Pancreas and Digestion
As we work our way down the digestive tract, we encounter two major "outpouchings" -- the pancreas and the liver. Like the mouth and the stomach, these outpouchings represent evolutionary adaptations of the GI tract from its original straight line tube construction as found in more primitive animals such as worms. In today's newsletter, we are going to focus on the pancreas, both its anatomy and physiology. The pancreas actually plays two major roles in the body. It both produces hormones and digestive juices that dump into the duodenum, and it produces sugar and growth regulating biochemicals that empty directly into the bloodstream. In this newsletter, we will focus on the digestive functions (and the problems associated with those functions) and save the sugar and growth regulating functions for a later discussion when we explore the body's endocrine system. We will also explore how abuse of this commonly ignored organ (through poor diet, inadequate supplementation, and lack of regular cleansing) can lead to serious -- even fatal -- health problems.
There is one important note/perspective before we begin. The word pancreas actually means something. Translated from the original Greek, it reads as "all flesh" (pan -- all, kreas -- flesh), which refers to its ability to digest virtually all flesh (protein based tissue), including itself.
Physical facts about the pancreas
Most organs in the abdomen, such as the intestines, stomach, and liver are located in the peritoneal cavity. Just like we saw with the heart, which was located in the pericardial cavity, the peritoneal cavity is lined with a sac like membrane called the parietal peritoneum. Also, as with the heart, the organs inside the peritoneal cavity are covered with a visceral membrane.
The pancreas, however, does not fit this description. Like the kidneys, the rectum, and most of the duodenum, the pancreas is what is called a retroperitoneal organ. That means it lies within the peritoneal cavity but outside (behind) the visceral peritoneum or membrane. From a natural health perspective, as we explore the anatomy and physiology of the pancreas, this distinction has little meaning. On the other hand, to the surgeon, it matters a great deal.
Physically, the pancreas is located in the middle to upper abdominal cavity, towards the back or posterior. It is about 12 inches long and tapers from right to left. (Remember, as with our discussion of the heart, anatomically speaking, left and right are referenced from behind the body so they are actually reversed in most diagrams that view the body from the front.) The thick part, the head, comprises almost 50% of the mass of the pancreas and lies to the right, nestled in the curve of the duodenum. This location, as we will learn in a bit, is key to the functioning of the pancreas. As for the body of the pancreas, it moves up and to the left, tapering into what is known as the tail of the pancreas, which terminates at the junction of the spleen.
This locates the pancreas in terms of its head and tail. As for the front surface of the pancreas, it rests mostly against the back (posterior) wall of the stomach. The rest of it nestles against the first portion of the duodenum. This can be important in the case of duodenal ulcers that actually penetrate the duodenum -- as the ulcer will now begin to spread to the pancreas, leading to severe, often fatal, pancreatitis.
As might be suspected for such an important organ, the pancreas is richly supplied with arteries and veins. It is served by branches from the hepatic artery, the gastroduodenal artery, the pancreaticoduodenal artery, the superior mesenteric artery, and the splenic artery.
Pancreatic duct system
The pancreas shares a duct system with the liver in what is known as the biliary tree. We will discuss the complete tree in more detail when we talk about the liver in our next issue of the newsletter. When it comes to natural health, a complete understanding of the biliary tree and how to keeps its functioning optimized is essential to maintaining optimal health. For now, though, we will focus on that part of the tree that resides in the pancreas.
The pancreas is served by a major pancreatic duct (the duct of Wirsung) that runs down the middle of the pancreas and empties into the duodenum at the head of the pancreas through a valve called the ampulla of Vater. (Some people have a secondary duct (the duct of Santorini) that splits off from the main duct and empties into the duodenum just above the ampulla of Vater -- but this duct is usually non-functional.) It is important to note that the main duct joins the common bile duct (through which the liver and gallbladder empty) at the point it enters the duodenum. This is important as stones from the gallbladder can find their way down into the pancreatic duct, blocking it at the ampulla of Vater and leading to pancreatitis.
Secretory cells that release pancreatic juice are arranged in acini (clusters of cells that resemble many-lobed "berries") around small ducts that feed into progressively larger ducts and ultimately into the main duct -- virtually identical to the tracheal-bronchi tree we saw in the lungs.
