Positive Feedback: Definition, Mechanism, and Examples (2023)

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There are two types of feedback in the feedback loop: positive feedback and negative feedback. They function to keep the body balanced in a variety of situations. Feedback loops are biological systems that maintain the internal integrity of a live entity based on its reaction. It occurs when the result of an activity, or any other output, changes the bodyโ€™s reaction. The change or output is amplified or magnified by positive feedback. The effect of the reaction is intensified, allowing it to happen much faster. The systemโ€™s output is improved with this type of feedback. Negative feedback, on the other hand, reduces or prevents production.

What is Positive Feedback?

To work effectively, each bodily mechanism, such as temperature, blood pressure, and quantities of particular nutrients, must be in the optimum range. A normal value around which the standard range fluctuates is called an optimal value. The body remains healthy and stable when the standard or optimal range is maintained. Various biological systems act on the bodyโ€™s input and output as a result of certain stimuli.

In order to maintain homeostasis, feedback loops are critical. Homeostasis is the protection of the bodyโ€™s internal environment from the effects and fluctuations of the external environment, and it aids in body stability.

Homeostasis is determined by two key factors:

1. Organismal classification

2. The organismโ€™s habitat

A cold-blooded species, such as a fish, maintains a lower body temperature in response to its surroundings, whereas a warm-blooded animal, such as a whale, maintains a greater body temperature to maintain internal stability. A favourable response or a self-reinforcing response to external or internal stimuli is known as positive feedback. In this case, the effector increases the stimulus, which improves product creation and maintains body stability. Instead of correcting a physiological change, positive feedback encourages it.

A physiological system that supports the change is called positive feedback (works to reinforce or intensify the change). The receptor detects the variation, and the effector then tries to create the same result, enhancing the physiological change. The positive feedback loop will continue to increase the real change until the stimulus is eliminated.

Positive Feedback Examples

Consider the following scenarios: clot formation, delivery, fruit ripening, and the menstrual cycle. Each one shows the operation of a positive feedback mechanism:

โ€ข To seal a wound, clotting factors are released.

โ€ข When a baby is born, the uterusโ€™s walls dilate, causing a contraction that stimulates the uterus to stretch even more (this continues until birth).

โ€ข When fruits ripen, ethylene is released, which helps to keep the ripening process going.

โ€ข The oestrogen hormone stimulates the release of other hormones that lead to ovulation throughout the menstrual cycle.

i. Blood Clot Formation
(Video) Positive feedback mechanism + normal childbirth

The bodyโ€™s endeavour to reverse the harm produced by any injury is one of the most prominent examples of positive feedback. Excessive blood loss is a serious hazard to life when the body is damaged. At the location of the injury, blood pressure and blood flow are decreased. Blood clotting factors are produced at the location of the injury to start the clotting process. When the procedure starts, it accelerates the clotting process. As a result, the process of closing the damaged region has sped up in general. Clotting factors are the substances that cause a clot to develop in an injured or damaged region. One of the most life-saving examples of good feedback is this.

ii. Child Birth

1. The Ferguson reflex is the start of contractions during delivery.

2. In the case of childbirth, the uterine walls ultimately expand due to the babyโ€™s development, which is represented by the stretch receptors.

3. This stretching will promote the release of oxytocin hormones, which will engage the uterine muscles and reduce the uterine gap.

4. It causes the uterus to expand more, resulting in additional contractions until the initial trigger (the foetus) is gone (i.e., birth).

iii. Fruit Ripening

Fruit ripening is another example of a positive feedback loop in action. If you look at a plant or a tree that has a lot of fruit, youโ€™ll see that the fruits move through three stages: unripe, ripe, and overripe. When the first fruit begins to mature, the process will begin. When it is fully ripe, it emits a gas called ethylene (C2H4). The surrounding fruits that are exposed to ethylene begin to ripen as a result. These fruits continue to emit ethylene gas as they continue to mature. This feedback loop is commonly employed in the fruit industry, where exposure to ethylene gas accelerates the ripening process.

iv. Menstrual Cycle

Before a woman ovulates, the oestrogen hormone begins to release from her ovary. The oestrogen hormone goes to the brain, where it triggers the release of two other hormones. The hypothalamus is engaged, causing gonadotropin hormone to be released, while the pituitary gland is stimulated, causing luteinizing hormone to be released. Luteinizing hormone, in turn, boosts oestrogen production. Ovulation occurs when the levels of these hormones, as well as follicle-stimulating hormones, rise.

