membrane
a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants
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 biological tissue membrane, assess its integrity and function, and identify actions compatible with the structures it covers, lines or connects.
A biological membrane is a thin, deformable sheet - ranging from a protein-studded lipid bilayer a few nanometres thick to a millimetre-scale laminate of epithelium and connective tissue - that bounds or partitions a cell, organelle, organ or body cavity and both separates compartments and mediates selective mechanical or molecular exchange.
It can be Map the membrane's extent, faces and attachments against anatomical landmarks.; Inspect or measure local thickness, continuity and movement using a suitable method.; Assess passage of a specified substance across a specified region under stated conditions.; Compare observations over time while accounting for preparation, hydration and loading differences.; Evaluate proposed sampling, separation, stretching or repair against the membrane's role and the consequences for adjacent structures..
Distinguishing features
The candidate forms a tissue sheet with identifiable faces and an anatomical covering, lining or connecting relationship, rather than merely being any soft tissue mass.
Its identity follows a sheet across an anatomical surface or between attachments, rather than following the bulk volume of an organ.
A cavity is the space bounded by a membrane; the membrane is the material sheet forming part of that boundary.
Where a named structure includes several tissues, evidence must establish whether the name denotes the membrane itself or a larger composite wall.
A molecular bilayer or an acellular supporting layer requires an explicit scope decision before it is treated as the tissue sheet described by this registry entry.
Scope
+ Anatomical identity, extent and biological context of the membrane
+ Sheet organisation, constituent tissue layers and local specialisations
+ Faces, compartments, covered surfaces and attachment relationships
+ Mechanical integrity and membrane-specific barrier, exchange or sliding functions
+ Observed changes, permissible handling and consequences of disruption
- Whole-organ or whole-organism condition beyond its effects on the membrane
- Contents of adjacent cavities or compartments except where they interact with the membrane
- Molecular transport machinery as an independently modelled system
- Synthetic filtration sheets, packaging films and architectural membranes
- Clinical diagnoses and treatment plans as independently governed decisions
Characteristics
- Biological and anatomical identity
- Organism, developmental stage, anatomical name and evidence-supported membrane type; unresolved permitted A shared name does not establish equivalent structure, function or permissible action across organisms and sites.
- Anatomical extent
- Covered, lined or connected structures; boundaries; continuities with neighbouring tissue Defines which sheet is being assessed and prevents findings from being assigned to an adjacent wall or organ.
- Face orientation
- Each identifiable face mapped to its adjacent tissue, space or external environment; orientation unknown permitted Exposure, movement and passage through the sheet depend on which face is involved.
- Thickness distribution
- µm or mm, with location, method and preparation state Local thickness helps distinguish regions and interpret changes without assuming the whole sheet is uniform.
- Tissue organisation
- Observed constituent layers, cellular or extracellular components, and regional differences Identifies which components provide the functions or bear the damage being assessed.
- Continuity and defects
- Continuous, normally fenestrated, disrupted or indeterminate; defect location and dimensions Distinguishes expected openings from tears or other losses of integrity.
- Mechanical response
- Strain %, force N or pressure Pa, paired with direction, loading conditions and method where measured Supports assessment of deformation and loading without treating pliability as proof of strength.
- Passage across the membrane
- Substance-specific flux or permeability in method-appropriate units, with direction, driving conditions and measurement area Passage of one substance does not establish permeability to another or demonstrate general barrier failure.
- Attachment and mobility
- Site-specific attachment, sliding, tethering, adhesion or separation; expected condition recorded separately A sheet can remain continuous while abnormal attachment or restricted movement compromises its role.
- Observation context
- In situ, excised, fresh, fixed or otherwise prepared; hydration, loading and observation time Preparation and environmental conditions can alter apparent thickness, pliability and integrity.
Analytical facets
- substance
- living
- origin
- natural
- agency
- inert
- mobility
- not-applicable
- scale
- not-applicable
- affordances
- observable
Also called
+49
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 · 30 questions.
Anatomical sheet identity Establish what tissue sheet is being referred to and where its identity begins and ends.
The word membrane alone does not distinguish a tissue sheet from a molecular boundary, supporting layer or composite organ wall.
