Inflammation and wound healing

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  • Created by: evepoag
  • Created on: 14-10-22 14:09
Tissue injury activates the process of wound healing.
What are the 4 stages of wound healing?
1. Homeostasis
2. Inflammation
3. Proliferation or granulation
4. Remodelling
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What happens in the homeostasis stage?
Initial damage to blood vessels causes platelets to adhere to the site and form a plug. Fibrin joins and forms a blood clot (coagulation)
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What is the purpose of the homeostasis stage?
Prevent blood loss and limits damage by encourage immobilisation
(the site is too painful to use)
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The next stage is inflammation. What is the purpose of this stage?
Defensive: white blood cells (leucocytes) rush to the area

Promotes repair of injured tissue
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What are the 5 cardinal signs of inflammation?
1. heat
2. redness
3. pain
4. swelling
5. loss of function
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What vascular changes result in inflammation?
Increased blood flow
Leakage of plasma proteins to the tissue
Neutrophil emigration to the site
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What do the leucocytes do at the site during inflammation?
They ingest bacteria and foreign particles
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When leucocytes emigrate to the effected area, what is this called?
Leucocyte extravasation
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During this, mast cells detect injury. What do they then release?
Histamine
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What does the release of histamine do?
Histamine triggers endothelial cells to express selections that capture circulating white blood cells
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Mast cells also release the cytokine called TNFa. What is this?
Tumour Necrosis Factor alpha
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What does TNFa do?
It causes the endothelial cells to express cell adhesion molecules that tightly bind the cells. these endothelial cells stretch creating little gaps between them, allowing plasma proteins to leak out into tissue
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Describe the entire leucocyte extravasation process?
An inflammatory signal make the endothelial cells to produce selections. These selections attract and capture passing leucocytes to roll over them until they adhere. TNFa allows gaps to form, so leucocyte and plasma protein enter the tissue
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What are the first white blood cells to arrive to the site?
Neutrophils
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What is it called when these remove bacteria and debris?
Phagocytosis
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What are the next white blood cells to arrive?
Macrophages
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Simply describe phagocytosis
Microbes adhere to the phagocyte. The phagocyte ingests the microbe, forming a phagosome. Phagosomes fuse with lysosome. Enzymes digest this, and digestion products are released.
Cytokines (chemical mignals) are also released which cause inflammatory rea
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What chemical signals control inflammatory responses?
1. Prostaglandins - lipids
2. Cytokines - small proteins/peptides
3. Chemokines - chemoattractant for more WBCs
4. Interleukins - activate/mature immature cells
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What are the dangers of inflammatory responses?
A cytokine storm can occur, resulting in multi-organ failure
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Overall, mast cells secrete factors that mediate what?
Vasodilation and vascular constriction
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What 2 white blood cells remove pathogens by phagocytosis?
Neutrophils and macrophages
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Macrophages secrete hormones called what?
Cytokines
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What is the purpose of the proliferation and remodelling stage and what do they ultimately do?
Reparative

Increases cell numbers and secretes new tissue matrix
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What happens during the proliferation stage?
Fibroblasts proliferate and migrate to the wound. They synthesise collagen to create granulation tissue. They form new blood vessels (angiogenesis) and contract to close the wound
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What happens during the remodelling stage?
Remodelling of the granulation tissue is broken-down by collagen and replaced with functional tissue
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The degree of tissue remodelling varies by tissue type. What are 3 types of tissues?
1. Bone
2. Skin
3. Articular cartilage
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What are the 3 possible outcomes of inflammation?
1. Resolution/repair - removal of stimulus, apoptosis of inflammatory cells, normal function
2. Scarring/Fibrosis - repaired with granulation tissue, scar forms, no normal function
3. Chronic inflammation - stimulus is not resolved, longterm presence of i
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What are the 3 steps of scarring?
- Immune cell infiltration
- Matrix remodelling
- Fibrous capsule formation
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Name 2 causes for both acute inflammation and chronic inflammation?
Acute - infection and burn

Chronic - autoimmune disease and cancer
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In inflammation, what causes heat?
Increased blood flow to the area
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In inflammation, what causes redness?
Increased blood flow to the area
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In inflammation, what causes swelling?
Increased extracellular fluid due to 'leaky' blood vessels
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In inflammation, what causes pain?
Stimulation of pain receptors by inflammatory mediators and swelling
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In inflammation, what causes loss of function?
pain limits use of area to give it time to repair
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What is the most common outcome of injury/inflammation of the liver?
Regenerates with new tissue
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What is the most common outcome of injury/inflammation of the brain or nervous tissue?
Nervous tissue is not usually capable of regeneration
=
forms a scar
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What is the most common outcome of injury/inflammation of bone?
Regenerates with new tissue
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What is the most common outcome of injury/inflammation of skin?
Forms a scar
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What is the most common outcome of injury/inflammation of cardiac muscle?
Forms a scar
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What is the most common outcome of injury/inflammation of the lungs?
Regenerates with new tissue
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What is the most common outcome of injury/inflammation of cartilage?
Cartilage has no capacity for regeneration
=
forms a scar
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What is the most common outcome of injury/inflammation of the lining of the large intestine?
Regenerates with new tissue
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If you have prolonged or chronic inflammation, why would this lead to disease?
Your body's inflammatory response can eventually start damaging healthy cells, tissues and organs
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Card 2

Front

What happens in the homeostasis stage?

Back

Initial damage to blood vessels causes platelets to adhere to the site and form a plug. Fibrin joins and forms a blood clot (coagulation)

Card 3

Front

What is the purpose of the homeostasis stage?

Back

Preview of the front of card 3

Card 4

Front

The next stage is inflammation. What is the purpose of this stage?

Back

Preview of the front of card 4

Card 5

Front

What are the 5 cardinal signs of inflammation?

Back

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