{"id":8193,"date":"2026-08-09T20:56:51","date_gmt":"2026-08-09T18:56:51","guid":{"rendered":"https:\/\/blueportance.com\/knowledge-base\/expert-guides\/living-flows\/continuous-flow-organization\/internal-environment-cells\/"},"modified":"2026-10-25T22:44:01","modified_gmt":"2026-10-25T21:44:01","slug":"internal-environment-cells","status":"publish","type":"page","link":"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/living-flows\/continuous-flow-organization\/internal-environment-cells\/","title":{"rendered":"KB 3_Expert Guide_02_Living Flows_01_Continuous-Flow Organization_02_The Internal Environment: The Living Environment of Cells"},"content":{"rendered":"\n\n<!-- BDC \u2014 Continuous-Flow Organization - A2_The Internal Environment: The Living Environment of Cells \u2014 Blue Portance -->\n\n<style>\n    .bp-bdc-breadcrumb{\n      max-width: 900px;\n      margin: 0 auto;\n      padding: 20px 16px 0;\n      font-size: .85rem;\n      color: #6b7280;\n    }\n    .bp-bdc-breadcrumb a{\n      color: #2a7fba;\n      text-decoration: none;\n    }\n    .bp-bdc-breadcrumb a:hover{\n      text-decoration: underline;\n    }\n\n  .bp-figure {\n      margin: 40px auto;\n      text-align: center;\n      max-width: 760px;\n  }\n\n  .bp-figure img {\n      display: block;\n      margin: 0 auto;\n      max-width: 100%;\n      height: auto;\n      border-radius: 8px;\n  }\n\n  .bp-figure figcaption {\n      margin: 10px auto 0;\n      max-width: 650px;\n      text-align: center;\n      color: #666;\n      font-size: 0.85em;\n      line-height: 1.45;\n  }\n\n  .bp-fig-title {\n      display: block;\n      margin: 0 0 4px;\n      padding: 0;\n      font-style: normal;\n      font-weight: 700;\n      font-size: 1em;\n      color: #333;\n      line-height: 1.3;\n  }\n\n  .bp-fig-text {\n      display: block;\n      margin: 0;\n      padding: 0;\n      font-style: italic;\n  }\n  \n    .bp-bdc-navigation a::before{content:\"\u2190 \";}\n  <\/style>\n\n<nav class=\"bp-bdc-breadcrumb\" aria-label=\"Breadcrumb\">\n  <a href=\"\/en\/\">Blue Portance<\/a> \u2192 <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/\">Knowledge Base<\/a> \u2192 <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/\">Expert Guides<\/a> \u2192 <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/living-flows\/\">Living Flows<\/a> \u2192 <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/living-flows\/continuous-flow-organization\/\">Continuous-Flow Organization<\/a> \u2192 The Internal Environment\n<\/nav>\n\n\n\n\n<section class=\"bp-bdc-wrap\">\n\n  <header class=\"bp-bdc-hero\">\n    <h1>2. The Internal Environment: The Living Environment of Cells<\/h1>\n    <p>Knowledge Base \u2013 Expert Guide: Continuous-Flow Organization<\/p>\n    <div class=\"bp-bdc-meta\">Blue Portance Knowledge Base \u00b7 Non-commercial reproduction permitted with source attribution<\/div>\n  <\/header>\n\n  <p>\n    Most of the body&#8217;s cells are not in direct contact with the outside environment. Instead, they are\n    bathed in an intermediate extracellular environment. Its physicochemical properties \u2014 notably\n    temperature, pH and ion concentrations \u2014 must remain compatible with cell function.\n    In practice, this environment consists mainly of blood plasma and interstitial fluid. Part of this\n    fluid also\n    becomes lymph once it enters the lymphatic vessels. The stability of this environment is therefore not\n    stillness. Rather, it results from the continuous regulation of transfers of water, ions, nutrients, gases and\n    metabolic products.