Free The Pancreas OCR A Level Biology revision notes – covering specification points 5.1.4 (ci) and 5.1.4 (cii).
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The Pancreas
The pancreas is located behind the stomach, where it is connected to the duodenum of the small intestine by the pancreatic duct.
The diagram below shows the position of the pancreas:
The pancreas has exocrine and endocrine tissue.
Exocrine Glands
The exocrine glands (acini) secrete the pancreatic juices into the duodenum through the pancreatic ducts:
Acini → Intercalated ducts → Intralobular ducts → Main pancreatic duct → Duodenum
Endocrine Glands
The endocrine glands (islets of Langerhans) secrete hormones directly into the bloodstream:
Islet cells → Capillaries → Portal venules → Hepatic portal vein → Liver first
The islets of Langerhans produce insulin and glucagon to control blood glucose concentration.
The table below outlines the effects that insulin and glucagon have on target cells:
| Hormone | When Released | Main Effects |
|---|---|---|
| Insulin | When blood glucose rises (e.g. after eating) |
|
| Glucagon | When blood glucose falls (e.g. fasting, exercise) |
|
The diagram below shows the arrangement of alpha and beta cells in the Islet of Langerhans:
