Chapter 25 - Section 25.4 - Study Guide - Assess Your Learning Outcomes - Page 991: 7

The pancreas is composed of both exocrine and endocrine components. The exocrine portion is responsible for producing and secreting digestive enzymes, while the endocrine portion is involved in hormone secretion, primarily insulin and glucagon. Let's focus on the structure of the pancreatic acini, the duct system, and its connection to the duodenum, which are all part of the exocrine function of the pancreas: **Pancreatic Acini:** The exocrine portion of the pancreas is made up of clusters of cells called pancreatic acini. These acini are responsible for producing and releasing digestive enzymes into the small intestine. Each acinus is a spherical cluster of cells with a central lumen, and it is surrounded by a network of tiny ductules. **Duct System:** The duct system of the pancreas is responsible for transporting the digestive enzymes and other substances produced by the acini to the duodenum, the first part of the small intestine. The duct system consists of various interconnected ducts that ultimately merge and lead to the main pancreatic duct, also known as the duct of Wirsung. The main components of the pancreatic duct system include: 1. **Intralobular Ducts**: These small ducts are located within the pancreatic lobules (lobes of the pancreas). They receive secretions from the acini and transport them to interlobular ducts. 2. **Interlobular Ducts**: These ducts are larger and located between the pancreatic lobules. They receive secretions from intralobular ducts and transport them toward the main pancreatic duct. 3. **Main Pancreatic Duct**: The main pancreatic duct runs lengthwise through the pancreas, collecting secretions from interlobular ducts. It travels through the pancreatic tissue and eventually merges with the common bile duct, forming the hepatopancreatic ampulla (also known as the ampulla of Vater). 4. **Accessory Pancreatic Duct (Duct of Santorini)**: In some individuals, an additional smaller duct called the accessory pancreatic duct can also be present. It joins the main pancreatic duct or enters the duodenum separately. **Connection to the Duodenum:** The connection between the pancreatic duct system and the duodenum is facilitated by the hepatopancreatic ampulla. The ampulla is a small opening located in the wall of the duodenum, near where it receives secretions from the common bile duct. The hepatopancreatic ampulla serves as the point of entry for both bile from the common bile duct and pancreatic secretions from the main pancreatic duct into the duodenum. The hepatopancreatic sphincter (sphincter of Oddi) surrounds the ampulla. It regulates the flow of both bile and pancreatic enzymes into the duodenum. When digestion is required, the hormone cholecystokinin (CCK) is released in response to the presence of fatty food in the duodenum. CCK causes the hepatopancreatic sphincter to relax, allowing the bile and pancreatic enzymes to enter the duodenum and participate in digestion. In summary, the exocrine function of the pancreas involves producing digestive enzymes in the acini, which are then transported through the duct system and released into the duodenum. The main pancreatic duct and its network of smaller ducts play a crucial role in delivering pancreatic secretions to the small intestine for digestion.

The pancreas is composed of both exocrine and endocrine components. The exocrine portion is responsible for producing and secreting digestive enzymes, while the endocrine portion is involved in hormone secretion, primarily insulin and glucagon. Let's focus on the structure of the pancreatic acini, the duct system, and its connection to the duodenum, which are all part of the exocrine function of the pancreas: **Pancreatic Acini:** The exocrine portion of the pancreas is made up of clusters of cells called pancreatic acini. These acini are responsible for producing and releasing digestive enzymes into the small intestine. Each acinus is a spherical cluster of cells with a central lumen, and it is surrounded by a network of tiny ductules. **Duct System:** The duct system of the pancreas is responsible for transporting the digestive enzymes and other substances produced by the acini to the duodenum, the first part of the small intestine. The duct system consists of various interconnected ducts that ultimately merge and lead to the main pancreatic duct, also known as the duct of Wirsung. The main components of the pancreatic duct system include: 1. **Intralobular Ducts**: These small ducts are located within the pancreatic lobules (lobes of the pancreas). They receive secretions from the acini and transport them to interlobular ducts. 2. **Interlobular Ducts**: These ducts are larger and located between the pancreatic lobules. They receive secretions from intralobular ducts and transport them toward the main pancreatic duct. 3. **Main Pancreatic Duct**: The main pancreatic duct runs lengthwise through the pancreas, collecting secretions from interlobular ducts. It travels through the pancreatic tissue and eventually merges with the common bile duct, forming the hepatopancreatic ampulla (also known as the ampulla of Vater). 4. **Accessory Pancreatic Duct (Duct of Santorini)**: In some individuals, an additional smaller duct called the accessory pancreatic duct can also be present. It joins the main pancreatic duct or enters the duodenum separately. **Connection to the Duodenum:** The connection between the pancreatic duct system and the duodenum is facilitated by the hepatopancreatic ampulla. The ampulla is a small opening located in the wall of the duodenum, near where it receives secretions from the common bile duct. The hepatopancreatic ampulla serves as the point of entry for both bile from the common bile duct and pancreatic secretions from the main pancreatic duct into the duodenum. The hepatopancreatic sphincter (sphincter of Oddi) surrounds the ampulla. It regulates the flow of both bile and pancreatic enzymes into the duodenum. When digestion is required, the hormone cholecystokinin (CCK) is released in response to the presence of fatty food in the duodenum. CCK causes the hepatopancreatic sphincter to relax, allowing the bile and pancreatic enzymes to enter the duodenum and participate in digestion. In summary, the exocrine function of the pancreas involves producing digestive enzymes in the acini, which are then transported through the duct system and released into the duodenum. The main pancreatic duct and its network of smaller ducts play a crucial role in delivering pancreatic secretions to the small intestine for digestion.