Anatomic.us > Digestive System

Digestive System

Systema digestorium is the Latin pronunciation for Digestive System. Digestive System of the body helps to breakdown the food into smaller components by the process of digestion. Digestion is a two stage process i.e.

  • Mechanical Digestion

  • Chemical Digestion

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Digestive System

Mechanical Digestion helps in breakdown of large pieces of food into smaller pieces, so that these can be accessed by the digestive Enzymes. Chemical Digestion helps in the breakdown of food through Enzymes into molecules for body to use.

Human Digestive System starts its function when food enters in the mouth. At that point an action of Mechanical Digestion called Mastication (chewing process carried out by teeth) starts. The process is assisted by the release of Saliva, secreted from Salivary Glands. It contains an enzyme called Salivary Amylase that starts the digestion of Starch present in the food. After the process of mastication and digestion of starch, the food is turned into a ball like structure called Bolus which travels through Esophagus into the Stomach by action of Peristalsis (waves of contraction and relaxation moving along stomach wall).

Gastric Juices of stomach contains Hydrochloric acid and Pepsin, which helps in digesting food proteins. The damaging chemical effect of gastric juice is prevented by a layer of slime called Mucus, which thoroughly covers the mucosa of stomach . In addition to chemical digestion,  Mechanical mixing by Peristalsis allows the mass of food to further mix up with gastric juice. This mixing speeds up the digestion of food particles.

After 1 to 2 hours of chemical and mechanical mixing inside the stomach, a thick liquid called Chyme (partly digested food) is produced. A valve like structure is present at the junction of stomach and duodenum. This valve is called Pyloric sphincter. Chyme enters the Duodenum (first section of Small Intestine) when Pyloric Sphincter (Valve) opens. There it mixes up with the digestive enzymes of Pancreas and pass into the Small Intestine. In Small Intestine 95% of the nutrient digestion occurs. Water and minerals are absorbed in blood stream in Large Intestine (Colon). Waste materials are excreted out through Rectum during Defecation (final act of digestion, eliminating waste through anus).

 

ANATOMY:

Anatomically Digestive System is divided into 9 regions i.e.

  • Mouth:

The digestive journey of food starts from the Mouth, also known as Oral Cavity. The accessory structures in the Oral Cavity helps in the digestion process of food. These structures are as follows.

  • Teeth are 32 small structures found at the anterior and lateral edge of mouth. Teeth are made of hard bony material called Dentin further covered by substance called Enamel. They are designed to cut and grind food into simpler form.

  • Tongue is located inferior to mouth and posterior and medial to teeth. It is composed of several pairs of muscles. The outside of tongue has many Papillae (small hair like structure on the surface of tongue) that help in gripping of the food. Tongue also has taste buds that help detect the taste of food. It then pushes the food to posterior part of the oral cavity for swallowing.

  • Salivary Glands are accessory organs present in three sets, which secrete Saliva aiding in digestion of Carbohydrates.

 

  • Pharynx:

Pharynx, also called Throat, is a funnel like tube connected to the posterior end of mouth. It passes the chewed food into the Esophagus. Pharynx also helps in Respiratory function so it contains a flap known as Epiglottis that acts to pass the food into Esophagus and air into Larynx.

 

  • Esophagus:

Esophagus is connected to Pharynx. It carries the food along its length into the Stomach. Lower end of Esophagus has a muscular ring called Cardiac Sphincter or lower esophageal sphincter that closes it and entraps the food in Stomach. The movement of food through this sphincter is like a one way traffic i.e. this sphincter allows the movement of food from esophagus to stomach but prevents its backward flow.

 

  • Stomach:

Located lower to Diaphragm on left side of Abdominal Cavity is a muscular sac called Stomach. This is the major organ of Digestive System and stores the food inside so that it can be digested properly. It contains gastric juices containing Hydrochloric Acid and Pepsin, which aids in digestion process.

 

  • Small Intestine:

Connected to the terminal part of Stomach and taking up most of the Abdominal Cavity space is Small Intestine. It is a structure coiled like hose with many ridges and folds inside. These folds (called villi and microvilli) maximize the digestion of food and nutrient absorption. By the time food leaves the Small intestine 90% of nutrients have already been absorbed from it.

 

  • Liver :

Located at right of Stomach, lower of Diaphragm and upper to Small Intestine is an accessory Digestive System organ called Liver. The main function of Liver is assistance in digestion, production of Bile and its secretions into the Small Intestine.

 

  • Gallbladder:

Located on to undersurface of Liver is  a small pear shaped organ called Gallbladder. Its main function is the storage of excess Bile.

  • Pancreas:

Located on the lower and posterior side of the Stomach is a large gland, Pancreas. It has two parts i.e.

