Inflammation 1: Vascular changes & formation of cellular exudate

Question 1

Define inflammation

Answer 1

it’s the Dynamic response of any vascularised tissue agianst to tissue injury, to eliminate cause of cell injury & initiate repairing

Question 2

local Vascular reaction/ vascular change during inflammation is divided into

Answer 2

• Change in vascular Caliber (diameter) & flow
• Increase in Vascular permiability

Question 3

Describe the changes of vascular Caliber & flow during vascular change of inflammation

Answer 3

1. transient Vasoconstricition
2. Histamine released from damaged tissue causes:
   * Ateriole vasodilatation —> Hyperemia
   * redness (erythrema) & Hotness = Flare
3. Increase in hydrostatic pressure (fluid capillary permiability increases) so more fluid exits
4. the exit of fluid causes increase in blood viscosity (thrombosis/ stasis)
5. Formation of Exudate containing fluids & cells

Question 4

Causes Increase in vascular permibaility during vascular change of inflammation

Answer 4

• histamine & Bradykinin causes contraction & shortening of endothelial cells & forming intracellular gaps
• Endothelial cellular damage during burns or some infections

Question 5

Define exudate

Answer 5

fluid rich in protein which moves into extravascular tissue

Question 6

Describe how exudate moves into extravascular tissue

Answer 6

• It’s protein rich, meaning it has increased osmotic presure favoring movoment outside, so it moves down osmotic gradient
• The increased hydrostatic pressure caused the vasodilatation

Question 7

Enumerate benefits of Exudate/ inflammatory edema

Answer 7

1. Dilutes any toxins
2. Facilitate the entry of antibodies (lysis or opsonization)
3. Transportation of antibiotics to infected site
4. transportation of Fibrin to the site of injury/ infection:
   * trap organisms & facilitate phagocytosis
   * Matrix for healing
5. deliver oxygen & Nutreints

Question 8

Formation of cellular Exudate is divded into

Answer 8

• Recruitement of Leukocytes (WBC)
• Activation of Leukocytes

Question 9

Steps of Leukocyte recruitment

Answer 9

1. Margination
2. Rolling
3. Pavementation
4. Emigration/migration/infiltration
5. Chemotaxis

Question 10

Define margination of leukocytes

Answer 10

the Neutrophils will flow from laminar blood flow to plasmatic zone due to loss of intravascular fluid (increased stasis & viscosity)

Question 11

which receptors are responsible for the rolling of leukocytes

Answer 11

Selectin P & E receptors

Question 12

Which receptors are responsible for the pavementation of leukocyes onto endothelium after rolling

Answer 12

Integrins

Question 13

describe attachement and rolling of leukocytes onto endothelium

Answer 13

1. After reaching plasmatic zone, leukocytes attach to sticky enothelium by P & E selectin receptors
2. they continue to detach and attach, causing them to tumble onto endothelial surface

Question 14

describe pavementation of leukocytes onto endothelium

Answer 14

tight adhesion of neutrophils to vascular endothelium by integrins

Question 15

mechanism of integrins

Answer 15

they are present on the WBC, they attach to their ligands that are present on the endothelial wall

Question 16

Describe Emigration, migration & infiltration of Leukocytes

Answer 16

Leukocytes squeeze themselves through widened endothelial spaces (mainly of venules) by pseudopodia by amoeboid movement driven by cytokines

• they release collagenase to be able to digest and pass through basement membrane

Question 17

Define Chemotaxis & explain its mechanism

Answer 17

The movement of Leukocytes towards the site of injury via chemical attractor/chemostatic substances, they do that by:
1. reacting on receptor of Leukocyte from the direction of the injury
2. this causes assembly of cytoskeleton contractile elements forming pseudopods facing direction of injury
3. pseudopods anchor to ECM to the pull the cell in the direction of the extension

Question 18

Enumerate chemotactic factors

Answer 18

• Exogenous (lipids & peptides of baterial products)
• C3a & C5: complement system from plasma
• IL8 (interleukin 8): cytokines of chemokine family produced by cells
• LB4 (leukotriene B4): from arachidonic acid

Question 19

Define Luekocyte activation/ phagocytosis

Answer 19

Attachement of recongition particles to ingesting leukocytes, causing them to ingulf & kill organisms & degrade the ingested material

Question 20

Enumerate Opsonins

Answer 20

• IgG
• C3b

Question 21

define opsonisation

Answer 21

the process of which opsonins coat organisms to make them a target for phagocytosis

Question 22

describe engulfing mechanism

Answer 22

Luekocytes surround bacteria by pseudopodia & engulf them by endocytosis inside vacuoles called phagosomes
* Inside the leukocyte, phagosomes bind with lysosomes to form phagolysosomes

Question 23

describe killing & degenration of bacteria done by leukocytes

Answer 23

• By oxygen dependent mechanism (ROS) or oxygen independent (acidic pH)
• after bacteria is dead and broken down, chemical mediators are released (arachidonic acid metabolites & cytokines) causing more recruitement of WBCs
• finally, moncytes (macrophages) arrive at the site

Question 24

role of Macrophages in acute inflammaiton

Answer 24

• do not predominate until later stages
• play lesser role in phagocytesis compared to neutrophils
• clean tissue debris and damaged cells
• digest inflmmatory exudate and drain them in lymphatics
• secrete growth factor for repair

Question 25

Final fate of exudate

Answer 25

to be digest by macrophages (monocytes) and drained into lymphatics