INFLAMMATION - PATHOLOGY 2021

 INFLAMMATION - PATHOLOGY

INFLAMMATION - PATHOLOGY

Inflammation is the reaction or a response to the injury that have the vascular response and migration and activation of leukocytes.

Inflammation is the body's defense mechanism can also be harmful.

CAUSES

• Physical agents: Radiation, heat, mechanical trauma.

• Chemical agents: Organic and inorganic poisons.

• Infectious agents: Bacteria, parasites and virus.

• Immunological agents: Hypersensitivity reactions.

TYPES

1. Acute inflammation
2. Chronic inflammation

ACUTE INFLAMMATION

It is a transient process, it occurs the next minute of injury and it lasts for hours to days and this is the body's early reaction to the injury.

• Then the injury is followed by repair: The process by which the tissue is restored to its original state.

CARDINAL SIGNS

• Redness-rubor: it occurs due to the dilation of small blood vessels in the injured area.
• Heat -calor: occurs due to the increased blood flow due to the vascular dilatation.
• Swelling-tumor: occurs due to the fluid accumulation in the extravascular space. 
• Pain-dolor: occurs due to the destruction of the tissue due to the inflammatory edema and formation of pus. and also some other like bradykinins, serotonin and prostaglandins also induce pain.
• Loss of fuction-functio laesa: due to the severe swelling it might also physically immobilize the tissue.

CELLULAR EVENTS

There are 4 steps:

1. Migration, Rolling, Pavementing and Adhesion of leukocytes
2. Transmigration of leukocytes
3. Chemotaxis
4. Phagocytosis

Basically blood cells especially erythrocytes in the venule will always be in the central zone that is also known to be axial zone, and plasma will be in the peripheral zone. 

 1.MIGRATION, ROLLING, PAVEMENTING AND ADHESION OF LEUKOCYTES

• Margination is the peripheral positioning of the leukocytes along with the endothelial cells.

• Eventually the leukocytes will fall slowly along the endothelium : Rolling.

• The endothelium is lined by leucocytes and this process is known as Pavementing.

• The binding of leukocytes with the endothelial cells is initiated by cell adhesion molecules like selectin, immunoglobulin, integrins.

2. TRANSMIGRATION OF LEUCKOCYTES

• Escaping of leucocytes from the venules and veins is transmigration.

The mechanism of leukocytes emigration is through widening of the inter-endothelial junctions after endothelial cells contractions, the basement membrane will be disrupted and again replaced back immediately.

3.CHEMOTAXIS

All the granulocytes , monocytes and few lymphocytes exhibits movement to the injured area which is inhibited by chemotactic agents.

4. PHAGOCTOSIS

Engulfment and killing of bacteria, invading microorganisms, damaged cells, tissue debris.

STEPS OF PHAGOCYTOSIS

1. Recognition and attachment
2. engulfment
3. killing an degradation. 

1. RECOGNITION AND ATTACHMENTS

• Phagocytosis is enhanced if the there is any harmful organisms to be phagocytosed.

• It is coated with a plasma protein and that is opsonins.

• Opsonins promote the adhesions between the particular material and phagocytes cell membrane.

• There are 3 opsonins. They are:

- FC fragment of immunoglobulin,

- Components of the complement system C3b and C3bi,

- Carbohydrate- binding protein- lectins.

• So this is how IgG binds to receptor for Fc fragment of the immunoglobulin(FcR).

• Here 3cb and 3bi are ligands for CR1 AND CR2.

2. ENGULFEMENT

Bacteria is engulfed by pseudopodia and is trapped within phagocytic vacuole.

phagocytic vacuole fuses with lysosomal granule.

3. KILLING AND DEGRADATION

Neutrophils and monocytes are oxygen dependent as well as oxygen independent mechanisms for killing bacteria.

CHRONIC INFLAMMATION

Prolonged duration 

It last for weeks to months.