Inflammation acute inflammation

Mohamed Hassany Ali 1

Inflammation- Acute Inflammation

Prepared by/ Mohamed Hassany AliB.Sc.

Inflammation:

• When living tissue is damaged, a series of local processes are initiated in order to contain the offensive agent, to neutralize its effect, to limit spread and hopefully to eradicate.

• So, we can define it as :The mechanism by which the body deals with an

injury. Tissue injury stimulates inflammation.Inflammation known by Suffix “itis”.

Signs and Symptoms:

• Rubor: redness• Calor: heat• Dolor: pain• Tumor: Swelling• Functio Laesae : loss of function

Types of Inflammation:

• Acute inflammation• Chronic inflammation

Acute inflammation:

• short duration, lasting from a few minutes to a few days and the cellular exudate is rich in neutrophil polymorphonuclear leucocytes with some macrophages arriving after the initial insult.

Process of Acute inf.

• Microvasculature (vascular change)• Cellular mediators (cellular change)

Microvasculature

• Vasodialation: increase the blood flow rate causing redness and heat.

• Permiability: of vessels causing swelling by outpouring of extracellular excudate. And the affected part lose the ability of proper function.

• Chemical mediator: and the stretching of tissue by exudate cause pain.

• exudate is the fluid within the extravascular spaces which is rich in protein and hence has a specific gravity of greater than 1.020.

Cellular mediators:

• Leukocytes ingest offending agents, kill bacteria and other microbes, And get rid of necrotic tissue and foreign substances.

This animation demonstrates the actions of neutrophils in the acute inflammatory process.

As in the preceding diagram, here PMN's that are marginated along the dilated venule wall (arrow) are squeezing through the basement membrane (the process of diapedesis) and spilling out into extravascular space.

Acute inflammatory cells:

• In most forms of acute inflammation, neutrophils predominate in the inflammatory infiltrate during the first 6 to 24 hours, then are replaced by monocytes in 24 to 48 hours.

• In viral infections: lymphocytes• In hypersensitivity reactions: eosinophils

Neutrophils:

• Most abundant granulocyte and resembles (40-75%) of white blood cells in all mammals.

• Containing nucleus of 2-5 lobes.• Named due to H&E staining as it stains by neutral pink.• Polymorphonuclear cell.• Bacterial killing and phagocytosis.• Bone marrow origin.

Eosinophils:

• Common in Allergic and parasites condition.• Named due to H&E staining as it stains by bright red

(acid-loving).• Resemble 1-6 % in normal persons.• Contain large granules.• Have two lobes.

Basophils:

• Resembles less than 1% of all leukocytes.• Have large granules contain Histamine that cause

vasodialation.• Named due to H&E staining as it stains by dark blue

(Alkali-loving).• Bone marrow origin

Lymphocyte:

• Agranulocyte with clear cytoplasm.• Have three types: (T cells, B cells and NK cells).• Resembles 25-35%• T cells: recognition, killing and regulation of immune

system.• Lymphoid tissue and thymus origin.• B cells: give rise to plasma cells.• Lymphoid tissue and bone marrow origin

Monocyte:

• Resembles 6-9% of all white blood cells.• Agranulocyte large cell.• Unilobar nucleus.• Migrates to tissues to become macrophage which capable

of phagocytosis.• Bone marrow origin

Plasma cell:

• Secretes large volumes of antibodies.• Lymphoid tissue and bone marrow origin.

Pus cell:

a necrotic polymorphonuclear leucocyte, a major component of pus. Also called pus corpuscle.

Acute inflammation, cytology:

Types of Acute inflammation:

• Suppurative Acute inflammation “pus formation”.• Non suppurative Acute inflammation “no pus formation”.

Types of suppurative inf.

• Localized• Diffuse

Acute suppurative Inflammation:

• Def. : severe acute inf. Characterized by Pus formation.

• Causes: Pyogenic microorganisms like:» Staphylococcus aureus.» Streptococcus haemolyticus.» Pneumococcus.» Bacillus coli.

• Composition of Pus:– Living and dead bacteria and their toxins.– Liquefied necrotic tissue.– Cellular exudate: leucocytes, pus cells, macrophages and RBCs.– Inflammatory tissue exudate.

