reaction
a bodily process occurring due to the effect of some antecedent stimulus or agent
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a bodily reaction, assess its course and significance, and identify justified observations or actions without treating a suspected trigger as a proven cause.
A reaction in this sense is an organism-level physiological or pathological process elicited by a prior stimulus or exogenous agent and mediated by neural, immune, endocrine, or local tissue mechanisms, ranging from a normal reflex or homeostatic response to hypersensitivity and other adverse effects.
It can be Recognise and delimit a candidate reaction episode from bodily observations and antecedent context.; Associate candidate triggers with the episode while retaining competing explanations.; Track manifestations against an appropriate baseline and identify changes in course.; Compare repeated episodes without assuming identical triggers or mechanisms.; Identify missing observations and request review when recorded criteria warrant it.; Record authorised responses and subsequent changes without treating improvement as proof of causation..
Distinguishing features
Identify a bodily process, rather than relying on the word 'reaction' to denote an opinion, decision or social response.
Identify an antecedent stimulus or agent, or explicitly record that one is hypothesised but unidentified; a bodily change alone does not establish the causal relationship.
Distinguish the reaction episode from its manifestations: a sign or sensation can indicate a reaction without defining the entire process.
Distinguish the episode from a persistent condition that may predispose to, result from or resemble it.
Record whether intentional behaviour accompanies the process without assuming that intention either establishes or excludes a bodily reaction.
Scope
+ The bodily process constituting the reaction and the organism or body region in which it occurs
+ The antecedent stimulus or agent and evidence connecting it to the reaction
+ Observable manifestations and reported bodily experiences
+ Onset, progression, resolution and recurrence of the reaction
+ Context affecting interpretation and constraints on observation or intervention
- The identity and lifecycle of the stimulus or causal agent independently of this reaction
- Diseases, injuries and persistent conditions beyond their relationship to the episode
- Deliberate actions and decisions considered independently of bodily reactions
- Emotional appraisals, opinions and social responses without a bodily process in scope
- Chemical reactions considered independently of a bodily process
- Treatment protocols and clinical decisions owned by appropriate care models
Characteristics
- Reacting organism and bodily locus
- Organism reference; body region or system; localisation uncertain Establishes whose bodily process is being described and where its manifestations occur.
- Antecedent stimulus or agent
- Stimulus, exposure or agent reference; unidentified; multiple candidates Connects the episode to the antecedent required by the registry definition.
- Causal attribution status
- Unassessed; suspected; supported; disputed; unresolved Separates observed sequence from the strength of the explanation connecting trigger and process.
- Manifestation
- Described bodily change, with observed, instrument-detected or subject-reported basis Makes the reaction recognisable without requiring an established mechanism.
- Onset latency
- Elapsed time from a specified antecedent event, in seconds, minutes, hours or days; interval estimate; unknown Records temporal fit while preserving uncertainty about exposure and onset.
- Episode duration
- Elapsed time with explicit start and end criteria; ongoing; unknown Supports comparison and distinguishes completed observations from an episode still unfolding.
- Manifestation magnitude
- Manifestation-specific physical unit or named rating scale, including baseline and uncertainty Avoids treating unlike bodily changes as if they shared a universal intensity measure.
- Course
- Onset; increasing; stable; decreasing; fluctuating; resolved; unknown Supports decisions about further observation and review.
- Functional consequence
- Affected bodily function or activity, with described change and evidence Distinguishes detectable change from consequences relevant to the organism.
Analytical facets
- substance
- activity
- origin
- conceptual
- agency
- inert
- mobility
- not-applicable
- scale
- not-applicable
- affordances
- observable
Also called
+95
Where this came from
oewn:2024 · CC BY 4.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Bodily episode Establishes the bodily process being treated as a reaction and the limits of its episode.
A reaction must be distinguishable from a label, an isolated manifestation and an ongoing condition.
Process identification
Identifies the reacting organism and the bodily change under consideration.
Candidate bodily process
Records what bodily process is proposed as the reaction and the observations supporting its recognition.
- What bodily process is occurring, in which organism and at which known or suspected bodily locus? definition
- What observation or report supports recognising this process, and who or what supplied it? provenance
Episode boundaries
Separates one reaction episode from background processes and neighbouring episodes.
