Compare and contrast negative and positive feedback loops. Which one is more common? Why?

A negative feedback mechanism or loop is a pathway stimulated by the deviation in the output, which causes changes in output to the direction opposite to the initial deviation.
The negative feedback mechanism moves the variable factors towards the stable state or homeostasis after the control unit interprets the extent of the deviation.
Negative feedback loops are more common than positive ones as they tend to stabilize the system.
The loop detects the change in output and acts in the opposite direction to nullify the stimulus causing the change.
These loops are activated under two conditions; when the value of the variable is above the normal value and has to be brought down and when the value of the variable is below the normal values and has to be brought up.
Negative feedback mechanisms occur as a part of homeostasis to bring the variables back to their normal levels by counteracting the stimulus, causing the deviation in the first place.
Like in a positive feedback mechanism, a negative feedback mechanism also contains different components that together help to maintain a stable state.

Examples of Negative Feedback Mechanism

1. Regulation of blood glucose level

2. Temperature regulation

Positive Feedback Loop

A positive feedback mechanism, as the name suggests, is a pathway that in response to a deviation in the output causes the output to change even more in the direction of the initial deviation.
A positive feedback mechanism amplifies the deviations and brings state changes to the output.
Positive feedback mechanisms are far less common than negative feedback mechanisms as it moves the body away from homeostasis.
The process of positive feedback mechanism progressively amplifies the response as long as the stimulus is continued.
The positive feedback loop can consist of either a single component that activates its own activity or several components with direct and indirect interactions.
Positive feedback loops in biological processes are often observed in processes that need to occur quickly and towards completion as the output tends to increase the effect of the stimulus.
Positive mechanisms are very few within living systems like the human body, but these can also be observed in the ecosystem, like in the case of ripening of fruit.

Examples of Positive Feedback Mechanism

1. Menstrual cycle

2. Childbirth

Negative feedback loops are more common than positive ones as they tend to stabilize the system.

Definition

The positive feedback mechanism is a pathway that in response to a deviation in the output causes the output to change even more in the direction of the initial deviation.
A negative feedback mechanism or loop is a pathway stimulated by the deviation in the output, which causes changes in output to the direction opposite to the initial deviation.

Effect on the homeostasis

A positive feedback mechanism breaks down the homeostasis system of the body.
A negative feedback mechanism works to maintain the conditions of homeostasis in the body.

Occurrence

The positive feedback mechanism is less common and occurs in specific situations.
The negative feedback mechanism is more common and occurs in different organs and systems in the body.

Stability

Effect

In a system with a positive feedback mechanism, the effective input is increased by the addition of actual input with the feedback signal.
In a system with a negative feedback mechanism, the effective input is decreased as the feedback signal inhibits the actual input.

External interruption

Changes

Examples

Positive feedback mechanism in nature is observed during childbirth in humans and during the ripening of fruits.
The negative feedback mechanism is observed during thermoregulation and maintaining the blood glucose level.