Question

Which of the answer choices is an example of negative feedback altering homeostatic control?

A person with a bacterial infection runs a fever and his body temperatures rises and stays elevated for several days. The concentration of salt in a person's urine increases after that person eats a large bag of salty chips. A person's heart rate remains elevated over the course of a long run. The production of oxytocin (a hormone) increases in a pregnant woman's body as oxytocin levels in her body rise.

Answer 1

Negative feedback involves a response that is the reverse of the change detected. It functions to reduce the change or it serves to maintain a normal status of change.

Whereas, Positive feedback results in amplification or increase of output signal or response. It keeps the sequence of events going up.

• Bacterial infection and fever is an example positive feedback. Fever increases the chemical reactions of the body by an average of about 12 per cent for every 1°C rise in temperature. It increases the metabolic rate, which increases heat production, which in turn raises body temperature even more.
• Consumption of salt increase the plasma salt level. To decrease or reverse the effect, body homeostatic mechanism excrete th salts and thus increase the urine salt concentration. Thus it is an example of negative feedback.
• Elevated heart rate during course of long run is an example of positive feedback. During a run, body muscle use more oxygen and nutients and to meet the supply heart need to pump more blood. Local chemical changes in muscles stimulates chemoreceptor and signal results in increase heart rate.
• Here, production of oxytocin is an example of positive feedback. Here, oxytocin increase the level of oxytocin to rise in pregnant women.