Inflammation and wound healing

Question 1

What is a wound?

Answer 1

A wound is a breakdown in the protective function of the skin (loss of continuity of epithelium)

Question 2

What are the five components of inflammation?

Answer 2

Redness
Swelling
Pain
Heat
Loss of function

Question 3

what is the aim of inflammation?

Answer 3

To expel foreign body/infection if present

Structural and functional repair

Question 4

Describe briefly what causes each clinical feature of inflammation?

Answer 4

Redness: small blood vessel dilation
Swelling: Fluid in extracellular matrix
Pain: stretching of skin due to oedema, mediators such as bradykinin and serotonin stimulate pain receptors.
Heat: increase in blood flow to the area due to vasodilation and fever
LOSS of function: movement inhibited by pain and swelling immobilises area.

Question 5

What are possible outcomes of inflammation?

Answer 5

Resolution
Scar
Abscess via liquefactive necrosis = transformation of tissue into liquid viscous mass

Chronic inflammation

Question 6

What effect does vasodilation have on vessels?

Answer 6

It increases their permeability and allows emigration of plasma components and cells.

Question 7

List 6 vasoactive mediators

Answer 7

Histamine
Prostaglandin
C3a
C5a
Bradykinin
Cytokines

Question 8

Name 2 vasoactive mediators

Answer 8

Serotonin - found in platelets

Histamine - abundant in granules in mast cells

Question 9

What does bradykinin achieve?

Answer 9

Vasodilation

Pain

Question 10

What do arachidonic acid metabolites produce?

Answer 10

Leukotrienes
Prostaglandins
Thromboxane A2

Question 11

What is the main function of nitric oxide?

Answer 11

Vasodilation

Question 12

Outline the process of cell infiltration to an inflammatory site

Answer 12

Rolling adhesion
Tight Binding
Diapedesis
Migration

Question 13

What is found on the surface of endothelial cells which the WBC/leukocytes bind to?

Answer 13

P and E selectin

Question 14

What do monocytes differentiate/mature into as they move from the bloodstream into tissue?

Answer 14

Macrophages

Question 15

Which cell is key in activating an adaptive response?

Answer 15

Dendritic cell

Question 16

what are the 3 phases of wound healing?

Answer 16

Inflammation
Proliferation
Remodelling/maturation

Question 17

describe the inflammatory phase of wound healing

Answer 17

Platelets initiate Haemostasis to limit blood loss and allow blood clotting

Wound site become red, warm and swollen. This is due to increased vasodilation which also increases the permeability of blood vessels so that plasma contents and cells may migrate easily.

Chemokines, cytokines and growth factors stimulate the migration of neutrophils to arrive at the injury site first. Macrophages also arrive at the injury site. They also send out signals for more cells to migrate.

Bacteria and debris is removed by neutrophils and macrophages via phagocytosis. Neutrophils have a short half-life and die quick to form pus. Macrophages remove them too.???

Question 18

How long doe she inflammatory phase last?

Answer 18

24-48 hours

Question 19

describe the proliferative stage of wound healing

Answer 19

Epidermal Growth factors stimulate epithelial cells to loosen their desmosome adhesions to allow keratinocytes to migrate to the wound site. The cells cover the site in a single layer of keratinocytes to cover granulation tissue.

Once granulation tissue is covered, keratinocytes proliferate to produce more epithelial cells. Granulation tissue is formed and it consists of type III collagen.

PD Growth factors attract fibroblasts to the site and they synthesise the ECM and produce MMPs.

Endothelial cells undergo angiogenesis to repair blood vessels and deliver oxygen to cells to allow wounds to heal.

Question 20

describe the remodelling stage of wound healing

Answer 20

Granulation tissue is replaced with mature scar tissue.
Collagen is organised into thick, parallel bundles and cross linked to form a mature scar.
Tissue collagen is replaced with type I collagen.

Question 21

What ever of tissue strength is restored?

Answer 21

70-80% of tissue strength is restored to pre-injury strength

Question 22

What are local factors that may effect wound healing?

Answer 22

Oxygenation
Infection
Vascular supply
Foreign body

Question 23

What are systemic factors that may effect wound healing?

Answer 23

Age
Obesity
Alcohol and Smoking
Mediations e.g. Corticosteroids
Diseases e.g. diabetes

Question 24

What are interleukin 1, 6 and TNF alpha involved in ?

Answer 24

Inflammation