Solutions Manual for Seeleys Anatomy & Physiology 13th Edition VanPutte
Chapter 1 Homeostasis Purpose: Develop a deeper understanding of the concepts of homeostasis, negative feedback, and positive feedback in relation to human physiology.
Goal: Focus on the concept of homeostasis, outlining the mechanism of homeostatic control and the concepts of negative and positive feedback.
Grading: Online quiz.
Activity: Complete each of the following prompts.
- A very effective strategy for learning complex material is developing your own
“representation” of the process. Most of us do this through figures. Some are more inclined to “act it out”, while others just like to re-write it in their own words. All of these are good strategies because it allows you to really think about what the words you are reading or hearing actually mean.
In the space below, describe or draw your own representation of a homeostatic control mechanism. How would you explain this to someone that is less knowledgeable than you?
Students can develop their own representation to illustrate the interactions among the three components. They should convey that homeostatic control maintains a relatively constant internal environment despite fluctuation in the external environment.
- In this chapter you learned that the body maintains homeostasis primarily through
negative-feedback mechanisms. List the three components of a typical negative-feedback mechanism.
- receptor: monitors a particular variable and detects changes in that variable
- control center: determines the set point for a variable, receives signals from
- effector: responds to changes in the variable 1 / 4
receptor about the variable, and controls the response of the effector
- In the space below, develop a diagram that represents the interactions among the three
parts of the negative-feedback mechanism. (This may be similar to the figure you developed in question 1.)
Verify that students convey the correct sequence of communication and that there is an opposing response to the original stimulus.
- Another effective strategy is to develop analogies that represent the concept. This can
be harder than it sounds, but the process of developing an analogy is extremely helpful is clarifying the details of a difficult concept. Try to think of everyday events or items that
represent each of the following, providing an explanation for each:
- Negative Feedback
The classic example is the household thermostat used to maintain the temperature of our home but see what other examples your students can describe.
- Positive Feedback
This one can be harder for students but the concept of ever increasing/decreasing values is key. One of my students used the example of her toddler’s whining for a snack.
- Homeostatic variables, such as body temperature, fluctuate within a normal range
around the set point, or ideal, for a given homeostatic condition. For example, 98.6°F is the set point for body temperature. The response of the effector determines whether or not the homeostatic variable remains in the normal range or deflects farther away from the set point. In the space below, draw a diagram similar to Figure 1.4 but representing Blood Glucose levels, with the set point at 75 mg/dL with a normal range between 65 and 85 mg/dL.
Students can copy the image from Figure 1.4 and change the labels and variable on the Y axis. 2 / 4
- Using the diagram above, simulate changes in blood glucose levels representing normal
negative feedback response and abnormal positive feedback response for each of the following scenarios.
Scenario 1: Decrease in blood glucose (negative feedback). Trace a line
representing a decrease in blood glucose levels. (Add a legend labeling this particular line color as Decrease (Negative feedback). Predict the direction the line will continue when negative feedback occurs. Indicate the time of response by drawing an arrow on the x- axis. Did your line move closer to or farther away from the set point once negative feedback occurred?
Students should indicate a decrease in the variable with change in direction BEFORE decreasing below the lower bound of the normal range. This is an important point to clarify. Homeostasis maintains a relatively constant internal environment WITHIN the normal range.
Scenario 2: Increase in blood glucose (negative feedback). Using a different
color pen or pencil, trace a line representing an increase in blood glucose levels. (Add a legend labeling this particular line color as Increase (Negative feedback). Predict the direction the line will continue when negative feedback occurs. Did your line move closer to or farther away from the set point once feedback occurred?
Similarly, the line should indicate an increase with a change BEFORE moving above the upper bound of the normal range.
So, based on these two steps, what can you say about the role of negative feedback mechanisms?
Negative feedback functions to maintain variable within the normal range.
Scenario 3: Decrease in blood glucose (positive feedback). Using a third
color pen or pencil, trace a line representing a decrease in blood glucose levels. (Add a legend labeling this particular line color as Decrease (Positive feedback). Predict the direction the line will continue if positive feedback occurs. Would this restore homeostatic blood glucose levels?
Positive feedback would result in a continuous decrease, moving outside of the normal range. 3 / 4
Chapter 1 Homeostasis Purpose: Develop a deeper understanding of the concepts of homeostasis, negative feedback, and positive feedback in relation to human physiology.
Goal: Focus on the concept of homeostasis, outlining the mechanism of homeostatic control and the concepts of negative and positive feedback.
Grading: Online quiz.
Activity: Complete each of the following prompts.
- A very effective strategy for learning complex material is developing your own
“representation” of the process. Most of us do this through figures. Some are more inclined to “act it out”, while others just like to re-write it in their own words. All of these are good strategies because it allows you to really think about what the words you are reading or hearing actually mean.
In the space below, describe or draw your own representation of a homeostatic control mechanism. How would you explain this to someone that is less knowledgeable than you?
- In this chapter you learned that the body maintains homeostasis primarily through
- / 4
negative-feedback mechanisms. List the three components of a typical negative- feedback mechanism.