Parts of Positive Feedback

Homeostasis is achieved by the interaction of four fundamental components.

1. Stimulus

2. Sensor (Receptor)

3. Control Centre

4. Effector

(Video) Negative Feedback VS. Positive Feedback Explained w/ Examples

i. Stimulus

Any external chemical that disrupts the bodyโ€™s homeostasis can be used as a stimulant (it is the process of maintaining balance in all body systems). Controlled factors give the stimulation. In general, the stimulus shifts or fluctuates the optimal range away from the usual or standard range. Physical injuries, illnesses, or changes in the external environment are all examples of stimuli. They interfere with the bodyโ€™s physiological functioning.

ii. Sensor

The receptor is another name for the sensor. The physiological value is detected by this component of the feedback system. The sensor detects changes in the bodyโ€™s balance. It not only keeps track of how much has changed, but it also transmits signals to the control centre. During delivery, for example, nerve cells in the cervix detect the foetusโ€™s head pressure. The sensorโ€™s sensory nerves will alert the control centre to the change.

iii. Control Center

The control centre is a component of the feedback system that compares the magnitude of variation to the average value. Not only does it receive signals from sensors, but it also analyses them. The brainโ€™s control centre notices the alterations and compares them to normal levels. If the value is not within the optimal range, the control centre sends an instantaneous signal to the effector to preserve bodily balance.

The pituitary gland is positioned near the brain, which is the command centre for a variety of responses. In reaction to the stimulation, it releases hormones such as oxytocin, antidiuretic hormone, and growth hormone.

iv. Effector

The effector can be any muscle, organ, gland, or other tissue that responds to the stimuli in accordance with the control centreโ€™s signal. The stimulus is either opposed or enhanced by the effector. The effectorโ€™s reaction is determined by the command received by a control centre. The effectorโ€™s objective is to keep the variable close to the standard point in order to preserve stability.

The contraction of the uterus, for example, is the outcome of positive feedback in labour. The uterus is the effector organ in this case.

(Video) Homeostasis and Negative/Positive Feedback

Positive Feedback vs Negative Feedback

Feedback loops are biological processes that aid in the bodyโ€™s maintenance of homeostasis. This happens when a product or event occurs that changes the bodyโ€™s reaction.

A positive feedback loop keeps the stimulus in the same direction and presumably speeds up the action. An explosion of chemical events that lead to blood clotting, also known as coagulation, is an example of positive feedback loops seen in the animal body. As one clotting factor activates, it will prompt the activation of others in a chain reaction until a clot, fibrin, is produced. This method maintains the eventโ€™s course rather than changing it, thus it has positive feedback.

Positive feedback includes contractions during delivery and fruit ripening. The transformation is slowed by a negative feedback loop. To return the system to a stable condition, the response impact is reduced.

Negative feedback occurs when a change or output is minimised. To return the system to an even and stable state, the responseโ€™s influence is decreased. In every homeostatic process, changing the direction of the stimulus creates a negative feedback loop. Negative feedback alters the stimulusโ€™s magnitude but does not allow it to continue its action. In other words, when the levels are high, the body exerts effort to reduce them, and when the levels are low, the body exerts effort to raise them.

Regulating blood glucose levels and osmoregulation are two examples of negative feedback. Thermoregulation is another. When the body temperature deviates from its usual range, the system kicks in to bring it back to normal. In homeostatic physiological processes, the negative reaction happens more frequently than the positive response. A disruption in the natural bodily system is the root of many diseases. As productivity rises, so does the amount of action in positive feedback. As a result, the reaction impact is magnified in the end.