\n  <\/p>\n\n  <nav class=\"bp-bdc-toc\" aria-label=\"Contents\">\n    <h2>Contents<\/h2>\n    <ul>\n      <li><a href=\"#notion-fondamentale\">1. The internal environment: a foundational concept<\/a><\/li>\n      <li><a href=\"#compartiments\">2. The extracellular compartments<\/a><\/li>\n      <li><a href=\"#pas-contact-sang\">3. In most tissues, cells are not in direct contact with blood<\/a><\/li>\n      <li><a href=\"#interstitium\">4. The interstitium and interstitial fluid<\/a><\/li>\n      <li><a href=\"#composition-regulee\">5. A continuously regulated composition<\/a><\/li>\n      <li><a href=\"#microenvironnements\">6. Distinct tissue microenvironments<\/a><\/li>\n      <li><a href=\"#echanges-compartiments\">7. Exchanges among several compartments<\/a><\/li>\n      <li><a href=\"#pressions-equilibre\">8. Pressures and fluid balance<\/a><\/li>\n      <li><a href=\"#so-what\">9. What this means for sitting<\/a><\/li>\n      <li><a href=\"#references\">Scientific References<\/a><\/li>\n    <\/ul>\n  <\/nav>\n\n  <article class=\"bp-bdc-content\">\n\n  <section id=\"notion-fondamentale\">\n  <h2>1. The internal environment: a foundational concept<\/h2>\n\n  <p>\n    In the 19<sup>th<\/sup> century, Claude Bernard formulated a foundational idea. In his view, cells live in a\n    relatively stable internal environment, distinct from the external environment <span class=\"bp-inline-ref\">(Bernard, 1865)<\/span>.\n    This concept later transformed physiology profoundly.\n  <\/p>\n\n  <p>\n    The organism does not merely place its cells in contact with the environment. Instead, it actively builds\n    and regulates that environment. Specifically, temperature, pH, ion concentrations and the\n    availability of certain substances are kept within ranges compatible with cellular activity.\n  <\/p>\n\n  <p>\n    The &#8220;internal environment&#8221; is therefore not limited to the blood. In fact, it refers more broadly to\n    all the extracellular fluids that surround cells and mediate their exchanges with the rest of the\n    organism. The\n    main compartments involved are the following:\n  <\/p>\n  <ul>\n    <li>plasma, located inside the vessels;<\/li>\n    <li>interstitial fluid, present around the cells;<\/li>\n    <li>lymph, derived from interstitial fluid collected by the lymphatic vessels;<\/li>\n    <li>certain specialized fluids, such as cerebrospinal fluid.<\/li>\n  <\/ul>\n\n  <p>\n    In practice, extracellular fluid forms the immediate environment of many cells. In particular,\n    it supplies them with the substances they need and, in return, receives the products of their activity\n    <span class=\"bp-inline-ref\">(Boron &amp; Boulpaep, 2017)<\/span>.\n  <\/p>\n\n  <\/section>\n\n  <section id=\"compartiments\">\n  <h2>2. The extracellular compartments<\/h2>\n\n  <p>\n    To begin with, plasma is the liquid fraction located inside the blood vessels. Among other things, it\n    carries water, ions, nutrients, dissolved gases, hormones and proteins.\n  <\/p>\n\n  <p>\n    Part of the water and solutes crosses the microvascular walls. In doing so, it helps\n    form the interstitial fluid that surrounds the cells within tissues. A fraction of this interstitial\n    fluid, along with the macromolecules it contains, is subsequently collected by the lymphatic capillaries.\n    Once it enters the lymphatic network, this fluid is called lymph. It then circulates through\n    a specialized network before returning to the bloodstream\n    <span class=\"bp-inline-ref\">(Boron &amp; Boulpaep, 2017; Wiig &amp; Swartz, 2012)<\/span>.\n  <\/p>\n\n  <p>\n    In addition to these compartments, there are specialized fluids such as cerebrospinal fluid, synovial\n    fluid and certain serous fluids. Moreover, their composition and renewal are governed by specific\n    physiological requirements.\n  <\/p>\n\n  <p>\n    These compartments communicate with one another, but they are not interchangeable. Indeed, their compositions, their\n    barriers and their functions differ. As a result, this organization allows the body to maintain\n    local environments suited to the needs of different tissues.\n  <\/p>\n\n  <\/section>\n\n  <figure class=\"bp-figure\">\n    <img decoding=\"async\"\n      src=\"https:\/\/blueportance.com\/wp-content\/uploads\/flux-a2-1-the-main-compartments-of-the-internal-environment.png\"\n      alt=\"Diagram of the extracellular compartments: plasma, interstitial fluid, lymph and specialized fluids.