{"id":564,"date":"2021-07-14T19:02:08","date_gmt":"2021-07-14T23:02:08","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/pathology\/?post_type=chapter&#038;p=564"},"modified":"2025-11-14T23:33:40","modified_gmt":"2025-11-15T04:33:40","slug":"normal-anatomy-physiology-of-lungs","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/pathology\/chapter\/normal-anatomy-physiology-of-lungs\/","title":{"raw":"Video Lessons on Normal Anatomy and Histology of Lungs","rendered":"Video Lessons on Normal Anatomy and Histology of Lungs"},"content":{"raw":"<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\">Learning Objectives<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nAt the end of this section, you will be able to:\r\n<ul>\r\n \t<li>List differences in lung tissue between being in the body vs. preserved and mounted for presentation.<\/li>\r\n \t<li>Identify bronchioles and alveoli by gross anatomy and microscopically, being aware of the limitations of visualization.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<h2>Normal Lung: Gross Anatomy<\/h2>\r\nLungs are normally encased in the thoracic (chest) cavity, within pleural membranes, under negative pressure (a vacuum). Thus, when we remove lungs to put in a specimen case, the lungs will appear more shrunken than its size when in the chest, thanks to the high amount of elastin within the lung. The high elastin content allows the lungs to 'snap' back into a smaller volume: this is akin to an elastic band which, when relaxed, snaps back to a smaller size. Due to this elasticity, exhalation is a passive process - i.e. no muscle contraction is necessary as all of the work is done by the elastin snapping back and squeezing the air.\r\n\r\nKnowing that lungs will be smaller than in the chest, let's look at the gross anatomy of the internal lung.\r\n\r\n&nbsp;\r\n<div>\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\">Critical Thinking Exercises<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"textbox__content\">\r\n<p class=\"textbox__title\"><strong>Looking at the gross anatomy of lung, what are the black specks?<\/strong><\/p>\r\nEvery breath one takes in their lifetime, we inhale pathogens, irritants, and debris. The lung's defenses (e.g. ciliated epithelia, mucous, coughing, alveolar macrophages, etc.) can trap &amp; remove them physically or immunologically. However, one does inhale irritants which the lung's defenses can't remove. As such, what can't be removed stays within the lungs for one's entire life. These black specks can be from everyday environmental pollution, forest fire smoke, inhaled occupational dust, etc. Thus, over the years, a certain amount (albeit small) of lung tissue will not be able to ventilate due to these accumulated foreign debris plugging up the airways.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n&nbsp;\r\n\r\n<\/div>\r\n<h2>Histology of Normal Lung Tissue<\/h2>\r\nRecall that the bulk of the lung's volumes are alveoli - thus giving the lungs an incredible amount of surface area for gas exchange. Thus, when viewing lung tissue at lower power magnification, the majority of the tissue seen are alveoli of similar shape and size, thus giving a [pb_glossary id=\"2377\"]homogenous [\/pb_glossary]pattern. Large spaces are bronchioles, with the amount of cartilage visible (stains purple with H&amp;E) indicating the proximal airways to the primary bronchi and the amount of smooth muscle indicating the distal airways, closer to the alveoli. Although H&amp;E stain protein in general, it cannot differentiate between protein types (e.g. elastin vs collagen). However, normal lungs have a relatively large amount of elastin.\r\n\r\nLet's listen to histopathologist Dr. Jonathan Bush examine normal lung tissue, stained with H&amp;E, at low- and high-power magnification.\r\n\r\n[h5p id=\"66\"]\r\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup><strong>Histology of Normal Lung on Lower Power Magnification<\/strong> (<em>DHPLC E-slide: Path 304 - 030a)<\/em>\u00a0 by Jonathan Bush, licensed under <a href=\"https:\/\/choosealicense.com\/no-license\/\">All Rights Reserved<\/a><\/sup><\/p>\r\n[h5p id=\"65\"]\r\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup><strong>Histology of Normal Lung on High Power Magnification<\/strong> (<em>DHPLC E-slide: Path 304 - 030a) <\/em>\u00a0by Jonathan Bush and Adrian Marcuzzi, licensed under <a href=\"https:\/\/choosealicense.com\/no-license\/\">All Rights Reserved<\/a><\/sup><\/p>\r\n\r\n<h2>Section Review<\/h2>\r\n<ul>\r\n \t<li>Lungs are highly vascularized (via pulmonary blood vessels) and in the body, fully expanded, because of the negative pressure within the chest cavity. However, during preservation and mounting, the lungs have the blood either washed out or react with preservatives giving it a grey colour. Similarly, the lungs are smaller and collapsed in the presentation case as they are no longer under negative pressure.