Bad feedback, on the other hand, slows down the rate at which a condition develops, which can have either positive or negative repercussions. As a result, the reaction response is stifled.

Negative feedback, as opposed to positive feedback, is closely linked to stability since it reduces the impact of stimuli. Positive responses, on the other hand, lead to production, which might lead to unpredictability. Negative feedback demonstrates resistance to changes by working to restore the bodyโ€™s system to its original condition and reverse the change. Positive feedback, on the other hand, tends to encourage transformation and change.

External intervention is usually required to stop a good reaction from working. When the body is under circulatory shock, for example, it receives positive feedback in order to deal with the situation. The blood pressure continues to decrease in this situation, which might lead to heart failure. To halt positive feedback in such instances, medical therapy is necessary. Negative feedback, on the other hand, is completely self-contained. It will come to an end once stability has been attained.

Biological Importance of Positive Feedback

The internal mechanism of the body cannot establish equilibrium if it is deprived of feedback. It indicates that the bodyโ€™s ability to manage its systems is deteriorating. While negative input is frequent in sustaining stability, good feedback is equally important.

Hormonal response pattern: hormone concentration in plasma is influenced by factors such as secretion rate and serum hormone concentration.

Corticotropin hormone is secreted by the hypothalamus, which stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH). The adrenal gland is stimulated to produce cortisol by ACTH. When ACTH levels in the blood begin to rise, the hypothalamus receives a signal to halt CRH production. Cortisol also โ€œreturnsโ€ to the pituitary gland and brain when plasma levels rise, preventing the production of adrenocorticotropic and corticotropin hormones, respectively. As a result, a small change in the defined region triggers a corrective action on the opposite side. Negative feedback helps to avoid excessive hormone release in this way.

Because of breast sucking, there is a neural reaction in the spinal cord during lactation. The pituitary gland is stimulated as a result of this reaction ascending to the hypothalamus. As a result, more prolactin is generated, which encourages the production of milk.

Another significant aspect of positive feedback is that it causes ovulation by increasing oestrogen levels throughout the menstrual cycle phase. Positive reactions are also influenced by the generation of sensory nerve impulses, which is an essential physiologic component.

The membrane produces a modest leak of sodium ions through sodium channels in the nerve fibre. This causes a shift in membrane potential, which in turn causes numerous sodium channels to activate (Hodgkin cycle). The first tiny leak triggers a cascade of sodium leaks, which are necessary for the propagation of the nerve action potential.

Positive feedback is also useful for sustaining other cell signalling systems, such as enzyme kinetics and physiological mechanisms. Positive feedback can be utilised to boost B cell activity. When a B cellโ€™s antibodies attach to an antigen, it triggers an immunological response in which additional antibodies are generated and released.

Apoptosis is a type of planned cell death that attempts to rid the body of damaged and undesirable cells. If this mechanism does not function properly, severe repercussions, such as cancer, will result. The auto-activation of caspases lies at the heart of this process, which may be followed by a positive feedback loop.

Positive feedback is a type of feedback that reacts to a disturbance in the same way as the perturbation does. It has a tendency to start or speed up a biological process. The perturbation signal is magnified in this system, and the output might rise exponentially or even hyperbolically. The beginning of contractions during delivery is an example of biological positive feedback.

When a contraction occurs, the hormone oxytocin is released into the body, which causes the body to contract even more. As a result, the amplitude and frequency of contractions increase. Another example occurs during the coagulation of blood. Signal molecules are produced when a tissue is damaged. These chemicals cause circulating platelets to release additional chemicals, causing more platelets to be activated, which is necessary for the development of a blood clot. Nerve signal production and gene regulation are two more instances of positive feedback.

Zygote: Definition, Stages, and Diagram

Positive Feedback Citations
(Video) Physiological concept of positive and negative feedback | Behavior | MCAT | Khan Academy


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What is an example of positive feedback mechanism homeostasis? โ€บ

Oxytocin increases uterine contractions, and thus pressure on the cervix. This causes the release of even more oxytocin and produces even stronger contractions. This positive feedback loop continues until the baby is born. Normal childbirth is driven by a positive feedback loop.