\"\n      class=\"bp-figure-image\"\n      loading=\"lazy\"\n    >\n\n    <figcaption class=\"bp-figure-caption\">\n      <span class=\"bp-fig-title\">\n        Figure 1 \u2014 The main compartments of the internal environment\n      <\/span>\n\n      <span class=\"bp-fig-text\">\n        Cells are connected to the blood through interfaces and through interstitial fluid; lymph recovers part of the interstitial excess. \u00a9 Blue Portance 2026.\n      <\/span>\n    <\/figcaption>\n  <\/figure>\n\n  <section id=\"pas-contact-sang\">\n  <h2>3. In most tissues, cells are not in direct contact with blood<\/h2>\n\n  <p>\n    In most tissues, cells are not directly exposed to circulating blood. Plasma remains\n    inside the vessels, while the cells are bathed in interstitial fluid.\n  <\/p>\n\n  <p>\n    Consequently, exchanges between these two compartments take place across the walls of the microvessels.\n    Interstitial fluid thus serves as an interface between the vascular compartment and the cellular environment.\n  <\/p>\n\n  <p>\n    This organization therefore places several barriers and transfer spaces between plasma and\n    cells. The composition of the cellular environment depends in particular on:\n  <\/p>\n  <ul>\n    <li>microvascular permeability;<\/li>\n    <li>the properties of the interstitium;<\/li>\n    <li>the extracellular matrix;<\/li>\n    <li>cellular activity;<\/li>\n    <li>local pressures;<\/li>\n    <li>the uptake of interstitial fluid by the lymphatic system.<\/li>\n  <\/ul>\n\n  <p>\n    Blood thus contributes to maintaining the internal environment. Nevertheless, it is not the direct\n    environment of all cells. This distinction matters because it keeps us from reducing the physiology of\n    exchange to blood circulation alone. Between the blood and the cell, there are in fact interfaces,\n    gradients and local transformations.\n  <\/p>\n\n  <\/section>\n\n  <section id=\"interstitium\">\n  <h2>4. The interstitium and interstitial fluid<\/h2>\n\n  <p>\n    This term refers to the extracellular space located between the cells and the microvessels. Specifically,\n    it includes a fluid phase \u2014 the interstitial fluid \u2014 an extracellular matrix, solutes and\n    various resident cells. Interstitial fluid is therefore one component of the interstitium, but the two terms\n    are not synonymous.\n  <\/p>\n\n  <p>\n    The interstitium should not be thought of as a mere empty space filled with water. On the\n    contrary, it is an organized microenvironment whose properties depend on several factors:\n  <\/p>\n  <ul>\n    <li>the quantity and composition of the fluid;<\/li>\n    <li>the structure of the extracellular matrix;<\/li>\n    <li>the presence of proteins and macromolecules;<\/li>\n    <li>interstitial pressure;<\/li>\n    <li>the permeability of the microvessels;<\/li>\n    <li>the activity of neighboring cells.<\/li>\n  <\/ul>\n\n  <p>\n    For instance, Wiig and Swartz describe the interstitium as a microenvironment made up of fluid, proteins,\n    solutes and extracellular matrix. They also emphasize that changes in it can influence\n    cell function and fluid transport within tissues\n    <span class=\"bp-inline-ref\">(Wiig &amp; Swartz, 2012)<\/span>.\n  <\/p>\n\n  <p>\n    Interstitial fluid is thus a dynamic interface between the microvessels, the matrix and the\n    cells.\n  <\/p>\n\n  <\/section>\n\n  <figure class=\"bp-figure\">\n    <img decoding=\"async\"\n      src=\"https:\/\/blueportance.com\/wp-content\/uploads\/flux-a2-2-the-interstitium-an-interface-between-microvessels-and-cells.png\"\n      alt=\"Microvessel, interstitium, tissue cell and lymphatic capillary linked by exchanges of water and solutes.\"\n      class=\"bp-figure-image\"\n      loading=\"lazy\"\n    >\n\n    <figcaption class=\"bp-figure-caption\">\n      <span class=\"bp-fig-title\">\n        Figure 2 \u2014 The interstitium, an interface between microvessels and cells\n      <\/span>\n\n      <span class=\"bp-fig-text\">\n        The interstitium forms the physical interface between the microvessels, the cells and lymphatic uptake. \u00a9 Blue Portance 2026.