Gastrointestinal Tract – Diagram, Anatomy, & Disorders

The gastrointestinal (GI) tract is a long, twisting tube made up of hollow organs that starts at the mouth and ends at the anus. It comprises organs such as the mouth, esophagus, stomach, small intestine, and large intestine. Food taken in through the mouth undergoes the process of digestion in the stomach, absorption of nutrients and energy in the small intestine, and the waste stored in the large intestine is expelled at the anus as feces.

In this article, we will study in detail the definition of the gastrointestinal tract, its anatomy, digestive mechanism, functions of the GI tract, infection, and disorders that occur in the GI tract.

Gastrointestinal Tract Definition

The gastrointestinal (GI) tract is a long, continuous tube that connects the mouth to the anus. It is responsible for digestion, absorbtion and elimination of waste from the body.

What is the Gastrointestinal Tract?

The gastrointestinal (GI) tract, or the digestive system, is the passageway of the digestive system that runs from the mouth to the anus. It contains organs such as the mouth, oesophagus, stomach, small intestine, and large intestine. The gastrointestinal tract begins with mastication of food in the mouth. In the mouth enzymes like amylase initiate digestion and the food travels through the oesophagus to the stomach.

In the stomach gastric juices helps in further breakdown. The primary site of nutrient absorption is small intestine, consisting of the duodenum, jejunum, and ileum.The pancreas and liver contribute digestive enzymes and bile, respectively. The large intestine absorbs water and electrolytes, forming faeces, which are stored in the rectum before elimination through the anus.

Gastrointestinal Tract Diagram

The labelled diagram of Gastrointestinal Tract is given below:

Gastrointestinal Tract Anatomy

The gastrointestinal (GI) tract, also known as the digestive tract or alimentary canal, is a long, continuous tube that runs from the mouth to the anus. The length of the GI tract is around 9 metre. It contains all the major organs of the digestive system, including the oesophagus, stomach, and intestines. The GI tract can be subdivided into two halves by the suspensory muscle of the duodenum. The divsion is as follows:

• Upper Gastrointestinal Tract
• Lower Gastrointestinal Tract

Upper Gastrointestinal Tract

The upper gastrointestinal (GI) tract includes the mouth, pharynx, oesophagus, stomach, and the first part of the small intestine (duodenum).

Mouth

The mouth, also known as the oral cavity is an oval-shaped cavity inside the skull that allows food and air to enter the body. It is surrounded by lips and includes structures like vestibule, gums, teeth, hard and soft palate, tongue, and salivary glands. Saliva, containing enzymes like amylase, begins the chemical breakdown of carbohydrates.

Pharynx

The pharynx, also known as the throat, is a muscular passageway that connects the mouth and nose to the oesophagus and larynx. It serves both the respiratory and digestive systems. The pharynx permits the passage of swallowed solids and liquids into the esophagus, and conducts air to and from the trachea during respiration.

Oesophagus

The oesophagus is a muscular tube that connects the mouth to the stomach. The upper part of the oesophagus is located behind the windpipe. When we swallow, the walls of the oesophagus contract and relaxes. Th food move down to the stomachs through the movement known as peristalsis.

Stomach

The stomach is a muscular organ, located between the oesophagus and the small intestine. It is the most dilated part of the digestive system. The stomach is a J-shaped bag-like organ and is divided into four main regions: the cardia, fundus, body, and pylorus. The stomach secretes gastric juices for the chemical digestion of food and break it down into chyme.

Lower Gastrointestinal Tract

The lower GI consists of the following organs:

Small Intestine

The small intestine is a long, narrow tube that extends from the stomach to the large intestine. It is the longest part of the digestive system, measuring about 22 feet long on average. It has three parts: the duodenum, jejunum, and ileum. The small intestine is the primary site for the absorption of nutrients from digested food.

Large Intestine

The large intestine or colon, is the last part of the digestive system. It’s a long tube that continues from the small intestine and extends to the anus. It includes the colon, rectum, and anus. The function of the large intestine is to process indigestible food and turn it into stool. It also absorbs water and stores waste material in the rectum as feces. When you poop, the large intestine passes the stool from your body.

Digestive Process

An overview of the digestive process is as follows:

Ingestion → Mechanical Digestion (Chewing) → Chemical Digestion (Salivary Amylase) → Formation of Bolus → Swallowing → Peristalsis in oesophagus → Lower oesophageal Sphincter (LES) → Stomach → Pyloric Sphincter → Small Intestine( Duodenum, Jejunum, Ileum ) → Large Intestine (Colon) → Rectum → Anus

Gastrointestinal Tract Functions

The gastrointestinal (GI) tract, also known as the alimentary canal, has the following functions:

• Ingestion or intake of the food through the mouth.
• Mechanical breakdown of the food into small particles.
• By the action of the enzymes the food is chemically broken down into simpler form for absorption.
• Absorption of the nutrients, water and electrolytes from digested food into the bloodstream.
• Release of digestive enzymes, acids, and other substances from glands such as salivary glands, stomach, and pancreas that facilitates digestion.
• Beneficial bacteria in the large intestine ferment undigested carbohydrates, producing vitamins and gases.
• Absorption of the water and nutrients take place in the large intestine and liquid chyme is converted into solid faeces.
• Indigestible waste (feces) is expelled from the body through the rectum and anus.

