In the exocrine pancreas, the relationship between structure and function, as well as between normal and pathological functioning, can be easily understood if presented in a systematic and logical manner. In this chapter, we explain pancreas physiology. We start by explaining the embryological and ontogenetic development of the pancreas and describe the basic anatomical characteristics of the mature gland, i.e. the macro- and microscopic structure, its vascular supply and innervation. These form the foundation necessary to understand the mechanisms of acinar and ductal cell secretion and their regulation, which are covered in the middle part, with an emphasis on the ionic part of the pancreatic juice. In the last part, we focus on the enzymatic part of the pancreatic juice and its role in digestion of all main groups of energy-rich nutrients, i.e. carbohydrates, proteins and lipids. Two main sources of additional information will help the reader grasp the main concepts in pancreas physiology: figures summarize and combine various concepts encountered in the main text, and clinical boxes contain examples of how a given piece of knowledge can be relevant to understand some diseases.
Part of the book: Challenges in Pancreatic Pathology
Insulin resistance in key target organs and beta cell dysfunction due to gluco- and lipotoxicity, are the two main factors driving type 2 diabetes mellitus pathogenesis. Recently, it has been suggested that ectopic fat deposition in the pancreas, named non-alcoholic fatty pancreas disease, occurs in metabolic syndrome, and may play an etiological role in islet dysfunction and damage the exocrine pancreas, increasing its susceptibility to pancreatitis and pancreatic cancer. In this chapter, we present transmission electron microscopy (TEM) as a valuable method to detect early changes in the ultrastructure of pancreatic cells during the development of the metabolic syndrome in mice fed with a western diet (WD). Mice fed with a WD develop pathological ultrastructural alterations in the exocrine and endocrine cells. We demonstrate how to use image segmentation methods and ultrastructural morphometry to analyze and quantify structural changes in cellular organelles and evaluate the presence of lipid droplets, autophagic structures, and vacuolization. Since ultrastructural lesions can be detected early during the progression of the metabolic syndrome, are in many aspects subtle, and by far precede cell apoptosis, necrosis, fat infiltration, and overt functional changes, TEM is not only a suitable but probably the crucial method for detecting early pancreas dysfunction.
Part of the book: Electron Microscopy