Inflammation

From the Latin inflammare , to set on fire From the Latin inflammare , to set on fire. Definition: The term for the pathological process that occurs at the site of tissue damage, a process that enables the body's defensive and regenerative resources to be channeled into tissues which have suffered damage or are contaminated with abnormal material (such as invading micro-organisms).

It also tends to limit the damaging effects of any contamination, to cleanse and remove  foreign particles  and damaged  tissue debris , and allows healing  processes to restore tissues  towards normality . Fundamentally important  for survival .

The classic components of the inflammatory response are: heat, redness, swelling and pain. a localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection.

immune cells, blood vessels, and molecular mediators. Inflammation is a protective response that involves: immune cells, blood vessels, and molecular mediators. Inflammation can be classified as either acute or chronic

Acute inflammation: Is the initial response of the body to harmful stimuli and is achieved by the increased movement of plasma and leukocytes (especially granulocytes) from the blood into the injured tissues. A series of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue.

Inflammation is not a synonym for infection Inflammation is not a synonym for infection. Infection describes the interaction between the action of microbial invasion and the reaction of the body's inflammatory defensive response .

the two components are considered together when discussing an infection, and the word is used to imply a microbial invasive cause for the observed inflammatory reaction. Inflammation on the other hand describes purely the body's immunovascular response, whatever the cause may be.

But because of how often the two are  correlated, words which refers to inflammation are sometimes informally described as referring to infection. For example, the word urethritis strictly means only "urethral inflammation", but clinical health care providers usually discuss urethritis as a urethral infection because urethral microbial invasion is the most common cause of urethritis.

It is useful to differentiate inflammation and infection as there are many pathological situations where inflammation is not driven by microbial invasion - for example, atherosclerosis, type III hypersensitivity, trauma, ischaemia.

Causes of acute inflammation: 1 Causes of acute inflammation: 1. Physical: Burns, Frostbite, Physical injury, blunt or penetrating, Foreign bodies, including dirt and debris, Trauma, Ionizing radiation 2. Biological:Infection by pathogens,

3. Immune reactions due to hypersensitivity,Stress 4. Chemical: Chemical irritants, Toxins, Alcohol. 5. Psychological:Excitement

Clinical signs: Acute inflammation is a short-term process, usually appearing within a few minutes or hours and begins to cease upon the removal of the injurious stimulus. It is characterized by five clinical signs:

An acronym that may be used to remember the key symptoms is "PRISH", for pain, redness, immobility (loss of function), swelling and heat. 1. Redness and heat are due to increased blood flow at body core temperature to the inflamed site. 2. swelling is caused by accumulation of fluid; 

3. pain is due to the release of chemicals such as bradykinin and histamine that stimulate nerve endings. 4. Loss of function has multiple causes. Acute inflammation of the lung (pneumonia) does not cause pain unless the inflammation involves the parietal pleura, which does have pain-sensitive nerve endings.

Process of acute inflammation The process of acute inflammation is initiated by resident immune cells already present in the involved tissue, (cell-derived mediators) mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells and mast cells.

These cells possess surface receptors known as pattern recognition receptors (PRRs), which recognize (i.e., bind) two subclasses of molecules:  1. pathogen-associated molecular patterns(PAMPs) are compounds that are associated with various pathogens, which are distinguishable from host molecules.

2. damage-associated molecular patterns (DAMPs) are compounds that are associated with host-related injury and cell damage. At the onset of an infection, burn, or other injuries, these cells undergo activation (one of the PRRs recognize a PAMP or DAMP) and release inflammatory mediators responsible for the clinical signs of inflammation:

In addition to cell-derived mediators, several acellular biochemical cascade systems consisting of preformed plasma proteins act in parallel to initiate and propagate the inflammatory response.

These include the complement system activated by bacteria and the coagulation  and fibrinolysis systems activated by necrosis, e.g. a burn or a trauma.

The acute inflammatory response requires constant stimulation to be sustained. Inflammatory mediators are short-lived and are quickly degraded in the tissue. Hence, acute inflammation begins to cease once the stimulus has been removed.