BA

DF

Islets of Langerhans > Clusters of Rounded Endocrine cells amougst the Exocine Pancreas > 1-2% of total volume of pancrease, 500K/pancreas

Function 1) Regulate Serum Glucose > Insulin: lowers blood sugar > Glucagon: raises blood sugar 2) Somatostatin 3) VIP 4) 5HT 6) Amylin 7) Pancreatic Polypeptide

Cell Types in the Islets of Langerhans Alpha: 15-20% Glucagon @ Outer Mantle Beta: 70% Insulin @ Inner Core Delta >> Portal Vein >>> Liver > Glucagon >>> Insulin > Insulin >>> Insuline (Autocrine) > Insulin ---x Glucagon > Somatostatin ---x (Insulin + Glucagon) SS~R~Exocrine Cells ---x HCO3 + Digestive EnzymesCell Morphology

> made for regulated secretion of peptide hormones > Large RER, prominentn Golgi, Storage Granules (Dense-Core Secretory vesicles with HALOs) glycoprotein

Innervation: Sympathetic + Parasympathetic, 10% of cells are Synapsed Upon > Gap Junctions between B-Cells

Islets of Langerhans

D

B

A

Insulin

Somatostatin

Gluc

agon

To Portal Vein

Bloo

d Fl

ow

Insu

lin

GlucagonSom

atostatin