Feedback Mechanisms
Feedback occurs when reponse to either a biotic or abiotic factor has an effect on the person of some kind (or animal/mammal). There are two types of feedback, negative and positive feedback. Negative feedback is most common in biological systems, for example:
doing excercise creates metabolic heat which raises the core temperature of the body, then due to cooling mechanisms such as flushed skin or sweatingbegin and the temperature decreases.
Three basic factors to the feedback system:
1. a receptor: monitors change and sends message to the control centre in the form of a chemical signal or a nerve impulse
2. a control centre: sets range of what the maintained balance in the body should be. It evaluates the input it recieves from the receptors and generates command outputs when needed. output is also in the form of a nerve impulse or chemical system
3. an effector: recieves outputs from the control center and produces a response or effect that changes the condition. nearly every body organ and tissue can behave an an effector.
There are internal and external factors that affect out body making physiological feedback mechanisms essential for the body to stay stable and retain a balance. When homeostasis is altered there are two possible responses. The first one is activating the negative feedback loop which responses to reverse the change of direction, as this keeps constant, the maintenance of homeostasis is allowed. For example a fall in calcium levels in the blood will be detected by the parathyroid gland which will then in turn secrete more parathyroid hormone, making the bones
increase its calcium release. The second response is activating the positive feedback loops which increase the change in the same direction, something that does not result in homeostasis. Positive feedback kicks in when rapid change is needed. An example of this is when the hormone oxytocin in childbirth is produced to stimulate and enhance labour contractions.
(Homeostasis– Part 1: anatomy and physiology, ©2012)
doing excercise creates metabolic heat which raises the core temperature of the body, then due to cooling mechanisms such as flushed skin or sweatingbegin and the temperature decreases.
Three basic factors to the feedback system:
1. a receptor: monitors change and sends message to the control centre in the form of a chemical signal or a nerve impulse
2. a control centre: sets range of what the maintained balance in the body should be. It evaluates the input it recieves from the receptors and generates command outputs when needed. output is also in the form of a nerve impulse or chemical system
3. an effector: recieves outputs from the control center and produces a response or effect that changes the condition. nearly every body organ and tissue can behave an an effector.
There are internal and external factors that affect out body making physiological feedback mechanisms essential for the body to stay stable and retain a balance. When homeostasis is altered there are two possible responses. The first one is activating the negative feedback loop which responses to reverse the change of direction, as this keeps constant, the maintenance of homeostasis is allowed. For example a fall in calcium levels in the blood will be detected by the parathyroid gland which will then in turn secrete more parathyroid hormone, making the bones
increase its calcium release. The second response is activating the positive feedback loops which increase the change in the same direction, something that does not result in homeostasis. Positive feedback kicks in when rapid change is needed. An example of this is when the hormone oxytocin in childbirth is produced to stimulate and enhance labour contractions.
(Homeostasis– Part 1: anatomy and physiology, ©2012)
Below picture shows the stages in a negative feedback system.
Funny Analogy for Negative and Positive Feedback
“Negative feedback and positive feedback : a control process. When a hormone has had an effect on its target
organ the process of negative feedback can switch the endocrine organ off. Here
is a simple analogy to help you understand negative feedback.
Positive feedback is the reverse of negative
feedback. When we are having an arguement, we do not really listen to each
other. If I raise my voice to make you listen to me, you react by raising your
voice. eventually we are both shouting at each other. We still don’t listen. We
start to get angry. I throw a pot at you and you throw one back. If we are
unlucky positive feedback results in a death. One of us has a heart attack, or
we start hitting each other and one gets killed. Positive feedback always makes
matters worse. Suppose one of us starts to cry, this is a signal to stop. The
other one realises that matters have gone too far and stops shouting. Then we
start to talk instead of shouting. Now it is possible to listen properly.
Instead of killing each other, we listen and things get back to normal. The
crying had a negative feedback effect.”
A good laugh, but also helps.
(Nigel D Purchon, ©1997-2012)
organ the process of negative feedback can switch the endocrine organ off. Here
is a simple analogy to help you understand negative feedback.
Positive feedback is the reverse of negative
feedback. When we are having an arguement, we do not really listen to each
other. If I raise my voice to make you listen to me, you react by raising your
voice. eventually we are both shouting at each other. We still don’t listen. We
start to get angry. I throw a pot at you and you throw one back. If we are
unlucky positive feedback results in a death. One of us has a heart attack, or
we start hitting each other and one gets killed. Positive feedback always makes
matters worse. Suppose one of us starts to cry, this is a signal to stop. The
other one realises that matters have gone too far and stops shouting. Then we
start to talk instead of shouting. Now it is possible to listen properly.
Instead of killing each other, we listen and things get back to normal. The
crying had a negative feedback effect.”
A good laugh, but also helps.
(Nigel D Purchon, ©1997-2012)