Lesson 1- Physiology
The Digestive System
The digestive system in our body is responsible for the breakdown of the foods that we eat, extracting the nutrients from that food, and eliminating the waste. The extraction of these nutrients in vital to our health. The foods that we eat are broken down into 3 basic categories; proteins, fats and carbohydrates. These three macro-nutrients need to be further be broken down into there more basic components that get absorbed and utilized by our cells. The process of digestion is very complex and in my opinion, one of the most vital aspects of our health. The human body is of the most complex machine in the world. It needs the proper fuel, maintenance and protection to function optimally. Imagine if you had a Ferrari. A Ferrari is a complex, fine tuned machine that needs to be fueled, maintained and protected properly. You wouldn't put crappy gas or neglect the maintenance of a Ferrari! First,because it wouldn't run correctly. Second, because its too valuable to neglect. There is nothing more valuable than your own body, yet we feed it poor fuel and neglect to maintain and protect it. When you put poor fuel into your machine, it performs poorly. Are we surprised that there is so much chronic disease and illness nowadays when we know that most of our foods are highly processed and laden with harmful chemicals.
In this lecture we are going to discuss the physiology of the digestive system. You are going to learn exactly how it is supposed to function. In the second lecture, you will learn the pathology or diseases of the digestive system. Finally, in the 3rd lecture, you will learn how to treat and prevent diseases of the system.
Once again, proper digestion and assimilation(use) of nutrients are vital to our health. Unless we breakdown these nutrients properly, we will never be able to get them to our cells for use. If one of the processes of digestion is not working properly, our health will suffer and we will be more prone to disease.
So lets begin with the mouth and end with...well you know
The Mouth
The process of digestion begins in the mouth. Well actually begins before it enters your mouth. Have you ever smelled food and had your mouth water? We all have, especially if you grew up in an Italian home like me. That watering is from the release of saliva that contains enzymes that start breaking down your food. Saliva is produced by several salivary glands surrounding the mouth. The saliva not only breaks down the food but it also helps moisten the food to aid in swallowing. The microbiome of our mouth also helps breakdown this food as well; especially food that remains in the mouth and between the teeth.
Speaking of teeth, chewing is another essential part of the digestion process. Chewing breaks food down into smaller pieces which makes it easier for the stomach to digest. Some say you should chew your food 30 times before swallowing. Well it depends on what you are eating. You obviously have to chew a steak more than you would mashed potatoes. The point is that you want to chew your food as much as possible to aid the absorption of nutrients from your food. Once chewed thoroughly, the food is formed into a bolus (ball) by your tongue to make it ready to swallow. Drinking water while eating will also help moisten the food to aid in the swallowing process. Once swallowed, the food makes its way down the esophagus, which is the tube that leads from the mouth to the stomach. There is a lot of coordination that goes on when you swallow. The epiglottis, which is a flap has to cover the breathing tube or trachea so that food or liquid does not go towards the lungs. We have all experienced when food or liquid "goes down the wrong pipe". It's quite uncomfortable to say the least. Anther point to make is that eating too quickly, like I do, can make it more difficult on the stomach to digest the food and will also make you swallow more air, which leads to bloating and gas.
The Stomach
The stomach is now ready to receive the bolus of food. The stomach has already gotten a head start by starting to produce stomach acid (HCl or hydrochloric acid) when you first bite into your food. This acid is extremely powerful and literally starts to erode the food to make it ready for the small intestines to absorb nutrients. When the food fully enters the stomach a tiny sphincter muscle closes to prevent the material from entering back into the esophagus (reflux or heartburn). This muscle acts kind of like a check valve. Your stomach acid has two major purposes - pay attention here- 1) It helps to dissolve or break down the food for the intestines. 2) It kills pathogens like bacteria, viruses and fungus that may be in what we ingest. The small intestine, unlike the colon, does not harbor much, if any bacteria. Maintaining a sterile small intestine is extremely important to our health. Thousands of Americans take PPI's or proton pump inhibitors for GERD or reflux. These drugs block to production hydrochloric acid to relive the pain of heartburn. Putting two and two together from the previous statements, you can see that these drugs can lead to two problems. First, the food from your stomach is not broken down properly which prevents vitamins and nutrients from being absorbed from the small intestine. I cannot tell you how many people that take these medicines that I have uncovered vitamin deficiencies, like B-12, zinc and magnesium. The second problem that can arise from lack of acid, is the inability to kill pathogens which allows then to enter the small intestine. This can cause some serious health issues which we will discuss in the next lecture. Before the invention and heavy use of PPI's, we never as doctors encountered these issues. Doesn't it make more sense to treat the cause of the acid reflux rather than just putting a band-aid on the symptoms? I have had almost a 100% success rate in treating GERD/reflux through dietary modification and supplementation.
