What Is Negative Feedback in Hormone Regulation?
Learn how negative feedback regulates hormone levels, with GCSE Biology examples involving blood glucose, insulin, glucagon and thyroxine.
Negative feedback is a control mechanism that reverses a change in the body, returning conditions towards their optimum level. In hormone regulation, glands release hormones when a condition moves away from its normal range. Once the condition has been corrected, hormone release is reduced.
This is an important part of homeostasis: the regulation of internal conditions to maintain the best conditions for enzymes and cells to function.
How negative feedback works
A negative feedback system usually follows these stages:
- Receptors detect a change in an internal condition.
- A coordination centre, such as the pancreas or brain, processes the information.
- An effector, such as a gland, produces a response.
- The response reverses the original change.
- Hormone release decreases once the condition returns towards its optimum level.
Worked example: blood glucose
After a carbohydrate-rich meal, blood glucose concentration rises.
- The pancreas detects the increase and releases insulin.
- Insulin causes glucose to move from the blood into cells.
- It also causes excess glucose to be converted into glycogen in liver and muscle cells.
- Blood glucose concentration falls towards its optimum level, so less insulin is released.
If blood glucose concentration becomes too low, the pancreas releases glucagon. Glucagon causes stored glycogen to be converted into glucose and released into the blood. Insulin and glucagon therefore have opposite effects.
Thyroxine levels are also controlled by negative feedback. Thyroxine is released by the thyroid gland and helps control the basal metabolic rate.
Common exam mistake
Do not say that negative feedback always makes a condition decrease. It opposes the original change: a value that is too high is lowered, while a value that is too low is raised.
Scope assumption: this explanation assumes AQA GCSE Biology Higher Tier. The interaction of insulin and glucagon in a negative feedback cycle, and the negative feedback control of thyroxine, are Higher Tier content.