Episode membership
Makes explicit why particular manifestations belong to one episode rather than separate or persistent processes.
- What criteria mark the start and end of this episode? boundary
- What supports grouping these manifestations into one reaction rather than several reactions or an ongoing condition? boundary
Antecedent attribution Connects the bodily process to candidate antecedent stimuli or agents without overstating causation.
Dependence on an antecedent is central to this registry entry, but temporal sequence alone leaves the explanation unsettled.
Stimulus contact
Describes the antecedent event and how it could have affected the organism.
Antecedent event
Records candidate stimuli or agents, timing and relevant contact or exposure circumstances.
- Which stimulus or agent preceded the bodily process, and how did it reach or affect the organism? definition
- What is known about its timing, duration and magnitude, and which details were measured rather than inferred? measurement
Causal support
Assesses the basis and limits of assigning the reaction to an antecedent.
Trigger hypothesis
Keeps evidence for the proposed connection separate from alternative explanations and unknown mechanisms.
- What evidence beyond temporal order supports attributing this bodily process to the proposed antecedent? provenance
- Which alternative triggers, coincident processes or missing observations leave that attribution uncertain? boundary
Bodily expression Describes how the reaction presents and what changes it produces in bodily function.
Recognition and assessment require concrete manifestations, not an unexplained reaction label or universal severity score.
Manifestation evidence
Separates measured changes, externally observed signs and reported sensations.
Manifestation profile
Records the location, character and magnitude of each manifestation with its observation basis.
- Which bodily changes were observed, instrument-detected or reported, and where did each occur? definition
- How was each change measured or described, against what baseline and with what uncertainty? measurement
Functional effect
Identifies consequences of the reaction for bodily function and activity.
Consequence assessment
Distinguishes manifestation magnitude from experienced burden and functional impact.
- Which bodily functions or activities changed during the episode, and how was the change assessed? measurement
- What evidence links those consequences to the reaction rather than a pre-existing or concurrent condition? provenance
Reaction course Tracks the reaction through time and relates repeated episodes to their circumstances.
An agent must distinguish an emerging reaction, a resolving episode and an apparent recurrence before interpreting its state.
Within-episode dynamics
Tracks latency, progression, fluctuation and observed resolution.
Temporal trajectory
Records changes over time while distinguishing observed endpoints from gaps in observation.
- When did manifestations begin relative to the antecedent, and how have their magnitude and distribution changed? measurement
- Does the latest observation support resolution, persistence or an unknown state because observation ended? boundary
Recurrence context
Compares episodes with attention to changes in antecedents and organism state.
Cross-episode comparison
Records similarities and differences without presuming a shared mechanism.
- Have comparable manifestations followed comparable antecedents before, and what records support the comparison? provenance
- Which differences in exposure, baseline bodily state or concurrent conditions limit comparison between episodes? boundary
Response and reassessment Connects the reaction's observed state to justified monitoring, review and authorised responses.
A useful model must support decisions while avoiding unsupported treatment choices or deliberate trigger testing.
Observation and review
Identifies what needs to be observed next and when an appropriate reviewer is needed.
Next assessment
Records observation priorities and externally established criteria for escalation or specialist assessment.
- Which additional observation would clarify whether the reaction is progressing, resolving or affecting function? action
- Which applicable review criteria have been supplied by an appropriate authority, and do current observations meet them? action
Response outcome
Records actions affecting the episode and the evidence needed to assess their consequences.
Action-linked reassessment
Relates authorised actions to subsequent observations without assuming that sequence demonstrates effectiveness.
- What response is authorised within the agent's role, and what instruction or decision establishes that authority? action
- What changed after the response, and what concurrent changes or natural progression limit attributing that outcome to the action? measurement
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Neural reflex (stretch, withdrawal, and autonomic reflexes)
- Immediate (Type I) hypersensitivity / IgE-mediated allergic reaction
- Delayed-type (Type IV) hypersensitivity
- Adverse drug reaction (Type A/augmented versus Type B/idiosyncratic)
- Anaphylaxis and anaphylactoid/non-IgE immediate systemic reaction
- Transfusion reaction (haemolytic, febrile non-haemolytic, TRALI, allergic)
- Local and systemic injection or vaccine reactogenicity
- Acute-phase inflammatory reaction to injury, infection, or toxin
- Which of these kinds and varieties hold for the sense of reaction this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- WordNet 3.1 sense key - reaction%1:22:00:: - Noun process sense matching the gloss 'a bodily process occurring due to the effect of some antecedent stimulus or agent'.
