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Alteration in Inflammation

*Alteratio*

For medical students2 min readUpdated 2026-10-10

Alteration is the initial stage of the inflammatory process, characterized by tissue damage caused by a phlogistic (pathogenic) agent. It manifests as profound structural, metabolic, and functional changes within the focus of inflammation.

Core ProcessPrimary damage to tissue structures, metabolism, and functions.

Zones of InjuryPrimary (direct action of the agent) and secondary (peripheral).

MetabolismThe initial phase is characterized by a predominance of catabolic reactions.

MediatorsProduction of biologically active substances that regulate pain, hemostasis, and the immune response.

What Happens in the Focus of Inflammation

The term alteratio literally means "change." In the zone of inflammation, the damage affects five key aspects:

Structure: destruction of cellular and tissue elements.
Metabolism: reorganization of metabolic pathways.
Physicochemical properties: alteration of the microenvironment in the lesion.
Spectrum of biologically active substances: synthesis of mediators of inflammation, pain, and hemostasis.
Function: impairment of the normal activity of the damaged area.

Zones of Alteration

The injury process is heterogeneous and is divided into two zones:

Primary alteration: occurs instantaneously at the site of direct contact with the phlogistic agent. It is characterized by severe, often irreversible structural damage.
Secondary alteration: encompasses the periphery of the lesion. It develops within seconds or minutes under the influence of metabolic disorders, inflammatory mediators, and neural regulation disturbances. These changes are typically reversible.

Metabolic Dynamics

Metabolic shifts during alteration go through two stages:

Catabolic: predominates at the beginning of the process in both alteration zones.
Anabolic: dominates with the development of arterial hyperemia and proliferation. This is necessary to support local adaptive responses aimed at eliminating the agent and restoring the tissue.

Mnemonic

AAA: Alteration — Agent (cause) — Adaptation (goal). Primary is direct, Secondary is surrounding.

Frequently asked questions

What physicochemical changes occur in the focus of inflammation during alteration?

Pronounced shifts in physicochemical parameters occur within the inflammatory focus during alteration. The main ones include:

Acidosis — a shift of pH toward the acidic side due to the accumulation of excess acidic metabolites.
Hyperosmia — an increase in osmotic pressure resulting from the breakdown of large organic molecules and salt hydrolysis.
Hyperoncchia — an increase in oncotic pressure due to elevated protein concentration and increased hydrophilicity of colloids.
Alteration of electrical properties — a decrease in surface charge, disruption of electrogenesis, and altered cell membrane potentials.
Decrease in surface tension — affecting cell membranes.
Alteration of the colloidal state — occurs within the cell cytoplasm.

Specifically, which inflammatory mediators are synthesized during the alteration stage?

During the alteration stage, the spectrum of biologically active substances in the inflammatory focus changes, generating inflammatory mediators. Cellular inflammatory mediators include:

Fatty acid derivatives and lipids — prostaglandins, leukotrienes, lipid peroxides.
Biogenic amines — histamine, serotonin.
Neuropeptides and neurotransmitters — norepinephrine, epinephrine, acetylcholine.
Peptides and proteins — leukokinins, cytokines, enzymes.
Nucleotides and nucleosides — adenine nucleosides, cyclic nucleotides, free nucleotides.
Nitric oxide.

Additionally, cellular inflammatory mediators include heparin, granulocytic factors, monokines, and lymphokines. Pain mediators in inflammation include prostaglandins complexed with histamine, serotonin, bradykinin, and substance P.

What is the difference between primary and secondary alteration?

Primary alteration is caused by the direct action of the phlogistic factor, whereas secondary alteration results from the indirect, mediated influence of inflammatory mediators, metabolic shifts, and blood flow disturbances on surrounding tissues.

When does secondary alteration begin?

It develops a few seconds or minutes after exposure to the damaging factor.

Are structural changes mandatory in alteration?

Yes, structural alterations of tissues and cells are an obligatory component of alteration, occurring both through the direct action of the agent and through the combined influence of secondary factors.

Go deeper

The role of inflammatory mediators in the development of secondary alteration.
Mechanisms of axonal transport impairment in inflammation.
The relationship between physicochemical shifts and enzymatic activity in the lesion.
The impact of microcirculatory disorders on the depth of tissue damage.
Mechanisms of transition from catabolic to anabolic processes.