Feedback Mechanisms in Biology

Many organ systems are controlled by feedback mechanisms.

There are two types of feedback mechanisms.

One is homeostatic mechanism (negative feedback).

Another is positive feedback.

Homeostatic mechanism (negative feedback) requires many organ systems to maintain its stable internal conditions. That is, homeostatic mechanism (negative feedback) works to correct back to the set point/norm—through these orderly process of the stimulus, sensor, control center, effector, and response.

The stimulus is a deviation from the set point/norm.

The sensor provides to the brain the information about the specific conditions (stimuli) in the body.

The control center (the brain) detects the deviation from the set point/norm and sends message out to the effector.

The effector causes a response to change the conditions in the body.

The response is the altered result that brings the organ systems back to its norm condition.

One example of homeostatic mechanism (negative feedback) is about the body temperature as follows:

Stimulus: body temperature rises above the norm

Sensor: sensory neurons send signals to the control center

Control center: detects irregularity (temperature) from the set point (98.6 degrees); then, signals the effector organs

Effector: skin blood vessels dilate (to release heat) and sweat glands activate (to sweat)

Response: body temperature drops to the norm

Another example of homeostatic mechanism (negative feedback) is about the thirst sensation as follows:

Stimulus: body thirst sensation rises above the norm

Sensor: sensory neurons send signals to the control center

Control center: detects irregularity thirst sensation from the set point; then, signals the effector organs

Effector: cause the person to drink water

Response: body thirst sensation drops to the norm

References:
https://cnx.org/contents/[email protected]:8Q_5pQQo@4/Homeostasis (Links to an external site.)Links to an external site.

https://quizlet.com/15273363/anatomy-positive-negative-feedback-flash-cards/ (Links to an external site.)Links to an external site.

Positive feedback maintains the direction of the stimulus (of many organ systems) and possibly accelerates it.

One example of positive feedback is the blood clotting, or coagulation.

As one clotting factor is activated, it activates the next factor in sequence until a fibrin clot is sealed. The direction (of the stimulus) is maintained—not changed; therefore, this is positive feedback.

Another example of positive feedback is the uterine contractions during childbirth.

The hormone oxytocin, made by the endocrine system, stimulates the contraction of the uterus. This produces pain sensed by the nervous system. Instead of lowering the oxytocin and causing the pain to subside, more oxytocin is produced until the contractions are powerful enough to produce childbirth.

Reference: https://courses.lumenlearning.com/boundless-biology/chapter/homeostasis/