Chapter 17 - Section 17.3 - Study Guide - Assess Your Learning Outcomes - Page 669: 8

Pancreatic islets, also known as islets of Langerhans, are clusters of endocrine cells within the pancreas that are responsible for producing and releasing hormones involved in regulating blood sugar (glucose) levels and various aspects of metabolism. There are several cell types within pancreatic islets, each producing a specific hormone with distinct functions. Here are the main cell types, hormones, and functions associated with pancreatic islets: **1. Alpha Cells:** - **Hormone:** Glucagon - **Function:** Alpha cells produce glucagon, which plays a crucial role in raising blood glucose levels when they are too low (hypoglycemia). Glucagon stimulates the liver to break down stored glycogen into glucose through a process called glycogenolysis. This glucose is released into the bloodstream to provide energy for cells. **2. Beta Cells:** - **Hormone:** Insulin - **Function:** Beta cells produce insulin, a hormone that lowers blood glucose levels by facilitating the uptake of glucose into cells. Insulin promotes the storage of glucose as glycogen in the liver and muscles, as well as the conversion of glucose into fat in adipose tissue. It also inhibits the release of glucagon and promotes the utilization of glucose for energy. **3. Delta Cells:** - **Hormone:** Somatostatin - **Function:** Delta cells produce somatostatin, a hormone that regulates the release of insulin and glucagon. Somatostatin inhibits the secretion of both insulin and glucagon, helping to maintain a balanced blood glucose level. It also inhibits the release of various other hormones in the digestive system. **4. PP Cells (Pancreatic Polypeptide Cells):** - **Hormone:** Pancreatic Polypeptide (PP) - **Function:** PP cells produce pancreatic polypeptide, which plays a role in regulating appetite and digestion. It inhibits the release of digestive enzymes from the pancreas and can influence the feeling of fullness after eating. **5. Epsilon Cells:** - **Hormone:** Ghrelin (minor presence in the pancreas) - **Function:** Ghrelin is primarily produced in the stomach, but a small number of epsilon cells in the pancreas also produce it. Ghrelin is known as the "hunger hormone" because it stimulates appetite and food intake. **6. F Cells (Pancreatic Polypeptide Cells):** - **Hormone:** Pancreatic Polypeptide (PP) - **Function:** Similar to PP cells, F cells also produce pancreatic polypeptide, which is involved in regulating digestion and appetite. In summary, pancreatic islets contain different types of endocrine cells, each producing specific hormones with distinct functions. Alpha cells produce glucagon to raise blood glucose levels, beta cells produce insulin to lower blood glucose levels, delta cells produce somatostatin to regulate hormone release, PP cells produce pancreatic polypeptide to influence digestion and appetite, epsilon cells produce ghrelin to stimulate hunger, and F cells also produce pancreatic polypeptide with similar functions as PP cells. These hormones collectively play a critical role in maintaining glucose homeostasis and regulating various metabolic processes in the body.

Pancreatic islets, also known as islets of Langerhans, are clusters of endocrine cells within the pancreas that are responsible for producing and releasing hormones involved in regulating blood sugar (glucose) levels and various aspects of metabolism. There are several cell types within pancreatic islets, each producing a specific hormone with distinct functions. Here are the main cell types, hormones, and functions associated with pancreatic islets: **1. Alpha Cells:** - **Hormone:** Glucagon - **Function:** Alpha cells produce glucagon, which plays a crucial role in raising blood glucose levels when they are too low (hypoglycemia). Glucagon stimulates the liver to break down stored glycogen into glucose through a process called glycogenolysis. This glucose is released into the bloodstream to provide energy for cells. **2. Beta Cells:** - **Hormone:** Insulin - **Function:** Beta cells produce insulin, a hormone that lowers blood glucose levels by facilitating the uptake of glucose into cells. Insulin promotes the storage of glucose as glycogen in the liver and muscles, as well as the conversion of glucose into fat in adipose tissue. It also inhibits the release of glucagon and promotes the utilization of glucose for energy. **3. Delta Cells:** - **Hormone:** Somatostatin - **Function:** Delta cells produce somatostatin, a hormone that regulates the release of insulin and glucagon. Somatostatin inhibits the secretion of both insulin and glucagon, helping to maintain a balanced blood glucose level. It also inhibits the release of various other hormones in the digestive system. **4. PP Cells (Pancreatic Polypeptide Cells):** - **Hormone:** Pancreatic Polypeptide (PP) - **Function:** PP cells produce pancreatic polypeptide, which plays a role in regulating appetite and digestion. It inhibits the release of digestive enzymes from the pancreas and can influence the feeling of fullness after eating. **5. Epsilon Cells:** - **Hormone:** Ghrelin (minor presence in the pancreas) - **Function:** Ghrelin is primarily produced in the stomach, but a small number of epsilon cells in the pancreas also produce it. Ghrelin is known as the "hunger hormone" because it stimulates appetite and food intake. **6. F Cells (Pancreatic Polypeptide Cells):** - **Hormone:** Pancreatic Polypeptide (PP) - **Function:** Similar to PP cells, F cells also produce pancreatic polypeptide, which is involved in regulating digestion and appetite. In summary, pancreatic islets contain different types of endocrine cells, each producing specific hormones with distinct functions. Alpha cells produce glucagon to raise blood glucose levels, beta cells produce insulin to lower blood glucose levels, delta cells produce somatostatin to regulate hormone release, PP cells produce pancreatic polypeptide to influence digestion and appetite, epsilon cells produce ghrelin to stimulate hunger, and F cells also produce pancreatic polypeptide with similar functions as PP cells. These hormones collectively play a critical role in maintaining glucose homeostasis and regulating various metabolic processes in the body.