Pancreas – Tissue and Systems

Pancreas – Tissue and Systems

This article describes the basic anatomy and function of the pancreas in order to better understand the symptoms of pancreatic cancer. The structure and functions of the pancreas are quite complex. The pancreas provides a number of key functions essential to life.

The pancreas is located in the center of the abdomen, deep to most other organs. The supply of blood vessels and nerves to the pancreas is complex. The main artery that feeds the intestines passes through it (i.e. the superior mesenteric artery). The pancreas looks like a thick piece of fatty meat hence its name. The term pancreas is derived from the Greek meaning “all-flesh” from pan and kreas. The pancreas is below the stomach, behind the colon and surrounded by the first part of the small intestine. The drainage from the liver and bile ducts pass through its head as well. This intimate association with many key structures of the body explains why a tumor of the pancreas can cause many severe symptoms involving those related structures. These close relations also explain why cancer of the pancreas is so difficult to treat as any treatment runs the risk of significant collateral damage to important adjacent structures.

The pancreas can be compared to a fish in structure. The pancreas is said to have a head, neck, body and tail and is long and slender. The tail of the pancreas is said to “tickle” the spleen as it usually sits just at the inner curve of the spleen.

The functions of the pancreas can be divided into two main categories, endocrine and exocrine. The exocrine function of the pancreas refers to secretions of enzymes that help in digestion. The pancreas makes digestive enzymes that help break down dietary fat and protein. The pancreas also secretes an alkaline fluid that helps neutralize stomach acids and also participates in digestion. The pancreas has a main central duct that these enzymes and secretions spill into and they are then released into the small intestine where food empties just after the stomach. These exocrine products work together with bile from the gallbladder and liver to help digest fat and proteins from the diet.

The endocrine functions of the pancreas deal largely with the metabolism and use of sugar. Dietary carbohydrates are converted and broken down into small sugars that are transported in the blood as glucose. The pancreas has cells that secrete insulin, glucagon and somatostatin. Insulin is a protein that is secreted directly into the blood and helps the body use glucose. When blood sugar is high, more insulin is secreted normally to help use the sugar and use the glucose. When blood sugar is low, normally less insulin is secreted to prevent a dangerous drop in blood sugar known as hypoglycemia. Glucagon works in an opposite manner as insulin and helps to raise the blood sugar when needed. Somatostatin is a regulatory hormone that controls several different kinds of digestive secretions.

These essential features of the pancreas help explain the several different kinds of symptoms and different kinds of tumors that can arise from the pancreas. When someone is said to have pancreatic cancer, this usually refers to pancreatic adenocarcinoma. A list of possible pancreatic tumors includes (but is not limited to):

  • Duct cell carcinoma (90%)
  • Acinar cell carcinoma
  • Mucinous Tumors of various types
  • Cystadenocarcinoma
  • Adenosquamous carcinoma
  • Neuroendocrine or Islet Cell Tumors including:

Gastrinoma

Glucagonoma

Insulinoma

Somatostatinoma

 

Pancreas cancer is a common cancer and is difficult to treat. Cancer of the pancreas is the 10th most common cancer for men and women in the United States. Pancreatic cancer is the 4th most common cause of death from cancer for men and women in the United States as well. It is difficult to predict who will get pancreatic cancer but cigarette smoking is an established risk factor emphasizing the importance of smoking cessation.

Understanding what structures pass near or through the pancreas is key to understanding the various symptoms that might arise. The first part of the intestine and exit of the stomach are very close to the head of the pancreas. A tumor is in this area may push on the passageway and partially or completely block food emptying from the stomach. Eating thus becomes difficult and causes nausea with vomiting. Eventually severe weight loss and dehydration will occur as well.

The drainage of the liver and bile ducts passes near the head of the pancreas and then empties into the first part of the intestine. A tumor of the head of the pancreas may partially or completely block the delivery of bile from the liver. Blockage of bile causes several problems. Bile is a normal part of digestion of fat. Without this key ingredient, malabsorption would occur and over time nutritional deficiency would develop. Blockage of bile causes inflammation and pain in the liver. Over time this may even lead to liver failure. Blockage of bile causes bacteria to accumulate in the bile ducts and cause serious or even fatal infection called cholangitis. Buildup of bile in the liver causes a buildup of bile throughout the body resulting in an orange or yellow discoloration of the skin and eyes. As bilirubin builds up in the skin this causes severe itching.

The normal function of the endocrine products (e.g. insulin and glucagon) becomes disrupted with a tumor of those production cells or if a significant part of the pancreas is destroyed from a cancer or from treatment of the cancer. A tumor that produced too much insulin would cause dangerous drops in the blood sugar.

The numerous functions and bodily systems impacted by the pancreas emphasize the importance of the relationship between the anatomy and symptoms of pancreatic cancer.

REFERENCES:

  1. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed. Chapter . New York, NY: Saunders.
  2. www.cancer.gov/cancertopics/types/pancreatic
  3. seer.cancer.gov/statfacts/html/pancreas.html
  4. www.cancer.gov/cancertopics/pdq/treatment/isletcell/HealthProfessional
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.