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Controlling blood glucose

Coordination and response · Homeostasis · note 2 of 4

Spec 14.3.5, 14.4.2, 14.4.4Download all Homeostasis notes (PDF)Download all notes (PDF)6 pages

Controlling blood glucoseSpec 14.3.5, 14.4.2, 14.4.4

The pancreas secretes the hormone insulin. Insulin decreases blood glucose concentration.

Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean

Insulin is secreted when the blood glucose concentration is too high, for example after a meal containing carbohydrate. The pancreas also secretes a second hormone, glucagon, when the blood glucose concentration is too low.

Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean

The role of the liver

Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean

The liver controls blood glucose concentration by storing and releasing glucose. It stores glucose as glycogen. Insulin and glucagon both act on the liver.

Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean
Control of blood glucose concentration
Blood glucose too highBlood glucose too low
Hormone secreted by the pancreasInsulinGlucagon
Response of the liverConverts glucose to glycogen, which it storesConverts glycogen to glucose and releases it into the blood
Effect on blood glucoseDecreasesIncreases
Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean
Negative feedback loop for blood glucose: when blood glucose is too high the pancreas secretes insulin and the liver converts glucose to glycogen and stores it, so blood glucose falls; when it is too low the pancreas secretes glucagon and the liver converts glycogen to glucose and releases it into the blood, so blood glucose rises. (opens full size in a new tab)
Control of blood glucose. Insulin lowers it and glucagon raises it, both acting on the liver.
Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean
Common mistake:

Insulin and glucagon are hormones. Glycogen is the storage carbohydrate. Do not mix up the three names.