Endocrine and exocrine functions coexist in the pancreas. By definition, endocrine organs secrete hormones directly into the bloodstream, whereas exocrine organs secrete hormones directly into the cavity (lumen) of another organ. The pancreas does both. The exocrine pancreas comprises 99% of pancreatic tissue. It secretes digestive juices into the duct system that carry them on into the cavity of the duodenum. The endocrine pancreas, on the other hand, secretes hormones (insulin, glucagon, and somatostatin) directly into the bloodstream. Simple math tells us that if 99% of pancreatic tissue serves the exocrine function of the pancreas, only 1% of pancreatic tissue is available for its endocrine function. Oh, but how important that 1% is. It is so important (and complex) that we will save our discussion of it for a separate newsletter when we explore the body's endocrine system. Once again, our focus on this issue is on the digestive system; therefore, our focus in this newsletter is on the exocrine function of the pancreas.
Finally, it should be noted that the major stimulation of the pancreas is primarily parasympathetic (originating in the brain stem), through the vagus nerve, and promotes secretion of digestive juices. Parasympathetic stimulation to the pancreas occurs in response to the digestive processes of the stomach. Food in the stomach stimulates the secretion of all pancreatic enzymes. And in fact, we covered the pancreatic triggering mechanisms in great detail in our exploration of the stomach.
Conversely, inhibition of pancreatic secretion of digestive juices is controlled by triggers and nerves outside of the central nervous system -- the sympathetic nervous system. Specifically, when acid chyme enters the duodenum, along with partially digested fats, proteins, and carbohydrates, enteroendocrine cells in the duodenum and small intestine release cholecystokinin (CCK) and secretin. Secretin decreases gastric secretion and CCK inhibits gastric emptying. These two enzymes circulate into the bloodstream. In addition, they stimulate further secretion of pancreatic enzymes and sodium bicarbonate into the small intestine, thus further raising the pH in the duodenum.
As we've discussed in previous newsletters, the primary processes of digestion occur in the stomach, and the primary processes of absorption occur in the small intestine. However, both these functions depend heavily on the digestive juices secreted by the pancreas -- specifically, the exocrine secretions of the pancreas that dump into the duodenum. The exocrine pancreas has the following components and functions.
The pancreas produces 1,000-1,500 mL (1-1.5 qts) of digestive juices per day. These juices consist primarily of water, NaCl (salt), and NaHCO3 (sodium bicarbonate). The purpose of the sodium bicarbonate is to neutralize the high acidity of the chyme (food plus stomach acid) raising it to an alkaline pH of 7.1-8.2. This both stops the action of gastric pepsins and stomach acid and prepares chyme for the process of nutrient absorption, which takes place in the small intestine.
In addition to containing sodium bicarbonate to neutralize the action of the digestive juices, pancreatic juice also contains a number of digestive enzymes (optimized to function in an alkaline environment) that help finish off the digestive process started in the stomach. (Obviously, and we will talk more about this later), the more complete the digestive process that took place in the stomach, the fewer digestive enzymes will be needed from the pancreas to finish the process. And in fact, the more complete will be the process of absorption in the small intestine.) These pancreatic enzymes include:
- Amylase digests the remaining complex carbohydrates into sugars -- mostly complex. Complex sugars are then further broken down into their individual component sugars in the small intestine:
- Maltose (glucose + glucose) is acted on by maltase and broken down into two molecules of glucose.
- Sucrose (glucose + fructose) is acted on by sucrase and broken down into glucose and fructose.
- Lactose (glucose + galactose) is acted on by lactase and broken down into glucose and galactose.
- Trypsin, chymotrypsin, and elastase all digest proteins.
- Lipase digests triglycerides into fatty acids and monoglycerides.
Almost all pancreatic enzymes are secreted in an inactive form to prevent autodigestion. (Remember, pancreas literally means "eats all flesh.") Inactive forms of enzymes end in "gen", e.g. trypsinogen. If the pancreatic enzymes were in the active form inside the pancreas, they would literally digest the pancreas itself. This is, of course, identical to what we saw in the stomach, in which the mucosal cells of the stomach lining release pepsinogen, pepsin's precursor -- which is converted into pepsin only after the pepsinogen has made its way out of the chief cells and into the stomach itself, where it is converted in the presence of stomach acid. Since the wall of the stomach is coated with mucous, the pepsin can only digest your meal and not your stomach. This would not be the case, of course, if the pepsinogen converted to pepsin while still in the stomach lining. And the same is true for the pancreatic enzymes, which only convert to their active form once they are fully clear of the pancreas itself. Incidentally, it is enterokinase (produced in the small intestine) that activates the pancreatic enzymes once they are in the safe confines of the small intestine. In the small intestine, the mucosal lining protects the tissue of the small intestine from autodigestion -- as in the stomach.
