Positive vs Negative Feedback

Question 1

How does a negative feedback system affect a controlled condition relative to its setpoint?

Answer 1

A negative feedback system affects a controlled condition by reversing a change in that condition, bringing it back to the setpoint. The “setpoint” is the maintained value of a controlled condition by the control center within a feedback system. This process is part of a cycle of events where a body condition is continuously monitored, evaluated, and adjusted.

Question 2

How does a positive feedback system affect a controlled condition relative to its setpoint?

Answer 2

A positive feedback system affects a controlled condition by strengthening or reinforcing a change in that condition, moving it away from the setpoint. This means that instead of reversing a deviation to restore balance, it intensifies the initial change. An example of a positive feedback system is childbirth, where initial contractions cause the child to move down the birth canal, stretching the cervix. This stretch leads to the release of oxytocin, which in turn causes the uterine muscles to contract more forcefully, further stretching the cervix and releasing more oxytocin, thereby reinforcing the contractions.

Question 3

Which feedback system primarily maintains homeostasis, and why doesn’t the other?

Answer 3

Negative feedback systems are primarily responsible for maintaining homeostasis. Homeostasis is defined as the maintenance of relatively stable conditions in the body’s internal environment. Negative feedback systems operate by reversing a change in a controlled condition, bringing it back to the setpoint. The body has built-in mechanisms that are activated whenever conditions change, aiming to restore balance. An example of this is blood pressure regulation, where an increase in blood pressure is detected, and effectors work to decrease it back to normal, thus restoring homeostasis.

Question 4

Provide an example for negative feedback, explaining its operation.

Answer 4

regulation of blood pressure

Question 5

Provide an example for positive feedback, explaining its operation.

Answer 5

childbirth