Module 7 Intro
1. Module 7 Intro
1.20. Page 4
Module 7—The Digestive and Respiratory Systems
Reflect and Connect
Self-Check
SC 3. Complete the following Reflect and Connect Self-Check exercise.
You may also want to work on questions from your textbook. If you would like feedback on any questions in your textbook, contact your teacher.
Discussion
Negative feedback mechanisms control breathing rates. Changes in carbon dioxide and/or oxygen concentrations in the blood drive these mechanisms. The first stimulus that triggers an increase in the breathing rate is high carbon-dioxide levels. Does it surprise you that it isn’t low oxygen concentrations?
chemoreceptor: detects chemical stimuli in the environment and turns stimuli into electrical nerve impulses that signal parts of the body to respond accordingly
Chemical receptors found in the medulla oblongata of the brain trigger a message. These chemoreceptors signal the diaphragm and intercostal muscles of the rib cage. The message is “increase breathing movements.” The result is a greater exhalation of carbon dioxide. This gives a lowered blood CO2 concentration—a negative feedback response.
Oxygen chemoreceptors are found in the aorta and carotid arteries. These chemoreceptors respond to low oxygen levels even if carbon-dioxide levels in the blood are normal. For example, this might occur at high altitudes. The negative feedback response would again be controlled by the medulla oblongata, which would again stimulate an increase in breathing movements. Blood-oxygen levels would increase.
Create a diagram that illustrates the negative feedback involved in the process of breathing. Do you have the right idea? Post your diagram in the discussion area. See what other students have posted. Do you need to make any modifications, or did you get it right the first time around?
Reflect on the Big Picture
Can you add to your analogy of your body being a bank now that you know more about the respiratory system?