- Gene Ontology - GO:0050896 - response to stimulus; parent biological process, not a clinical diagnosis.
- SNOMED CT - 281647001 - Adverse reaction (disorder); many more specific descendants exist (drug, vaccine, transfusion, allergic).
- MeSH - D064420 - Drug-Related Side Effects and Adverse Reactions.
- ICD-10 - T78 - Adverse effects, not elsewhere classified; related codes include T80 (infusion/transfusion) and T88.7 (unspecified adverse effect of drug).
- Wikidata - Q45959 - adverse drug reaction; the general physiological 'reaction' sense is not a single stable Wikidata item.
- MedDRA - SOC/HLGT hierarchy (e.g. Immune system disorders; HLGT Allergic conditions) - Individual reactions are coded as Preferred Terms, not as one code for the kind 'reaction'.
- Which of these identifiers and schemes hold for the sense of reaction this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ICH E2A (International Council for Harmonisation): definitions of adverse event versus adverse reaction and rules for expedited safety reporting.
- ICH E2B(R3) (ICH): electronic transmission of individual case safety reports.
- MedDRA (ICH / MedDRA MSSO): mandatory terminology for coding reactions in many regulatory submissions.
- EMA Good Pharmacovigilance Practices, Module VI (European Medicines Agency): management and reporting of adverse reactions in the EU.
- 21 CFR 312.32 and 21 CFR 314.80 (US FDA): IND safety reporting and postmarketing reporting of adverse drug experiences.
- WHO Programme for International Drug Monitoring / CIOMS reporting form (World Health Organization and CIOMS): international spontaneous reporting of suspected reactions.
- ISO 14155 (ISO): clinical investigation of medical devices, including adverse event and adverse device-effect definitions.
- NIAID/FAAN (and later WAO/EAACI) anaphylaxis criteria: clinical diagnostic standard for a life-threatening systemic reaction, not a statute.
- Which of these standards and regulation hold for the sense of reaction this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Documenting a patient's reaction after a new drug, radiocontrast agent, anaesthetic, or biologic infusion.
- Allergy-clinic skin-prick, intradermal, and patch testing to identify the eliciting agent.
- Emergency treatment of anaphylaxis with intramuscular adrenaline and observation for biphasic recurrence.
- Spontaneous reports of suspected ADRs to national centres (FAERS, Yellow Card, EudraVigilance) and onward to VigiBase.
- Trial and programme recording of vaccine reactogenicity (local swelling, fever, systemic symptoms).
- Pre-transfusion matching and bedside monitoring for haemolytic and non-haemolytic transfusion reactions.
- Measuring simple and choice reaction time in neurology, occupational toxicology, and human-factors assessment.
- Protocolised monitoring of cytokine-release and infusion reactions during monoclonal-antibody and CAR-T therapy.
- Which of these real-world use hold for the sense of reaction this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Simple visual reaction time (healthy adult) - 180-250 - ms
- Acute serum tryptase rise supporting anaphylaxis - peak ≥ (1.2 × baseline + 2); many labs treat baseline 95th percentile as about 11 - μg/L
- Skin-prick test mean wheal diameter versus negative control - positive if ≥3 - mm
- CTCAE reaction/event severity - 1-5 (5 = death) - grade
- Naranjo adverse-drug-reaction probability score - 0-13 (definite typically ≥9) - score
- Systolic blood-pressure change in anaphylaxis definitions - fall ≥30% from baseline, or absolute hypotension - mmHg or %
- Which of these typical measurements hold for the sense of reaction this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Anaphylactic shock, airway obstruction, and death.
- Severe cutaneous adverse reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS).
- Haemolytic transfusion reaction from ABO incompatibility.
- Cytokine-release syndrome and delayed neurotoxicity after cellular or T-cell-engaging therapy.
- Missed or delayed identification of the causal agent, allowing re-exposure.
- False 'allergy' labels (especially penicillin) that block first-line therapy and drive broader-spectrum antibiotics.
- Under-reporting and incomplete case details in spontaneous pharmacovigilance.
