Acute inflammation 1

Question 1

what is inflammation?

Answer 1

local physiological response to tissue injury

Question 2

what does the inflammatory response affect?

Answer 2

-a complex reaction in vascularised connective tissue

• Reaction of blood vessels which leads to accumulation of fluid and leucocytes in extravascular tissues

Question 3

what does inflammation serve to do?

Answer 3

• to destroy, dilute or wall off the injurious agent

•The inflammatory response is closely intertwined with the process of repair

Question 4

what type of response is inflammation?

Answer 4

protective response

Question 5

what would happen in the absence of inflammation?

Answer 5

• Wounds and injured organs would never heal

- Infections would go unchecked

Question 6

in what ways can inflammation and repair be potentially harmful?

Answer 6

• Life-threatening hypersensitivity reactions
• Chronic inflammatory diseases eg rheumatoid arthritis and Crohn’s disease
• Repair by fibrosis may lead to problems such as disfiguring scars

Question 7

what are the two types of inflammation?

Answer 7

• acute

- chronic

Question 8

what is acute inflammation?

Answer 8

the initial rapid and often short-lived series of tissue reactions to injury

Question 9

what is chronic inflammation?

Answer 9

the subsequent and often prolonged tissue reactions following the initial response

Question 10

what are the 5 principal causes of acute inflammation?

Answer 10

1) Infections- viruses
2) Hypersensitivity- excessive/inappropriate immune reaction which damages tissue)
3) physical agents- trauma
4) Irritant and corrosive chemicals - acid
5) Foreign bodies- dirt

Question 11

what are the physical characteristics of inflammation?

Answer 11

1) Redness (rubor)- dilation of small blood vessels
2) Heat (calor) -increased blood flow
3) Swelling - accumulation of fluid in the extravascular space
4) pain (dolor) -stretching and distortion of tissues caused by increased fluid. Various chemical mediators, including bradykinin are known to produce pain
5) Loss of function- movement is inhibited by pain

Question 12

what are processes of involved in initial rapid reaction of tissue?

Answer 12

1) i) vasodilatation
ii) Increased permeability of blood vessels
2) exudative and cellular phase

Question 13

what happens during vasodilatation?

Answer 13

Results in increased blood flow thus heat and redness

Question 14

what happens during increased permeability of blood vessels?

Answer 14

• Small blood vessels are lined by a single layer of endothelial cells
• The walls of small vessels act as a microfilter
• Oxygen, carbon dioxide and some nutrients transfer across the wall by diffusion
• The main transfer of fluid and solutes is by ultrafiltration as described by Starling

Question 15

what happens during increased vascular permeability -the formation of endothelial gaps in venules?

Answer 15

• Increased vascular permeability is brought about
by chemical mediators including histamine, bradykinin
• Leakage of fluid is confined to POST CAPILLARY VENULES • Gaps in venules are largely intercellular
• Endothelial cells contain contractile proteins, when stimulated by chemical mediators they pull open transient pores
• Endothelial cells are NOT damaged in this process

Question 16

what are the causes of increased vascular permeability?

Answer 16

• Immediate transient –>chemical mediators e.g. histamine
• Immediate sustained
• -> severe direct vascular injury
• delayed prolonged
• -> endothelial cell injury e.g. X-rays

Question 17

what is the net increase in extravascular fluid called?

Answer 17

oedema

Question 18

what is the fluid exudate?

Answer 18

• Proteins including immunoglobulins, important in destruction of invading organisms
• Fibrinogen  Fibrin on contact with the extracellular matrix (ECM), hence acutely inflamed organ surfaces commonly covered by fibrin
• Exudate is continually being removed by the lymphatics and replaced by new exudate

Question 19

what is the cellular component?

Answer 19

The diagnostic feature of acute inflammation is neutrophil accumulation in the extracellular space

Question 20

what is a neutrophil?

Answer 20

Leukocyte - white blood cell

Question 21

what are the functions of neutrophils?

Answer 21

• Kill microorganisms
• Ingest offending agents
• Degrade necrotic tissue
• Produce chemical mediators
• Produce toxic oxygen radicals
• Produce tissue damaging enzymes

Question 22

How does a neutrophil reach the site of an inflammatory stimulus?

Answer 22

1. Margination-Loss of intravascular fluid and increased plasma viscosity slows flow allowing neutrophils to flow in the plasmatic zone (ONLY in venules)
   2) Adhesion-Increased neutrophil adhesion results from interaction between adhesion molecules on its surface and the endothelial surface
   3) Transendothelial migration- neutrophils insert pseudopodia into the junctions between endothelial cells. They then cross through the basement membrane and into the extravascular space

Question 23

How do neutrophils find the site of the Inflammatory stimulus?

Answer 23

chemotaxis - locomotion orientated along a chemical gradient

Question 24

what are compounds chemotactic for neutrophils ?

Answer 24

• Bacterial products
• Complement components
• Cytokines
• Products produced by neutrophils themselves

Question 25

what are endogenous chemical mediators ?

Answer 25

chemicals that drive the process of inflammation and cause :

1. Vasodilatation
2. Emigration of neutrophils
3. Chemotaxis
4. Increased vascular permeability
5. Itching and pain

Question 26

what are 3 examples of a chemical mediators?

Answer 26

• Histamine
• chemokines
• lysosomal compounds

Question 27

what are the 4 enzymatic cascade systems in plasma?

Answer 27

1. Complement system
2. Coagulation system 3. Kinin system
3. Fibrinolytic system

Question 28

what breaks down blood clots?

Answer 28

Fibrinollytic