The intestine is a long tube in the abdomen, starting from the stomach and ending at the rectum. It is generally known as the gut. The intestine includes the small intestine, large intestine, and rectum. Intestines anatomy is important to know about the health conditions related to intestines and abdominal pain.

The small intestine is 6 meters (20 feet) long tube starting from the stomach and continuing into the large intestine. Its length is generally greater in males compared to females. The large intestine, which is also known as the colon or the large bowel is shorter, being about 5 feet in length.

The large and small intestines are not named such based on their length, but on their calibre, as the large intestine has almost 3 times the diameter of the small intestine. We will discuss further intestines anatomy in details to know about all Intestines Anatomy and health conditions.

Location and Anatomy of the Intestine:

The intestine starts from the stomach and lies in the abdominal cavity. The small intestine lies in the middle while the large intestine extends to the sides. The small intestine shows motility in the abdominal cavity while the large intestine is mostly fixed.

Since the small intestine is more suited for absorption, it has specialized finger-like structures called villi which helps in absorption.

Types of intestines: (Intestines Anatomy)

There are two types of intestines which are further divided into several parts. Here is a brief account of each type:

• Small intestines: it is around 6 meters long. It consists of the duodenum (25cm), jejunum (2.5m), and ileum (3.5m).
• Large intestines: it consists of the cecum, colon, and rectum. The colon is further divided into ascending, transverse, descending, and sigmoid colon. There is a rudimentary organ calkled appendix attached to the cecum. 

Large and Small Intestine and their Differences: (Intestines Anatomy)

Besides the differences in the dimensions and positions of both, the small and large intestines vary in their functionality as well.

The small intestine is involved in the digestion of food and absorption of nutrients while the large intestine is involved in the absorption of water and the production of vitamins, especially vitamin K and biotin. 

The function of the intestine: (Intestines Anatomy)

The intestine as a whole functions in the transportation, digestion, and absorption of food.

The small intestine is where the bulk of the digestion of the food occurs with the help of enzymes from the pancreas, while the large intestine is where the water and salts from the material that has not been digested as food are absorbed while getting rid of the remaining as waste.

Conditions of the Intestine:

1. Diarrhea:

Diarrhea usually occurs because of mild infection of the intestine. In diarrhea, the stools are frequent, loose, and watery.

• Traveller's Diarrhea:

This is the form of diarrhea that occurs due to water contamination with diarrhea resulting in loose stools, nausea, and fever.

• Constipation:

It is a gut disorder in which there is difficulty in defecating and the bowel movements are infrequent.

• Enteritis:

It is the inflammation of the small intestine as a result of infection with viruses, bacteria, or parasites. It is also known as the stomach flu.

• Celiac Disease:

It is a genetic condition in which there is an allergy to gluten, which is a protein in bread. It leads to symptoms of abdominal pain and weight loss.

• Colitis:

It is the inflammation of the colon caused by inflammatory bowel disease or any infection of the colon.

• Diverticulosis:

These are tiny pouches from the colon due to the presence of small weak areas in their muscular walls. They usually do not cause any problem but maybe lead to bleeding or inflammation.

• Diverticulitis:

When the diverticula become inflamed or infected, it is known as diverticulitis. It results in abdominal pain and constipation.

• Inflammatory Bowel Disease:

These are two diseases, Crohn's disease, and Ulcerative colitis, which are characterized by inflammation of the GI tract and pain in the abdomen.

1. Ulcerative Colitis:

It is a long-term inflammatory bowel disease that causes inflammation and pain in the large intestine and the rectum.

1. Crohn’s Disease:

It is also a type of inflammatory bowel disease. Unlike ulcerative colitis which occurs in the large intestine and the rectum, Crohn's disease can occur anywhere in the gastrointestinal tract and involve the full thickness of the bowel wall.

1. Irritable Bowel Syndrome:

It is a common condition of the digestive system that presents with stomach cramps, bloating, diarrhea, and constipation. It is also known as spastic colon, irritable colon, or mucous colitis.

1. Intussusception:

It is also known as the telescoping of the intestine. In this condition, the intestine collapses into itself like a telescope.  It must be treated urgently or it can become life-threatening with time.

1. Intestinal Obstruction:

It is an intestinal condition in which part of the small or large intestine can become blocked, twisted, or just stop working. It presents with abdominal pain and weight loss due to poor intestinal function.

1. Colon polyp:

Polyps are non-cancerous growths inside the colon. These can develop into tumors with time.

