The Endocrine System and Pancreatic Cancer
by Robert Tallitsch, PhD | May 12, 2022
Short video explaining the Endocrine System and Pancreatic Cancer with a Patient Case Example at the end of the video!
Written by: Robert Tallitsch. PhD
Homeostasis is defined as “the tendency toward a relatively stable equilibrium between interdependent factors, especially as maintained by physiological processes” (Berne et al., 2004). The maintenance of homeostasis in the human body involves the integration of numerous organs and systems throughout the body, including the integration and coordination of the nervous and endocrine systems. When comparing the roles played by these two systems, the nervous system provides short-term and very rapid adjustments in order to reinstate or maintain homeostasis, while the endocrine system produces adjustments that take longer to occur but are maintained for a much longer time period — often days or more. This Brain Builder will give a brief overview of the endocrine system, discuss the anatomy of the pancreas in greater detail, and then will discuss pancreatic cancer.
Overview of the Endocrine System
The classic view of the endocrine system is as follows: The endocrine system is composed of ductless glands that release a chemical signaling substance, termed a hormone, into either the interstitial fluid, lymphatic system, or cardiovascular system. This hormone then diffuses away from its source and exerts its chemical effect at a group of cells or an organ that is either in close proximity to the endocrine gland or distant from it.
Utilizing this view, the classic list of endocrine glands includes the:
- Pancreatic islets (also termed islets of Langerhans) within the pancreas
- Suprarenal (adrenal) glands
- Anterior and posterior pituitary glands
- Gonadal structures
- Thyroid gland
- Parathyroid gland
However, as our knowledge of hormones has increased, this view of the endocrine system has changed drastically. Now, in addition to the classic locations and structures of endocrine cells and glands, new knowledge of hormone production and action has increased the sources of hormones to organs and structures that have traditionally been thought to have no endocrine function what-so-ever. These new sources of hormones include the kidneys, heart, gastrointestinal cells, endothelial cells of blood vessels, and numerous cells of the lymphatic system — just to mention a few. Thus, the molecular variety of hormones, as well as their sources, has changed considerably within recent history.
Anatomy of the Pancreas
Functionally the pancreas is both an exocrine and endocrine gland. In its exocrine role the pancreas produces bicarbonate, which aids in the neutralization of stomach acid, and a series of digestive enzymes involved in the digestion of proteins, fats, and nucleic acids. These secretions are released into the duodenum of the small intestine by two ducts: the pancreatic duct and the accessory pancreatic duct.
The endocrine portion of the pancreas releases glucagon and insulin, two hormones that strive to maintain healthy blood sugar levels. These hormones are synthesized by, and are released from endocrine cells within the pancreatic islets (also termed the islets of Langerhans).
The pancreas lies along the posterior wall of the abdomen, passing from right to left. It is divided into four segments: head, neck, body, and tail.
The head of the pancreas is in contact with the c-shaped portion of the duodenum. The neck of the pancreas lies anterior to the superior mesenteric artery and the formation of the portal vein by the union of the superior mesenteric and splenic veins.
The body of the pancreas lies within the hypogastric region of the abdomen. The tail of the pancreas is in close proximity to the spleen within the left hypochondriac region of the abdomen.
Pancreatic enzymes are released into the duodenum by the pancreatic duct and the accessory pancreatic duct. The pancreatic duct begins in the tail of the pancreas and passes to the right, through the body of the pancreas. As it enters the head of the pancreas the pancreatic duct turns inferiorly, where it ultimately joins with the bile duct. This junction forms the hepatopancreatic ampulla (also termed the ampulla of Vater), which empties into the duodenum.
The accessory pancreatic duct drains the head of the pancreas and empties into the duodenum at a location slightly superior to the drainage of the pancreatic duct.
Pancreatic cancer is rarely detected in its early phases when it would be most curable. This is because pancreatic cancer typically doesn’t produce any symptoms until it has metastasized to other organs of the body.
Most cancers of the pancreas develop within the exocrine ducts of the pancreas and, therefore, are classified as exocrine cancers. Some cancers do begin within the pancreatic islets and these forms of cancer are classified as pancreatic neuroendocrine tumors. This form of pancreatic cancer presents a significantly greater prognosis for successful treatment than do exocrine cancers.
