{"id":6605,"date":"2021-09-13T20:55:15","date_gmt":"2021-09-13T18:55:15","guid":{"rendered":"https:\/\/meddists.com\/learn\/pre-clinical\/histology\/respiratory-system\/trachea\/"},"modified":"2022-07-30T23:03:51","modified_gmt":"2022-07-30T21:03:51","slug":"trachea","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/pre-clinical\/histology\/respiratory-system\/trachea\/","title":{"rendered":"Trachea"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><div class=\"intro\">The trachea (or windpipe) is a tubular structure connecting between the larynx and the main bronchi of the lungs. It conveys air and to some degree helps warm and moisten it, as well as clear out unwanted particles.<\/div><\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><a href=\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11.jpg\" target=\"_blank\" title=\"Trachea\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"723\" src=\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11-1024x723.jpg\" alt=\"\" class=\"wp-image-10796\" srcset=\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11-1024x723.jpg 1024w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11-300x212.jpg 300w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11-768x542.jpg 768w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11-1536x1085.jpg 1536w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2022\/05\/2308_The_Trachea11.jpg 2025w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><figcaption><strong>Figure 1. <\/strong>The trachea and bronchial tree (a) and a low-magnification histological slide of a cut-surface of the trachea (b)<\/figcaption><\/figure>\n<\/div>\n\n<span class=\"block-heading\" id=\"header_1\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Layers<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_1\">\n\n\n<ol class=\"wp-block-list\"><li>Mucosa<ol><li>Epithelium (pseudostratified columnar epithelium)<\/li><li>Lamina propria<\/li><\/ol><\/li><li>Submucosa<\/li><li>Cartilage<\/li><li>Adventitia<\/li><\/ol>\n\n\n<\/span><span class=\"block-heading\" id=\"header_2\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Mucosa<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_2\">\n\n<\/span><span class=\"block-heading\" id=\"header_3\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Epithelium<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_3\">\n\n\n<ul class=\"wp-block-list\"><li><strong>Ciliated pseudostratified columnar epithelium with goblet cells<\/strong> resting on a thick, well-defined basement membrane.<\/li><li>It is covered by a thin mucous layer consisting of mucopolysaccharides, produced by the goblet cells and mucosal glands of the submucosa.<\/li><li>The cell population consists of 5 types of cells; with the ciliated, goblet, and basal cells being most numerous.<ul><li><strong>Ciliated cells<\/strong>. Tall columnar cells with hair-like projections known as cilia.<ul><li>The most common cell type.<\/li><li>Cilia (~250 per cell) are protrusions that move with a sweeping motion, capturing and actively moving dust particles upward towards the pharynx and oral cavity, which are then swallowed.<\/li><li>The dark streak at the base of the kinocilia signifies aggregations of ciliary <strong>basal bodies<\/strong>.<\/li><\/ul><\/li><li><strong>Goblet cells<\/strong>. Produce and secrete mucous for lubrication and to prevent mucosal dryness.<ul><li>Not seen in standard H&amp;E slides as the mucous is washed away; they appear as cells with clear cytoplasm and a lack of kinocilia.<\/li><\/ul><\/li><li><strong>Basal cells<\/strong>. Stem cells that can differentiate into the various cells of the epithelium. Form a row close to the basement membrane.<\/li><li><strong>Brush cells.<\/strong> Chemoreceptor cells containing short and blunt microvilli; they can sense bitter compounds within the mucosa, and trigger trigeminal reflexes.<\/li><\/ul><ul><li><strong>Small granule cells<\/strong>. Also known as <em>Kulchitsky cells<\/em>; a sparse group of neuroendocrine cells that synthesize and store various substances.<ul><li>For example, one type produces catecholamines, while another type produces serotonin, calcitonin, bradykinin, and bombesin<\/li><li>The substances are stored within intracellular granules and released when necessary.<\/li><\/ul><\/li><\/ul><\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_4\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Lamina propria<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_4\">\n\n\n<ul class=\"wp-block-list\"><li>The lamina propria consists of loose, cell-rich connective tissue found below the basement membrane.<\/li><li>It contains numerous lymphocytes, plasma cells, mast cells, eosinophils, and fibroblasts that produce elastic fibers.<\/li><li>The lymphatic tissue of the trachea is equivalent to the bronchus-associated lymphatic tissue (<strong>BALT<\/strong>).<\/li><li>A special <strong>elastic membrane band<\/strong> separates it the lamina propria and the submucosa (usually, not visible on H&amp;E slides).<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_5\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Submucosa<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_5\">\n\n\n<ul class=\"wp-block-list\"><li>Unlike other organs, the submucosa of the trachea consists of loose connective tissue, denser than the lamina propria, housing submucosal mucous glands.<\/li><li>The submucosal mucous glands are composed of mucous-secreting acini with with serous demilunes, producing and secreting mucous onto the surface of the epithelium.<\/li><li>Lymphatic tissue from the lamina propria extends into the submucosa.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_6\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Cartilage<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_6\">\n\n\n<ul class=\"wp-block-list\"><li>The cartilage of the trachea is a <strong>hyaline type<\/strong> of cartilage covered by perichondrium. <\/li><li>It provides structural rigidity, to prevent the collapse of the trachea. On gross anatomy specimens, it is seen as C-shaped pieces of cartilage, with the free ends facing the esophagus.<\/li><li>A thin, smooth muscle known as the <strong>trachealis muscle<\/strong> spans between the free ends of the cartilage.<\/li><li>In older individuals, the cartilage may become calcified, and resemble bone.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_7\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Adventitia<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_7\">\n\n\n<ul class=\"wp-block-list\"><li>The adventitia of the trachea forms the outer layer, binding the trachea to nearby structures.<\/li><li>It contains the major neurovasculature of the tracheal wall.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_8\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Clinical information<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_8\">\n\n<\/span><span class=\"block-heading\" id=\"header_9\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Squamous metaplasia<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_9\">\n\n\n<ul class=\"wp-block-list\"><li>Recurring irritants and stress (such as those caused by smoking) may cause the production of squamous cells instead of columnar ones.<\/li><li>Squamous epithelium is more resistant to irritation, but offers inferior protection against dust and small particles.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_10\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">References<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_10\">\n\n\n<ol class=\"wp-block-list\"><li>Krasteva G, Canning BJ, Hartmann P, et al. Cholinergic chemosensory cells in the trachea regulate breathing. Proc Natl Acad Sci U S A. 2011;108(23):9478-9483. doi:10.1073\/pnas.1019418108<\/li><\/ol>\n<\/span><div id=\"the_titles\" style=\"display:none;\"><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Layers<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Mucosa<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Epithelium<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Lamina propria<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Submucosa<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Cartilage<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Adventitia<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Clinical information<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Squamous metaplasia<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">References<\/h3><\/div>","protected":false},"excerpt":{"rendered":"<p>Layers Mucosa Epithelium (pseudostratified columnar epithelium) Lamina propria Submucosa Cartilage Adventitia Mucosa Epithelium Ciliated pseudostratified columnar epithelium with goblet cells resting on a thick, well-defined basement membrane. It is covered by a thin mucous layer consisting of mucopolysaccharides, produced by the goblet cells and mucosal glands of the submucosa. The cell population consists of 5 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":6601,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-6605","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Trachea &#8211; Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/pre-clinical\/histology\/respiratory-system\/trachea\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/histology\\\/respiratory-system\\\/trachea\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/histology\\\/respiratory-system\\\/trachea\\\/\",\"name\":\"Trachea &#8211; 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