by bradykinin and prosteoglandins. Pressure from the swelling stimulates the pain receptors.
What is the function of neutrophil and macrophages
Undergo phagocytosis
How do neutrophil undergo their function
Use phagocytosis and chemical sprays (enzymes and free radicals) allow movement into tissue and break down damages tissue
-1-12hrs
Function of macrophages
Continue the clean up, remove old neutrophils, debris and bacteria.
Key to moving out of inflammation
-24-48hrs
How do phagocytes move into tissue
-margination
-rolling
-adhesion
-diapedesis/transmigration
-chemotaxis
Describe inflammation (5)
1) MARGINATION as blood flow becomes congested, phagocytes drop to the MARGINS
2)ROLLING/PAVEMENTING. week attraction and rolling along the endothelial cells.
3) ADHESION phagocyte attaches strongly to special attachment proteins
4) TRANSMIGRATION. Phagocyte squeezes through leaky membrane intointracellular space
5) CHEMOTAXIS. Cells move to area of damage following cytokine concentration gradient, cell debris etc
What do macrophages release, what does this stimulate?
-GROWTH FACTORS
-epithelial cells which have lost contact with each other in PROLIFERATION,are stimulated by gorwth factors (epidermal GF). They replicate and leap frog each other until they meet in the middle. They then make connections down a basement membrane.
Describe fibroblast growth factor in profliferation phase
-they migrate into the area from surrounding tissue and growth factors (fibroblast growth factor) stimulate them to replicate.
First they break down old extracellular matrix before making new ground substance (Proteoglycans ) and collagen (type 2)
Describe endothelial derived growth factor
-fibroblast and endothelial cell activity factors use up o2 (hypoxia) in the area
-endothelial cells from the surrounding blood vessels are stimulated by the hypoxia and grow due to growth factors (endothelial derived growth factor)
-new tissue made of fibroblast, proteoglycans,collagen type 2 and blood vessels is called GRANULATION TISSSUE
By the end of proliferation what has occurred?
-epithelial cells have recovered the site
-blood vessels have invaded and become organised
-fibroblasts have filled the wound with mostly type 3 and ground substance
-macrophages remain
Explain the role of Macrophages at the end of inflammation
Macrophages are pivotal in wound progression- they can release proinflammatory cytokines (chronic inflammation) or anti inflammatory cytokines and growth factors that progress the wound through REPAIR or RESOLUTION
After 12-24 hours the cellular phase of inflammation begins. Identify cells involved and describe their role in inflammation
NEUTROPHILLS- play major role in early phase (within 12 hours) bacterial clean up, plus further cytokine signalling
MACROPHAGES- play a later role (24 hrs) continue to clear bacteria plus cell debris/ damaged tisssue and dead neutrophils. Play major role in further cytokine signalling and controlling wound progression
Explain how these cells travel from blood to site of injury
Phagocytes move into tissue by MARGINATION- neutrophils and monocytes (immature macrophages) start to drop out of normal blood gathering towards the sides, ROLLING NEAUTROPHILS and MONOCYTES start to roll along the sides of the blood vessel wall, ADHESION,
- the endothelial cells in response to histamine make ‘Selectins’ which are hooks that attach to the neutrophils and monocytes and they attach DIAPEDDESIS
-neutrophils and monocytes squeeze through enlarged gaps ‘leaky’ and use CHEMOTAXIS, moving to the area of injury
List 2 phases of acute inflammation
Vascular
Cellular
State functions of vascular and cellular in acute inflammation
VASCULAR - to prevent further injury, dilute bacteria and their toxins, isolate the area to contain bacteria and preventing them from infecting other areas.
CELLULAR- remove bacteria, clean up tissue/ cellular damage and prepare for wound repair