Identity and evidence
Connect the membrane designation to the organism, anatomical site and supporting observation.
Supported membrane designation
Record what justifies identifying the candidate as a membrane within the registry's tissue-sheet scope.
- What organism, anatomical site and named tissue sheet does this observation concern? definition
- What anatomical reference or direct observation supports identifying this structure as a tissue membrane? provenance
Extent and continuity
Locate the sheet's margins and transitions into neighbouring structures.
Sheet boundaries
Record how the membrane is delimited when it continues into or shares layers with adjacent tissue.
- Which landmarks delimit this membrane, and where does it continue into another named tissue? boundary
- Does the observed name denote this sheet alone or a larger wall containing it? definition
Faces and attachments Represent what each face contacts and how the sheet is anchored or allowed to move.
Membrane function depends on the structures it separates, covers or connects and on its attachment geometry.
Oriented interfaces
Identify the tissue or space adjacent to each distinguishable face.
Face-to-compartment map
Record face orientation and the anatomical consequences of crossing the sheet.
- What tissue, cavity or environment lies against each face of the membrane? boundary
- What observation establishes face orientation, particularly for an excised or folded specimen? provenance
Anchoring and relative motion
Distinguish attachments that define the membrane from contacts that permit relative movement.
Attachment and mobility pattern
Record attached, mobile and separated regions relative to the expected anatomy.
- Where is the membrane attached, and where is relative sliding or separation expected? boundary
- What displacement or restriction is observed during a specified movement or load? measurement
Sheet architecture and mechanics Describe the tissue organisation and deformation behaviour that make this membrane a functional sheet.
Thinness and pliability do not establish composition, directional strength or resistance to tearing.
Regional tissue organisation
Resolve constituent layers and local variation without assuming every membrane has the same construction.
Layer and thickness profile
Record observed tissue components and thickness across relevant regions.
- Which constituent layers or components are demonstrated, and by what observation method? provenance
- How does thickness vary by location, and under what preparation and hydration conditions was it measured? measurement
Deformation under load
Relate bending, stretching and failure observations to their loading conditions.
Conditional mechanical response
Record mechanical behaviour without inferring safe limits from appearance or flexibility alone.
- What deformation occurs under a specified load, direction and duration? measurement
- What evidence, if any, supports a handling limit for stretching, bending or traction at this site? action
Barrier and surface function Establish which boundary and surface functions apply to this particular membrane.
A membrane may serve several roles, and the model must not assume that all membranes share the same selectivity or surface behaviour.
Transmembrane passage
Describe passage through the sheet for specified substances and conditions.
Substance-specific passage
Separate demonstrated transport or leakage from unsupported claims of general permeability.
- Which substance or material is observed crossing the membrane, in which direction and under what driving conditions? measurement
- What evidence distinguishes passage through tissue from passage through a normal opening, defect or specimen edge? boundary
Surface contact function
Identify the role and condition of faces that contact adjacent tissues or fluids.
Supported surface role
Record evidence for lining, protection or sliding roles and observations relevant to those roles.
- What role is supported for each face: lining, protection, sliding contact or another demonstrated function? definition
- What observed surface condition or contact behaviour indicates whether that role is being maintained? measurement
Integrity, change and intervention Assess disruption and change, then relate proposed actions to the membrane's anatomical role.
A local tear, separation or alteration can affect compartments and organs beyond the visible sheet.
Defects and evolution
Distinguish expected features, acquired changes and observation artefacts.
Qualified integrity assessment
Record defects and temporal changes with evidence for their interpretation.
- Where are discontinuities or altered regions, and what are their measured extent and depth through the sheet? measurement
- What supports classifying each feature as normal anatomy, a biological change or a preparation artefact? provenance
- Across comparable observations, has the affected region expanded, closed, thickened or otherwise changed? measurement
Action consequences
Connect proposed handling or intervention to the faces, layers and attachments it would affect.
Membrane-specific action bounds
Record the intended action, its evidence requirements and the boundary function that must be preserved or deliberately changed.
