Inflammation and Tissue Repair Flashcards by Alli Volkens

3 most common causes of inflammation

Pathogens (germs) like bacteria, viruses or fungi
External injuries like scrapes or foreign objects
Effects of chemicals or radiation

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3 Phases of Inflammation and Repair

1) Inflammation phase
2) Proliferation phase
3) Maturation phase

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When does the inflammatory phase occur?

Days 1-6

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What is the main goal of the inflammatory phase?

Attempts to destroy, dilute, or isolate cells/agents at fault

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What are the 5 cardinal signs of inflammation and what causes each?

1) Heat - caused by increased vascularity
2) Redness – caused by increased vascularity
3) Swelling – caused by blockage of lymphatic drainage
4) Pain – caused by physical pressure of chemical reaction
5) Loss of Function – caused by pain and swelling

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4 Responses of the Inflammatory Phase

1) Vascular Response
2) Hemostatic Response
3) Cellular Response
4) Immune Response

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What initially occurs during the vascular response?

Vasoconstriction

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What neurotransmitter mediates vasoconstriction?

Norepinephrine

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What prolongs the vascular response and where?

serotonin in mast cells and platelets

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What occurs after the initial vasoconstriction?

Vasodilation

The non-injured vessels around the injured area dilate, which causes increased capillary permeability

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What neurotransmitters initiate vasodilation and increase capillary permeability?

Histamine, Hageman factor, bradykinin, prostaglandins, complement fractions

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What else happens during the vascular response?

Adherence of blood vessel linings
Increased viscosity
Extravasation
Margination
Pavementing
Diapedesis
Emigration

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What is extraversion?

Migration of neutrophils (type of leukocyte) to injured area

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What is margination?

neutrophils line the margins of the vessels

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What is pavementing?

cells accumulate and lay down in layers

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What is diapedesis?

neutrophils squeeze through the vessel walls

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What occurs during the hemostatic response?

Platelets bind to exposed collagen which release fibrin and stimulate clotting

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What do platelets release during the hemostatic response? What does this protein do?

Platelets release a regulatory protein, platelet-derived growth factor (PDGF) that is chemotactic and mitogenic

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How does clot formation occur?

Fibrin and fibronectin form cross-links with collagen to create fibrin lattice which forms a temporary plug in blood and lymph vessels to limit local hemorrhage and fluid drainage

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What is the wound’s only source of tensile strength during inflammatory phase of healing?

Fibrin lattice

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What occurs during the cellular response?

RBCs transport oxygen and WBCs help to clear the injured site of debris and microorganisms

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Hematoma vs. Hemarthrosis

Accumulation of blood in a tissue or organ is called Hematoma
Bloody fluid present in a joint is called Hemarthrosis

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6 types of leukocytes present during the cellular response

Neutrophils
Eosinophils
Basophils
Monocytes
Lymphocytes
Marcophages

What 3 things occur during the immune response?

1) Increased vascular permeability
2) Increased phagocytosis
3) Chemotactic stimuli for leukocytes

When does the proliferative (2nd) phase occur?

Days 3-20

What are the 4 processes that occur simultaneously during the proliferative phase?

- Epithelialization - Collagen production - Wound contracture - Neovascularizatio

What is Epithelialization?

Covering the surface of the wound and closing the defect (i.e. reestablishment of the epidermis)

Two types of epithelialization?

Primary and Secondary (Indirect)

A small cut that can be closed with sutures will induce what type of epithelialization?

Primary Intention

A large gapping cut that will first undergo contraction will induce what type of epithelialization?

Secondary intention

When epithelialization does not provide enough strength what must occur?

Fibroplasia aka collagen production

What do fibroblasts initially produce?

thin weak structured collagen called Type III collagen

Around what day is type III collagen replaced by stronger type I collagen?

day 7

When does wound contracture begin and when does it peak?

5 days after injury, peaks at 2 weeks

What causes wound contracture?

Myofibroblasts

What theory does wound contracture occur under?

“Picture frame theory” in which a ring of myofibroblasts moves inward from wound margin

Describe the speed of wound healing between linear, square, and circular wounds

Linear wounds contract the most rapidly. Square wounds progress at a moderate pace. Circular wounds contract the slowest

What may cause wound contracture?

Uncontrolled wound contraction

What is Neovascularization?

Development of a new blood supply – the result of angiogenesis

What causes scars to appear whitish?

Capillary loops eventually cease to function and retract

When does the maturation phase occur?

Day 9 and on

What determines the rate of maturation and the final characteristics of the scar?

- Fiber orientation | - Balance of collagen synthesis and lysis

What type of collagen is the major collagen found in cartilage?

Type II

What is a keloid scar the result of?

Excessive collagen deposition caused by inhibition of lysis

What occurs when oxygen is low and why?

The scar is less bulky and softer because collagen synthesis is oxygen dependent, collagen lysis is not

What are the potential outcomes of Acute Inflammatory processes?

- Replacement of the injured tissue with like tissue - Healing by scar formation - Formation of an abscess - Progression to chronic inflammation

What is chronic inflammation?

Simultaneous progression of active inflammation, tissue destruction, and healing

2 types of chronic inflammation

1) Follows acute inflammation – due to continued presence of injurious agent (i.e. continued microtrauma) 2) Due to immune response (i.e. implant or suture) or the result of autoimmune disease (i.e. RA)

If the inflammatory response continues for more than 4 weeks what is it called?

subacute inflammation

What is the difference between steroids and NSAIDS?

NSAIDS reduce pain indirectly by reducing inflammation, whereas steroids are a higher powered antiinflammatory

When there is damage to cartilage what must occur and why?

Surgery, because it has a limited ability to heal with no lymphatics, blood vessels, or nerves

The 1st two stages of tendon healing are similar to healing of other tissues, but what occurs in the last stage?

scar maturation

Describe scar maturation in tendons

Collagen is oriented perpendicular to the long axis of the tendon early in healing, but around day 10 the fibers change to a parallel orientation

What types of ligaments heal and which typically do not?

Capsular and extracapsular ligaments generally have adequate repair response (i.e. MCL), whereas intracapsular ligaments often do not (i.e. ACL)

Can skeletal muscle regenerate?

2 mechanisms of healing of bone healing

Primary Healing – occurs with rigid internal fixation | Secondary Healing – occurs without fixation

4 stages of bone healing

1) Inflammation 2) Soft callus 3) Hard callus 4) Remodeling