Interstitium
| Interstitium | |
|---|---|
| Anatomical terminology |
The interstitium is a contiguous fluid-filled space existing between a structural barrier, such as a cell membrane or the skin, and internal structures, such as organs, including muscles and the circulatory system.[1][2] The fluid in this space is called interstitial fluid, comprises water and solutes, and drains into the lymph system.[2] The interstitial compartment is composed of connective and supporting tissues within the body – called the extracellular matrix – that are situated outside the blood and lymphatic vessels and the parenchyma of organs.[2][3] The role of the interstitium in solute concentration, protein transport and hydrostatic pressure impacts human pathology and physiological responses such as edema, inflammation and shock.[4]
Structure
The non-fluid parts of the interstitium are predominantly collagen types I, III, and V, elastin, and glycosaminoglycans, such as hyaluronan and proteoglycans that are cross-linked to form a honeycomb-like reticulum.[3] Collagen bundles of the extracellular matrix form scaffolding with a high tensile strength. Interstitial cells (e.g., fibroblasts, dendritic cells, adipocytes, interstitial cells of Cajal and inflammatory cells, such as macrophages and mast cells), serve a variety of structural and immune functions.[3][4] Fibroblasts synthesize the production of structural molecules as well as enzymes that break down polymeric molecules.[3] Such structural components exist both for the general interstitium of the body,[2] and within individual organs, such as the myocardial interstitium of the heart,[5] the renal interstitium of the kidney,[6] and the pulmonary interstitium of the lung.
The interstitium in the submucosae of visceral organs, the dermis, superficial fascia, and perivascular adventitia are fluid-filled spaces supported by a collagen bundle lattice. Blind end, highly permeable, lymphatic capillaries extend into the interstitium. The fluid spaces communicate with draining lymph nodes, although they do not have lining cells or structures of lymphatic channels.[7] Interstitial fluid entering the lymphatic system becomes lymph, which is transported through lymphatic vessels until it empties into the microcirculation and the venous system.[4]
Functions
The interstitial fluid is a reservoir and transportation system for nutrients and solutes distributing among organs, cells, and capillaries, for signaling molecules communicating between cells, and for antigens and cytokines participating in immune regulation.[2] The composition and chemical properties of the interstitial fluid vary among organs and undergo changes in chemical composition during normal function, as well as during body growth, conditions of inflammation, and development of diseases,[2] as in heart failure[5] and chronic kidney disease.[6]
The total fluid volume of the interstitium during health is about 20% of body weight, but this space is dynamic and may change in volume and composition during immune responses and in conditions such as cancer, and specifically within the interstitium of tumors.[2] The amount of interstitial fluid varies from about 50% of the tissue weight in skin to about 10% in skeletal muscle.[2]
Disease
In people with lung diseases, heart disease, cancer, kidney disease, immune disorders, and periodontal disease, the interstitial fluid and lymph system are sites where disease mechanisms may develop.[2][5][6][8]
See also
References
- ^ Bert JL; Pearce RH (1984). The interstitium and microvascular exchange. In: Handbook of Physiology. The Cardiovascular System. Microcirculation (sect. 2; pt. 1; chapt. 12; vol. IV ed.). Bethesda, MD: American Physiological Society. pp. 521–547. ISBN 0-683-07202-1.
- ^ a b c d e f g h i Wiig, H; Swartz, M. A (2012). "Interstitial fluid and lymph formation and transport: Physiological regulation and roles in inflammation and cancer". Physiological Reviews. 92 (3): 1005–60. doi:10.1152/physrev.00037.2011. PMID 22811424.
- ^ a b c d Scallan J; Huxley VH; Korthuis RJ (2010). The Interstitium. In: Capillary Fluid Exchange: Regulation, Functions, and Pathology. San Rafael, CA: Morgan & Claypool Life Sciences. Archived from the original on 2021-02-08. Retrieved 2018-03-29.
- ^ a b c Stewart, Randolph H. (2020-11-05). "A Modern View of the Interstitial Space in Health and Disease". Frontiers in Veterinary Science. 7. doi:10.3389/fvets.2020.609583. ISSN 2297-1769. PMC 7674635. PMID 33251275.
- ^ a b c Eckhouse SR; Spinale FG (2012). "Changes in the myocardial interstitium and contribution to the progression of heart failure". Heart Fail Clin. 8 (1): 7–20. doi:10.1016/j.hfc.2011.08.012. PMC 3227393. PMID 22108723.
- ^ a b c Zeisberg, M; Kalluri, R (2015). "Physiology of the Renal Interstitium". Clinical Journal of the American Society of Nephrology. 10 (10): 1831–1840. doi:10.2215/CJN.00640114. PMC 4594057. PMID 25813241.
- ^ Benias, Petros C.; Wells, Rebecca G.; Sackey-Aboagye, Bridget; Klavan, Heather; Reidy, Jason; Buonocore, Darren; Miranda, Markus; Kornacki, Susan; Wayne, Michael (2018-03-27). "Structure and Distribution of an Unrecognized Interstitium in Human Tissues". Scientific Reports. 8 (1): 4947. Bibcode:2018NatSR...8.4947B. doi:10.1038/s41598-018-23062-6. ISSN 2045-2322. PMC 5869738. PMID 29588511.
- ^ Berggreen, E; Wiig, H (2014). "Lymphatic function and responses in periodontal disease". Experimental Cell Research. 325 (2): 130–7. doi:10.1016/j.yexcr.2013.12.006. PMID 24503053.