Gastrointestinal Tract: Definition, Function, Diagram, Examples

What Is Gastrointestinal Tract?

The gastrointestinal tract is a long alimentary canal with a length of about 20 to 25 feet, which comprises a row of organs starting from mouth to anus including the mouth, oesophagus, stomach, small intestine and large intestine. The digestive and absorptive process starts from the mouth through mechanical and chemical digestion and continues in the stomach and small intestine through enzymatic and acidic digestion of food into absorbable nutrients lastly in the large intestine, water and electrolytes are absorbed and solid waste is obtained. For the body to be healthy and for there to be normal bodily function, the gut and the GI tract should work effectively.

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Anatomy Of The Gastrointestinal Tract

The major components of the gastrointestinal tract are:

Mouth

• Structure of the Mouth: The mouth is that anatomical structure made up of the oral cavity, which also comprises lips, teeth, tongue and palate. It is also the point of intake of foods and initiates the process of digestion.

• Role of Saliva and Salivary Glands: Expectedly, saliva from the salivary glands (parotid, submandibular, and sublingual) has enzymes, particularly amylase which initiates the digestion of carbohydrates also aids in the moistening of foods for easier swallowing.

• The Process of Mastication (Chewing): Mastication comprises the process of reducing the size of the food particles through the teeth and combination with saliva to form a Pulp which can conveniently be swallowed.

Esophagus

• Structure and Function of the Esophagus: A muscular tube which connects the mouth to the stomach and is lined by mucous membrane and helps in swallowing where food is conveyed through the process of peristalsis.

• The Role of Peristalsis in Food Movement: Swallowing is a process of moving food through the oesophagus and into the stomach through well-coordinated muscular contractions in the form of waves.

Stomach

• Anatomy of the Stomach: Hence, the stomach is J-shaped and hosts anatomic divisions such as the cardia, fundus, body, and pylorus and it is, in addition, lined by the gastric mucosa.

• Functions of the Stomach: It is a muscular sac which receives and mixes food with gastric juice and churns and breaks it down into a paste-like substance called chyme.

• Role of Gastric Juices and Enzymes: In the stomach, proteins are acted upon by enzymes such as hydrochloric acid and pepsin and digestion occurs in an acidic medium.

Diagram of stomach

Small Intestine

• Anatomy of the Small Intestine (Duodenum, Jejunum, Ileum): It is a long, coiled tube that forms three sections where the name is as follows; the first one is the duodenum; the second one is the jejunum; the third and the last one is the ileum, and all these three sections have specific functions in digestion and absorption of food in the body.

• Functions of the Small Intestine: Sorting and dealing with food and the process by which nutrients are transferred into the bloodstream.

• Role of Villi and Microvilli in Nutrient Absorption: Villi and microvilli make a lot of blood space available for the absorption of nutrients at the epithelial layer.

Diagram: Small Intestine Structure

Large Intestine

• Anatomy of the Large Intestine (Cecum, Colon, Rectum): Here we have the cecum, colon and rectum, and even though it is wider than the small intestine, it is shorter in length.

• Functions of the Large Intestine: It takes in water electrolytes from the non-digestible portion of the food and kneads the mass into faeces.

• Role in Water and Electrolyte Absorption: Reabsorbs water and electrolytes, and turns chyme into compact faecal matter.

Diagram: Anatomy Of The Large Intestine

Liver

• Structure and Functions of the Liver: An organ that is large and performs in the destruction of toxins, bile production, and vitamins and fats digestion.

• Role in Metabolism and Detoxification: It breaks foods down into usable forms, also cleanses the bloodstream removes unwanted items, it produces bile to aid in the digestion of fats.

Diagram: Liver Anatomy And Function

Pancreas

• Structure and Functions of the Pancreas: An elongated gnar located below the stomach; it has hormone-producing activity in the form of insulin production and it also has glandular activity in the form of digestion enzymes production.

• Role in Digestion and Blood Sugar Regulation: Secretes substances for the small intestine example digestive enzymes and hormones for sugar control like insulin.

