Human Physiology: An Integrated Approach 8th Edition by Dee Silverthorn test bank

Answer: (Note to instructor: This may be a good question to ask early in the semester, then again toward the end,
after the organ systems have been covered.) There is a brief discussion of using humans or animals in
research in the chapter. This question is intended to stimulate students to think about how science is
done, how data are generated, and how the process is challenged by social issues. Generally, there are
limitations to the usefulness of computer simulations and cell/tissue culture systems for the same reason
that nonhuman animal data are not 100% applicable to human physiology. How human organ systems
perform may be different in very subtle ways from corresponding systems in other species. Cells in
culture are in an artificial environment, and while much has been learned from such systems, it has also
been noted that the behavior of cells in culture is not identical to cells in a living body. Furthermore, cells
cultured from established lines can change over time, becoming less like the original cells from which
they were derived, and presumably less like normal cells. Computer simulations are valuable, but are
only as good as the data entered, and given that we don't know everything there is to know about
physiology, we can't write a perfect computer program. All three approaches are useful, but for different
reasons, and therefore one research system does not completely substitute for another, nor is it
appropriate to abandon one entirely.
45) You conduct an experiment on twenty 18-year-old male subjects to see how various levels of exercise influence
heart rate. Explain why only 18- year- old males were used as subjects.
Answer: An important part of scientific inquiry is to remove sources of variation from among subjects. By
choosing subjects of one gender in a particular age group, it is easier to determine that the dependent
variable (heart rate, in this case) depends ONLY on the independent variable, level of exercise. This also
allows a study to have fewer participants, assuming that subjects were randomly assigned to a level of
exercise. If subjects were of random ages and genders, data would have to be collected from many more
individuals.
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46) Use these terms to develop a reflex loop:
brain, sensory neuron, an eye, foot, soccer ball, motor neuron
Answer: Eye sees soccer ball.
Sensory neuron sends visual information.
Brain receives information and formulates a plan.
Motor neuron sends action information from the brain.
Foot and leg muscles contract, and the ball is kicked.
47) Provide an example of a control system. Be sure to include the three main parts: an input signal, an integrating
center, and an output signal.
Answer: Variable. One example is blood glucose concentration. The input signal is a blood glucose concentration
outside of the normal range, the controller is the pancreas, and the output signal is release of either
insulin or glucagon.
48) Write a teleological explanation for why heart rate increases during exercise. Now write a mechanistic
explanation for the same phenomenon.
Answer: Teleological: Heart rate increases because the increased activity of skeletal and cardiac muscles requires
increased delivery of blood contents such as oxygen and glucose. Mechanistic: Heart rate increases in
response to signals from the brain (pacemaker cells of the heart are stimulated by the nervous system).
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
49) What is a hypothesis? What are the steps involved in following the scientific method? How does one distinguish
the dependent variable from the independent variable in an experiment? How are each of these represented on
a graph?
Answer: This is discussed in "The Science of Physiology" section of the chapter and in Figure 1.15.
ESSAY. Write your answer in the space provided or on a separate sheet of paper.
50) You are designing a study to assess the effects of a new treatment for hypertension. What ethical considerations
would you employ when monitoring your progress?
Answer: Major considerations should involve assessing the efficacy of the treatment such that the control group
patients are not deprived as well as ensuring that the experimental treatment is not less effective than the
standard treatments.
51) You are designing a study to assess the effects of a new drug treatment for hypertension. Your subjects are
white males, ages 40 to 60 years. Can your study results be applied to all people? Explain.
Answer: Possibly, but not necessarily. There are gender differences in appropriate therapies because of
physiological effects of higher testosterone in males compared to females, for example. Drugs are often