- Which region, face, layer or attachment would the proposed action affect, and what membrane function could change? action
- Could the action expose underlying tissue or connect previously separated spaces, and what evidence is needed before proceeding? action
- What subsequent observation would establish whether the intended membrane condition was achieved? 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.
- mucous membrane (mucosa) lining tracts open to the exterior
- serous membrane (serosa: pleura, pericardium, peritoneum) lining closed coelomic cavities
- synovial membrane lining diarthrodial joints, bursae and tendon sheaths
- cutaneous membrane (skin) as the dry external covering
- basement membrane, the specialised extracellular-matrix sheet under epithelia and endothelia
- fetal membranes (amnion and chorion) enclosing the conceptus
- plasma membrane (plasmalemma), the cell's outer bilayer
- intracellular membranes (nuclear envelope, endoplasmic reticulum, Golgi, mitochondrial membranes, tonoplast)
- Which of these kinds and varieties hold for the sense of membrane 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.
- Wikidata - Q143276 - Item for biological membrane; the plasma membrane is separately Q29548.
- Gene Ontology - GO:0016020 - Cellular-component class 'membrane'; subclasses include GO:0005886 plasma membrane.
- MeSH - D008566 - Heading Membranes; related descriptors include D002462 Cell Membrane, D009092 Mucous Membrane, D001582 Basement Membrane, D013583 Synovial Membrane, D012704 Serous Membrane, D005163 Extraembryonic Membranes.
- Foundational Model of Anatomy - FMA anatomical-membrane class (numeric FMAID) - FMA treats membrane as an anatomical entity with mucous, serous, synovial and other subclasses; the exact FMAID was not re-verified in this pass.
- Which of these identifiers and schemes hold for the sense of membrane 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.
- Terminologia Anatomica and Terminologia Histologica, Federative International Programme for Anatomical Terminology (FIPAT) of the International Federation of Associations of Anatomists - govern official names of body membranes.
- Gene Ontology Consortium annotation guidance for GO:0016020 and child terms - governs how gene products are assigned to cellular membranes.
- 21 CFR Part 1271 Human Cells, Tissues, and Cellular and Tissue-Based Products, U.S. Food and Drug Administration - governs amniotic and other human membrane allografts when used as HCT/Ps.
- Directive 2004/23/EC on quality and safety of human tissues and cells, European Parliament and Council - governs procurement and distribution of human membrane grafts in the EU.
- ICD-11, World Health Organization - classifies disorders of the tympanic membrane, fetal membranes and hyaline-membrane disease, among others.
- Which of these standards and regulation hold for the sense of membrane 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.
- Mucous-membrane colour, moisture and capillary refill are used as a vital-sign window in veterinary and emergency examination.
- Amniotic membrane is grafted onto the ocular surface to reconstruct cornea and conjunctiva after burns, ulcers or surgery.
- Otoscopy inspects the tympanic membrane for perforation, effusion and otitis media.
- Rheumatologists sample or resect synovium in inflammatory arthritis; arthroscopy visualises synovial villi and pannus.
- Renal pathologists measure glomerular basement-membrane thickness and immune deposits to diagnose Alport syndrome, thin-basement-membrane nephropathy and anti-GBM disease.
- Obstetric care monitors fetal-membrane integrity; preterm premature rupture of membranes is a major cause of preterm birth.
- Drug discovery treats the plasma membrane as the barrier and the seat of receptors, ion channels and transporters.
- Surgeons use serosal surfaces as dissection planes and try to limit serosal injury that seeds adhesions or peritoneal carcinomatosis.
- Which of these real-world use hold for the sense of membrane 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.
- plasma-membrane thickness - 4-10 - nm
- basement-membrane thickness (general epithelia) - 50-300 - nm
- adult glomerular basement-membrane thickness - 300-350 - nm
- tympanic-membrane thickness (pars tensa) - 0.05-0.15 - mm
- resting membrane potential of typical animal cells - -90 to -40 - mV
- transepithelial electrical resistance of intact mucosal epithelia - 100-3000 - ohm·cm²
- amnion thickness - 0.02-0.5 - mm
- Which of these typical measurements hold for the sense of membrane 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.
- Rupture or perforation (tympanic membrane, amniotic membranes, traumatic serosal tears).