\n      <\/span>\n    <\/figcaption>\n  <\/figure>\n\n  <section id=\"composition-regulee\">\n  <h2>5. A continuously regulated composition<\/h2>\n\n  <p>\n    To function properly, a cell must maintain concentration differences between its\n    interior and its surroundings. These gradients involve, in particular:\n  <\/p>\n  <ul>\n    <li>sodium, potassium, calcium and chloride;<\/li>\n    <li>bicarbonate and glucose;<\/li>\n    <li>oxygen and carbon dioxide;<\/li>\n    <li>various proteins and dissolved molecules.<\/li>\n  <\/ul>\n  <p>\n    pH and temperature must also remain within ranges compatible with enzyme activity and\n    metabolic reactions.\n  <\/p>\n\n  <p>\n    However, the stability of the internal environment does not mean that these parameters remain perfectly\n    constant. In reality, they fluctuate with physical activity, diet, breathing,\n    temperature and physiological state. Some variations may also be local and depend on the\n    specific activity of a given tissue.\n  <\/p>\n\n  <p>\n    Acid-base balance, for example, is a case of complex regulation. Specifically, extracellular pH depends on\n    buffer systems, ion exchange, respiration and kidney function\n    <span class=\"bp-inline-ref\">(Boron &amp; Boulpaep, 2017; Kraut &amp; Madias, 2010)<\/span>.\n  <\/p>\n\n  <p>\n    The internal environment should therefore be understood as a regulated composition. In other words, it is not a\n    uniform fluid with identical properties throughout the body.\n  <\/p>\n\n  <\/section>\n\n  <section id=\"microenvironnements\">\n  <h2>6. Distinct tissue microenvironments<\/h2>\n\n  <p>\n    The overall stability of the internal environment does not imply perfect uniformity throughout the body.\n    Indeed, the cells of an active muscle, of nervous tissue, of cartilage or of an epithelium do not\n    experience the same local conditions. Their environment depends on their metabolic activity, their\n    blood supply, the extracellular matrix, temperature and uptake pathways.\n  <\/p>\n\n  <p>\n    For example, a contracting muscle locally increases its oxygen and energy needs. Nervous\n    tissue, in contrast, depends on particularly precise ion gradients. Finally, cartilage, which has\n    a limited blood supply, relies on exchange mechanisms different from those of richly\n    vascularized tissue.\n  <\/p>\n\n  <p>\n    The internal environment should therefore be understood as a nested organization:\n  <\/p>\n  <ul>\n    <li>general regulation at the level of the whole organism;<\/li>\n    <li>specific regulation at the level of organs;<\/li>\n    <li>local variations around the cells.<\/li>\n  <\/ul>\n\n  <p>\n    Still, this heterogeneity is not necessarily a flaw. On the contrary, it allows tissues to meet\n    different needs. It does mean, however, that a measurement taken in one compartment cannot\n    automatically be used to infer the state of another.\n  <\/p>\n\n  <\/section>\n\n  <figure class=\"bp-figure\">\n    <img decoding=\"async\"\n      src=\"https:\/\/blueportance.com\/wp-content\/uploads\/flux-a2-3-the-internal-environment-general-regulation-adapted-to-local-needs.png\"\n      alt=\"Three levels of regulation: organism, organ or tissue, and cellular microenvironment.\"\n      class=\"bp-figure-image\"\n      loading=\"lazy\"\n    >\n\n    <figcaption class=\"bp-figure-caption\">\n      <span class=\"bp-fig-title\">\n        Figure 3 \u2014 The internal environment: general regulation adapted to local needs\n      <\/span>\n\n      <span class=\"bp-fig-text\">\n        The overall stability of the internal environment remains compatible with local differences suited to the needs of tissues. \u00a9 Blue Portance 2026.\n      <\/span>\n    <\/figcaption>\n  <\/figure>\n\n  <section id=\"echanges-compartiments\">\n  <h2>7. Exchanges among several compartments<\/h2>\n\n  <p>\n    Maintaining the internal environment relies on constant exchanges between plasma, the interstitium\n    and cells. These exchanges involve water, ions, nutrients, respiratory gases, hormones,\n    proteins and metabolic products.\n  <\/p>\n\n  <p>\n    They do not, however, rely on a single mechanism. Depending on the substance and tissue involved, they may\n    involve filtration, diffusion, convective transport or membrane transport. These\n    mechanisms will be covered in detail in a later chapter devoted to tissue exchange.