👽👽👽 Acute And Chronic Inflammation

?- white cell assume a peripheral position along the endothelial surface

- leukocytes tumble slowly along the endothelium and adhere transiently

- the endothelium is lined firmly by white cells ( resembling pebbles over which a stream runs without disturbing them )

in most forms of acute inflammation, neutrophils predominatein the inflammatory infiltrate during the first 6-24 hours, then are replaced by monocytes in 24-28 hours

- in most forms of acute inflammation, neutrophils predominatein the inflammatory infiltrate during the first 6-24 hours, then are replaced by monocytes in 24-28 hours

Why ? first?

→ they are more numerous in the blood

→ they respond more rapidly to chemokines

→ they attach more firmly to the adhesion molecules

certain infxns have different pattern of cellular exudation

- neutrophils predominate over 2-4 days

- lymphocytes first

some hypersensitivity reaction - ? are the main cell type

- after extravasation, leukocytes emigrate in tissues toward thesite of injury by a process called

defined as locomotion oriented along a chemical gradient

- the chemoattractants could be exogenous or endogenous

• Exogenous chemoattractants

• Endogenous chemoattractants

- bacterial products

 most common

1. components of the complement system, particularly C5a

2. products of the lipooxygenase pathway, mainly leukotriene B4 (LTB4)

3. cytokines

- the efficiency of phagocytosis is greatly enhanced when microbesare opsonized by specific proteins (opsonins) for w/c thephagocytes express high-affinity receptors

the major opsonins are :

 IgG antibodies

 the C3b breakdown products

 plasma lectins

the 2 most important are:

 Mast cells

 Tissue macrophages

- complement proteins- kinins

 are normally sequestered in intracellular granulesthat need to be secreted (e.g. histamine in mast cells)

or are synthesized de novo (e.g. prostaglandins, cytokines) in response to a stimulus

- is marked by the outpouring of a thin fluid

- is derived from either the plasma or the secretions of mesothelial cells lining the peritoneal, pleural, and pericardial cavities (called effusion)

- the skin blister resulting from a burn or viral infection represents a large accumulation of serous fluid

- w/ more severe injuries & the resulting greater vascular permeability  larger molecules such as fibrinogen pass the vascular barrier

- & fibrin is formed & deposited in the extracellular space

-is charac. of inflammation in the lining of body cavities, such as the meninges, pericardium & pleura

- charac. by the production of large amounts of pus or purulent exudate consisting ofcertain bacteria (e.g. staphylococci) produce this localized suppuration

- are localized collections of purulent inflammatory tissue caused by suppuration buried in a tissue / organ

- is a local defect, or excavation, of the surface of an organ or tissue that is produced by sloughing (shedding) of inflammatory necrotic tissue

- occur only when tissue necrosis exist on or near a surface

- commonly encountered in:

 mucosa of the mouth, GIT & genitourinary tract

 subcutaneous tissue

- is an inflammation of prolonged duration (weeks or months) in w/c

 active inflammation

 tissue destruction

 attempts at repair

are proceeding simultaneosly

- arise in the following settings (causes):

• Persistent infections

• Prolonged exposure to potentially toxic agents (exogenous or endogenous)

• Autoimmunity

- Morphologic features are:

 infiltration with mononuclear cells

- Morphologic features are:

 tissue destruction, induced by persistent offending agentor by the inflammatory cells

- Morphologic features are:

 attempts at healing by connective tissue replacement of damaged tissue, accomplished by proliferation of small bld vessels (angiogenesis) &, in particular, fibrosis

- the dominant cellular player in chronic inflammation

- derived from blood monocyte

- secrete a variety of biologically active products