The figure below shows another way of diagramming negative feedback regulation of internal body temperature. In each discussion, you can probe student thinking and help them develop a sound understanding of the concepts and information covered before moving on to the next group of related questions. In the Student Handout, numbers in bold indicate questions for the students to answer.Ī key is available upon request to Ingrid Waldron ( The following paragraphs provide additional instructional suggestions and background information – some for inclusion in your class discussions and some to provide you with the relevant background that may be useful for your understanding and/or for responding to student questions.įor the analysis and discussion questions, you can maximize student participation and learning, by having your students work individually, in pairs, or in small groups to complete groups of related questions and then having a class discussion after each group of related questions. "Negative Feedback and the Regulation of Breathing" experiment and begin analysisĪnalyze and interpret negative feedback experiment and plan experiments for "Homeostasis and Changes in Breathing Due to Exercise"įinish planning and carry out exercise experiments and analyze and interpret results you may want to assign question 29 as homework. If time is limited, you may want to use just sections I-III and omit section IV, Homeostasis and Changes in Breathing Due to Exercise if you have some teaching time after final tests have been administered at the end of the year, you may want to use section IV during that time.Īnalysis and discussion questions on "Homeostasis and Negative Feedback" and "Respiration and Circulation" + Prepare for negative feedback experiment The following timeline may be appropriate for this multi-part activity (assuming you have 50-minute class periods). Instructional Suggestions and Background Information For a scientific investigation to yield accurate results, scientists need to begin by developing reliable, valid methods of measuring the variables in the investigation.To maintain homeostasis during exercise, breathing rate and depth increase to supply more O 2 and remove more CO 2. This requires a substantially increased rate of cellular respiration. When a person exercises, his or her muscle cells use much more ATP per second than when he or she is resting.Increased blood levels of CO 2 stimulate increased breathing (especially increased depth of breathing). Negative feedback regulation of blood levels of CO 2 and O 2 helps to ensure that enough O 2 is delivered to meet the cells’ needs for cellular respiration and enough CO 2 is removed to prevent harmful effects.CO 2 produced by cellular respiration moves through the blood to the lungs where it is exhaled. O 2 diffuses from the blood into the cells where O 2 is used in cellular respiration. The O 2-carrying blood is pumped by the heart to blood vessels near all the cells in the body. O 2 diffuses from the air in the tiny air sacs of the lungs into the blood. When a person inhales, air with O 2 is brought into the lungs. The respiratory and circulatory systems work together to bring O 2 to cells all over the body and get rid of CO 2.Cellular respiration requires O 2 and produces CO 2. Cells carry out cellular respiration to make ATP, a molecule that provides energy in a form that cells can use.For example, positive feedback facilitates the rapid formation of a platelet plug which helps to prevent excessive blood loss when a blood vessel is injured. Positive feedback is useful when there is an advantage in making a rapid change. Positive feedback occurs when a change in a variable triggers a response which causes more change in the same direction.For example, negative feedback helps to maintain a relatively constant internal body temperature. Negative feedback plays an important role in maintaining homeostasis. Negative feedback occurs when a change in a regulated variable triggers a response which reverses the initial change and brings the regulated variable back to the setpoint.Homeostasis refers to the maintenance of relatively constant internal conditions.
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