\n  <\/p>\n\n  <p>\n    For now, the key point is enough. In short, cells depend on an ongoing balance between\n    the supply of the substances they need and the removal of the products they no longer need. A tissue\n    whose extracellular environment is altered is therefore not necessarily cut off from exchange right away.\n    Its local composition, gradients and transfer conditions, on the other hand, may be altered.\n  <\/p>\n\n  <\/section>\n\n  <section id=\"pressions-equilibre\">\n  <h2>8. Pressures and fluid balance<\/h2>\n\n  <p>\n    The movement of water between the microvessels and the interstitium depends on several factors:\n  <\/p>\n  <ul>\n    <li>hydrostatic and oncotic pressures;<\/li>\n    <li>the permeability of the vascular wall;<\/li>\n    <li>the properties of the interstitium and the extracellular matrix;<\/li>\n    <li>lymphatic uptake.<\/li>\n  <\/ul>\n\n  <p>\n    Notably, the current understanding of these exchanges has led to a revision of the classic formulation of the\n    Starling principle. Consequently, microvascular exchange can no longer be described as a simple balance\n    between two forces that mechanically cancel each other out. In particular, the endothelial glycocalyx and the local characteristics\n    of the vascular wall play an important role <span class=\"bp-inline-ref\">(Levick &amp; Michel, 2010)<\/span>.\n  <\/p>\n\n  <p>\n    In many tissues at steady state, capillaries produce a small net filtration\n    into the interstitium. The excess fluid and macromolecules are then mainly recovered by\n    the lymphatic system. Capillary reabsorption may nevertheless occur transiently, or in certain specialized\n    vascular beds <span class=\"bp-inline-ref\">(Levick &amp; Michel, 2010; Reed &amp; Rubin, 2010)<\/span>.\n  <\/p>\n\n  <p>\n    Interstitial pressure and matrix properties also contribute to the conditions of transfer\n    between the microvessels and the tissues <span class=\"bp-inline-ref\">(Reed &amp; Rubin, 2010)<\/span>. This\n    point is important. Indeed, the balance of the internal environment does not depend solely on the amount of\n    fluid present. It also depends on the properties of barriers, gradients and uptake pathways.\n  <\/p>\n\n  <\/section>\n\n  <section id=\"so-what\">\n  <h2>9. What this means for sitting<\/h2>\n\n  <div class=\"bp-box bp-box--info\">\n    <strong>Caution<\/strong>\n    <p>\n      Sitting does not bring cells into direct contact with an external object. It\n      first alters the mechanical relationships between the body, the tissues and the support surface. For example, when seated,\n      seat configuration and pressure-relief maneuvers can alter the distribution of interface\n      pressures. They also influence measured perfusion in the gluteal tissues. These effects depend\n      in particular on the magnitude and duration of the load, the contact area, tissue properties and\n      the opportunities for repositioning <span class=\"bp-inline-ref\">(Makhsous et al., 2007, 2012)<\/span>. More broadly,\n      prolonged mechanical loading can locally alter interstitial pressure and the conditions under\n      which tissue exchange takes place\n      <span class=\"bp-inline-ref\">(Reed &amp; Rubin, 2010; Makhsous et al., 2007, 2012)<\/span>.\n    <\/p>\n  <\/div>\n\n  <p>\n    This does not mean, however, that a compressed area immediately becomes a closed space, or that\n    exchange stops there entirely. The consequences instead depend on many factors:\n  <\/p>\n  <ul>\n    <li>the magnitude of the load and the duration of exposure;<\/li>\n    <li>the contact area and the type of tissue;<\/li>\n    <li>the ability to reposition;<\/li>\n    <li>vascular and metabolic status;<\/li>\n    <li>individual sensitivity.<\/li>\n  <\/ul>\n\n  <p>\n    This article therefore does not yet allow us to conclude that dynamic sitting improves exchange. In fact, it\n    only helps explain why the local environment of cells depends on regulated mechanical, fluid\n    and biological conditions. The following articles in this guide will cover the extracellular matrix, and then the\n    physical mechanisms \u2014 diffusion, osmosis, filtration \u2014 that make these exchanges possible.