{"id":4272,"date":"2017-03-28T18:58:01","date_gmt":"2017-03-28T18:58:01","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=4272"},"modified":"2024-04-26T02:42:15","modified_gmt":"2024-04-26T02:42:15","slug":"thermoregulation-2","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/thermoregulation-2\/","title":{"raw":"Thermoregulation","rendered":"Thermoregulation"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Explain how the skin helps maintain body temperature<\/li>\r\n<\/ul>\r\n<\/div>\r\nBody temperature is primarily regulated by an area in the brain known as the hypothalamus. The hypothalamus sets the body\u2019s temperature and controls it by opening and closing sweat glands and contracting muscles.\r\n\r\nThe integumentary system helps regulate body temperature through its tight association with the sympathetic nervous system, the division of the nervous system involved in our fight-or-flight responses. The sympathetic nervous system is continuously monitoring body temperature and initiating appropriate motor responses.\r\n\r\nRecall that sudoriferous glands, accessory structures to the skin, secrete sweat\u00a0to cool the body when it becomes warm. Even when the body does not appear to be noticeably sweating, approximately 500 mL of sweat (insensible perspiration) are secreted a day. If the body becomes excessively warm due to high temperatures, vigorous activity (Figure 1), or a combination of the two, sweat glands will be stimulated by the sympathetic nervous system to produce large amounts of sweat, as much as 0.7 to 1.5 L per hour for an active person. When the sweat evaporates from the skin surface, the body is cooled as body heat is dissipated.\r\n\r\nIn addition to sweating, arterioles in the dermis dilate so that excess heat carried by the blood can dissipate through the skin and into the surrounding environment (Figure 1). This accounts for the skin redness that many people experience when exercising.\r\n\r\n[caption id=\"attachment_2859\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-2859\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08172355\/515_Thermoregulation-1024x453.jpg\" alt=\"Part A is a photo of a man skiing with several snow-covered trees in the background. Part B is a diagram with a right and left half. The left half is titled \u201c Heat is retained by the body,\u201d while the right half is titled \u201cHeat loss through radiation and convection.\u201d Both show blood flowing from an artery through three capillary beds within the skin. The beds are arranged vertically, with the topmost bed located along the boundary of the dermis and epidermis. The bottommost bed is located deep in the hypodermis. The middle bed is evenly spaced between the topmost and bottommost beds. In each bed, oxygenated blood (red) enters the bed on the left and deoxygenated blood (blue) leaves the bed on the right. The left diagram shows a picture of snowflakes above the capillary beds, indicating that the weather is cold. Blood is only flowing through the deepest of the three capillary beds, as the upper beds are closed off to reduce heat loss from the outer layers of the skin. The right diagram shows a picture of the sun above the capillary beds, indicating that the weather is hot. Blood is flowing through all three capillary beds, allowing heat to radiate out of the blood, increasing heat loss. Part C is a photo of a man running through a forested trail on a summer day.\" width=\"1024\" height=\"453\" \/> Figure 1. During strenuous physical activities, such as skiing (a) or running (c), the dermal blood vessels dilate and sweat secretion increases (b). These mechanisms prevent the body from overheating. In contrast, the dermal blood vessels constrict to minimize heat loss in response to low temperatures (b). (credit a: \u201cTrysil\u201d\/flickr; credit c: Ralph Daily)[\/caption]\r\n\r\nWhen body temperatures drop, the arterioles constrict to minimize heat loss, particularly in the ends of the digits and tip of the nose. This reduced circulation can result in the skin taking on a whitish hue. Although the temperature of the skin drops as a result, passive heat loss is prevented, and internal organs and structures remain warm. If the temperature of the skin drops too much (such as environmental temperatures below freezing), the conservation of body core heat can result in the skin actually freezing, a condition called frostbite.\r\n<div class=\"textbox exercises\">\r\n<h3>Practice Questions<\/h3>\r\nWhy do people sweat excessively when exercising outside on a hot day?\r\n\r\n[practice-area rows=\"2\"][\/practice-area]\r\n[reveal-answer q=\"666424\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"666424\"]Sweating cools the body when it becomes warm. When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating heat.\r\n\r\n[\/hidden-answer]\r\n<div id=\"fs-id1178547\" class=\"problem\">\r\n<p id=\"fs-id1516170\">Explain your skin\u2019s response to a drop in body core temperature.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1037880\" class=\"solution ui-solution-visible\">\r\n<div class=\"ui-toggle-wrapper\">[practice-area rows=\"2\"][\/practice-area]\r\n[reveal-answer q=\"916\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"916\"]When the core body temperature drops, the body switches to heat-conservation mode. This can include an inhibition to excessive sweating and a decrease of blood flow to the papillary layers of the skin. This reduction of blood flow helps conserve body heat.[\/hidden-answer]<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/3202ff56-3caa-4340-bdf5-fd6c5f07f6b8\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Explain how the skin helps maintain body temperature<\/li>\n<\/ul>\n<\/div>\n<p>Body temperature is primarily regulated by an area in the brain known as the hypothalamus. The hypothalamus sets the body\u2019s temperature and controls it by opening and closing sweat glands and contracting muscles.<\/p>\n<p>The integumentary system helps regulate body temperature through its tight association with the sympathetic nervous system, the division of the nervous system involved in our fight-or-flight responses. The sympathetic nervous system is continuously monitoring body temperature and initiating appropriate motor responses.