The Complexity of Your Intestinal System


Did you know that the most complex journey of your food digestion is through the intestinal system?

The food digestion process kicks off at the mouth to end up in the winding stretch of the intestinal system before getting out through the exit. The intestinal system plays a vital role in nourishing your entire body with nutrients and vitamins.

The gastrointestinal tract (GI or GTI) or digestive tract is in two parts, the upper gastrointestinal tract which covers the mouth to the duodenum. The lower gastrointestinal tract includes the small intestine and the large intestine. 

What is Intestinal System?

The intestinal system is the lower gastrointestinal tract. It includes the small intestine and the large intestine. It starts from the pyloric sphincter which connects to the underside of the stomach ending at the anal section.

The Small Intestine

The length of the small intestine is between 3m and 6m depending on the average size of a person. The small intestine is between the stomach and the large intestine. It has three sections due to its functions, duodenum, jejunum, and ileum.

The Duodenum

The first part of the small intestine is the duodenum. It is also the smallest section of the three. It takes the shape of 'C' because of its location. From the stomach, chyme enters the duodenum by the pylorus sphincter.

The food from the stomach mixes with gastric juice that contains hydrochloric acid. The duodenum produces an alkaline mucus with bicarbonate which neutralizes the acidity in the chyme (partly digested food from the stomach).

The food continues with the chemical digestion using enzymes from the bile and pancreatic juice.

Bile Juice

The bile juice comes from the liver then empties into the gallbladder for storage. The gallbladder then releases the bile juice into the duodenum for digesting and emulsifying the fat in the food. The bile juice also contains alkaline that helps to balance the acid in the chyme.

Pancreatic Juice

The pancreatic juice comes from the pancreas. It enhances the digestive system in the small intestine. In the duodenum, the enzymes from the pancreatic juice digest carbohydrates, fats, and proteins.

The duodenum absorbs iron and lives most nutrients for absorption by the other two sections of the small intestine.


From the duodenum, the food is pushed by muscle contraction into the jejunum. The jejunum is the second section of the small intestine. The part is in the middle of the duodenum and ileum.

Most of the nutrient absorption takes part in the jejunum. The jejunum which has finger-like projections called villi has high nutrient absorption than the other sections of the small intestine. Carbohydrates, fats, proteins, electrolytes, and minerals are all the nutrients that the jejunum absorbs into the bloodstream.


The ileum is the part at the base of the small intestine. It is the section that precedes the large intestine. The ileum being the last part of the small intestine, absorbs B12, bile salts, and other absorption leftovers of the jejunum.

The ileum is a significant part of the small intestine compared to the other two sections of the small intestine. The essential function of ileum is to enhance nutrient absorption to nourish the body.

The three sections of the small intestine share water absorption by osmosis. 80% of water absorption takes place in the small intestine. 10% in the large intestine and the remaining 10% passed out through excretion.

The ileum being the last section of the small intestine connects to the cecum, the large intestine initial section. The digested food empties into the large intestine through the ileocecal sphincter. The sphincter also prevents the reflux of the digested food from the large intestine into the small bowel.

Diseases of the Small Intestine

During digestion and absorption of the food procedures, the small intestine can encounter some health conditions that may interfere with its proper functioning. Some of the regular diseases of the small intestinal as listed by U.S. NLM (National Library of Medicine) include:

Celiac Disease

Celiac is an immune system disease of the small intestine that causes sensitivity to gluten. It is a prevalent disease of the small intestine that affects approximately 1 in 100 people globally. Gluten which is a protein from wheat, barley, rye or supplements causes an autoimmune disease. It attacks and damages the small intestine's villi (the finger-like lining that absorbs nutrients) to interfere with nutrient absorption.

Crohn's Disease

Crohn's disease falls under the umbrella of IBD (inflammatory bowel disease) hence causing inflammation to any part of the digestive system. But, the most affected by the disease is the ileum. The condition can lead to rectal bleeding, diarrhea, fever, malnutrition, and weight loss.

Peptic Ulcer

A peptic ulcer is a common disease of the stomach and duodenum. It affects the walls of the two organs causing soreness of the lining and hence a severe burning pain. The leading cause of the disease is a bacterium known as helicobacter pylori. Others are an extended use of NSAIDs (nonsteroidal anti-inflammatory) drugs.

Intestinal Obstruction

The intestinal obstruction or bowel obstruction is the bowel blockage that prevents the digestion movement. The condition can happen in either of the two intestines.

Intestinal obstruction can occur due to the presence of a hernia, adhesions, some medicines, or cancers which can prevent food from moving through the small intestine. The disease can either happen wholly or partially. Severe abdominal cramping, pain, bloating, swollen abdomen, bowel sounds, and constipation are some of the disease's symptoms.

Small Intestine Cancer

Even though small intestine cancer is not common, it can happen due to some risk factors such as celiac disease, Crohn's disease, intestinal obstruction, or high-fat food. The common signs of cancer are abdominal pain, bloody stool, weight loss, and abdominal lump.

The Large Intestine

The last section of the digestive system is the large intestine or the large bowel. The large intestine absorbs 10% of the water in the food before excretion. The large intestine stores food waste until ready for exit.