\n  <\/p>\n\n  <\/section>\n\n  <hr>\n\n  <section id=\"references\">\n    <div class=\"bp-box bp-box--info\">\n      <h2>Scientific References<\/h2>\n\n      <h3>Internal environment and compartments<\/h3>\n      <ol>\n        <li>Bernard, C. (1865). <em>Introduction \u00e0 l&#8217;\u00e9tude de la m\u00e9decine exp\u00e9rimentale.<\/em> Paris: J.-B. Bailli\u00e8re.<\/li>\n        <li>Boron, W. F., &amp; Boulpaep, E. L. (2017). <em>Medical Physiology<\/em> (3rd ed.). Philadelphia: Elsevier.<\/li>\n        <li>Kraut, J. A., &amp; Madias, N. E. (2010). Metabolic acidosis: pathophysiology, diagnosis and management. <em>Nature Reviews Nephrology<\/em>, 6(5), 274\u2013285.<\/li>\n        <li>Wiig, H., &amp; Swartz, M. A. (2012). Interstitial fluid and lymph formation and transport: physiological regulation and roles in inflammation and cancer. <em>Physiological Reviews<\/em>, 92(3), 1005\u20131060.<\/li>\n      <\/ol>\n\n      <h3>Microvascular exchange and sitting<\/h3>\n      <ol>\n        <li>Levick, J. R., &amp; Michel, C. C. (2010). Microvascular fluid exchange and the revised Starling principle. <em>Cardiovascular Research<\/em>, 87(2), 198\u2013210.<\/li>\n        <li>Makhsous, M., Priebe, M., Bankard, J., et al. (2007). Measuring tissue perfusion during pressure relief maneuvers: insights into preventing pressure ulcers. <em>The Journal of Spinal Cord Medicine<\/em>, 30(5), 497\u2013507.<\/li>\n        <li>Makhsous, M., Lin, F., Hanawalt, D., Kruger, S. L., &amp; LaMantia, A. (2012). The effect of chair designs on sitting pressure distribution and tissue perfusion. <em>Human Factors<\/em>, 54(6), 1066\u20131074.<\/li>\n        <li>Reed, R. K., &amp; Rubin, K. (2010). Transcapillary exchange: role and importance of the interstitial fluid pressure and the extracellular matrix. <em>Cardiovascular Research<\/em>, 87(2), 211\u2013217.<\/li>\n      <\/ol>\n    <\/div>\n  <\/section>\n\n  <\/article>\n\n  <!-- NAVIGATION -->\n  <nav class=\"bp-bdc-box bp-bdc-navigation\" aria-label=\"Topic navigation\">\n    <strong>Navigation<\/strong>\n    <p>\n      <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/living-flows\/continuous-flow-organization\/\">\n        Back to the Continuous-Flow Organization guide\n      <\/a>\n    <\/p>\n    <p>\n      <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/living-flows\/\">\n        See the topic: Living Flows\n      <\/a>\n    <\/p>\n    <p>\n      <a href=\"https:\/\/blueportance.com\/en\/knowledge-base\/expert-guides\/\">\n        Explore the Expert Guides section of the Knowledge Base\n      <\/a>\n    <\/p>\n  <\/nav>\n\n  <!-- NOTE -->\n  <footer class=\"bp-bdc-footer\">\n    <strong>Note<\/strong>: this content aims to explain mechanisms.\n    It is not a medical diagnosis or a treatment prescription.\n  <\/footer>\n\n  <p class=\"bp-bdc-copyright\" style=\"font-size:.85em;color:#6b7280;margin-top:16px;\">\n    \u00a9 Gil Ayache. 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The Internal Environment: The Living Environment of Cells Knowledge Base \u2013 Expert Guide: Continuous-Flow Organization Blue Portance Knowledge Base \u00b7 Non-commercial reproduction permitted with source attribution Most of the body&#8217;s cells are not in direct contact [&#8230;]\n","protected":false},"author":6,"featured_media":0,"parent":8186,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_yoast_wpseo_title":"The Internal Environment of Cells | Blue Portance","_yoast_wpseo_metadesc":"Intracellular and extracellular compartments, interstitial fluid: how cells exchange with their immediate environment.","footnotes":""},"pathologie_secondaire":[],"effet_positif":[],"class_list":["post-8193","page","type-page","status-publish","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v28.7 (Yoast SEO v28.8) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>The 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