{"id":227362,"date":"2025-06-06T05:21:57","date_gmt":"2025-06-06T05:21:57","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=227362"},"modified":"2025-06-06T05:21:59","modified_gmt":"2025-06-06T05:21:59","slug":"time-to-trace-negative-feedback-loops-eearlier-in-this-unit-we-pointed-out-that-each-hormone-has-its-own-stimulus-for-secretion","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/06\/time-to-trace-negative-feedback-loops-eearlier-in-this-unit-we-pointed-out-that-each-hormone-has-its-own-stimulus-for-secretion\/","title":{"rendered":"Time to Trace! Negative Feedback Loops Eearlier in this unit we pointed out that each hormone has its own stimulus for secretion."},"content":{"rendered":"\n

Time to Trace! Negative Feedback Loops Eearlier in this unit we pointed out that each hormone has its own stimulus for secretion. The stimulus for secretion is generally a disturbance in the homeostasis of a particular physiologic variable such as blood pressure, the concentration of glucose in the blood, or body temperature. The hormone’s response is to act on distant target cells to cause changes that restore the variable to its normal range. When homeostasis is restored, the activity of the glands and concentration of the hormone declines. This type of response is called a negative feedback loop. In this exercise you will be tracing a hormone’s negative feedback loop from the initial homeostatic disturbance, through the hormone’s effects on its target cells to restore homeostasis, and finally the decline of the concentration of the hormone in the blood. Following is an example: Start: the concentration of glucose in the blood falls the pancreas releases glucagon ? the level of the hormone glucagon in the blood rises the hormone glucagon causes glycogenolysis by the liver the concentration of glucose in the blood rises the level of the hormone glucagon in the blood decreases ? End Now it’s your turn! After you have completed the activity, answer Check Your Understanding question 6 (p. 444). 1 Start: the concentration of the blood increases (i.e., there is inadequate water in the blood) the hypothalamus releases the hormone and stores it in the the stored hormone the hormone ?the concentration of the blood in the blood is released and so its level in the blood rises? causes the level of the hormone ? End 16 2 Start: the concentration of glucose in the blood increases the pancreas releases the hormone the level of the hormone in the blood rises the hormone ? blood glucose levels in the blood causes ?the level of the hormone ? End 3 Start: the concentration of calcium ions in the blood decreases the parathyroid glands release the hormone in the blood rises the hormone blood the blood ? the level of the hormone causes ?the concentration of calcium ions in the ? the level of the hormone in ? End Endocrine System UNIT 16 433<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

1. Osmoregulation (Water Balance)<\/strong><\/h3>\n\n\n\n

Start:<\/strong> The concentration of the blood increases (i.e., there is inadequate water in the blood)
\u2192 The hypothalamus releases the hormone antidiuretic hormone (ADH)<\/strong> and stores it in the posterior pituitary<\/strong>
\u2192 The stored hormone ADH<\/strong> is released and so its level in the blood rises
\u2192 The hormone ADH<\/strong> causes the kidneys to reabsorb more water<\/strong>, reducing water loss in urine
\u2192 The concentration of the blood decreases (i.e., water levels increase)<\/strong>
\u2192 The level of the hormone ADH<\/strong> in the blood decreases
End<\/strong><\/p>\n\n\n\n

\n\n\n\n

2. Glucose Regulation<\/strong><\/h3>\n\n\n\n

Start:<\/strong> The concentration of glucose in the blood increases
\u2192 The pancreas releases the hormone insulin<\/strong>
\u2192 The level of the hormone insulin<\/strong> in the blood rises
\u2192 The hormone insulin<\/strong> causes body cells to take in glucose and the liver to store glucose as glycogen<\/strong>
\u2192 Blood glucose levels in the blood decrease<\/strong>
\u2192 The level of the hormone insulin<\/strong> in the blood decreases<\/strong>
End<\/strong><\/p>\n\n\n\n

\n\n\n\n

3. Calcium Homeostasis<\/strong><\/h3>\n\n\n\n

Start:<\/strong> The concentration of calcium ions in the blood decreases
\u2192 The parathyroid glands release the hormone parathyroid hormone (PTH)<\/strong>
\u2192 The level of the hormone PTH<\/strong> in the blood rises
\u2192 The hormone PTH<\/strong> causes bones to release calcium, kidneys to retain calcium, and intestines to absorb more calcium<\/strong>
\u2192 The concentration of calcium ions in the blood increases<\/strong>
\u2192 The level of the hormone PTH<\/strong> in the blood decreases<\/strong>
End<\/strong><\/p>\n\n\n\n

\n\n\n\n

Explanation <\/strong><\/h3>\n\n\n\n

The endocrine system maintains homeostasis through a mechanism called the negative feedback loop<\/strong>, where a physiological change triggers a hormone response that ultimately negates or reduces the original change. Each hormone targets specific organs or tissues to correct the imbalance.<\/p>\n\n\n\n

In osmoregulation<\/strong>, when blood becomes too concentrated due to low water levels, the hypothalamus signals the release of ADH<\/strong> from the posterior pituitary. ADH increases water reabsorption by the kidneys, diluting the blood and lowering its osmolarity. Once water levels normalize, ADH secretion decreases.<\/p>\n\n\n\n

In glucose regulation<\/strong>, an increase in blood glucose after a meal stimulates the pancreas to release insulin<\/strong>. Insulin promotes glucose uptake by cells and storage as glycogen in the liver, thus reducing blood glucose levels. As normal glucose levels are restored, insulin secretion drops.<\/p>\n\n\n\n

In calcium homeostasis<\/strong>, low calcium levels in the blood stimulate the parathyroid glands<\/strong> to release PTH<\/strong>. PTH increases calcium levels by stimulating bone resorption, enhancing kidney reabsorption of calcium, and increasing calcium absorption in the intestines. When calcium levels rise, PTH secretion decreases.<\/p>\n\n\n\n

In all three cases, hormone secretion is directly linked to restoring balance, and once balance is achieved, hormone levels fall. This precise regulation prevents overcorrection and maintains internal stability.<\/p>\n\n\n\n

\"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

Time to Trace! Negative Feedback Loops Eearlier in this unit we pointed out that each hormone has its own stimulus for secretion. The stimulus for secretion is generally a disturbance in the homeostasis of a particular physiologic variable such as blood pressure, the concentration of glucose in the blood, or body temperature. The hormone’s response […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-227362","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/227362","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=227362"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/227362\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=227362"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=227362"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=227362"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}