[ODGP] Inflammations and Tissue Repair

inflammatio

latin word; to set on fire or to burn.

INFLAMMATION

the most important protective mechanism of the body. It is a defense response that prepares injured tissue for restoration to its normal (pre-morbid) state.

Inflammation

designed to:

• Eliminate the initial cause of cell injury

• Remove damaged or necrotic cells and tissues

• Destroy invading microorganisms

• Initiate tissue repair

Without (BLANK):

• Infections would continue unchecked.

• Wounds would never heal.

• Injured tissues would remain damaged permanently.

Redness (Rubor)

Swelling (Tumor)

Heat (Color)

Pain (Dolor)

Loss of Function (Functio laesa)

Cardinal Signs of Inflammation

Redness (Rubor)

• Caused by dilatation of small blood vessels

• Increased blood flow (hyperemia) makes the affected tissue appear red.

Swelling (Tumor)

• Results from accumulation of inflammatory fluid (exudate) in the extravascular tissues.

• Also caused, to a lesser extent, by accumulation of inflammatory cells.

Heat (Color)

• Due to increased blood flow (hyperemia).

• Warm blood is delivered to the inflamed tissue through dilated blood vessels.

Pain (Dolor)

(BLANK) occurs because of:

• Stretching of tissues caused by edema

• Chemical mediators of inflammation, especially:

  • Bradykinin

  • Prostaglandins

Loss of Function (Functio Laesa)

occurs because:

• Pain inhibits movement (consciously or reflexively).

• Severe swelling physically limits movement of the affected area.

Purpose of the Inflammatory Process

To localize the damage of tissues to specific area, and to get rid of the cause of injury, in addition to repairing the damaged area.

Local Effects

Systemic Effects

EFFECTS OF INFLAMMATION

systemic effects of acute inflammation

fever, malaise, and leukocytosis

local effects

usually beneficial, for example the destruction of invading microorganisms, but at other times they appear to serve no obvious function, or may even be harmful e.g., swelling and loss of function

Leukocytes

Fever

Increase Acute Phase Reactant

Systemic Effect of Inflammation

Leukocytes

a common feature of inflammatory reactions, leukocytosis means an abnormally high number of circulating white blood cells, and a general rule is that increased neutrophils indicate a bacterial infection whereas increased lymphocytes are most likely to occur in viral infections. This is one reason why we often do a CBC when as an initial routine test.

Fever

a common systemic response to inflammation. Fever is most often associated with inflammation that has an infectious cause, although there are some non-infectious ones, fever is produced by cytokines and interleukins.

Increase Acute Phase Reactant

Both of them are due to increased level of IL1, IL6, and TNF … etc. and other proteins produced from the liver in association with inflammation.

Beneficial Effect of Inflammation

Dilution effect results in removal and washout of the bacterial toxins through the lymphatic system away from the inflammatory areas. And promoting the immunity by enhancing immune response after bringing microorganism to the adjacent lymph node, in addition inflammatory process provides antibodies, WBCs to the site of inflammation, also provides different proteins like fibrinogen, complement system, and nutrition to the sick cells.

Swelling

Loss of Organ Function

Harmful Effects of Inflammation

Swelling

a sign of inflammation which may result in obstruction of lumen as in acute laryngitis, or increase intracranial pressure in encephalitis and ischemic injury if obstruction of blood supply take place.

Loss of Organ Function

For example, hepatitis (inflammation of liver ) is associated with impaired liver function tests. (harmful effects of inflammation)

Acute
Chronic

Types of Inflammation

Acute Inflammation

• Begins rapidly (within minutes)

• Lasts only hours to a few days

Its major characteristics include:

• Exudation of plasma proteins and fluid (edema)

• Migration of leukocytes

• Predominance of neutrophils (polymorphonuclear leukocytes)

If the offending agent is removed successfully, inflammation subsides.

Failure to eliminate the cause may lead to chronic inflammation.

MAJOR COMPONENTS OF ACUTE INFLAMMATION

1. Alteration in vascular caliber

2. Structural changes in microvasculature

3. Leukocyte emigration

Infections

Tissue necrosis

Foreign bodies

Immune reactions

Stimulus of Acute Inflammation

Exudate

Transudate

Edema

Pus

REACTIONS OF BLOOD VESSELS IN ACUTE INFLAMMATION

Exudate

extravascular fluid that has a high protein concentration.

Transudate

a fluid with low protein content (most of which is albumin).

Oedema

denotes an excess of fluid in the interstitial tissue or serous cavities.

Pus

a purulent exudate, is an inflammatory exudate rich in leukocytes (mostly neutrophils), the debris of dead cells and, in many cases, microbes.

REACTIONS OF LEUKOCYTES IN INFLAMMATION

A major function of inflammation is to deliver leukocytes to injured tissue.

The most important phagocytic cells are:

• Neutrophils

• Macrophages

Their primary function is elimination of the offending agent.

OUTCOMES OF ACUTE INFLAMMATION

Possible outcomes include:

1. Complete resolution

2. Healing by connective tissue replacement (fibrosis)

3. Progression to chronic inflammation

4. Abscess formation

Chronic inflammation

inflammation of prolonged duration, lasting for weeks, months, years, or even decades. Unlike acute inflammation, which resolves within a few days, chronic inflammation persists because the injurious stimulus is not completely eliminated.

It is characterized by the triad of:

• Persistence of the injurious agent

• Continuous (relentless) tissue injury

• Simultaneous attempts at tissue repair, occurring in varying combinations

Persistent infections

Immune-mediated

Prolonged exposure

Causes of Chronic Inflammation