Biological complexity: vital feedback loops (Introduction)

by David Turell , Monday, April 04, 2022, 21:36 (964 days ago) @ David Turell

They control what cells do:

https://www.albert.io/blog/positive-negative-feedback-loops-biology/

"Feedback is defined as the information gained about a reaction to a product, which will allow the modification of the product. Feedback loops are therefore the process whereby a change to the system results in an alarm which will trigger a certain result. This result will either increase the change to the system or reduce it to bring the system back to normal. A few questions remain: How do these systems work? What is a positive feedback? What is negative feedback? Where do we find these systems in nature?

"Biological systems operate on a mechanism of inputs and outputs, each caused by and causing a certain event. A feedback loop is a biological occurrence wherein the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback). Feedback loops are important because they allow living organisms to maintain homeostasis. Homeostasis is the mechanism that enables us to keep our internal environment relatively constant – not too hot, or too cold, not too hungry or tired. The level of energy that an organism needs to maintain homeostasis depends on the type of organism, as well as the environment it inhabits.

"Feedback loops can also occur to a larger degree: at the ecosystem level, a form of homeostasis is maintained. A good example of this is in the cycle of predator and prey populations: a boom in prey population will mean more food for predators, which will increase predator numbers. This will then lead to over predation, and the prey population will again decline. The predator population will decline in response, releasing the pressure on the prey population and allowing it to bounce back. (my bold)

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"A positive feedback loop occurs in nature when the product of a reaction leads to an increase in that reaction. If we look at a system in homeostasis, a positive feedback loop moves a system further away from the target of equilibrium. It does this by amplifying the effects of a product or event and occurs when something needs to happen quickly.

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"A negative feedback loop occurs in biology when the product of a reaction leads to a decrease in that reaction. In this way, a negative feedback loop brings a system closer to a target of stability or homeostasis. Negative feedback loops are responsible for the stabilization of a system, and ensure the maintenance of a steady, stable state. The response of the regulating mechanism is opposite to the output of the event.

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"The key difference between positive and negative feedback is their response to change: positive feedback amplifies change while negative feedback reduces change. This means that positive feedback will result in more of a product: more apples, more contractions, or more clotting platelets. Negative feedback will result in less of a product: less heat, less pressure, or less salt. Positive feedback moves away from a target point while negative feedback moves towards a target.

"Without feedback, homeostasis cannot occur. This means that an organism loses the ability to self-regulate its body. Negative feedback mechanisms are more common in homeostasis, but positive feedback loops are also important. Changes in feedback loops can lead to various issues, including diabetes mellitus. (my bold)

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"Feedback loops are biological mechanisms whereby homeostasis is maintained. This occurs when the product or output of an event or reaction changes the organism’s response to that reaction. Positive feedback occurs to increase the change or output: the result of a reaction is amplified to make it occur more quickly. Negative feedback occurs to reduce the change or output: the result of a reaction is reduced to bring the system back to a stable state. Some examples of positive feedback are contractions in child birth and the ripening of fruit; negative feedback examples include the regulation of blood glucose levels and osmoregulation."

Comment: our discussions about so-called cell intelligence has bought up feedback loops in the past. Feedback loops are circular protein molecule reactive loops that manage output levels by automatically measuring cell intake or output. What I have left out are explanatory examples which help to understand how they work. Cell intelligent actions cannot cannot be properly discussed unless this set of facts is completely understood. I have not seen evidence of full understanding. They are intelligently designed and work beautifully. This also applies to maintaining ecosystems.