Communication and Homeostasis The Pancreas

Spec (c) (i) the histology of the pancreas (ii) the examination and drawing of stained sections of the pancreas to show the histology of the endocrine tissues To include the endocrine tissues. PAG1 HSW4

Mark PPQ from last lesson FLIP Learning See Hormones 1 ppt

Learning Objective Success Criteria Know about the Pancreas Describe the histology of the pancreas Explain how blood glucose concentration is regulated by negative feedback

Starter Write down as much as you know about the pancreas in a mindmap

PANCREAS AND ASSOCIATED ORGANS

Has both endocrine and exocrine functions The Pancreas Has both endocrine and exocrine functions

Exocrine (duct) Most cells make and release digestive enzymes Cells are found in small groups surrounding tubules into which they secrete the enzymes Tubules join to make the pancreatic duct

Exocrine Enzymes in pancreatic fluid Amylase: A carbohydrase Trypsinogen: An inactive protease Lipase Contains sodium hydrogencarbonate (an alkaline) Neutralises digestive system (having just left the stomach)

Endocrine Islets of Langerhans contain two different type of cells that secrete hormones These are well supplied with blood capillaries so hormones can be secreted into blood

THE ALPHA AND BETA CELLS IN ISLET OF LANGERHANS Acinus of exocrine tissue

Pancreas Histology Micrographs and diagrams on p68-69

Pancreas Histology

Drawing Microscope Slides Annotations Whilst a label might be the name of a tissue, an annotation adds a descriptive quality such as shape, size or colour. Drawings from a microscope Single, clear lines drawn with a sharp pencil. No shading or colour on the diagram. Informative title to be included. Scale included (e.g. high power, low power, x80, x10) to show approximate magnification. High power diagrams show a few adjacent cells only; adjacent cells must have complete lines. Cells or tissues should be in correct proportions. Label lines drawn in pencil using a ruler.

Task Task: Draw a high power drawing of the pancreas

Alpha (α) cells Make and secrete the hormone GLUCAGON Target cells: hepatocytes Glucagon causes blood glucose levels to rise Glycogen to glucose (glycogenolysis) Amino acids and fats to glucose (gluconeogenesis)

Beta (β) cells Make and secrete the hormone INSULIN Target cell: hepatocytes, muscle Insulin causes blood glucose levels to go down Insulin binds activating adenyl cyclase, making cAMP Glucose converted to glycogen (glycogenesis)

Plenary Task: WITHOUT USING NOTES Make a flow diagram to show what happens in the pancreas when: Rise in blood glucose concentration Fall in blood glucose concentration Negative Feedback: Control of blood glucose concentration Can use feedback loop as a writing frame

Controlling Blood Glucose Concentration

RISE FALL Normal Concentration FALL RISE

Detected by β cells in the islets of Langerhans RISE FALL Normal Concentration FALL RISE

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood RISE FALL Normal Concentration FALL RISE

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood Insulin detected by receptors Cells remove glucose from blood RISE FALL Normal Concentration FALL RISE

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood Insulin detected by receptors Cells remove glucose from blood RISE FALL Normal Concentration FALL RISE Detected by α cells in the islets of Langerhans

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood Insulin detected by receptors Cells remove glucose from blood RISE FALL Normal Concentration FALL RISE α cells secrete glucagon into the blood Detected by α cells in the islets of Langerhans

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood Insulin detected by receptors Cells remove glucose from blood RISE FALL Normal Concentration FALL RISE α cells secrete glucagon into the blood Detected by α cells in the islets of Langerhans Glucagon detected by receptors

Detected by β cells in the islets of Langerhans β cells secrete insulin into the blood Insulin detected by receptors Cells remove glucose from blood RISE FALL Normal Concentration FALL RISE α cells secrete glucagon into the blood Detected by α cells in the islets of Langerhans Cells release glucose into blood Glucagon detected by receptors

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