In severe pancreatitis, however, activated enzymes may travel back into the pancreas and digest it. We will talk more about pancreatitis in a little bit, but for now, consider alcohol. Regular consumption of alcohol inflames the pancreas. When the inflammation is severe, the smaller ducts of the pancreas are squeezed shut. Thus, the pancreatic enzymes do not readily flow through the duct system, but rather are released into the blood of the pancreas, where they become active and start digesting the pancreas itself. (Blockage of the biliary tree is also a major problem and can cause enzymes to back up and autodigest pancreatic tissue. We will explore this in more detail in a couple of newsletters when we focus on the biliary tree.)
It should be noted that the pancreas has self-defense mechanisms that can help prevent auto digestion -- at least in minor cases of back up. For example, the acinar cells (mentioned earlier) contain a trypsin inhibitor that inactivates any active trypsin accidentally released into the pancreatic tissues.
The role of the pancreas in digestion
We've assumed a basic understanding of what the purpose of digestion is in all of our discussions of the digestive process so far, but never really defined it in specific detail. Now would be a good time. The purpose of digestion -- with the contribution of the pancreas -- is to take the generally complex molecules of the food you eat and break them down into simple molecules and reassemble those molecules into necessary compounds. That's it, in a nutshell. For example, by eating foods with proteins containing the essential amino acids, the body can break those proteins down into their component amino acids through the efforts of the stomach and the pancreas, then send those amino acids to the liver, which then reassembles them to produce the full complement of non-essential amino acids the body needs. Essential amino acids are those which the body cannot assemble in the liver. Non-essential amino acids are those which can be manufactured in the liver -- as long as the right mix of essential amino acids is present in the diet. Essentially the same process is involved in digesting carbohydrates and fats -- breaking down complex molecules of great variety into smaller molecules of limited variety.
That's the simple description. If we take it one level deeper, it becomes even more interesting.
As it turns out, the body has evolved to favor molecules with similar structures. This presents the body with two major advantages. First, it makes the digestive process easier, since the body has only a limited number of end products it is trying to produce. But even more importantly, it makes reassembling molecules into more complex structures that much simpler since they all have fundamental similarities no matter what their function. For example, the four ring cyclopentanophenanthrene structure is common to all of the steroid hormones including: cholesterol, estradiol, testosterone, and cortisol. The only differences between these compounds are one or two groups attached to the outside of the common ring structure. I discussed this in detail in Lessons from the Miracle Doctors when exploring the make-up of hormones in the body. They all look remarkably similar because they share the same basic ring structure, but with tiny variations. Look at how remarkably similar the testosterone and estrone molecules are -- and yet how remarkably different they are in function. One makes men; the other makes women.
The bottom line is that because they are remarkably similar, it is that much easier for the body to assemble the basic building blocks after digestion into whatever is needed: testosterone, DHEA, estrogen, cortisol, cholesterol. You name it. Thus, the body can easily replace any particular missing compound by modifying the creation process of a similar compound. And in fact, we see this all the time in the body. For example, if you remove the ovaries to drop estrogen production to combat breast cancer, it only provides temporary relief. Estrogen levels will miraculously start to rise again eventually. How? The adrenals take over and start producing estrogen from the almost identical cortisol building block. Miraculous!
Incidentally, that's why doctors now prefer tamoxifen to removing ovaries. Instead of eliminating the body's ability to produce estrogen (which always shifts over to another organ), tamoxifen works to block estrogen receptor sites so that vulnerable tissue cannot "take up" any estrogen circulating in the bloodstream. Of course, this can also be done using natural health resources without the side effects and cost, but that's a topic for another newsletter.
What can go wrong with your pancreas?
Problems with the pancreas usually come down to two things -- pancreatitis and pancreatic cancer.
Unfortunately, doctors and hospitals do not document the incidence of non-acute pancreatitis since they offer no treatment for it. But researchers such as Edmund Howell in his book Enzyme Nutrition declared that virtually 100% of all Americans have an enlarged pancreas by the time they are 40! Is this possible? In fact, yes! There are strong indications that a major factor in chronic non-acute pancreatitis is the stress put on the pancreas through a diet high in cooked and processed foods -- a diet deficient in natural or supplemented enzymes.