<\/p>\n<p>Recall that sudoriferous glands, accessory structures to the skin, secrete sweat\u00a0to cool the body when it becomes warm. Even when the body does not appear to be noticeably sweating, approximately 500 mL of sweat (insensible perspiration) are secreted a day. If the body becomes excessively warm due to high temperatures, vigorous activity (Figure 1), or a combination of the two, sweat glands will be stimulated by the sympathetic nervous system to produce large amounts of sweat, as much as 0.7 to 1.5 L per hour for an active person. When the sweat evaporates from the skin surface, the body is cooled as body heat is dissipated.<\/p>\n<p>In addition to sweating, arterioles in the dermis dilate so that excess heat carried by the blood can dissipate through the skin and into the surrounding environment (Figure 1). This accounts for the skin redness that many people experience when exercising.<\/p>\n<div id=\"attachment_2859\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2859\" class=\"size-large wp-image-2859\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/08172355\/515_Thermoregulation-1024x453.jpg\" alt=\"Part A is a photo of a man skiing with several snow-covered trees in the background. Part B is a diagram with a right and left half. The left half is titled \u201c Heat is retained by the body,\u201d while the right half is titled \u201cHeat loss through radiation and convection.\u201d Both show blood flowing from an artery through three capillary beds within the skin. The beds are arranged vertically, with the topmost bed located along the boundary of the dermis and epidermis. The bottommost bed is located deep in the hypodermis. The middle bed is evenly spaced between the topmost and bottommost beds. In each bed, oxygenated blood (red) enters the bed on the left and deoxygenated blood (blue) leaves the bed on the right. The left diagram shows a picture of snowflakes above the capillary beds, indicating that the weather is cold. Blood is only flowing through the deepest of the three capillary beds, as the upper beds are closed off to reduce heat loss from the outer layers of the skin. The right diagram shows a picture of the sun above the capillary beds, indicating that the weather is hot. Blood is flowing through all three capillary beds, allowing heat to radiate out of the blood, increasing heat loss. Part C is a photo of a man running through a forested trail on a summer day.\" width=\"1024\" height=\"453\" \/><\/p>\n<p id=\"caption-attachment-2859\" class=\"wp-caption-text\">Figure 1. During strenuous physical activities, such as skiing (a) or running (c), the dermal blood vessels dilate and sweat secretion increases (b). These mechanisms prevent the body from overheating. In contrast, the dermal blood vessels constrict to minimize heat loss in response to low temperatures (b). (credit a: \u201cTrysil\u201d\/flickr; credit c: Ralph Daily)<\/p>\n<\/div>\n<p>When body temperatures drop, the arterioles constrict to minimize heat loss, particularly in the ends of the digits and tip of the nose. This reduced circulation can result in the skin taking on a whitish hue. Although the temperature of the skin drops as a result, passive heat loss is prevented, and internal organs and structures remain warm. If the temperature of the skin drops too much (such as environmental temperatures below freezing), the conservation of body core heat can result in the skin actually freezing, a condition called frostbite.<\/p>\n<div class=\"textbox exercises\">\n<h3>Practice Questions<\/h3>\n<p>Why do people sweat excessively when exercising outside on a hot day?<\/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=\"q666424\">Show Answer<\/span><\/p>\n<div id=\"q666424\" class=\"hidden-answer\" style=\"display: none\">Sweating cools the body when it becomes warm. When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating heat.<\/p>\n<\/div>\n<\/div>\n<div id=\"fs-id1178547\" class=\"problem\">\n<p id=\"fs-id1516170\">Explain your skin\u2019s response to a drop in body core temperature.<\/p>\n<\/div>\n<div id=\"fs-id1037880\" class=\"solution ui-solution-visible\">\n<div class=\"ui-toggle-wrapper\"><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=\"q916\">Show Answer<\/span><\/p>\n<div id=\"q916\" class=\"hidden-answer\" style=\"display: none\">When the core body temperature drops, the body switches to heat-conservation mode. This can include an inhibition to excessive sweating and a decrease of blood flow to the papillary layers of the skin. This reduction of blood flow helps conserve body heat.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_3202ff56-3caa-4340-bdf5-fd6c5f07f6b8\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/3202ff56-3caa-4340-bdf5-fd6c5f07f6b8?iframe_resize_id=assessment_practice_id_3202ff56-3caa-4340-bdf5-fd6c5f07f6b8\" 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-4272\">\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><li>An eText of Human Anatomy and Physiology. <strong>Authored by<\/strong>: Dr. Bruce Forciea. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.bruceforciea.com\/etextchapters\/etexthumananatrevmay12.pdf\">http:\/\/www.bruceforciea.com\/etextchapters\/etexthumananatrevmay12.pdf<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/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":13,"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\"},{\"type\":\"cc\",\"description\":\"An eText of Human Anatomy and Physiology\",\"author\":\"Dr. Bruce Forciea\",\"organization\":\"\",\"url\":\"http:\/\/www.bruceforciea.com\/etextchapters\/etexthumananatrevmay12.pdf\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"250edd0b-345a-4a27-9a88-294b1947460b, 7bfbbbfc-54a6-46ca-bc1e-320925e49614","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4272","chapter","type-chapter","status-publish","hentry"],"part":3797,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4272","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":10,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4272\/revisions"}],"predecessor-version":[{"id":8716,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4272\/revisions\/8716"}],"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\/4272\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=4272"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=4272"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=4272"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=4272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}