- Inflammation of the lining (mucositis, serositis, synovitis, meningitis when meningeal membranes are involved).
- Pathologic thickening or sclerosis (diabetic glomerular basement-membrane thickening, tympanosclerosis, synovial fibrosis).
- Barrier failure with leak of fluid or protein (alveolar-capillary membrane oedema, protein-losing mucosal disease, synovial effusion).
- Autoimmune attack on membrane antigens (anti-GBM/Goodpasture disease, mucous-membrane pemphigoid).
- Neonatal respiratory-distress pathology with intra-alveolar hyaline membranes.
- Post-injury serosal adhesions and neoplastic seeding along serosa (peritoneal or pleural carcinomatosis).
- Loss of selective permeability or membrane potential at the cell scale (lysis, excitotoxicity, channelopathies).
- Which of these failure modes and hazards hold for the sense of membrane 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.
- English clinical speech prefers 'mucous membrane' and 'eardrum'; international anatomical Latin and many European languages use mucosa and membrana tympanica.
- Veterinary practice treats mucous-membrane colour as a routine vital sign; human primary care uses the same signs less systematically.
- The nictitating membrane is a functional third eyelid in most domestic mammals and birds, reduced in humans to the plica semilunaris.
- Botany does not use the mucous/serous/synovial four-fold classification; plant workers distinguish plasma membrane, tonoplast and organelle membranes.
- Some languages and older clinical usage call the hymen a 'vaginal membrane'; that usage is not anatomical standard.
- Which of these regional variation hold for the sense of membrane 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.
- fascia - Fascia is a connective-tissue plane without a free epithelial or mesothelial surface; a true lining membrane has an epithelium or mesothelium on histology.
- organ capsule - A capsule (for example renal capsule or Glisson's capsule) is dense irregular connective tissue around an organ; a serosa additionally bears mesothelium facing a coelomic cavity.
- adventitia - Retroperitoneal or mediastinal organs are bound by adventitia rather than serosa; the test is absence of a mesothelial free surface.
- cell wall - The cell wall is a rigid extracellular polysaccharide or peptidoglycan coat outside the plasma membrane in plants, fungi and bacteria; it is mechanically stiff and chemically not a lipid bilayer.
- cuticle - A cuticle is an acellular secreted covering (plant, arthropod or tooth); a membrane in this sense is a living cellular sheet or a bilayer.
- synthetic filtration membrane - Industrial membranes are manufactured polymer, ceramic or metallic barriers; they contain no cells or basement-membrane matrix and are identified by materials specification rather than histology.
- mucus (the secretion) - Mucus is the gel produced at a mucosal surface; the mucous membrane is the tissue that produces and carries it.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of membrane this model covers, and on what evidence? provenance
Sources
- Molecular Biology of the Cell - Structure, composition and transport functions of plasma and intracellular membranes; typical bilayer thickness and membrane potential as used in cell biology.
- Gray's Anatomy: The Anatomical Basis of Clinical Practice - Gross-anatomical treatment of mucous, serous, synovial and cutaneous membranes, fetal membranes, tympanic membrane and meninges.
- Terminologia Anatomica - Official Latin and English anatomical names for body membranes issued for international anatomical nomenclature.
- Histology: A Text and Atlas - Histological distinction of the four tissue membranes and of basement membrane layers (lamina lucida, lamina densa, lamina reticularis).
- Gene Ontology term GO:0016020 membrane - Controlled identifier and cellular-component definition used to annotate gene products to membranes.
- Medical Subject Headings descriptor Membranes (D008566) - NLM subject heading that groups anatomical and cellular membranes and their main subclasses in biomedical indexing.
What the second pass must settle
- Does this registry entry include cellular lipid membranes and acellular basement membranes, or do those belong to separate registered concepts despite sharing the name?
- Which plant structures satisfy the registry's tissue-sheet definition, and which anatomical terms provide reliable examples?
- For named capsules, fasciae and composite organ walls, what criteria determine whether the membrane is the whole registered thing or one constituent?
- Which membrane types require additional characteristics for specialised functions that the general tissue-sheet model does not capture?
- What site-specific reference evidence can distinguish normal variation from impaired integrity or function and support action limits?