<\/li>\r\n \t<li>Large airways such as bronchi and bronchioles are visible to the naked eye. Microscopic examination on high power allows for visualization of alveoli and pulmonary blood vessels.<\/li>\r\n \t<li>Alveoli are identifiable by a large air space, surrounded by a very thin wall, one cell thick, with blood vessels in close proximity.<\/li>\r\n<\/ul>\r\n<h1>Review Questions<\/h1>\r\n<div class=\"h5p\">[h5p id=\"236\"]<\/div>\r\n<div class=\"pdf\">\r\n\r\n<strong>1. You can visualize alveoli with the naked eye.<\/strong>\r\n<ul>\r\n \t<li>True<\/li>\r\n \t<li>False<\/li>\r\n<\/ul>\r\n<strong>2. What statement describes bronchi and bronchioles best?<\/strong>\r\n<ul>\r\n \t<li>As bronchi branch into increasingly smaller bronchioles, there is an increase in both cartilage and surface area<\/li>\r\n \t<li>As the bronchioles branch into bronchi, the amount of smooth muscle increases and the amount of cartilage decreases<\/li>\r\n \t<li>The walls of the bronchioles are very thin - only one cell thick - and surrounded by capillaries<\/li>\r\n \t<li>As bronchi branch into increasingly smaller bronchioles, there is a decrease in cartilage<\/li>\r\n<\/ul>\r\n<strong>3. Which statement is correct?\u00a0<\/strong>\r\n<ul>\r\n \t<li>Lungs are very elastic and mostly filled with air - akin to a balloon<\/li>\r\n \t<li>Lungs are very red and dense - akin to muscle<\/li>\r\n \t<li>Lungs are very heavy and dense due to all of the blood vessels<\/li>\r\n \t<li>Lungs are inelastic and red - akin to skin<\/li>\r\n<\/ul>\r\n<div class=\"textbox\">\r\n<h2>Answer Key<\/h2>\r\n<ol>\r\n \t<li>False<\/li>\r\n \t<li>As bronchi branch into increasingly smaller bronchioles, there is a decrease in cartilage<\/li>\r\n \t<li>Lungs are very elastic and mostly filled with air - akin to a balloon<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Learning Objectives<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>At the end of this section, you will be able to:<\/p>\n<ul>\n<li>List differences in lung tissue between being in the body vs. preserved and mounted for presentation.<\/li>\n<li>Identify bronchioles and alveoli by gross anatomy and microscopically, being aware of the limitations of visualization.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2>Normal Lung: Gross Anatomy<\/h2>\n<p>Lungs are normally encased in the thoracic (chest) cavity, within pleural membranes, under negative pressure (a vacuum). Thus, when we remove lungs to put in a specimen case, the lungs will appear more shrunken than its size when in the chest, thanks to the high amount of elastin within the lung. The high elastin content allows the lungs to &#8216;snap&#8217; back into a smaller volume: this is akin to an elastic band which, when relaxed, snaps back to a smaller size. Due to this elasticity, exhalation is a passive process &#8211; i.e. no muscle contraction is necessary as all of the work is done by the elastin snapping back and squeezing the air.<\/p>\n<p>Knowing that lungs will be smaller than in the chest, let&#8217;s look at the gross anatomy of the internal lung.<\/p>\n<p>&nbsp;<\/p>\n<div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Critical Thinking Exercises<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"textbox__content\">\n<p class=\"textbox__title\"><strong>Looking at the gross anatomy of lung, what are the black specks?<\/strong><\/p>\n<p>Every breath one takes in their lifetime, we inhale pathogens, irritants, and debris. The lung&#8217;s defenses (e.g. ciliated epithelia, mucous, coughing, alveolar macrophages, etc.) can trap &amp; remove them physically or immunologically. However, one does inhale irritants which the lung&#8217;s defenses can&#8217;t remove. As such, what can&#8217;t be removed stays within the lungs for one&#8217;s entire life. These black specks can be from everyday environmental pollution, forest fire smoke, inhaled occupational dust, etc. Thus, over the years, a certain amount (albeit small) of lung tissue will not be able to ventilate due to these accumulated foreign debris plugging up the airways.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<\/div>\n<h2>Histology of Normal Lung Tissue<\/h2>\n<p>Recall that the bulk of the lung&#8217;s volumes are alveoli &#8211; thus giving the lungs an incredible amount of surface area for gas exchange. Thus, when viewing lung tissue at lower power magnification, the majority of the tissue seen are alveoli of similar shape and size, thus giving a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_564_2377\">homogenous <\/a>pattern. Large spaces are bronchioles, with the amount of cartilage visible (stains purple with H&amp;E) indicating the proximal airways to the primary bronchi and the amount of smooth muscle indicating the distal airways, closer to the alveoli. Although H&amp;E stain protein in general, it cannot differentiate between protein types (e.g. elastin vs collagen). However, normal lungs have a relatively large amount of elastin.