L 28.2 Mechanisms of Homeostasis

L 28.2 Mechanisms of Homeostasis

* Learning Objectives: • Relate homeostasis to the internal environment of the body. • Explain how negative and positive feedback maintain homeostasis. 

Homeostasis is the regulation and maintenance of the internal environment.

•Homeostasis involves keeping the internal environment within set ranges.Homeostasis  is the regulation and maintenance of the internal environment—temperature, fluids, salts, pH, nutrients, and gases—within the narrow ranges that support human life. Your internal control systems respond quickly to change, whether from outside conditions or internal ones.  

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https://www.youtube.com/watch?v=XZxuQo3ylII (Embed)

Caption: : Watch the video, take notes to explain how homeostasis help maintain your internal environment stable

Control systems help maintain homeostasis like

A.. Sensors = gather data   senses B. Control Center= receives data, interprets info, sends messages out.    Brain receives information from the sensors. It then compares this information to the set points, or ideal values, at which the body functions best. When conditions move above or below a set point, the control center responds by sending messages through a communication system. C. Communication System= delivers messages to target organs, tissues   PNS (e.g. motor neurons) D. Targets = respond to change.   muscles, glands (release hormones)

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Feedback Mechanisms

Sensors, control centers, communication systems, and targets work together in what is known as a feedback loop. Feedback is information from sensors that allows a control center to compare current conditions to a set of ideal values. In a feedback loop, information moves continuously among sensors, a control center, and a target. Most functions in the body are regulated by negative feedback loops.

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Negative Feedback

*  Negative feedback loops are necessary for homeostasis. •Feedback compares current conditions to the body’s comfort levels (=Set Ranges). •Negative feedback counteracts change and brings the body back to homeostasis. * ExampleAs you hold your breath, sensors in the circulatory and respiratory systems send information to the brain stem, the body’s respiratory control center. Sensors signal a gradual increase in carbon dioxide (CO2) and a decrease in oxygen (O2). The control center compares this information with the set points for these gases. When the change becomes too great, the control center takes steps to counteract it. Messages are sent to the muscles of the diaphragm and the rib cage to relax and then contract, forcing you to exhale and then inhale deeply.  

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Negative Feedback mechanisms

* There are many examples of how negative feed back loops help maintain homeostasis:1) Thermoregulation2) Regulation of blood glucose levels3) Water levels in the bodyTask-1Watch the videos, use the internetto describe how your body uses negative feedback loop to maintain homeostasis. {Groups} 15 min. Note: rest of the videos are in the following slides

https://www.youtube.com/watch?v=YQMgV9pkwwA (Embed)

Negative Feedback Mechanism

https://www.youtube.com/watch?v=dJ8WXpsUXYQ (Embed)

https://www.youtube.com/watch?v=ae_jC4FDOUc (Embed)

Positive feedback mechanism

In positive feedback, a control center uses information from sensors to increase the rate of change away from the set points. Though not as common in the body, this type of feedback is important whenever rapid change is needed. For example, if you cut your finger, positive feedback mechanisms increase the rate of change in clotting factors in the blood until the wound is sealed. Once the injury heals, another positive feedback loop occurs as chemicals are released to dissolve the clot. Positive feedback also occurs in the release of certain growth hormones during puberty. Your body needs higher levels of these hormones to accomplish all of the changes that take place at this time. 

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A disruption of homeostasis can be harmful.

•Homeostasis can be disrupted for several reasons. 1. sensors fail (don’t detect changes) 2. targets do not receive messages (nerve issues) 3. injury (overwhelm homeostatic controls) 4. illness (viruses or bacteria) *Disruption of homeostasis can begin in one organ and cause a chain reaction in the others therefore causing a major body disturbance.

Complete the questions in the worksheet and upload to Showbie.

Use the provided resources to recap the main concepts covered today.

• Homeostasis

Activity

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Caption: :