{"id":4259,"date":"2017-03-28T18:34:05","date_gmt":"2017-03-28T18:34:05","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=4259"},"modified":"2024-04-26T02:41:51","modified_gmt":"2024-04-26T02:41:51","slug":"glands","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/glands\/","title":{"raw":"Nails and Glands","rendered":"Nails and Glands"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Describe the structure and function of nails and glands<\/li>\r\n<\/ul>\r\n<\/div>\r\n<h2>Nails<\/h2>\r\nThe nail bed is a specialized structure of the epidermis that is found at the tips of our fingers and toes. The <strong>nail body<\/strong> is formed on the <strong>nail bed<\/strong>, and protects the tips of our fingers and toes as they are the farthest extremities and the parts of the body that experience the maximum mechanical stress (Figure 1).\r\n\r\n[caption id=\"attachment_2851\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-2851\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08171245\/507_Nails-1024x309.jpg\" alt=\"These two images show anatomy of the fingernail region. The top image shows a dorsal view of a finger. The proximal nail fold is the part underneath where the skin of the finger connects with the edge of the nail. The eponychium is a thin, pink layer between the white proximal edge of the nail (the lunula), and the edge of the finger skin. The lunula appears as a crescent-shaped white area at the proximal edge of the pink-shaded nail. The lateral nail folds are where the sides of the nail contact the finger skin. The distal edge of the nail is white and is called the free edge. An arrow indicates that the nail grows distally out from the proximal nail fold. The lower image shows a lateral view of the nail bed anatomy. In this view, one can see how the edge of the nail is located just proximal to the nail fold. This end of the nail, from which the nail grows, is called the nail root.\" width=\"1024\" height=\"309\" \/> Figure 1. The nail is an accessory structure of the integumentary system.[\/caption]\r\n\r\nIn addition, the nail body forms a back-support for picking up small objects with the fingers. The nail body is composed of densely packed dead keratinocytes. The epidermis in this part of the body has evolved a specialized structure upon which nails can form. The nail body forms at the <strong>nail root<\/strong>, which has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously. The lateral <strong>nail fold<\/strong> overlaps the nail on the sides, helping to anchor the nail body. The nail fold that meets the proximal end of the nail body forms the <strong>nail cuticle<\/strong>, also called the <strong>eponychium<\/strong>. The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the <strong>lunula<\/strong> (the \u201clittle moon\u201d). The area beneath the free edge of the nail, furthest from the cuticle, is called the <strong>hyponychium<\/strong>. It consists of a thickened layer of stratum corneum.\r\n<div class=\"textbox\">\r\n\r\nNails are accessory structures of the integumentary system. Watch this video\u00a0to learn more about the origin and growth of fingernails.\r\n\r\n<iframe src=\"\/\/plugin.3playmedia.com\/show?mf=6377763&amp;p3sdk_version=1.10.1&amp;p=20361&amp;pt=375&amp;video_id=TxZWOXgnt3A&amp;video_target=tpm-plugin-dyqwvnvf-TxZWOXgnt3A\" width=\"800px\" height=\"450px\" frameborder=\"0\" marginwidth=\"0px\" marginheight=\"0px\"><\/iframe>\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Practice Question<\/h3>\r\nDescribe the structure and composition of nails.\r\n\r\n[practice-area rows=\"2\"][\/practice-area]\r\n[reveal-answer q=\"744481\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"744481\"]Nails are composed of densely packed dead keratinocytes. They protect the fingers and toes from mechanical stress. The nail body is formed on the nail bed, which is at the nail root. Nail folds, folds of skin that overlap the nail on its side, secure the nail to the body. The crescent-shaped region at the base of the nail is the lunula.[\/hidden-answer]\r\n\r\n<\/div>\r\n<h2>Glands<\/h2>\r\n<h3>Sweat Glands<\/h3>\r\nWhen the body becomes warm, <strong>sudoriferous glands<\/strong> produce sweat to cool the body. Sweat glands develop from epidermal projections into the dermis and are classified as merocrine glands; that is, the secretions are excreted by exocytosis through a duct without affecting the cells of the gland. There are two types of sweat glands, each secreting slightly different products.\r\n\r\n[caption id=\"attachment_2852\" align=\"alignright\" width=\"400\"]<img class=\"wp-image-2852\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08171347\/508_Eccrine_gland.jpg\" alt=\"This diagram shows an eccrine sweat gland embedded in a cross section of skin tissue. The eccrine sweat gland is a bundle of white tubes embedded in the dermis. A single white tube travels up from the bundle and opens on to the surface of the epidermis. The opening is called a pore. There are several pores on the small block of skin portrayed in this diagram.\" width=\"400\" height=\"385\" \/> Figure 1. Eccrine glands are coiled glands in the dermis that release sweat that is mostly water.[\/caption]\r\n\r\nAn <strong>eccrine sweat gland<\/strong> is type of gland that produces a hypotonic sweat for thermoregulation. These glands are found all over the skin\u2019s surface, but are especially abundant on the palms of the hand, the soles of the feet, and the forehead (Figure 1). They are coiled glands lying deep in the dermis, with the duct rising up to a pore on the skin surface, where the sweat is released. This type of sweat, released by exocytosis, is hypotonic and composed mostly of water, with some salt, antibodies, traces of metabolic waste, and dermicidin, an antimicrobial peptide. Eccrine glands are a primary component of thermoregulation in humans and thus help to maintain homeostasis.\r\n\r\nAn <strong>apocrine sweat gland<\/strong> is usually associated with hair follicles in densely hairy areas, such as armpits and genital regions. Apocrine sweat glands are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis, with the duct normally emptying into the hair follicle. In addition to water and salts, apocrine sweat includes organic compounds that make the sweat thicker and subject to bacterial decomposition and subsequent smell. The release of this sweat is under both nervous and hormonal control, and plays a role in the poorly understood human pheromone response. Most commercial antiperspirants use an aluminum-based compound as their primary active ingredient to stop sweat. When the antiperspirant enters the sweat gland duct, the aluminum-based compounds precipitate due to a change in pH and form a physical block in the duct, which prevents sweat from coming out of the pore.\r\n<div class=\"textbox\">Sweating regulates body temperature. The composition of the sweat determines whether body odor is a byproduct of sweating. <a href=\"https:\/\/www.mayoclinic.org\/diseases-conditions\/sweating-and-body-odor\/basics\/definition\/con-20014438\" target=\"_blank\" rel=\"noopener\">Visit this link to learn more about sweating and body odor.<\/a><\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Practice Question<\/h3>\r\nExplain the differences between eccrine and apocrine sweat glands.\r\n\r\n[practice-area rows=\"2\"][\/practice-area]\r\n[reveal-answer q=\"694256\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"694256\"]Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They release a watery sweat, mixed with some metabolic waste and antibodies. Apocrine glands are associated with hair follicles. They are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis. They release a thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor.[\/hidden-answer]\r\n\r\n<\/div>\r\n<h3>Sebaceous Glands<\/h3>\r\nA <strong>sebaceous gland<\/strong> is a type of oil gland that is found all over the body and helps to lubricate and waterproof the skin and hair. Most sebaceous glands are associated with hair follicles. They generate and excrete <strong>sebum<\/strong>, a mixture of lipids, onto the skin surface, thereby naturally lubricating the dry and dead layer of keratinized cells of the stratum corneum, keeping it pliable. The fatty acids of sebum also have antibacterial properties, and prevent water loss from the skin in low-humidity environments. The secretion of sebum is stimulated by hormones, many of which do not become active until puberty. Thus, sebaceous glands are relatively inactive during childhood.\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/583ca055-b825-45a4-a612-f5835e04515f\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Describe the structure and function of nails and glands<\/li>\n<\/ul>\n<\/div>\n<h2>Nails<\/h2>\n<p>The nail bed is a specialized structure of the epidermis that is found at the tips of our fingers and toes. The <strong>nail body<\/strong> is formed on the <strong>nail bed<\/strong>, and protects the tips of our fingers and toes as they are the farthest extremities and the parts of the body that experience the maximum mechanical stress (Figure 1).