Chapter 10, Problem 1RQ

To determine

The definitions of negative and positive feedback with examples.

Answer to Problem 1RQ

The negative feedback takes place when the output of a process tends to decrease the input of the process. For example, in case of high temperature, body produces sweat, which tends to decrease the body temperature by evaporative cooling. Positive feedback occurs when the initial stimulus is progressively increased by the output of the process. For example, blood clotting cascade.

Explanation of Solution

Negative feedback: When the output of a system or mechanism tend to decrease the input of the process to alter the rate of output, it is called negative feedback.

Example of negative feedback: During high temperature, the homeostatic systems of the body temd to induce sweating. This leads to a decrease in the overall body temperature due to evaporative cooling.

Positive feedback: In case of positive feedback loop, the original input is gradually increased by the output of the process.

Example of positive feedback: In the course of blood clotting, the initial stimulus stimulates the aggregation of platete cells. The aggregation of these cells leads further recruitment of clotting factors, which increase the overall extent of blood clotting.