Stages of acute inflammation

Which inflammatory mediators are released during the alteration stage?

During the alteration stage, cellular and plasma (humoral) inflammatory mediators are released. Substances with vasodilatory action accumulate in the damage zone:

• Kinin — cause vasodilation.
• Prostaglandin E2 — promotes vasodilation.
• Adenosine — participates in vascular reactions.
• Complement components — activated by tissue mediators.

These biologically active substances provide chemical links between reactions in the focus, alter metabolism, and form local and systemic signs of the inflammatory process.

Which cells participate in the formation of "cellular cooperation" in the morphological phase of alteration?

The formation of primary cellular cooperation involves resident producer cells of mediators that enter the damage zone first. These include:

• Resident macrophages — occupy a central place, produce colony-stimulating factors, and participate in creating primary cooperation.
• Labrocytes (mast cells) — initiate the process by releasing biologically active substances.
• Eosinophils — participate in the initiation of inflammation.
• NK cells (natural killers) — are also present at the initial stage.

As a result of their interaction, autoregulatory mechanisms arise and a division of functions occurs among the cells.

What microcirculatory changes occur following the alteration stage?

Following the alteration stage, a vascular reaction is engaged, marking the launch of the exudation stage. The following changes develop in the microvasculature:

• Short-term spasm — rapidly replaced by vessel expansion.
• Arterial hyperemia — occurs due to the accumulation of vasodilatory mediators and increased parasympathetic influences.
• Vessel "paralysis" — loss of ability to respond to neural and humoral influences.
• Increased permeability — leads to increased blood plasma output from the vessel followed by the emigration of formed blood elements.

Which etiological factors can cause primary tissue alteration?

Primary tissue alteration is caused by the direct action of exogenous and endogenous phlogistic agents. The main etiological factors include:

• Biological factors — viruses, animal parasites, bacteria, as well as immune complexes and antibodies.
• Physical factors — radiation and electrical energy, high and low temperatures (burns, frostbite), mechanical trauma.
• Chemical factors — exogenous (poisons, toxins, chemicals) and endogenous (toxins formed in the body, e.g., in uremia).

The action of these factors leads to tissue structure damage and gross physical and chemical disturbances at the site of direct contact.

What are the possible outcomes of acute inflammation?

The possible outcomes of acute inflammation are:

• Recovery — the most frequent outcome.
• Death or disability — possible.
• Inflammation culminates in repair after the destruction and elimination of the damaging factor.