The stomach is also lined with a layer of smooth muscle which contracts literally churns the food -acid mixture. If you have ever vomited, you know how strong these stomach contractions can be. The stomach continues to churn the food for about 2 hours to get it ready for the small intestine, where the majority of nutrient absorption occurs.
The Small Intestine
The thoroughly churned and dissolved food now enters the first part of the small intestine or duodenum. When the food enters the duodenum, there is another sphincter muscle or check valve that prevents food from re-entering the stomach. The major roles of the small intestines are to further breakdown food and to start absorbing nutrients, vitamins and minerals. We spoke about the three major categories of foods- proteins, fats and carbohydrates. They get broken down into their building blocks which are the absorbable microscopic components. Proteins get broken down into amino acids, carbohydrates into sugar and fats into fatty acids and glycerol. The duodenum connects with the secondary digestive organs- the liver, gall bladder and pancreas. These organs secrete other digestive enzymes to further break down the food. The gallbladder secretes bile which breaks down or emulsifies fats. The pancreas produces pancreatic enzymes to break down carbohydrates and proteins. All of these enzymes are essential for optimal digestion and absorption of nutrients. The small intestine contains tiny finger-like projections called villi which increase the surface area for absorption of nutrients that go from the intestine into the blood stream. Once in the blood steam, hormones like insulin transport the nutrients into your cells.
Basically what you need to know here is that your body at this point has all of these processes going on to get nutrients from the intestine into the bloodstream. Many people that I consult with have inadequate production of digestive enzymes. Some people have had their gallbladders removed, some just don't produce enough enzyme and thus, have digestive issues. It's usually a simple fix... supplement digestive enzymes. Anything that is not absorbed in the small intestine moves on into the colon or large intestine. Anything that gets absorbed into the bloodstream goes to the liver for processing.
The remaining two parts of the small intestine, the jejunum and ileum, continue to extract nutrients from the food into the bloodstream.
The Large Intestine
The large intestine, to me is where all of the magic happens. When I was trained in medical school, we learned that the colon's main function was to reabsorb water from the stool back into the body. When not enough water was reabsorbed, the result is watery stool or diarrhea, if too much water was reabsorbed, the result is dry stool or constipation. I also learned that the large intestine is responsible for electrolyte, vitamin and mineral absorption (most of which are produced by the intestinal bacteria) and is also responsible for the elimination of waste. It turns out that, this is just the tip of the iceberg. The remaining food that did not get digested in the small intestine now becomes the food for the trillions of bacteria that reside in our colons.
The Gut Microbome
If you have ever heard one of my talks or seen my social media posts, you know that I am obsessed with the gut microbiome. Why? Well, it turns out that our body has more bacterial cells than human cells and more bacterial DNA than human DNA. That should tell you how important the gut microbiome is. It tuns out that our bodies are not completely our own. We have a symbiotic relationship with the bacteria that live within us; which means that we rely on each other for survival. Amazing!!
The food that enters the colon has a tremendous effect on your health. But before we go there let me back up a minute. As previously stated, the colon houses trillions of bacteria as well as fungi and viruses. Some are good and some are bad. I will refer to them moving forward as the good bugs and the bad bugs. I want you to think of your colon as a garden. The good bugs are the flowers and the bad bugs are the weeds. In order for flowers to grow they need fertilizer. The weeds also need food to grow but they are a lot less picky. In order to have a beautiful, healthy garden, you need to eliminate the weeds and feed the flowers. Well, the same goes for the colon. The good bugs love fiber from healthy foods like vegetables and resistant starches like sweet potato. The bad bugs love one thing and one thing only- SUGAR. When we eat too much sugar (including the sugar in fruit), we are feeding the bad bugs. At some point, if we don't take care of our garden, the weeds take over. This is exactly what happens when you eat too much sugar. This is called gut dysbiosis. Much more on this in the next section.
So getting back to our journey; the food that makes its way into the colon can either be food for the good bugs or food for the bad bugs. In this lecture since we are talking about normal physiology, lets assume that there are mostly good bugs. The food that has now entered the colon starts to get broken down by the gut bacteria. This food for the bacteria is called prebiotics. Prebiotics are essential for the microbiome to thrive. These bacteria use this food to survive. The byproduct of this breakdown is the key to our health. This byproducts are called metabolites. We are learning more and more how important these metabolites are, through the hundreds of ongoing studies. One example, of these metabolites are neurotransmitters. Neurotransmitters like serotonin are essential for brain health. We used to believe that our body made its own supply of neurotransmitters. It turns out that that latest research shows, that the majority of our neurotransmitters are actually made by the gut bacteria!! It turns out that these bacteria produce many of the essential chemicals that our body requires to function. Some other really important metabolites are butyrate and proprionate (which you can see in the diagram) that help increase energy intake to the cells. When these are missing the result is inflammation! I use specific stool testing to check these metabolite levels. By feeding the good bacteria and adding probiotics, we can increase the production of these good metabolites and decrease inflammation.
