Acute inflammation

What is inflammation

What is the goal?

Defense mechanism to injurious stimuli

Aims to dilute,isolate,and eliminate stimulus

What is acute inflammation

occurs within hours to days

hallmarks of acute inflammation

short duration,exudates (especially fibrinous)Neutrophilic inflammation due to innate immunity

What are the three phases of acute inflammation

fluidic-leakage of fluid,protein,cells resulting in exudate to dilute stimulus and bring in inflammatory mediator

cellular-neutrophil exit vessels to isolate and eliminate offending agent

reparative-if solved in timely manner inflammation ceases and tissue will regenerate without permanent damage

What are the exogenous causes of acute inflammation

microbes, foreign body, mechanical/physical, chemical toxins, nutrition

What are the endogenous causes of acute inflammation

Degenerative or neoplastic cells, hypersensitivity reaction(I&IV)

what are the effector cells of Acute inflammation

Vascular endothelial cell(main in fluid response), Neutrophil, mast cell, basophil, eosinophil, macrophage/monocytes, NK cells

What is the role of vascular endothelial cells

allows for exudates to form and for paracellular passage of water/cells

Isolates the response and expresses adhesion

What is role of neutrophils in acute inflammation

kill microbes and remove foreign material via phagocytosis

Neutrophils in intracellular microbial destruction

Respiratory burst, form phagolysosome, facilitate myeloperoxidase to kill microbes

Neutrophil mechanism of extracellular microbial destruction

release neutrophil granule contents. myeloperoxidase—>pus formation

Which species do not have neutrophils

Birds and reptiles-heterophils. Exudate=caseous

Role of mast cells/basophils in acute inflammation

degranulation and release preformed histamine

Role of eosinophils in acute inflammation

recruited from blood sites of allergic reaction/parasite infection

Bridge chronic&acute

Role of macrophage/monocyte in acute inflammation

first responder-survelliance and phagocytic role

Role of NK cells in acute inflammation

Trigger cell death without previous antigen exposure

What is the fluidic phase of acute inflammation characterized by

Vasodilation- hyperemia + heat increased vascular permeability and exudation—>swelling(edema)

What is key difference in edema vs exudate? Increased interendothelial gaps in…

inflammation(edema)

What are some gross manifestation of fluidic phase of acute inflammation

effusion,fibrin,hyperemia

What is the purpose of the cellular phase of acute inflammation

Bring leukocytes to site of injury to eliminate the cause

What are the 4 steps of cellular phase of acute inflammation

Margination-vasodilation= slower flow=leukocyte settle

Rolling=selectins=initial attachment of leukocytes

Tight binding=inflammatory mediators express integrin=stable adhesion

Diapedesis& migration=leukocytes pass through the endothelium to reach the tissue

Functions of Histamine and Serotonin as cell derived mediators

Vasodilation, increase vascular permeability, eosinophil chemotaxis

Function of cytokines and interferons as cell derived mediators

Regulate immune response

Function of free radicals as cell derived mediators

Increase vascular permeability, activate endothelium, promote chemokine production, inactivate protease

Role of fibrin in acute inflammation

Attempts to wall off site of inflammation

Role of MAC

insert on bacterial wall create a pore and lead to lysis of cell

What are the four outcomes in reparative phase of acute inflammation

Resolution (ultimate goal), healing by fibrosis, abscess formation, progress to chronic inflammation

For resolution to occur in acute inflammation what must occur

Macrophages and lymphatics remove exudate, incite cause eliminated, stroma intact for regeneration, epithelial cells regenerate along basement membrane

5 cardinal sign of inflammation

Calor, rubor, tumor, dolor

Serous exudate characteristics

watery, clear fluid

Characterized by low protein, low cellularity

Causes: thermal injury, allergies, viral infection

Catarrhal exudate characteristics

Mucoid discharge-cloudy tan to light yellow

Abundant mucus and neutrophils

Causes: chronic allergies and viral infections

Fibrinous inflammatory exudate characteristics

Tan to yellow stringy often lining serosal surface

Caused by bacterial infections, viral infections that injure endothelium

Suppurative/purulent exudate characteristics

Tan to yellow, thick liquid to semi solid caseous material

Pus

Hemorrhagic exudate characteristics

Red foci

#erythrocytes caused by trauma, coagulopathies

Morphologic diagnosis-duration What is acute?

Necoris,fibrin,hemorrhagic,suppurative inflammation

For morphologic diagnosis duration-what is chronic?

Fibrosis, granulomatous inflammation, altered size

When we name a morphologic diagnosis what do we use?

Duration, severity, distribution, modifier, process