Gastrointestinal Tract Infection

Gastrointestinal (GI) infections are caused by viruses, bacteria, or parasites. It causes inflammation of the gastrointestinal tract and gastroenteritis. Infections can spread through contaminated food or water, person-to-person contact, or contact with contaminated surface.

• Microorganisms: Microorganisms that causes infection includes
  • Bacteria: Salmonella, Escherichia coli (E. coli), Campylobacter, and Shigella.
  • Viruses: Norovirus, rotavirus, and enteric viruses .
  • Parasites:Giardia lamblia and Cryptosporidium
  • Fungi
• Symptoms include diarrhea, vomiting, nausea, cramps, dehydration, abdominal pain, lack of appetite, and fever.
• Diagnosis involve stool tests to identify the causative agent, blood tests, and imaging studies.
• Most GI infections go away on their own in a few days. For viral gastroenteritis, there’s often no specific medical treatment. For lingering GI infections, treatment can include antibiotics or antiparasitic medications. Common antibiotics used to treat GI infections include Penicillin, Cephalosporin, Antifolate, etc.

Gastrointestinal Tract Diseases

Gastrointestinal (GI) diseases affect the digestive tract, from the mouth to the anus. There are two types of GI diseases: functional and structural. Some common gastrointestinal tract diseases includes:

• Gastroesophageal Reflux Disease (GERD): Gastroesophageal reflux disease (GERD) is a condition that occurs when stomach contents leak backward into the oesophagus. It’s caused by frequent acid reflux or reflux of nonacidic content from the stomach. Symptoms include heartburn, regurgitation, nausea, burping and bloating.
• Constipation: Constipation is when bowel movements become less frequent and stools become difficult to pass. This is caused due eating a lot of high-fat meats, dairy products, and eggs, sweets, or processed foods, not taking enough fluids and lack of physical activity.
• Gastroenteritis: Gastroenteritis, also known as the stomach flu or infectious diarrhea, is an inflammation of the gastrointestinal tract. It can affect the stomach, small intestine, and large intestine. It is caused by viral or bacterial infections and symptoms includes diarrhea, vomiting, and abdominal cramps.
• Irritable Bowel Syndrome: A functional gastrointestinal disorder characterized by abdominal pain, bloating, and changes in bowel habits without any structural damage. It causes pain in the stomach, bloating, constipation, diarrhea and change in the appearance of stool.
• Colon Cancer: Colon cancer is a disease that develops when tumorous growths form in the large intestine. It starts as benign polyps and often leads to symptoms like blood in the stool, abdominal pain, and changes in bowel habits. It can be treated with surgery, chemotherapy, and radiation therapy.
• Haemorrhoids: Hemorrhoids, also known as piles, are swollen veins in the anus and lower rectum. Constipation, straining during bowel movements, and sitting on the toilet too long can increase your risk of hemorrhoids.

Conclusion: Gastrointestinal Tract

In conclusion, the gastrointestinal (GI) tract is a complex system important for digestion and nutrient absorption. It consists of organs such as the mouth, stomach, small intestine, and large intestine. The digestive system breaks down food into nutrients that can be absorbed into the blood. The body uses these nutrients for energy, growth, and repair. Diseases affecting the gastrointestinal tract can impact digestion, nutrient absorption, and overall health of the individual. Therefore, it is important to maintain the gastrointestinal health and take a balanced diet for the optimal functioning of the GI tract.

FAQs – Gastrointestinal Tract

What is Gastritis Caused by?

Gastritis refers to the inflammation of the lining of the stomach. Symptoms may include stomach pain, nausea, vomiting, and abdominal bleeding.

What are Gastrointestinal Symptoms?

Gastrointestinal Symptoms includes abdominal pain or cramping, bloating, change in bowel habits, constipation, incomplete bowel movements, diarrhea, etc.

What are the 3 Main Hormones that Regulate Digestion?

The three main hormones that regulates digestion are Gastrin, Secretin, and Cholecystokinin.

What are Gastrointestinal Tract Problems?

Gastrointestinal (GI) disorders are conditions or diseases that affect the gastrointestinal tract. GI symptoms can include Constipation, Bloating, Reflux, Nausea, Vomiting, Diarrhea, Abdominal pain and cramping.

What are the 3 Basic Regulatory Systems of the Gastrointestinal Tract?

The three basic regulatory systems of the gastrointestinal (GI) tract are autonomous smooth muscle function, neural regulation, and GI hormones and paracrine mediators.

What are the 3 main Purposes of the Gastrointestinal Tract?

The gastrointestinal (GI) tract, also known as alimentary canal, or the digestive tract has three main functions: digestion, absorption, excretion.