<p><img alt="" src="https://data.ulearngo.com/assets/0f523863-822f-4ecc-9fd0-1e7ebf0dde84" width="400"/></p>
<h3><strong>What happens if stability is disrupted?</strong></h3>
<p>Remove one stone and the whole arch collapses. The same is true for the human body. All the systems work together to maintain stability or homeostasis. Disrupt one system, and the whole body may be affected.</p>
<h2>Homeostasis</h2>
<p>All of the organs and organ systems of the <a data-lesson="human-body" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/human-body">human body</a> work together like a well-oiled machine. This is because they are closely regulated by the nervous and endocrine systems. The <strong>nervous system</strong> controls virtually all body activities, and the <strong>endocrine system</strong> secretes <strong>hormones</strong> that regulate these activities. Functioning together, the organ systems supply body cells with all the substances they need and eliminate their wastes. They also keep temperature, pH, and other conditions at just the right levels to support <a href="https://app.ulearngo.com/tutorials/introducing-study-of-life/what-is-life">life</a> processes.</p>
<h3>Maintaining Homeostasis</h3>
<p>The process in which organ systems work to maintain a stable internal environment is called <strong>homeostasis</strong>. Keeping a stable internal environment requires constant adjustments. Here are just three of the many ways that human organ systems help the body maintain homeostasis:</p>
<ul>
<li>Respiratory system: A high <a data-lesson="basic-principles-of-gas-exchange" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/basic-principles-of-gas-exchange">concentration</a> of carbon dioxide in the <a data-lesson="blood-2" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/blood-2">blood</a> triggers faster breathing. The <a data-lesson="types-of-breathing" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/types-of-breathing">lungs</a> exhale more frequently, which removes carbon dioxide from the body more quickly.</li>
<li>Excretory system: A low level of <a data-lesson="water-and-life-2" data-subject="biology" data-tutorial="biology-foundations" href="https://app.ulearngo.com/biology/biology-foundations/water-and-life-2">water</a> in the blood triggers retention of water by the kidneys. The <a data-lesson="kidneys" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/kidneys">kidneys</a> produce more concentrated urine, so less water is lost from the body.</li>
<li>Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a <a data-lesson="hormone" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/hormone">hormone</a> that helps cells absorb sugar from the blood.</li>
</ul>
<p>So how does your body maintain homeostasis? The regulation of your internal environment is done primarily through negative feedback. <strong>Negative feedback</strong> is a response to a stimulus that keeps a variable close to a set value (the figure below). Essentially, it "shuts off" or "turns on" a system when it varies from a set value.</p>
<p>For example, your body has an internal thermostat. During a winter day, in your house a thermostat <a data-lesson="senses" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/senses">senses</a> the temperature in a room and responds by turning on or off the heater. Your body acts in much the same way. When body temperature rises, receptors in the skin and the brain sense the temperature change. The temperature change triggers a command from the brain. This command can cause several responses. If you are too hot, the skin makes sweat and <a data-lesson="blood-vessels-2" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/blood-vessels-2">blood vessels</a> near the skin surface dilate. This response helps decrease body temperature.</p>
<p>Another example of negative feedback has to do with blood <a data-lesson="connections-of-other-sugars-to-glucose-metabolism" data-subject="biology" data-tutorial="cellular-respiration" href="https://app.ulearngo.com/biology/cellular-respiration/connections-of-other-sugars-to-glucose-metabolism">glucose</a> levels. When glucose (sugar) levels in the blood are too high, the <a data-lesson="pancreas" data-subject="biology" data-tutorial="endocrine-system" href="https://app.ulearngo.com/biology/endocrine-system/pancreas">pancreas</a> secretes insulin to stimulate the absorption of glucose and the conversion of glucose into glycogen, which is stored in the liver. As blood glucose levels decrease, less insulin is produced. When glucose levels are too low, another <strong>hormone</strong> called glucagon is produced, which causes the liver to convert <a data-lesson="increase-in-cellular-metabolism" data-subject="biology" data-tutorial="cell-communication" href="https://app.ulearngo.com/biology/cell-communication/increase-in-cellular-metabolism">glycogen</a> back to glucose.</p>
<div class="wp-caption alignnone" style="width: 500px"><img alt="Negative feedback regulation is used to regulate the temperature of the body" height="331" src="https://data.ulearngo.com/assets/c7e7e343-f6b8-4781-88ae-4b31fe29d01a" title="Negative feedback regulation is used to regulate the temperature of the body" width="500"/><p class="wp-caption-text">Feedback Regulation. If a raise in body temperature (stimulus) is detected (receptor), a signal will cause the brain to maintain homeostasis (response). Once the body temperature returns to normal, negative feedback will cause the response to end. This sequence of stimulus-receptor-signal-response is used throughout the body to maintain homeostasis.</p></div>
<h3>Positive Feedback</h3>
<p>Some processes in the body are regulated by positive feedback. <strong>Positive feedback</strong> is when a response to an event increases the likelihood of the event to continue. An example of positive feedback is milk production in nursing mothers. As the baby drinks her mother's milk, the hormone prolactin, a chemical signal, is released. The more the baby suckles, the more prolactin is released, which causes more milk to be produced. Other examples of positive feedback include contractions during childbirth. When constrictions in the uterus push a baby into the birth canal, additional contractions occur.</p>
<h3>Failure of Homeostasis</h3>
<p>Many homeostatic mechanisms such as these work continuously to maintain stable conditions in the human body. Sometimes, however, the mechanisms fail. When they do, cells may not get everything they need, or toxic wastes may accumulate in the body. If homeostasis is not restored, the imbalance may lead to <a data-lesson="neurodegenerative-disorders" data-subject="biology" data-tutorial="nervous-system" href="https://app.ulearngo.com/biology/nervous-system/neurodegenerative-disorders">disease</a> or even death.</p>
<p><iframe allowfullscreen="allowfullscreen" frameborder="0" height="318" src="https://www.youtube.com/embed/62e8IV-WT8c?rel=0&amp;modestbranding=1&amp;cc_lang_pref=en&amp;cc_load_policy=1" width="551"><span class="mce_SELRES_start" data-mce-type="bookmark" style="display: inline-block; width: 0px; overflow: hidden; line-height: 0;">﻿</span></iframe></p>
<h3>Science : Diary of A Snakebite Death</h3>
<p>What does it feel like to be bitten by a venomous snake? In this video by Science Friday, learn about how Dr. Karl P. Schmidt wrote about the effects of snake bite venom while he was dying.</p>
<p><iframe allowfullscreen="allowfullscreen" frameborder="0" height="318" src="https://www.youtube.com/embed/jEyjF2bNQOA?rel=0&amp;modestbranding=1&amp;cc_lang_pref=en&amp;cc_load_policy=1" width="551"><span class="mce_SELRES_start" data-mce-type="bookmark" style="display: inline-block; width: 0px; overflow: hidden; line-height: 0;">﻿</span></iframe></p>
<h2>Summary</h2>
<ul>
<li>All of the organ systems of the body work together to maintain homeostasis of the organism.</li>
<li>If homeostasis fails, death or disease may result.</li>
</ul>

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Homeostasis

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

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Homeostasis

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