What is positive feedback mechanism in biology? โ€บ

Positive feedback is a process in which the end products of an action cause more of that action to occur in a feedback loop. This amplifies the original action. It is contrasted with negative feedback, which is when the end results of an action inhibit that action from continuing to occur.

What is feedback mechanism and examples? โ€บ

The feedback mechanism is the mechanism of the body to maintain the levels of hormones in the body within the desired limits. An increase or decrease in the levels of the hormones triggers the feedback mechanism. The body has two types of feedback mechanisms, positive and negative feedback mechanism.

What are the two examples of positive feedback? โ€บ

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.

Which is an example of a positive response? โ€บ

Generic positive review response examples

โ€œThanks so much for sharing your experience with us.โ€ โ€œThank you so much for taking the time to leave us feedback.โ€ โ€œIs there anything we can do to improve?โ€ โ€œWe hope to see you again soon!โ€

Which is an example of positive feedback quizlet? โ€บ

A good example of a positive feedback system is child birth. During labor, a hormone called oxytocin is released that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born.

What is meant by positive feedback? โ€บ

: feedback that tends to magnify a process or increase its output.

What is positive feedback in the body? โ€บ

In a positive feedback loop, feedback serves to intensify a response until an endpoint is reached. Examples of processes controlled by positive feedback in the human body include blood clotting and childbirth.

What is positive feedback and negative feedback mechanism? โ€บ

Positive feedback loops enhance or amplify changes; this tends to move a system away from its equilibrium state and make it more unstable. Negative feedbacks tend to dampen or buffer changes; this tends to hold a system to some equilibrium state making it more stable.

What is an example of a negative feedback mechanism? โ€บ

Mechanical Negative Feedback

Flushing a toilet - The ballcock in a toilet rises as the water rises, and then it closes a valve that turns off the water. The fly-ball governor - This was used in controlling the speed of a steam engine.

What is a real world example of positive feedback? โ€บ

Great job!โ€ Examples of positive feedback: Fake feedback: โ€œYou're really reliable.โ€ Real feedback: โ€œI know that whatever I give you to do will get done the first time I ask and will be accurate.

What is positive and examples? โ€บ

In the simplest sense, positive means good โ€” or the opposite of negative. If you have a positive attitude about homework, for example, you're more likely to get positive feedback on your report card.

How do you respond to positive feedback examples? โ€บ

Some things you can say:
  1. โ€œThis review made our day!โ€
  2. โ€œThank you so much for taking the time to leave us this amazing review.โ€
  3. โ€œWe are so grateful for your kind words. Thanks for sharing your review with us and the community.โ€
Feb 15, 2022

What is positive and negative response? โ€บ

Negative Response. When the response generated by plants against a stimulus is towards the stimulus, the response is called a positive response. When the response generated by plants against a stimulus is away or not in favour of the stimulus, the response is called a negative response.

What are examples of positive feedback for students? โ€บ

The student:
  • is a conscientious, hard-working student.
  • works independently.
  • is a self-motivated student.
  • consistently completes homework assignments.
  • puts forth their best effort into homework assignments.
  • exceeds expectations with the quality of their work.
  • readily grasps new concepts and ideas.

Which of the following is an example of a positive feedback mechanism quizlet? โ€บ

Which of the following is an example of a positive feedback? In order to prevent blood loss, the body needs a mechanism that amplifies the action that leads to clotting in a short period of time. This cascade or enhancement of a process is a positive feedback mechanism.

Which of the following is an example of positive feedback system *? โ€บ

The menstrual cycle is a good example of positive feedback.

Is heart rate an example of positive feedback? โ€บ

When the brain receives messages from the body about an internal change in one of its systems, it works to restore the system to its normal state. Negative feedback mechanisms are found in the regulation of blood pressure, heart rate, and internal temperature controls.


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