<\/p>\n<div id=\"attachment_2851\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2851\" class=\"size-large wp-image-2851\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08171245\/507_Nails-1024x309.jpg\" alt=\"These two images show anatomy of the fingernail region. The top image shows a dorsal view of a finger. The proximal nail fold is the part underneath where the skin of the finger connects with the edge of the nail. The eponychium is a thin, pink layer between the white proximal edge of the nail (the lunula), and the edge of the finger skin. The lunula appears as a crescent-shaped white area at the proximal edge of the pink-shaded nail. The lateral nail folds are where the sides of the nail contact the finger skin. The distal edge of the nail is white and is called the free edge. An arrow indicates that the nail grows distally out from the proximal nail fold. The lower image shows a lateral view of the nail bed anatomy. In this view, one can see how the edge of the nail is located just proximal to the nail fold. This end of the nail, from which the nail grows, is called the nail root.\" width=\"1024\" height=\"309\" \/><\/p>\n<p id=\"caption-attachment-2851\" class=\"wp-caption-text\">Figure 1. The nail is an accessory structure of the integumentary system.<\/p>\n<\/div>\n<p>In addition, the nail body forms a back-support for picking up small objects with the fingers. The nail body is composed of densely packed dead keratinocytes. The epidermis in this part of the body has evolved a specialized structure upon which nails can form. The nail body forms at the <strong>nail root<\/strong>, which has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously. The lateral <strong>nail fold<\/strong> overlaps the nail on the sides, helping to anchor the nail body. The nail fold that meets the proximal end of the nail body forms the <strong>nail cuticle<\/strong>, also called the <strong>eponychium<\/strong>. The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the <strong>lunula<\/strong> (the \u201clittle moon\u201d). The area beneath the free edge of the nail, furthest from the cuticle, is called the <strong>hyponychium<\/strong>. It consists of a thickened layer of stratum corneum.<\/p>\n<div class=\"textbox\">\n<p>Nails are accessory structures of the integumentary system. Watch this video\u00a0to learn more about the origin and growth of fingernails.<\/p>\n<p><iframe loading=\"lazy\" src=\"\/\/plugin.3playmedia.com\/show?mf=6377763&amp;p3sdk_version=1.10.1&amp;p=20361&amp;pt=375&amp;video_id=TxZWOXgnt3A&amp;video_target=tpm-plugin-dyqwvnvf-TxZWOXgnt3A\" width=\"800px\" height=\"450px\" frameborder=\"0\" marginwidth=\"0px\" marginheight=\"0px\"><\/iframe><\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Practice Question<\/h3>\n<p>Describe the structure and composition of nails.<\/p>\n<p><textarea aria-label=\"Your Answer\" rows=\"2\"><\/textarea><\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q744481\">Show Answer<\/span><\/p>\n<div id=\"q744481\" class=\"hidden-answer\" style=\"display: none\">Nails are composed of densely packed dead keratinocytes. They protect the fingers and toes from mechanical stress. The nail body is formed on the nail bed, which is at the nail root. Nail folds, folds of skin that overlap the nail on its side, secure the nail to the body. The crescent-shaped region at the base of the nail is the lunula.<\/div>\n<\/div>\n<\/div>\n<h2>Glands<\/h2>\n<h3>Sweat Glands<\/h3>\n<p>When the body becomes warm, <strong>sudoriferous glands<\/strong> produce sweat to cool the body. Sweat glands develop from epidermal projections into the dermis and are classified as merocrine glands; that is, the secretions are excreted by exocytosis through a duct without affecting the cells of the gland. There are two types of sweat glands, each secreting slightly different products.<\/p>\n<div id=\"attachment_2852\" style=\"width: 410px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2852\" class=\"wp-image-2852\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08171347\/508_Eccrine_gland.jpg\" alt=\"This diagram shows an eccrine sweat gland embedded in a cross section of skin tissue. The eccrine sweat gland is a bundle of white tubes embedded in the dermis. A single white tube travels up from the bundle and opens on to the surface of the epidermis. The opening is called a pore. There are several pores on the small block of skin portrayed in this diagram.\" width=\"400\" height=\"385\" \/><\/p>\n<p id=\"caption-attachment-2852\" class=\"wp-caption-text\">Figure 1. Eccrine glands are coiled glands in the dermis that release sweat that is mostly water.<\/p>\n<\/div>\n<p>An <strong>eccrine sweat gland<\/strong> is type of gland that produces a hypotonic sweat for thermoregulation. These glands are found all over the skin\u2019s surface, but are especially abundant on the palms of the hand, the soles of the feet, and the forehead (Figure 1). They are coiled glands lying deep in the dermis, with the duct rising up to a pore on the skin surface, where the sweat is released. This type of sweat, released by exocytosis, is hypotonic and composed mostly of water, with some salt, antibodies, traces of metabolic waste, and dermicidin, an antimicrobial peptide. Eccrine glands are a primary component of thermoregulation in humans and thus help to maintain homeostasis.