<\/p>\n<p>Let&#8217;s listen to histopathologist Dr. Jonathan Bush examine normal lung tissue, stained with H&amp;E, at low- and high-power magnification.<\/p>\n<div id=\"h5p-66\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-66\" class=\"h5p-iframe\" data-content-id=\"66\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Histology of Normal Lung on Low Power Magnification\"><\/iframe><\/div>\n<\/div>\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup><strong>Histology of Normal Lung on Lower Power Magnification<\/strong> (<em>DHPLC E-slide: Path 304 &#8211; 030a)<\/em>\u00a0 by Jonathan Bush, licensed under <a href=\"https:\/\/choosealicense.com\/no-license\/\">All Rights Reserved<\/a><\/sup><\/p>\n<div id=\"h5p-65\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-65\" class=\"h5p-iframe\" data-content-id=\"65\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Histology of Normal Lung on High Power Magnification\"><\/iframe><\/div>\n<\/div>\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup><strong>Histology of Normal Lung on High Power Magnification<\/strong> (<em>DHPLC E-slide: Path 304 &#8211; 030a) <\/em>\u00a0by Jonathan Bush and Adrian Marcuzzi, licensed under <a href=\"https:\/\/choosealicense.com\/no-license\/\">All Rights Reserved<\/a><\/sup><\/p>\n<h2>Section Review<\/h2>\n<ul>\n<li>Lungs are highly vascularized (via pulmonary blood vessels) and in the body, fully expanded, because of the negative pressure within the chest cavity. However, during preservation and mounting, the lungs have the blood either washed out or react with preservatives giving it a grey colour. Similarly, the lungs are smaller and collapsed in the presentation case as they are no longer under negative pressure.<\/li>\n<li>Large airways such as bronchi and bronchioles are visible to the naked eye. Microscopic examination on high power allows for visualization of alveoli and pulmonary blood vessels.<\/li>\n<li>Alveoli are identifiable by a large air space, surrounded by a very thin wall, one cell thick, with blood vessels in close proximity.<\/li>\n<\/ul>\n<h1>Review Questions<\/h1>\n<div class=\"h5p\">\n<div id=\"h5p-236\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-236\" class=\"h5p-iframe\" data-content-id=\"236\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"videolesson on normal lung\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<div class=\"pdf\">\n<p><strong>1. You can visualize alveoli with the naked eye.<\/strong><\/p>\n<ul>\n<li>True<\/li>\n<li>False<\/li>\n<\/ul>\n<p><strong>2. What statement describes bronchi and bronchioles best?<\/strong><\/p>\n<ul>\n<li>As bronchi branch into increasingly smaller bronchioles, there is an increase in both cartilage and surface area<\/li>\n<li>As the bronchioles branch into bronchi, the amount of smooth muscle increases and the amount of cartilage decreases<\/li>\n<li>The walls of the bronchioles are very thin &#8211; only one cell thick &#8211; and surrounded by capillaries<\/li>\n<li>As bronchi branch into increasingly smaller bronchioles, there is a decrease in cartilage<\/li>\n<\/ul>\n<p><strong>3. Which statement is correct?\u00a0<\/strong><\/p>\n<ul>\n<li>Lungs are very elastic and mostly filled with air &#8211; akin to a balloon<\/li>\n<li>Lungs are very red and dense &#8211; akin to muscle<\/li>\n<li>Lungs are very heavy and dense due to all of the blood vessels<\/li>\n<li>Lungs are inelastic and red &#8211; akin to skin<\/li>\n<\/ul>\n<div class=\"textbox\">\n<h2>Answer Key<\/h2>\n<ol>\n<li>False<\/li>\n<li>As bronchi branch into increasingly smaller bronchioles, there is a decrease in cartilage<\/li>\n<li>Lungs are very elastic and mostly filled with air &#8211; akin to a balloon<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_564_2377\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_564_2377\"><div tabindex=\"-1\"><p>uniform in composition or character (i.e. color, shape, size, texture, etc.) <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":1232,"menu_order":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["jen-2"],"pb_section_license":""},"chapter-type":[],"contributor":[59],"license":[],"class_list":["post-564","chapter","type-chapter","status-publish","hentry","contributor-jen-2"],"part":328,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/564","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/users\/1232"}],"version-history":[{"count":26,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/564\/revisions"}],"predecessor-version":[{"id":9827,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/564\/revisions\/9827"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/parts\/328"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/564\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/media?parent=564"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapter-type?post=564"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/contributor?post=564"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/license?post=564"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}