Some of the risk factors contributing to pancreatic cancer include:
- Chronic pancreatitis
- Being overweight
- Age, in that most pancreatic cancers develop in individuals over the age of 45, with 2/3 of the patients being older than 65.
- Gender, in that males develop pancreatic cancer at a higher rate than females.
- Race, in that African Americans are slightly more likely to develop pancreatic cancer.
- Family history
When pancreatic cancer does exhibit symptoms the tumors are typically quite large or the cancer has metastasized to other organs. When symptoms are present they typically include:
- Jaundice (yellowing of the eyes and skin)
- Abdominal and/or back pain
- Nausea and vomiting
- Weight loss and poor appetite
- Blood clots
- Enlargement of the gallbladder or liver
Although research on earlier detection of pancreatic cancer and new and various treatments continue, the five-year survival rates for the various stages of exocrine pancreatic cancer range from a high of 39% to a low of 3%. In contrast, neuroendocrine pancreatic cancer has a five-year survival rate ranging between 93% for localized tumors to 24% in patients where the cancer has metastasized to other organs (American Cancer Society).
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Homeostasis - Homeostasis is defined as the tendency toward a relatively stable equilibrium between interdependent factors, especially as maintained by physiological processes.
Hormone - A chemical signaling substance that diffuses away from its source and exerts its chemical effect at an organ or a group of cells that is either in close proximity to the endocrine gland or distant from it.
Endocrine gland - A ductless gland that releases a chemical signaling substance termed a hormone.
Accessory pancreatic duct - A pancreatic duct that drains the head of the pancreas. This duct empties into the duodenum slightly superior to the drainage of the pancreatic duct.
Glucagon and insulin - Two hormones produced within the pancreatic islets that attempt to keep blood sugar at a healthy level.
Jaundice - Yellowing of the eyes and/or skin.
Exocrine pancreatic tumors - A pancreatic tumor that develops within the ducts of the pancreas.
Pancreatic neuroendocrine tumors - Pancreatic cancer that develops within the pancreatic islets (islets of Langerhans).
- The body of the pancreas lies within which region of the abdominal cavity?
a. Right hypochondriac
b. Left hypochondriac
A: Option c. Hypogastric
- True or False? The pancreas lies along the posterior body wall and crosses the abdominal cavity from right to left.
- True or False? The accessory pancreatic duct drains the tail of the pancreas.
A: False. The accessory pancreatic duct drains the head of the pancreas.
- True or False? The head of the pancreas is in contact with the c-shaped portion of the duodenum.
- List the two hormones produced and released from the endocrine portion of the pancreas.
A: Glucagon and insulin
- True or False? The two pancreatic ducts (pancreatic duct and accessory pancreatic duct) both release pancreatic enzymes into the same location within the duodenum.
A: False. The accessory pancreatic duct empties into the duodenum at a location that is slightly superior to the opening of the pancreatic duct.
- True or False? The effects to maintain or re-establish homeostasis by the nervous system are faster and more short-lived than those of the endocrine system.
- True or False? There are two types of pancreatic cancers and both have the same 5-year survivability rates.
A: False. Pancreatic neuroendocrine tumors produce a form of pancreatic cancer that has a higher survivability rate.
- True or False? Pancreatic cancer demonstrates significant symptoms that aid in diagnosis, even in its early stages of development.
A: False. When pancreatic cancer does exhibit symptoms the tumors are typically quite large or the cancer has metastasized to other organs.
- True or False? Most cancers of the pancreas develop within the endocrine portions of the pancreas and, therefore, are classified as endocrine cancers.
A: False. Most cancers of the pancreas develop within the exocrine ducts of the pancreas and, therefore, are classified as exocrine cancers. The accessory pancreatic duct drains the head of the pancreas.
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Berne, RM et al. (2004) Physiology (5th ed). Philadelphia: Mosby/Elsevier.
Survival Rates for Pancreatic Neuroendocrine Tumor. American Cancer Society. (2022, February 28). Retrieved May 10, 2022, from https://www.cancer.org/cancer/pancreatic-neuroendocrine-tumor/detection-diagnosis-staging/survival-rates.html