- Paradoxical, withdrawal, and cross-reactive reactions that do not match the expected pharmacology.
- Which of these failure modes and hazards hold for the sense of reaction this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Specialists in Europe (EAACI and related bodies) more strictly reserve 'allergy' for immune-mediated disease; US clinical and lay use often folds in non-immune intolerance.
- National reporting channels differ: FDA FAERS (United States), MHRA Yellow Card (United Kingdom), EudraVigilance (EU), PMDA (Japan), all feeding WHO VigiBase in Uppsala.
- East Asian dermatology still leans on Japanese morphological classifications of drug eruption alongside Gell-Coombs types.
- Adrenaline autoinjector products, licensed doses, school-carry rules, and public-access laws for anaphylaxis vary widely by country.
- Traditional-medicine products are in routine pharmacovigilance in China and parts of South and East Asia but are often coded poorly or omitted in Western ADR datasets.
- Which of these regional variation hold for the sense of reaction this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- chemical reaction - A molecular transformation that does not require a living body; test whether the system is an organism responding to a stimulus rather than reactants forming products.
- adverse event - Any untoward medical occurrence temporally associated with a product, causal or not; ICH/CIOMS causality (certain, probable, possible, unlikely, unrelated) is what promotes an event to a suspected reaction.
- side effect - Usually an expected, often dose-related labelled effect (Type A); a 'reaction' in clinical safety language more often implies a suspected causal, sometimes unexpected, response.
- intolerance - Non-immune mechanism (metabolic, pharmacologic, or irritant), as in lactose intolerance; separate by absence of specific immune markers (sIgE, basophil activation, T-cell assays) and by reproducible dose-related physiology.
- reflex - A stereotyped, neurally mediated subclass of reaction; separate by short latency, a defined spinal or brainstem pathway, and independence from immune or drug-metabolic mediators.
- adaptation / acclimatization - A slower, often compensatory adjustment to a sustained condition; separate by time course (days to weeks versus seconds to hours) and by reduced rather than expressed effect of the stimulus.
- symptom - A reported experience, not the bodily process itself; a reaction can be observed or measured (wheal, tryptase, reflex latency) without a verbal report.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of reaction this model covers, and on what evidence? provenance
Sources
- WordNet 3.1, synset reaction (noun: bodily process) - The exact gloss used as the research sense, and the grouping of physiological response with examples such as a bad reaction to a medicine.
- ICH Harmonised Guideline E2A: Clinical Safety Data Management - Definitions and Standards for Expedited Reporting - Regulatory distinction between adverse event and adverse (drug) reaction, causality, and expedited reporting of serious unexpected reactions.
- Adverse drug reactions: definitions, diagnosis, and management - Clinical definition of ADR, Type A versus Type B classification, diagnosis, and management as used in pharmacovigilance and therapeutics. The Lancet, 2000, Edwards and Aronson.
- Clinical Aspects of Immunology - The Gell and Coombs Types I-IV classification that still structures how clinicians name hypersensitivity reactions. Blackwell Scientific Publications, Gell and Coombs.
- Gene Ontology term GO:0050896, response to stimulus - The organism- and cell-level biological-process identifier for a change elicited by a stimulus, the closest controlled-vocabulary neighbour to this sense.
- Second symposium on the definition and management of anaphylaxis: summary report - Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium - Clinical diagnostic criteria used for anaphylaxis as a life-threatening systemic reaction. Journal of Allergy and Clinical Immunology, 2006, Sampson et al.
- The Importance of Pharmacovigilance: Safety Monitoring of Medicinal Products - WHO operational definition of adverse reaction, spontaneous reporting, and the international drug-monitoring programme (VigiBase / Uppsala Monitoring Centre).
What the second pass must settle
- Does the registry intend this entry to cover bodily reactions across all organisms, and how should organism-specific extensions be bounded?
- How should this entry relate to neighbouring concepts such as reflex, physiological response, symptom and adverse reaction without duplicating their models?
- What minimum evidence permits classification as a reaction when the antecedent or causal mechanism remains unidentified?
- Which episode-boundary conventions are appropriate for delayed, overlapping, sustained or repeatedly triggered bodily processes?
- Which manifestation-specific measures and authoritative review criteria should be incorporated through specialised extensions?