Abscess:

• Acute localized suppurative inflammation.• Site: any tissue.• Cause: staphylococcus aureus

Abscess

Abscess, Brain

• Abscess is an exudative purulent localized inflammation. • In the white matter, a recent abscess consisting in pus :

neutrophils (normal or in lisis), fibrin, necrotic debris, germs. Vessels present congestion and important perivascular edema.

Abscess, Brain

Acute pyelonephritis

• is an acute suppurative inflammation of the kidney caused by bacterial infections (Escherichia coli in 70 - 80 % of cases, Proteus mirabilis, Klebsiella pneumoniae, Enterococus fecalis, Staphylococcus).

Microscopic:

• The renal presents abscesses (suppurative necrosis), consisting of purulent exudate (pus) :

• neutrophils, fibrin, cell debris and central germ colonies (hematoxylinophils).

• Tubules are damaged by exudate and may contain neutrophil casts, which can be found in urine. In the early stages, glomeruli and vessels are spared.

Acute Pyelonephritis

Acute suppurative:

• The general morphology of a suppurative inflammation typically involves several layers:

A necrotic zone is a central focus of proteolytic liquefaction with lipid- rich detritus producing yellowish pus.A pus zone contains large numbers of neutrophils and surrounds the

central necrotic area.A hyperemic zone with perifocal edema of serous exudate is also

present.

Acute suppurative appendicitis:

Acute suppurative tonsillitis

Purulent meningitis

• Purulent leptomeningitis (suppurative leptomeningitis) is a diffuse purulent inflammation.

• The leptomeninges (arachnoida and piamater) contain purulent exudate (pus): leukocytes (neutrophils), fibrin, germs, proteins, necrotic debris. Blood vessels in the subarachnoidian space and those intracerebral are congested and neutrophil margination is present.

Purulent meningitis

Acute non-suppurative:

1. Catarrhal Inflammation: mucous membrane.2. Membranous Inflammation.3. Sero-fibrinous Inflammation.4. Fibrinous Inflammation.5. Serous Inflammation.6. Haemorrahgic Inflammation.7. Necrotizing Inflammation.8. Allergic Inflammation.

Catarrhal Inflammation:

• Def. Acute non-suppurative secreting exudate rich in mucin.

• Site: GIT, Nose.• Ex: Catarrhal rhinitis• Causes: Common cold virus.

Catarrhal rhinitis:

Hemorrhagic inflammation:

• Definition: Acute inflammation involving microvascular injury with massive microvascular bleeding, producing an exudate with a high erythrocyte content ( A).

• Biologic purpose: Exudative inflammation despite severe vascular injury.

• Morphology: The inflamed area is usually necrotic and filled with blood.

Hemorrhagic Inflammation

Fibrinous inflammation:• Definition: Acute inflammation with exudation of fibrinogen-containing

serum that polymerizes to fibrin outside the blood vessels ( A, B). Here the exudate takes the form of serum- containing fibrinogen.

• Biologic purpose: Immediate temporary barrier against additional effects of inflammation.

• Etiologic factors include:Infectious toxic tissue injury;Tissue injury from physical trauma;Chemical and toxic tissue injury;Excretion of toxic metabolites (uremic toxins);Ischemic tissue injury.

Fibrinous inflammation

Fibrinous pericarditis

• Fibrinous pericarditis is an exudative inflammation. The visceral pericardium (epicardium) is infiltrated by the fibrinous exudate.

• This consists in fibrin strands and leukocytes. Fibrin describes an eosinophilic (pink) network, amorphous.

• Leukocytes (mainly, neutrophils) are found within the fibrin.

• Vascular congestion is also present.

Fibrinous Pericarditis

Psedomembranous inf:

• Acute non-suppurative inflammation charactrized by exudate rich in membrane-like material.

• Site: mucous membrane, GIT, upper respiratory tract.• Cause: Diphtheria bacilli

Pseudomembranous Diphtheria

Pseudomembranous colitis

Necrotizing inflammation:

• Definition: Acute inflammation in which tissue necrosis predominates.

• Several types are differentiated according to demarcation of the inflammation or infestation with putrefactive bacteria. These include:

Ulcerous necrotizing type;Diffuse necrotizing type;Nonreactive necrotizing type;Gangrenous type.

Necrotizing inflammation

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