This is where that symbiotic relationship comes in. We provide the bacteria with food and the bacteria, in turn, makes the chemicals, vitamins and nutrients our bodies need to survive. One can't survive without the other.
There is so much more that these good gut bugs do- they police the intestine from overgrowth of bad bacteria, they metabolize drugs and they have a profound effect on our immune system
Watch this video which describes some of the other functions of the microbiome:
The Gut- Blood Barrier
This is one of the most important topics when it comes to almost all inflammatory and specifically Autoimmune diseases.....understanding the relationship between the colon mucosa and the bloodstream. The barrier between the inside of the gut and the blood stream is only ONE CELL LAYER- that's all! This one cell layer has one of the most important functions in the body - it regulates what goes between the colon and the blood. The left side reflects a normal cell junction- these junctions are very tight and do not allow the passage of pathogens or allergens to enter the blood stream. When there is inflammation in the gut, which can be caused by food, toxins, chemicals, etc, this layer becomes damaged and the junctions loosen up (right side of the diagram). This is called Leaky Gut. I wanted to mention this here for completeness sake, but we will be spending a lot of time on this in the next section. Once you grasp this concept you will start to understand how critical gut health is to your overall health.
The Gut- Brain Connection
The gut-brain connection is no joke; it can link anxiety to stomach problems and vice versa. Have you ever had a "gut-wrenching" experience? Do certain situations make you "feel nauseous"? Have you ever felt "butterflies" in your stomach? We use these expressions for a reason. The gastrointestinal tract is sensitive to emotion. Anger, anxiety, sadness, elation — all of these feelings (and others) can trigger symptoms in the gut.
The brain has a direct effect on the stomach and intestines. For example, the very thought of eating can release the stomach's juices before food gets there. This connection goes both ways. A troubled intestine can send signals to the brain, just as a troubled brain can send signals to the gut. Therefore, a person's stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression. That's because the brain and the gastrointestinal (GI) system are intimately connected.
This is especially true in cases where a person experiences gastrointestinal upset with no obvious physical cause. For such functional GI disorders, it is difficult to try to heal a distressed gut without considering the role of stress and emotion.
Given how closely the gut and brain interact, it becomes easier to understand why you might feel nauseated before giving a presentation, or feel intestinal pain during times of stress. That doesn't mean, however, that functional gastrointestinal conditions are imagined or "all in your head." Psychology combines with physical factors to cause pain and other bowel symptoms. Psychosocial factors influence the actual physiology of the gut, as well as symptoms. In other words, stress (or depression or other psychological factors) can affect movement and contractions of the GI tract.
In addition, many people with functional GI disorders perceive pain more acutely than other people do because their brains are more responsive to pain signals from the GI tract. Stress can make the existing pain seem even worse.
Based on these observations, you might expect that at least some patients with functional GI conditions might improve with therapy to reduce stress or treat anxiety or depression. Multiple studies have found that psychologically based approaches lead to greater improvement in digestive symptoms compared with only conventional medical treatment. We must utilize a more holistic approach when treating disorders like depression, anxiety, ADHD, etc. I treat the gut first along with behavioral modification and natural supplementation with things like GABA and SAMe.
The Vagus Nerve and the Nervous System
Neurons are cells found in your brain and central nervous system that tell your body how to behave. There are approximately 100 billion neurons in the human brain. Interestingly, your gut contains 500 million neurons, which are connected to your brain through nerves in your nervous system. The vagus nerve is one of the biggest nerves connecting your gut and brain. It sends signals in both directions. For example, in animal studies, stress inhibits the signals sent through the vagus nerve and also causes gastrointestinal problems. Similarly, one study in humans found that people with irritable bowel syndrome (IBS) or Crohn’s disease had reduced vagal tone, indicating a reduced function of the vagus nerve. An interesting study in mice found that feeding them a probiotic reduced the amount of stress hormone in their blood. However, when their vagus nerve was cut, the probiotic had no effect. This suggests that the vagus nerve is important in the gut-brain axis and its role in stress.
In fact for every 2 nerve fibers in the vagus nerve that runs from the brain to the gut, there are 8 that go from the gut to the brain! This tells us just how much information goes from the gut to the brain. Some people refer to the gut as the "second brain". i believe this to be true. Se the two diagrams below. Not included in this diagram are the signals for stress and anxiety and depression!!!
All About Poop
Fittingly, the last section of this lecture s all about your stool. The stool tells us a lot about the health of your gut. I always ask my clients about their bowel habits and expect detailed answers.
Healthy poop can be as varied and as unique as the individuals who make it. But there are a few general rules to follow if you want to assess your poop artistry for optimum health.
Color
The poop emoji has one thing right — the brown coloring. Bilirubin, which is a pigment compound formed from the breakdown of red blood cells in the body, gets the credit for this oh-so-lovely shade of brown.
