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Positive and negative feedback - Coggle Diagram
Positive and negative feedback
Negative feedback loops: Buffers changes attempting to hold an equilibrium state making it more stable / negative feedback mechanisms detect departures from a set point norm and act to restore the steady state.
Negative feedback process and control systems: thermoregulation example
Stressor e.g exercise raises the body temperature above the optimum bod temperature
change picked up by receptors and appropriate corrective mechanism activated to bring body temperature back to optimum. E.g sweating.
corrective mechanisms act to restore optimum conditions
Negative feedback stabilising ability provides the specific conditions of temperature, pH, and osmolarity required for enzyme catalysed reactions along metabolic pathways
NEGATIVE FEEDBACK
Ø Keeps values near a set point
Ø Body Temperature
Ø Blood Pressure
Ø Osmotic Balance
Ø Level of Blood Glucose
Ø Level and Balance of Respiratory Gases
Positive feedback: enhance changes to move a system away from an equilibrium state and make it more unstable / Positive feedback results in the escalation of a response to a stimulus. It causes system instability and is used where a particular outcome or resolution is required.
Positive feedback and response escalation: fever example.
body temperature fluctuates on a normal, regular basis around a narrow set point
pathogen enters the body
the body detects the pathogen and macrophages attack it. Macrophages release interleukins which stimulate the hpyothalamus to increase prostaglandin production and rest the body's thermostat to a higher 'fever' level by shivvering (the chill pahse)
the feave breaks when the infection subsides. Leves of circulateing interleukins (and other fever-associated chemicals) fall, and the body's thermostat is reset to normal. This ends the positive feedback escalation and normal controls resume, If the infection persists, the escalation mat continue, and the fever may intensify. Body temperatures in excess of 43oC are often fatal or result in brain damage
Positive feedback amplify a physiological response usually to achieve a particular outcome. Positive feedback loop usually ends when a natural resolution is reached. Much less common than negative feedback loops as it is unstable. Can sometimes be dangerous or fatal if left unchecked
POSITIVE FEEDBACK
Ø Move values away from a set point
Ø Birth of baby
Ø Fruit ripening
!Homeostatic control systems have three functional components:
• A receptor to detect change
• A control centre
• An effector to produce
an appropriate response
