Transudate Vs Exudate
TRANSUDATE
EXUDATE
is protein-poor ultra filtrate of plasma increased hydrostatic pressure.
protein-rich fluid which has leaked out of inflamed vessels. Occurs due to inflammation It contains neutrophils and necrotic debris (pus). Specific gravity of > 1.020
Specific gravity 1.010
Chemotaxis
CHEMOTAXIS
The movement of leukocytes towards the site of injury along a chemical gradient of chemoattractants
Exogenous and endogenous stimuli can act as chemoattractants
Exogenous:
bacterial product
Endogenous: anaphylatoxins (C5a), leukotrienes (LTB4), Cytokines (e.g IL-8)
Chemotactic agents bind to the surface leucocytes Calcium mobilization and assembly of actin filaments Leukocytes extend pseudopods and migrate towards the stimuli
Phagocytosis or Killing
Derived from the Greek words “Eat , cell”. - Cellular process of eating
Phagocytosis is carried out by white blood cells: Neutrophils, macrophages, and occasionally eosinophils.
Phagocytosis
Responsible for elimination of injurious agents Involves 3 distinct steps : Recognition & attachment of the particle to the leucocyte Its engulfment Killing & degradation of the ingested material
1.
2. 3.
1. Recognition & attachment
Recognition and Binding
How do the leucocytes recognise the injurious agent ?
by a process known as OPSONISATION
Complement components (C3b)
IgG
bind to microbial surface and this coating is required for recognition of the microbe or foreign particle
Engulfment
Extension of plasma membrane to form psuedopods around the particle and engulfment to form a sac called phagosome Inside the cell, phagosome fuses with lysosome to form phagolysosome
Killing
Oxygen dependent Oxygen independent
Oxygen dependent killing
H2O2 - MPO – Halide
system 2 the most efficient O is
NADPH OXIDASE
MPO
bactericidal system in O2
CL H2O2 OHHOCL
neutrophils.
H2O2 –MPO –Halide system
Reactive oxygen species
Hydrogen peroxide (H2O2) MPO (azurophilic granules) converts hydrogen peroxide to HOCl- (in presence of Cl-) Killing of microbes by halogenation(HOCL), or lipid/protein peroxidation
Oxygen independent killing
Other antimicrobials in leukocyte granules Bactericidal permeability increasing protein (BPI)
Lysozyme Lactoferrin: iron binding protein present in the neutrophil Defensins (punch holes in membranes)
Defects in leucocyte function
Genetic
Acquired
Leucocyte Adhesion Deficiency - (LAD)
LAD 1 : Defective integrins Lead to recurrent bacterial infections,
LAD 2 : Defective selectins Lead to recurrent infections – Milder form
Defect in phagolysosome function
Chediak- Higashi Syndrome
Defective degranulation Delayed microbial killing Giant neutrophil granules
Defective microbicidal killing
Myeloperoxidase deficiency : Absent MPO-H2O2 system Chronic Granulomatous Disease: Inherited defect in genes coding NADPH oxidase defective formation of reactive O2 species.
Outcome of acute inflammation
RESOLUTION
INJURY
ACUTE INFLAMMATION
CHRONIC INFLAMMATION
FIBROSIS / SCAR
Outcome of acute inflammation
Complete resolution
due to elimination of the offending agent and regeneration of injured tissue with normal function
Healing by connective tissue replacement (fibrosis/scar formation)
Occurs after large tissue destruction, tissue without regeneration capabilities
Progression to chronic inflammation
Resolution
Staphylococcal infection
Patterns of acute inflammation
Serous inflammation
Purulent inflammation
Fibrinous inflammation
ulcers
Patterns of acute inflammation
SEROUS Watery, protein-poor effusion (e.g., blister) FIBRINOUS
Fibrin accumulation Presence of pus (pyogenic staphylococcu spp.) Necrotic and eroded epithelial surface
SUPPURATIVE/PURULENT
ULCERATION