Shape
A somewhat log-like shape is how most poop should come out due to its formation within the intestines. However, as we’ll get to later, there are a variation of shapes that poop can have.
And when they differentiate from the log/sausage shape, that’s when your poop is trying to tell you something’s up.
Size
Poops shouldn’t come out in small pellets (something else we’ll get to later) but instead should be a couple inches in length, comfortable and easy to pass.
Consistency
Anywhere between a firm and soft consistency is pretty much normal. If it sways one way or another, it could suggest some digestion or fiber issues.
Length of time (how long it takes)
A commonly heard joke is that when someone takes too long in the bathroom, it must mean they’re pooping. A healthy poop, however, should be easy to pass and take only a minute to push out.
That said, some people do spend a bit more time on the toilet, so as a general rule, a poop should take no more than 10 to 15 minutes.
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Frequency (how often)
Fun fact: Did you know most people poop around the same time every day?
On average, a person with healthy digestion will poop anywhere between every other day to three times a day. Any less could suggest possible constipation. This means you need some more water to move the “boat.”
What is the Bristol Stool Scale?
This scale is an overarching indicator of how and why different types of poops look or feel a certain way. It’s broken up into seven categories based on a 2,000-person study, , and it makes poop knowledge basic and easy to understand.
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Type 1 Appearance: Hard and separate little lumps that look like nuts and are hard to pass
Indicates: These little pellets typically mean you’re constipated. It shouldn’t happen frequently.
Type 2 Appearance: Log-shaped but lumpy
Indicates: Here we have another sign of constipation that, again, shouldn’t happen frequently.
Type 3 Appearance: Log-shaped with some cracks on the surface
Indicates: This is the gold standard of poop, especially if it’s somewhat soft and easy to pass.
Type 4 Appearance: Smooth and snake-like
Indicates: Doctors also consider this a normal poop that should happen every one to three days.
Type 5 Appearance: These are small, like the first ones, but soft and easy to pass. The blobs also have clear cut edges.
Indicates: This type of poop means you are lacking fiber and should find ways to add some to your diet through cereal or vegetables.
Type 6 Appearance: Fluffy and mushy with ragged edges.
Indicates: This too-soft consistency could be a sign of mild diarrhea. Try drinking more water and fruit juice to help improve this.
Type 7 Appearance: Completely watery with no solid pieces.
Indicates: In other words, you’ve got the runs, or diarrhea. This means your stool moved through your bowels very quickly and didn’t form into a healthy poop.
What does a person’s poop color mean?
As with size and consistency, poop’s color can be a helpful signal about what’s going on within your body. As we previously mentioned, varying shades of brown are what’s considered the norm.
According to Mayo Clinic, even a hint of green is considered healthy. But if your poop is veering toward other ends of the rainbow, you might want to assess.
SBlack
If you’ve had licorice, iron supplements, or bismuth medications (such as Pepto-Bismol), that could be the explanation behind black stool. If you haven’t had any of that, black poop could be a sign of bleeding in the upper gastrointestinal tract.
It may seem like red would be a more likely color for this sort of concern, but since it’s taken a while to travel down, it’s older and therefore darker.
Green
Like I mentioned, hints of green are actually quite normal. But when it’s pretty much turned from brown to full green, it means one of two things. Either you’ve added lots of green foods like spinach to your diet, or your stools passing through you too fast. When it doesn’t pick up as much of the brown-tinting bilirubin, it has more bile salts that turn it this color.
Pale, white, or clay-colored
If your poop is a chalky light shade, it probably means you’re lacking bile. Bile is a digestive fluid that comes from your liver and gallbladder, so if you’re producing white stool, it probably means your duct is blocked.
Pale poop could also be a side-effect of certain medications like anti-diarrhea medicine. Either way, if it continues, you should probably consult a doctor.
Red
You’re probably not surprised to hear that red poop can mean bleeding, either due to hemorrhoids or to bleeding in the lower intestinal tract. If your stool is red, though, there’s no need to immediately fret.
There are other less-serious reasons for the change in color. Foods like beets, cranberries, red gelatin, or tomato juice can turn poop red as well.
Yellow
Greasy, stinky, yellow stool is typically a sign of too much fat. This could also be a direct relation to a malabsorption disorder like celiac disease, where your body isn’t absorbing enough nutrients.
In my practice, I highly recommend a stool test called Viome. It uses a very sophisticated method to analyse stool which tells you exactly what foods you should eat, what foods to avoid and lists every bug living in your bowel. To me, this is the best test on the market. Some of the sections you can interpret on your own, however, you should consult with a practitioner that is familiar with hoe to interpret the test to get the most bang for your buck. You do not need a doctor to order this test. However, certain states, like NY, have restrictions.
Here is the link:
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