Week 2 - Acute inflammation

Question 1

What is inflammation? What is its function?

Answer 1

response to injury of vascularised living tissue to deliver defensive material- leucocytes and plasma proteins to the site of injury protecting the body against infection and to clear damaged tissue initiating repairesponse to injury of vascularised living tissue to deliver defensive material- leucocytes and plasma proteins to the site of injury protecting the body against infection and to clear damaged tissue initiating repair.

Question 2

Give three properties of acute inflammation

Answer 2

Innate, stereotyped and rapid

Question 3

When is acute inflammation needed?

Answer 3

When local defenses are no longer adequate.

Question 4

How do most defensive agents circulate?

Answer 4

In the blood in inactive form and are delivered/ activated when needed.

Question 5

What must defensive agents be able to do?

Answer 5

leave blood vessel at the site without interrupting blood flow as this is needed at further sites

Question 6

Give 6 causes of acute inflammation

Answer 6

Foreign bodies
Immune reactions
Infections and microbial toxins
Tissue necrosis
Trauma ( blunt and penetrating)
Physical and chemical agents( thermal injury, environmental chemicals)

Question 7

Give the 5 signs of acute inflammation and explain why

Answer 7

Rubor – redness caused by dilation of blood vessels
Color- heat caused by dilation of blood vessels
Tumour – swelling caused by fluid and leucocytes in tissue
Dolor – pain caused by specialised nerve endings stimulated by mediators - bradykinin
Loss of function which enforces rest and decreases chance of further damage

Question 8

Give the first stage of formation of exudate

Answer 8

Vasoconstriction

Question 9

Give the second step in the formation of exudate and what brings this about?

Answer 9

2. Vasodilation of arterioles- brought about by vasoactive mediators histamine from mast cells and platelets, nitric oxide from macrophages and endothelium

Question 10

What changes about the venule walls during exudate formation? What does this allow?

Answer 10

They become leaky allowing plasma to escape through

Question 11

Loss of fluid from the venules leads to what?

Answer 11

Increased haemocrit within the venules and increased resistance to blood flow reducing it to further along venules and increased pressure upstream. This causes their lumens to dilate and reducing the blood flow speed.

Question 12

The increased pressure in the venules leads to what?

Answer 12

Increased fluid into the tissues and therefore increased proteins to the site of injury.

Question 13

What is generally the first mediator in acute inflammation?

Answer 13

Histamine

Question 14

Where is histamine found usually?

Answer 14

Cells in the tissue and platelets. It is also stored in the granules of Mast cells and basophils.

Question 15

What is histamine used as in the brain?

Answer 15

Neurotransmitter

Question 16

What effects does histamine induce in acute inflammation?

Answer 16

Produces pain.
Causes arteriolar dilation
Venular leaking by causing endothelial cells to contract and pull apart allowing proteins to pass

Question 17

What other mediator is similar to histamine in terms of the effects exerted? What other effect does it cause ?

Answer 17

Serotonin

Stimulates fibroblasts

Question 18

What chemical mediator is made from cell membrane phospholipids?

Answer 18

Prostaglandins

Question 19

What effects do prostaglandins have?

Answer 19

Vasodilation
Makes skin increase sensitive
Cause fever

Question 20

What drugs block the production of prostaglandins? How?

Answer 20

Steriods - inhibit the phopholipases therefore cannot go from phospholipids to arachondonic acid
Aspirin and NSAIDs inhibit cyclo-oxygenases therefore cannot go from arachadonic acid to prostaglandin

Question 21

What defensive proteins are found in the exudate? What are their functions?

Answer 21

Opsonins – coat foreign material and make them easy to phagocytose
Complement – group of proteins assembled locally to produce bacteria perforating structure
Antibodies – bind to surface of microorganisms – act as opsonins

Question 22

Explain how lymphadenitis occurs

Answer 22

 Excessive fluid drains from tissue in lymphatic taking with it microorganisms and antigens therefore presenting them to the immune system within lymph nodes – can become inflamed, swollen and painful – LYMPHADENITIS

Question 23

Explain the difference between exudate and transudate

Answer 23

Rich in proteins - exudate

Low in proteins - transudate

Question 24

When does transudate occur?

Answer 24

secondary to osmotic or hydrostatic imbalance across a vessel wall without increase in permeability

Question 25

What chemical mediators induce vascular leakage

Answer 25

histamine, serotonin, bradykinin and complement components c3a, c4a and c5a

Question 26

Under normal conditions where are neutrophils found

Answer 26

blood and bone marrow

Question 27

What is the lifespan of a neutrophil

Answer 27

12-20hrs

Question 28

What must neutrophils be able to do to be effective in inflammation

Answer 28

1. Chemotaxis
2. Activation
3. Margination
4. Diapedisis
5. Recognition attachment
6. Phagocytosis
7. Kill

Question 29

Explain chemotaxis for a neutrophil

Answer 29

Summoned to the place of injury. Movement towards chemotaxins.

Question 30

How do neutrophils move?

Answer 30

By producing filopodia that pull back of cell in direction of extension

Question 31

Give some example of chemotaxins for neutrophils

Answer 31

Bacterial products
Leukotrienes (B4)
C3a/4a/5a
Clotted blood - fibrin

Question 32

Explain what activation means in terms of neutrophils

Answer 32

Switching a to a higher metabolism level and increased stickiness

Question 33

How is the change in activation of a neutrophil brought about?

Answer 33

Binding of chemotaxin which leads to influx of sodium and calcuim ions. Electrolytes moving causes water to also move.

Question 34

Explain margination of a neutrophil.

Answer 34

Sticking to the endothelium surface. Leucocytes assume marginal position in vessel ,sticking to the walls of venules and roll along before becoming trapped and crawl out of the vessel.

Question 35

What mediators are invovled during margination of a neutrophil? What happens to the number of these during acute inflammation?

Answer 35

Selectins and integrins

Increase

Question 36

What is diapedisis of a neutrophil?

Answer 36

Crawling through the endothelim by production of collagenase whihc digests the basement membrane

Question 37

Once outside the venule how do neutrophils move?

Answer 37

Pulling on collagen fibres