Course Hero Logo

14 thermoregulation a negative feedback loop negative

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 18 - 21 out of 34 pages.

14Thermoregulation: A Negative Feedback LoopNegative feedback is the most common feedback loop in biological systems.The system acts to reverse the direction of change. Since this tends to keep thingsconstant, it allows the maintenance of homeostatic balance. For instance, when theconcentration of carbon dioxide in the human body increases, the lungs are signaledto increase their activity and exhale more carbon dioxide, (your breathing rateincreases). Thermoregulation is another example of negative feedback. When bodytemperature rises, receptors in the skin and the hypothalamus sense the temperaturechange. The temperature change (stimulus) triggers a command from the brain. Thiscommand, causes a response (the skin makes sweat and blood vessels near the skinsurface dilate), which helps decrease body temperature. Figure 5 shows how theresponse to a stimulus reduces the original stimulus in another of the body’s negativefeedback mechanisms.
15Figure 5: Control of blood glucose level is an example of negative feedback. Blood glucoseconcentration rises after a meal (the stimulus). The hormone insulin is released by thepancreas, and it speeds up the transport of glucose from the blood and into selected tissues(the response). Blood glucose concentrations then decrease, which then decreases the originalstimulus. The secretion of insulin into the blood is then decreased.Positive feedback is less common in biological systems. Positive feedback actsto speed up the direction of change. An example of positive feedback is lactation (milkproduction). As the baby suckles, nerve messages from the mammary glands causethe hormone prolactin, to be secreted by the pituitary gland. The more the babysuckles, the more prolactin is released, which stimulates further milk production.Not many feedback mechanisms in the body are based on positive feedback. Positivefeedback speeds up the direction of change, which leads to increasing hormoneconcentration, a state that moves further away from homeostasis.
16System InteractionsEach body system contributes to the homeostasis of other systems and of theentire organism. No system of the body works in isolation and the well-being of theperson depends upon the well-being of all the interacting body systems. A disruptionwithin one system generally has consequences for several additional body systems.Most of these organ systems are controlled by hormones secreted from the pituitarygland, a part of the endocrine system.Main examples of homeostasis in mammals are as follows:oThe regulation of the amounts of water and minerals in the body. This isknown asosmoregulation. This happens primarily in the kidneys.oThe removal of metabolic waste. This is known as excretion. This is doneby the excretory organs such as the kidneys and lungs.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 34 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Spring
Professor
NoProfessor
Tags

Newly uploaded documents

Show More

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture