Pathogensis Of Acute Inflammation

Question 1

What are the changes in vascular flow and caliber

Answer 1

Vasodilation
Inc permeability of microvasculature
Stasis of blood flow

Question 2

Describe vasodilation

Answer 2

Earliest manifestations of acute inflammation
First arterioles and then leading to opening of new capillary beds in area
Induced by histamine
Inc blood flow and inc hydrostatic pressure which causes redness

Question 3

Describe inc permeability

Answer 3

Quickly followed by vasodilation with outpouring of exudate in to extra vascular tissues
Causes swelling and edema

Question 4

Describe stasis of blood flow

Answer 4

Due to loss of fluid and inc vessel diameter
Conc of rbcs inc and inc viscosity
Result in engorgement of small vessels jammed with slowly moving red cells seen histologically as vascular congestion and externally as redness

Question 5

What are the mechanisms for inc vascular permeability

Answer 5

Contraction of venule endothelium to form intercellular gaps resulting in opening of interendothelial spaces is the most common mechanism of vascular leakage
By histamine, bradykinin and leukotrienes
Rapid
Location:post capillary venules

Direct endothelial injury: resulting in endothelial cell necrosis and detachment
Causes: burns, microbes, microbial toxins that target endothelial cells or by effect of recruited neutrophils to site of inflammation with release of ROS
Location:venules, capillaries and arterioles

Question 6

Responses of lymphatic vessels and lymph nodes

Answer 6

Lymphatic flow is inc to drain edema fluid, leukocytes and cell debris from extravascular space
Lymphangtis: red streaks and lymph vessels
Lymphadenitis: enlarged painful nodes
Due to lymphoid follicle and sinusoidal phagocyte hyperplasia

Question 7

What is recruitment

Answer 7

Neutrophils and macrophages are recruited to recognize invading pathogens and necrotic debris, eliminate them and produce growth factors to facilitate repair

Question 8

What infections recruit neutrophils

Answer 8

Bacterial infections

Question 9

What do viral infections recruit

Answer 9

Leukocytes

Question 10

What do allergic reactions recruit

Answer 10

Eosinophils

Question 11

Leukocyte recruitment steps

Answer 11

1-margination,rolling and adhesion
2-transmigration across the endothelium
3-migration in interstitial tissue toward a chemotactic stimulus

Question 12

How does adhesion and rolling occur

Answer 12

Occurs under effect of stasis of blood

Occur by interactions between complementary adhesion molecules on leukocytes and endothelium

Question 13

What are the adhesion molecules

Answer 13

Selectins, mediate rolling and initial weak interactions between leukocytes and endothelium

Integrins mediate firm adhesion between leukocytes and endothelium

Enhanced by cytokines including TNF and IL-1

Question 14

Describe transmigration

Answer 14

Leukocytes migrate through vessel wall primarily by squeeing between cells
Further movement is driven by chemokines
Leukocytes pierce basement membrane by secreting collagenases

Question 15

What is chemotaxis

Mechanism

Answer 15

Locomotion along a chemical gradient
Chemotactic agents bind to specific leukocyte receptors and trigger polymerization of actin at leading edge of cell and facilitate cell movement in direction of chemoattractant

Question 16

What are the chemotactic agents

Answer 16

Exogenous bacterial products
Endogenous mediators such as
C5a
Arachidonic acid LT b4
Chemokines il8

Question 17

What are other functions of leukocytes

Answer 17

Cytokines that can amplify or limit inflammatory reactions
Growth factors
Enzymes that can remodel connective tissues

Question 18

How does termination occur

Answer 18

Mediators have short half lives

Stop signals activated such as anti inflammatory cytokines such as TGF-b and IL-10