Lab 1-Homeostasis and Negative Feedback Systems Exam with verified detailed answers

Lab 1-Homeostasis and Negative Feedback Systems Exam
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with verified detailed answers
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Homeostasis

A relatively constant internal environment.
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• Maintained by cells, tissues, and organs that operate through negative feedback systems.
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Negative Feedback ||




• If a variable fluctuates around a set point, external factors stress the system and cause the
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variable to to increase or decrease.
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• Negative feedback detects and change and moves the variable back to its set point in the
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organism.




Controlled Variable and Set Point || || || ||




• A graph of a controlled variable show the variable fluctuating around a set point.
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• Normal range of values is a range of measurements that includes most healthy people.
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Homeostasis more information || ||




1. Homeostasis is constancy of the internal environment.
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,2. The main purpose of our physiological mechanisms is to maintain homeostasis.
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3. Deviation from homeostasis indicates disease.
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4. Homeostasis is accomplished most often by negative feedback loops.
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Negative Feedback Loops
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1. Pathway
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a. Sensors in the body to detect change and send information to the:
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b. Integrating center, which assesses change around a set point. The integrating center then
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sends instructions to an:
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c. Effector, which can make the appropriate adjustments to counter the change from the set-
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point




Mechanism of Negative Feedback Loops || || || ||




a. Moves in the opposite direction from the change
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b. Makes the change from the set-point smaller
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c. Reverses the change in the set-point
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, d. This is a continuous process, always making fine adjustments to stay in homeostasis
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Negative Feedback loops || ||




Body Temperature Example of Negative Feedback Loops
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a. Sensors in the brain detect deviation from 37°C. Another part of the brain assesses this as
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actionable, and effectors (sweat glands) are stimulated to cool the body.
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b. Once the body is cool, sensors alert the integrating center, and sweat glands are inhibited.
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c. The end result regulates the entire process. Production of the end product shuts off or
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down-regulates the process. This is why it is called a negative feedback loop. || || || || || || || || || || || ||




Antagonistic Effectors ||




a. Homeostasis is often maintained by opposing effectors that move conditions in opposite
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directions.

1) This maintains conditions within a certain normal range, or dynamic constancy.
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2) When you are hot, you sweat; when you are cold, you shiver. These are antagonistic
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reactions.



b. Other examples - blood glucose levels, blood calcium levels, heart rate, and blood pH
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