<\/p>\n<p>An <strong>apocrine sweat gland<\/strong> is usually associated with hair follicles in densely hairy areas, such as armpits and genital regions. Apocrine sweat glands are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis, with the duct normally emptying into the hair follicle. In addition to water and salts, apocrine sweat includes organic compounds that make the sweat thicker and subject to bacterial decomposition and subsequent smell. The release of this sweat is under both nervous and hormonal control, and plays a role in the poorly understood human pheromone response. Most commercial antiperspirants use an aluminum-based compound as their primary active ingredient to stop sweat. When the antiperspirant enters the sweat gland duct, the aluminum-based compounds precipitate due to a change in pH and form a physical block in the duct, which prevents sweat from coming out of the pore.<\/p>\n<div class=\"textbox\">Sweating regulates body temperature. The composition of the sweat determines whether body odor is a byproduct of sweating. <a href=\"https:\/\/www.mayoclinic.org\/diseases-conditions\/sweating-and-body-odor\/basics\/definition\/con-20014438\" target=\"_blank\" rel=\"noopener\">Visit this link to learn more about sweating and body odor.<\/a><\/div>\n<div class=\"textbox exercises\">\n<h3>Practice Question<\/h3>\n<p>Explain the differences between eccrine and apocrine sweat glands.<\/p>\n<p><textarea aria-label=\"Your Answer\" rows=\"2\"><\/textarea><\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q694256\">Show Answer<\/span><\/p>\n<div id=\"q694256\" class=\"hidden-answer\" style=\"display: none\">Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They release a watery sweat, mixed with some metabolic waste and antibodies. Apocrine glands are associated with hair follicles. They are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis. They release a thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor.<\/div>\n<\/div>\n<\/div>\n<h3>Sebaceous Glands<\/h3>\n<p>A <strong>sebaceous gland<\/strong> is a type of oil gland that is found all over the body and helps to lubricate and waterproof the skin and hair. Most sebaceous glands are associated with hair follicles. They generate and excrete <strong>sebum<\/strong>, a mixture of lipids, onto the skin surface, thereby naturally lubricating the dry and dead layer of keratinized cells of the stratum corneum, keeping it pliable. The fatty acids of sebum also have antibacterial properties, and prevent water loss from the skin in low-humidity environments. The secretion of sebum is stimulated by hormones, many of which do not become active until puberty. Thus, sebaceous glands are relatively inactive during childhood.<\/p>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_583ca055-b825-45a4-a612-f5835e04515f\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/583ca055-b825-45a4-a612-f5835e04515f?iframe_resize_id=assessment_practice_id_583ca055-b825-45a4-a612-f5835e04515f\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-4259\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Anatomy &amp; Physiology. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.79\">http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.79<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.79<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":10,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Anatomy & Physiology\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.79\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at http:\/\/cnx.org\/contents\/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.79\"}]","CANDELA_OUTCOMES_GUID":"939a0072-a991-4dcd-b47e-b607cc13a258, eb449b4b-e87c-4bb8-ac94-e88b427b0d70","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4259","chapter","type-chapter","status-publish","hentry"],"part":3797,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4259","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":11,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4259\/revisions"}],"predecessor-version":[{"id":8713,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4259\/revisions\/8713"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/parts\/3797"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4259\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=4259"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=4259"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=4259"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=4259"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}