Research done on rats and chickens that were fed cooked foods revealed that the pancreas enlarged to handle the extra burden of the enzyme-deficient diet. In other words, the pancreas will enlarge over time when called upon to compensate for a diet high in enzyme deficient foods. Ruminant animals such as cattle, goats, deer, and sheep get along with a pancreas about a third as large as the human pancreas because of their raw food diet. However, when these animals are fed heat-processed, enzyme-free food, their pancreas enlarges up to three times the normal size than when fed on a raw plant diet. Grossman, M. Greengard, H, Ivy, A. American Journal of Physiology. 141:38-41, 1944. Make no mistake; long-term, non-acute pancreatitis is a condition that affects virtually every person living on a modern diet -- given enough time. And just because doctors ignore it because it appears to be asymptomatic (at least in the short term), does not mean that you should be so cavalier about it. Over time, it has a profound impact on your health.
Surgical treatment of pancreatic cancer involves removing the pancreas, duodenum, the bile ducts, and half the stomach and reconnecting the remaining organs (the Whipple procedure). This is one of the biggest surgeries known, requiring from 6-14 hours to complete. It has a five year survival rate of just 2%, and in fact, almost half of all patients die on the operating table. Treatment of pancreatic cancer is especially difficult because the location of the pancreas means that tumors tend to spread rapidly to highly innervated (rich in nerves) regions of the back and spine.
The causes of the rising incidence are unknown within the "medical community," although one link that has definitely been established is smoking. The bottom line is that if you get pancreatic cancer, there is very little the medical community can do for you. When the medical community accuses the natural health community of diverting people away from effective treatments for cancer, there is no way they could be looking in a mirror if they are talking about pancreatic cancer. All the medical community can offer in the case of pancreatic cancer is great pain and suffering -- and at huge cost. On the other hand, within the natural health community, we can once again make some educated assumptions that may allow you to better your odds of never getting pancreatic cancer in the first place.
Using natural health to optimize your pancreas
The steps for taking care of your pancreas are fairly simple.
Basic concepts of pancreatic health
- Chronic pancreatitis: Long-term inflammation of the pancreas (pancreatitis) has been linked to cancer of the pancreas. In fact, long-term, non-acute inflammation of the pancreas may be the single leading cause of pancreatic cancer. Reducing inflammation of the pancreas, both acute and non-acute is fundamental to pancreatic health.
- Diabetes: Diabetes is not only a symptom of pancreatic cancer, but long-standing Type 1 diabetes significantly increases the risk of pancreatic cancer.
- Obesity: Obesity also significantly increases the risk of pancreatic cancer.
- Alcohol: Consume alcohol only in moderation as even small quantities of alcohol inflame the pancreas, not to mention the liver.
- And quit smoking: Statistically, smoking doubles the risk of pancreatic cancer. It has been estimated that as many as one in four cases of pancreatic cancer are the direct result of smoking cigarettes. Conversely, the risk of pancreatic cancer drops close to normal in people who quit smoking.
Diets high in meats, cholesterol, fried foods, and nitrosamines increase the risk of both pancreatic cancer and pancreatitis, while diets high in raw fruits and vegetables reduce risk. The bottom line is that a Mediterranean diet is pancreas friendly.
Supplemental digestive enzymes
Unless you're living on an all raw food diet, you need to be supplementing with digestive enzymes. Insufficient live digestive enzymes in the diet force the pancreas to overwork and overstress resulting in long-term, non-acute enlargement of the pancreas. Using digestive enzymes with every meal is one of the simplest things you can do to improve the health of your pancreas.
Kidney, gallbladder, liver flushes
We will cover this issue in more detail when we focus on the liver and biliary tree. However, there can be no question but that regularly softening and flushing of gallstones that can block both the gallbladder and the pancreatic ducts is fundamental to preventing pancreatitis and pancreatic cancer.
All of the above steps will help with maintaining the health of the endocrine pancreas, but there is more that you can do to support that 1% of pancreatic function. However, we need to save that for our discussion of the body's endocrine system, when we will have time to explore that function in detail. In the meantime, for a heads up on additional steps you can take, check out Diabetes: the Echo Effect.
In our next issue of the newsletter, we will continue our exploration of the digestive system as we take on the liver -- one of the most fascinating and important organs in the body.