Acute Inflammation

Question 1

Some causes of inflammation:

Answer 1

• Infection
• Hypersensitivity
• Trauma
• Chemicals
• Necrosis

Question 2

Hypersensitivity:

Answer 2

Excess immune response due to altered state of immunological responsiveness

Question 3

Cardinal signals of acute inflammation

Answer 3

Redness - dial action of vessels
Heat - increased blood flow
Swelling - accumulation of fluid

Pain - due to distortion of tissue (chemical mediators released e.g. prostaglandins)

Loss of function

Question 4

6 stages of inflammation:

Answer 4

• Release of chemical mediators
•Vasodilatation
•Increased vascular permeability
•Fluid accumulation
•Cellular recruitment
•Phagocytosis

Question 5

Functions of neutrophils:

Answer 5

They can move via:
• Contracting microtubules
• Chemotaxis

They can stick to opsonised microorganisms:
• When bacteria encounter immunoglobulins or complement components, neutrophils can bind to them

They are Phagocytes

Question 6

What allows neutrophils to marginate?

Answer 6

• Loss of intravascular fluid
• Slowing of flow to the site

Question 7

Adhesion

Answer 7

Neutrophils adhere to vascular endothelium

Caused by interaction between paired adhesion molecules on the neutrophil and endothelial surfaces

Question 8

Emigration

Answer 8

When neutrophils pass between endothelial cells through basal lamina and into adventitia

Question 9

Chemical agents in acute inflammation (4)

Answer 9

Cytokines
Complement
Histamine
Prostaglandins

Question 10

Role of PAF:

Answer 10

Docks with corresponding receptor on neutrophil and promotes expression molecules allowing firm neutrophil adhesion to endothelial surface

Question 11

Function of histamine

Answer 11

Causes vascular dilation and permeability

Question 12

What do prostaglandins cause?

Answer 12

Some cause increased vacular permeability, some cause platelet aggregation

Question 13

Chemokines

Answer 13

Family of chemicals which attract more white blood cells to site of inflammation

Eg IL-8 attracts neutrophils

Question 14

Benefits of inflammation:

Answer 14

•Dilution of toxins
•Entry of antibodies
•Stimulation of immune response

Question 15

Harmful effects of inflammation

Answer 15

Digestion of normal tissue
Swelling
Inappropriate inflammatory response

Question 16

What is resolution?

Answer 16

Everything is back to normal

Ideal conditions include:
•Good regenerative capacity
•Minimal tissue damage/cell death
•Quick elimination of the causative agent
•Good vascular drainage to remove fluid and debris

Question 17

What makes up the organisation state after acute inflammation?

Answer 17

Formation of granulation tissue

Can occur with substantial amounts of tissue loss, or large amounts of fibrin

New capillaries, leading to more macrophages, leading to proliferation of fibroblasts, leading to fibrosis and/or scarring

Question 18

What is suppuration?

Answer 18

Formation of pus:
- Mix of neutrophils, debris, bacteria etc

If it gets walled off, can form abscess

Question 19

Difference in healing outcomes in different tissue types:

Answer 19

Bone - Replaced by stronger lamellar bone

Liver - Can get complete healing unless architecture is damaged then there is scarring

Kidney - Epithelium can regenerate, architecture can’t

Smooth muscle - Only vascular smooth muscle can regenerate other smooth muscle is replaced by scar tissue

Neural tissue - Does not repair well, peripheral nerves may regrow but recovery is variable

Question 20

What predisposes progression from acute to chronic inflammation?

Answer 20

If causative agent is not removed

The cellular exudate starts to change:
• Neutrophils are replaced with lymphocytes, plasma cells, macrophages

Question 21

When might you get primary chronic inflammation?

Answer 21

Acute inflammation fails to resolve

Collection of pus, abscess formation and walling off with granulation and fibrous tissue

Presence of foreign material:

Recurring cycles of acute inflammation then healing

Question 22

What cells are involved in chronic inflammation?

Answer 22

Lymphocytes (Small purple dots):

Plasma cells (Fried eggs):

Macrophages (Bigger blobby ones)

Sometimes eosinophils (Tomatoes with sunglasses)

Question 23

What is granulomatous inflammation?

Answer 23

A collection of histiocytes

Examples of conditions:
•Tuberculosis
•Sarcoidosis
•Crohn’s disease

Question 24

Primary and Secondary healing (skin):

Answer 24

Primary intention:
•Two edges of the wound can be brought together
•Fibrin joins the edges together weakly
•Over time, epidermal regrowth and collagen synthesis makes a stronger join

Secondary intention:
•Tissue defect filled in by granulation tissue
•Epithelial regrowth over the surface
•Fibrous scar forms and contracts over time

Question 25

Role of lymphocytes in chronic inflammation:

Answer 25

B cells turn into plasma cells and produce immunoglobins/antibodies

T killer cells are cytotoxic and recruit other cells

Helper T cells activate killer T cells and plasma cells