Diagram: Pancreas Anatomy And Function

Gallbladder

• Structure and Functions of the Gallbladder: A small pouch in which it stores and superconcentrates the produced bile by the liver.

• Role in Bile Storage and Release: Reaches the small intestine where it is of use in digestion and absorption of fats by regurgitating bile.

Diagram: Gallbladder Anatomy And Function

Common Disorders Of The Gastrointestinal Tract

Some common disorders related to the gastrointestinal tract are:

Constipation

• Causes: They become constipated because they are on a low-fiber diet, they do not drink water, are physically inactive, or because of a certain medication or disease.

• Symptoms: They include constipation, constipation-predominant irritable bowel syndrome, refractory and severe constipation, celiac sprue, and constipation due to other gastrointestinal diseases.

• Treatments: The management of the problem, therefore, entails changing the diet to increase fibre and fluid intake and exercising; medication such as laxatives or stool softeners may be prescribed. It may also be necessary to make other preparations for other related disorders that may need to be controlled.

Irritable Bowel Syndrome (IBS)

• Causes: There is debate concerning what brings about IBS; however, factors believed to have a role include the gut-brain signalling problem, stress, and diet.

• Symptoms: It involves abdominal discomfort, pain, and or changes in bowel practices that may include diarrhoea constipation or both.

• Treatments: They are dietary interventions (for example, low FODMAP diet), stress reduction strategies, and medications for symptom relief.

Colon cancer

• Causes: Some of the causes of colon cancer include; age, family history of colon cancer, diet rich in red or processed meats, smoking, and conditions such as; Crohn’s disease, and ulcerative colitis; which are forms of inflammatory bowel diseases.

• Symptoms: It is characterised by changes in bowel habits, the presence of blood in stools, pain in the abdomen and unexplained weight loss.

• Treatments: Therapies frequently include surgery, chemotherapy, and/or radiation therapy based on the stage of the malignancy.

Haemorrhoids

• Causes: They are a condition that develops when there is excessive pressure on the rectal as well as anal veins, mainly as a result of bowel movements, pregnancy or sitting down for long periods.

• Symptoms: Some of the symptoms include; itching, pain, swelling around the anus and even bleeding when one is defecating.

• Treatments: Measures are dietary changes such as increasing fibre intake, use of creams and in the worst-case scenarios; surgery like hemorrhoidectomy.

• Hepatitis: Inflammation of the liver commonly resulting from viral infections of the liver (hepatitis A, B, C), alcoholism, or other ailments. Some include yellowness of the skin, constant tiredness, and stomach ache. Since it is an umbrella term, the treatment depends on the specific type, though it may consist of antiviral medications as well as other modifications in the patient’s life.

• Cirrhosis: A pathologic state of the liver in which liver tissues are gradually replaced with fibrous tissues and the organ’s function starts to deteriorate as a result of excessive alcohol intake or hepatitis. Some of the symptoms of the condition are: will be difficulty in liver functioning such as jaundice, ascites, and liver complications. Symptoms are managed throughout the treatment by implementing measures to treat or remove the cause.

• Liver Cancer: It develops mostly from conditions that affect the liver for example cirrhosis or hepatitis. Some of the manifestations are peritoneal signs, anorexia nausea, and icterus. There are different forms of treatment; these include surgery, chemotherapy or some targeted therapies.

Preventive Measures And Healthy Practices

• Importance of a Balanced Diet: It is the source of essential nutrients, provides energy, maintains digestive health and prevents digestive diseases.

• Role of Fiber in Digestive Health: Used to make the stool bulky and thus relieve the individual from constipation and related complaints.

• Benefits of Regular Exercise: It aids in the stimulation of bowel movements and helps in keeping your weight in check thus preventing digestive problems.

• Importance of Hydration: Promotes the easing of bowel movement, and digestion as well as guards against constipation.

• Avoiding Harmful Substances: It has a positive effect on the prevention of digestive disorders and cancer mainly resulting from alcohol and tobacco taking.

Table: Foods Beneficial for GI Health