The entire large intestine has five sections:

  • Cecum which includes the appendix
  • Ascending colon
  • Transverse colon
  • Descending colon
  • The sigmoid colon which consists of the rectum and the anus

Functions of the Large Intestine

The primary services of the large intestine include:

Water Absorption. The large intestine absorbs some of the remaining water to pass the rest for excretion.

Storing and Removing Waste. The large intestine stores the waste product of the digested food until ready for excretion. The waste passes through the rectum to then exit through the anus.

Gut Microbiome

The large intestine is the home of most of the microbiome, also known as the gut flora or bacterial flora in the entire digestive system. Your gut contains about ten trillions of microbiome. The microbiome co-exists with the large intestine to form a special relationship beneficial to your health.

Since the introduction to the human gut microbiota, it is now clear that microbiome or the gut flora is an essential bacteria to your health and for a good reason. The microbiome benefits your health by:

  • Regulating gut immunity
  • Promoting gut integrity
  • Protecting the host against pathogens
  • Setting the intestinal lining
  • Energizing your whole being

Despite the presence of microbiome and the regulation of your immune system in the large intestine, the organ is still susceptible to diseases.

Large Intestine Diseases

Some of the diseases that can interfere with the smooth functioning of the large intestine include:

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is prevalent in women. It affects twice as many women as men. The disease is also typical with people aged 45 years and younger. It is a disease most common in the large intestine. It can change bowel habits, cause diarrhea, constipation, bloating, and cramping.

Ulcerative Colitis

Ulcerative colitis (UC) or ulcers is a health condition that can affect the lining of your large intestine and the rectum. The disease which is under the umbrella of IBD or inflammatory bowel disease can cause sores and inflammation. Some of the symptoms of ulcerative colitis are abdominal pain, diarrhea, bloody stool and stool with pus.

Diverticulitis and Diverticulosis

Diverticular are some tiny bulging pouches that can occur in the lining of the large intestine. If you have such bags, it means you have a disease known as diverticulosis. When the pouches become inflamed and painful, the condition is known as diverticulitis. The disease is prevalent among the senior adults of over 60 years and above. One of the common causes of diverticulosis is eating low-fiber food.

Symptoms of diverticular disease are pain in the lower part of the abdomen, especially the left side, fever, constipation, vomiting, nausea, and abdominal tenderness.


Hemorrhoids, otherwise known as piles are swollen and inflamed veins or connective tissue at the base of the muscles that hold the anal opening. The muscles close the anal opening tightly to prevent fluid or waste leakage. Sometimes during constipation, pregnancy, or strained bowel movement, the connective tissue or the veins around the rectum or anus can overstretch to irritate.

The disease can cause inflammation and hence become painful, especially when passing stool. Some of the hemorrhoids' symptoms are soreness, pain, irritation, itching, swelling around the anal area.

Colonic Polyps

Colonic polyps are some tissue growth in the colon. Even though the polyps might not cause any pain or cause any worry, some can transform into cancerous swelling.

Most cases of large intestine polyps can exist without causing any symptoms. On rare occasions, the disease can reveal some signs. You can notice blood on the toilet paper you use after passing stool, spot blood on underwear, bloody stool, extended diarrhea, and constipation.


The intestinal system consists of many nerve cells independent from all the other brain-controlled neurons. The nervous system of the intestine is called the enteric nervous system or ENS which operates intrinsically.

The intestinal system, however, depends on your help in eating the right food, which should be high in fiber and low in fat to aid the last part of the digestive system. You may avoid unnecessary use of antibiotics and antibiotic-rich foods such as animal products suspected to have had antibiotic treatment. Such kinds of food can destroy and reduce your microbiome or your healthy bacteria which helps in maintaining your immune system.

To ensure a healthy intestinal system, use free-range animal products and chemical-free food. If you suspect to use such foods or drinks, you need to run some tests. You could not only rule out some of the intestinal system conditions but have early treatment in case of any.

Within the past 30 years of clinical experience, Yvonne has put together with the help of Nature Sunshine, a list of products which can benefit your intestinal system. It is always best to have a consultation with Yvonne before guessing as to what you need.

Do you question your intestinal system? "Time heals" is a cliché you might seriously consider. Visit Island Healthworks Clinic as early as you can for checkup using modern technology with immediate results.

You can book for an appointment for any of our services by calling us on 250.468.7685 or write to us at This email address is being protected from spambots. You need JavaScript enabled to view it.

Do you want to read more about other body systems? Stay right here for more!! Over the course of the next 10 weeks, we will be covering in detail, the list of the Body Systems, their function, Importance, disease causes, symptoms, and treatment. Be sure not to miss any of the articles we post.

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Elizabeth Njuguna is a freelance writer, with a focus on natural health. Her aim is to promote healthy lifestyles through information. Connect with Elizabeth at This email address is being protected from spambots. You need JavaScript enabled to view it.

Editor: Yvonne Dollard Perc
Research Assistant: Elizabeth Njuguna

Designer: Sherry Robb 

Yvonne Dollard Perc offers in-person and virtual consultations featuring health and lifestyle coaching, and the best of integrative natural health care. To book your consultation, please call 250-468-7685!

This article is intended for educational purposes and the information contained within is not intended to treat, diagnose or cure any disease or health problem. Please seek appropriate medical attention for any health complaints. We cannot take responsibility for your health care decisions. Our intent is only to offer health information to help you with your search for better health. 

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Tuesday, 26 May 2020