1. Colon cancer:

It is one of the most common cancers in the world.  It can develop from a colon polyp.

1. Rectal cancer:

Colon and rectal cancers are very similar in their prognosis and treatment. They are sometimes together grouped as colorectal cancer. Colorectal cancer is the 3^rd most common cancer in the world, right after breast and lung cancer.

1. Salmonellosis:

It is an intestinal disorder caused by the salmonella bacteria. Salmonella contaminates the food and leads to diarrhea and stomach cramps.

1. Shigellosis:

Shigella is a bacteria that affects the intestine just like salmonella. It can lead to fever, stomach cramps, and bloody diarrhea.

Tests for Intestinal Conditions:

1. Colonoscopy:

In this intestinal screening test, an endoscope is inserted into the rectum and advances to the colon. The doctor can examine the entire colon through it. It can be used in the screening of colorectal cancer.

• Virtual Colonoscopy:

It is a test in which the image inside of the colon is created using an X-ray machine and a computer. If any problem is found, traditional colonoscopy is usually needed for proper diagnosis.

• Colon Biopsy:

While performing a colonoscopy, a small piece of intestinal tissue may be removed for testing. It can help diagnose problems in the colon like cancer, infection, and inflammations.

• Stool culture:

In this test, a stool sample is collected from the patient and it is checked for the presence of causative bacteria, the color, and consistency of the stool to determine the possible condition.

• Capsule endoscopy:

It is a procedure that helps in identifying problems in the small intestine like bleeding, detecting polyps, ulcers, inflammatory bowel disease, and tumors.

In this procedure, the patient swallows a capsule that has a camera. The camera takes pictures of possible problems in the small intestine and transmits the images to a data recorder. The capsule, also known as a PillCam passes normally through the colon and is eliminated in the stool in 24 hours.

• Sigmoidoscopy:

The sigmoid is the last part of the large intestine of the lower left side of the abdomen. In a sigmoidoscopy, an endoscope is inserted into the rectum and advanced through the left side of the colon. Sigmoidoscopy cannot be used to visualize the middle and right sides of the colon.

Causes of different Intestinal Conditions:

Most of the problems with the intestine are easily preventable and are mainly due to poor choices regarding diet and nutrition, some of the most common causes of intestinal problems are;

1. Low fiber diet:

Fibers are an important component of the overall diet. It helps in producing the feeling of satiety and aids in the digestion of food. A diet low in fiber causes bloating, constipation, and abdominal pain.

• Poor hydration:

Drinking 8 glasses of water every day, which is almost 2 liters, is recommended by the WHO. Poor hydration can lead to problems in digestion and general gastrointestinal unease.

• Stress:

Stress and anxiety, even though are mental problem has been shown to affect digestive health as well. They have been shown to cause loss of appetite, cramping, bloating, and inflammation.

• Inactivity:

Having a sedentary lifestyle is detrimental to the overall health of an individual, especially causing GI and cardiovascular problems.

• Age:

Aging is, unfortunately, an unavoidable cause of gastrointestinal problems.  With increasing age, gastrointestinal activities decrease which increases the risk for cancers related to the digestive system.

• Genetic factors:

It is another unavoidable cause of GI problems. Some individuals are more prone to problems like celiac disease, ulcerative colitis, and Crohn's disease because of their genetic make-up.

• Poor lifestyle choices:

Not being physically active and taking unhealthy processed food on regular basis can lead to intestinal problems.

Treatments for Intestinal Conditions:

1. Anti-diarrhea:

These are various drugs that treat diarrhea, reducing the frequency and discomfort of bowel movements.

• Laxatives:

These are used against constipation and they work by increasing the bowel movements and bringing in more water to the intestine.

• Anti-inflammatories:

They are used against problems like inflammatory bowel syndrome to reduce the inflammation and hence the swelling in the intestine.

• Lifestyle Modifications:

Eating a lot of fiber, being hydrated, and getting enough exercise is essential in treating intestinal problems and preventing any future problem. People with celiac disease should cut out gluten from their diet, while people with lactose intolerance should avoid dairy.

• Colon Surgery:

Colon surgery becomes necessary in conditions like severe bleeding, cancer, and ulcerative colitis. Colon surgery may be open or laparoscopic (It is a surgery in which a small cut is made in the abdomen and the tissues inside are cut, sew and treated using long narrow instruments).

• Polypectomy:

It is a surgical procedure to remove colon polyp.