The tunica externa (Neo-Latin "outer coat"), also known as the tunica adventitia (Neo-Latin "additional coat"),[1][2] is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina. The collagen serves to anchor the blood vessel to nearby organs, giving it stability.
The tunica externa is made from collagen and elastic fibers in a loose connective tissue.[1][2] This is secreted by fibroblasts.[1] This is normally the thickest tunic in veins and may be thicker than the tunica media in some larger arteries. The outer layers of the tunica externa are not distinct but rather blend with the surrounding connective tissue outside the vessel, helping to hold the vessel in relative position.[3]
Functionedit
The tunica externa provides basic structural support to blood vessels.[1] It prevents vessels from expanding too much from internal blood pressure, particularly arteries.[2] It is also relevant in controlling vascular flow in the lungs.[1]
Clinical significanceedit
A common pathological disorder concerning the tunica externa is scurvy, also known as vitamin C deficiency. Scurvy occurs because vitamin C is essential for the synthesis of collagen, and without it, the faulty collagen cannot maintain the vein walls and rupture, leading to a multitude of problems.
This article incorporates text in the public domain from page 499 of the 20th edition ofGray's Anatomy(1918)
^ abcdeHunt, J. M.; Graham, B. B. (2014-01-01), McManus, Linda M.; Mitchell, Richard N. (eds.), "Pulmonary Hypertension/Pulmonary Arterial Hypertension", Pathobiology of Human Disease, San Diego: Academic Press, pp. 2625–2635, doi:10.1016/b978-0-12-386456-7.05306-5, ISBN978-0-12-386457-4, retrieved 2020-12-29
^ abcMaleszewski, J. J.; Lai, C. K.; Veinot, J. P. (2016-01-01), Buja, L. Maximilian; Butany, Jagdish (eds.), "Chapter 1 - Anatomic Considerations and Examination of Cardiovascular Specimens (Excluding Devices)", Cardiovascular Pathology (Fourth Edition), San Diego: Academic Press, pp. 1–56, doi:10.1016/b978-0-12-420219-1.00001-x, ISBN978-0-12-420219-1, retrieved 2020-12-29
^ This article incorporates text available under the CC BY 4.0 license. Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (June 8, 2023). Anatomy & Physiology. Houston: OpenStax CNX. 20.1 Structure and function of blood vessels. ISBN978-1-947172-04-3.
External linksedit
- Comparative Organology at University of California, Davis - "Bird, vessels (LM, High)"
tunica, externa, tunica, externa, latin, outer, coat, also, known, tunica, adventitia, latin, additional, coat, outermost, tunica, layer, blood, vessel, surrounding, tunica, media, mainly, composed, collagen, arteries, supported, external, elastic, lamina, col. The tunica externa Neo Latin outer coat also known as the tunica adventitia Neo Latin additional coat 1 2 is the outermost tunica layer of a blood vessel surrounding the tunica media It is mainly composed of collagen and in arteries is supported by external elastic lamina The collagen serves to anchor the blood vessel to nearby organs giving it stability Tunica externaSection of a medium sized artery DetailsPart ofWall of blood vesselsIdentifiersLatintunica externa tunica adventitiaTA98A12 0 00 017TA23920THH3 09 02 0 01009Anatomical terminology edit on Wikidata The three layers of the blood vessels are an inner tunica intima a middle tunica media and an outer tunica externa Contents 1 Structure 2 Function 3 Clinical significance 4 Additional images 5 See also 6 References 7 External linksStructure editThe tunica externa is made from collagen and elastic fibers in a loose connective tissue 1 2 This is secreted by fibroblasts 1 This is normally the thickest tunic in veins and may be thicker than the tunica media in some larger arteries The outer layers of the tunica externa are not distinct but rather blend with the surrounding connective tissue outside the vessel helping to hold the vessel in relative position 3 Function editThe tunica externa provides basic structural support to blood vessels 1 It prevents vessels from expanding too much from internal blood pressure particularly arteries 2 It is also relevant in controlling vascular flow in the lungs 1 Clinical significance editA common pathological disorder concerning the tunica externa is scurvy also known as vitamin C deficiency Scurvy occurs because vitamin C is essential for the synthesis of collagen and without it the faulty collagen cannot maintain the vein walls and rupture leading to a multitude of problems Additional images edit nbsp Transverse section through a small artery and vein of the mucous membrane of the epiglottis of a child Tunica adventitia is at a nbsp Microphotography of arterial wall with calcified violet colour atherosclerotic plaque H amp E stain See also editAdventitiaReferences edit nbsp This article incorporates text in the public domain from page 499 of the 20th edition of Gray s Anatomy 1918 a b c d e Hunt J M Graham B B 2014 01 01 McManus Linda M Mitchell Richard N eds Pulmonary Hypertension Pulmonary Arterial Hypertension Pathobiology of Human Disease San Diego Academic Press pp 2625 2635 doi 10 1016 b978 0 12 386456 7 05306 5 ISBN 978 0 12 386457 4 retrieved 2020 12 29 a b c Maleszewski J J Lai C K Veinot J P 2016 01 01 Buja L Maximilian Butany Jagdish eds Chapter 1 Anatomic Considerations and Examination of Cardiovascular Specimens Excluding Devices Cardiovascular Pathology Fourth Edition San Diego Academic Press pp 1 56 doi 10 1016 b978 0 12 420219 1 00001 x ISBN 978 0 12 420219 1 retrieved 2020 12 29 nbsp This article incorporates text available under the CC BY 4 0 license Betts J Gordon Desaix Peter Johnson Eddie Johnson Jody E Korol Oksana Kruse Dean Poe Brandon Wise James Womble Mark D Young Kelly A June 8 2023 Anatomy amp Physiology Houston OpenStax CNX 20 1 Structure and function of blood vessels ISBN 978 1 947172 04 3 External links editAnatomy photo Circulatory vessels vessels7 vessels4 Comparative Organology at University of California Davis Bird vessels LM High Portal nbsp Anatomy Retrieved from https en wikipedia org w index php title Tunica externa amp oldid 1211564104, wikipedia, wiki, book, books, library,
