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Coordination and control - The human endocrine system - Edexcel Role of glucagon in blood sugar levels – Higher

The endocrine system secretes hormones into the bloodstream from glands throughout the body. Hormones travel in the blood stream to specific target organs, where they have an effect.

Part of Biology (Single Science)Animal coordination, control and homeostasis

Role of glucagon in control of blood sugar levels - Higher

Negative feedback

In blood glucose regulation, the hormone insulin plays a key role. When blood sugar rises in the blood, insulin sends a signal to the liver, muscles and other cells to store the excess glucose. Some is stored as body fat and other is stored as glycogen in the liver and muscles. If the blood glucose level is too low, the pancreas releases the hormone glucagon. This travels to the liver in the blood and causes the break-down of glycogen into glucose. The glucose enters the blood stream and glucose levels increase back to normal.

This is an example of negative feedback.

A flowchart to demonstrate negative feedback

How glucose is regulated

Blood glucosePancreasLiverEffect on glucose
Too highInsulin secreted into the bloodLiver converts glucose into glycogenGoes down
Too lowGlucagon (not insulin) is secreted into the blood.Liver does not convert glucose into glycogen. Glycogen is converted to glucose.Goes up
Blood glucoseToo high
PancreasInsulin secreted into the blood
LiverLiver converts glucose into glycogen
Effect on glucoseGoes down
Blood glucoseToo low
PancreasGlucagon (not insulin) is secreted into the blood.
LiverLiver does not convert glucose into glycogen. Glycogen is converted to glucose.
Effect on glucoseGoes up