  • Head: connected to Duodenum

  • Tail: directed towards the left wall of Abdominal Cavity

It completes the chemical digestion of food by secreting digestive enzymes into the Small Intestine.

 

  • Large Intestine:

Located in the lower portion of Stomach and lateral side of Small Intestine is a long thick tube called Large Intestine. It absorbs the water and extracts small amounts of nutrients by breaking down wastes with the help of residing Symbiotic Bacteria in it.

Feces from the Large Intestine exit through Anal Canal.

 

FUNCTION:

Digestive System takes in whole food and turns into the basic constituents (proteins, carbohydrates and fats). The Nutrients and Energy generated from the food is essential for body function, growth and repair. Digestive System is the only way for the intake of nutrients in the human body that is why this system alone fulfils the nutrient requirement of body.

 

CLINICAL SIGNIFICANCE:

Among many known diseases of Digestive System, the most common condition is Colon Cancer. If diagnosed early it can be controlled, as it is a slow growing cancer.

Many conditions of Digestive System are chronic and difficult to diagnose and treat. These conditions are as follows.

  • Irritable Bowel Syndrome

  • Lactose Intolerance

  • Diverticulitis

  • Crohn’s Disease

  • Celiac Disease

  • Peptic Ulcer

  • Hiatal Hernia

Diagnosis of Digestive System disorders is carried out through a procedure called Colonoscopy.  The technique makes use of flexible, fiberoptic viewing instrument called Colonoscope.


Mechanical Digestion helps in breakdown of large pieces of food into smaller pieces, so that these can be accessed by the digestive Enzymes. Chemical Digestion helps in the breakdown of food through Enzymes into molecules for body to use.

Human Digestive System starts its function when food enters in the mouth. At that point an action of Mechanical Digestion called Mastication (chewing process carried out by teeth) starts. The process is assisted by the release of Saliva, secreted from Salivary Glands. It contains an enzyme called Salivary Amylase that starts the digestion of Starch present in the food. After the process of mastication and digestion of starch, the food is turned into a ball like structure called Bolus which travels through Esophagus into the Stomach by action of Peristalsis (waves of contraction and relaxation moving along stomach wall).

Gastric Juices of stomach contains Hydrochloric acid and Pepsin, which helps in digesting food proteins. The damaging chemical effect of gastric juice is prevented by a layer of slime called Mucus, which thoroughly covers the mucosa of stomach . In addition to chemical digestion,  Mechanical mixing by Peristalsis allows the mass of food to further mix up with gastric juice. This mixing speeds up the digestion of food particles.

After 1 to 2 hours of chemical and mechanical mixing inside the stomach, a thick liquid called Chyme (partly digested food) is produced. A valve like structure is present at the junction of stomach and duodenum. This valve is called Pyloric sphincter. Chyme enters the Duodenum (first section of Small Intestine) when Pyloric Sphincter (Valve) opens. There it mixes up with the digestive enzymes of Pancreas and pass into the Small Intestine. In Small Intestine 95% of the nutrient digestion occurs. Water and minerals are absorbed in blood stream in Large Intestine (Colon). Waste materials are excreted out through Rectum during Defecation (final act of digestion, eliminating waste through anus).

 

ANATOMY:

Anatomically Digestive System is divided into 9 regions i.e.

  • Mouth:

The digestive journey of food starts from the Mouth, also known as Oral Cavity. The accessory structures in the Oral Cavity helps in the digestion process of food. These structures are as follows.

  • Teeth are 32 small structures found at the anterior and lateral edge of mouth. Teeth are made of hard bony material called Dentin further covered by substance called Enamel. They are designed to cut and grind food into simpler form.

  • Tongue is located inferior to mouth and posterior and medial to teeth. It is composed of several pairs of muscles. The outside of tongue has many Papillae (small hair like structure on the surface of tongue) that help in gripping of the food. Tongue also has taste buds that help detect the taste of food. It then pushes the food to posterior part of the oral cavity for swallowing.

  • Salivary Glands are accessory organs present in three sets, which secrete Saliva aiding in digestion of Carbohydrates.

 

  • Pharynx:

Pharynx, also called Throat, is a funnel like tube connected to the posterior end of mouth. It passes the chewed food into the Esophagus. Pharynx also helps in Respiratory function so it contains a flap known as Epiglottis that acts to pass the food into Esophagus and air into Larynx.

 

  • Esophagus:

Esophagus is connected to Pharynx. It carries the food along its length into the Stomach. Lower end of Esophagus has a muscular ring called Cardiac Sphincter or lower esophageal sphincter that closes it and entraps the food in Stomach. The movement of food through this sphincter is like a one way traffic i.e. this sphincter allows the movement of food from esophagus to stomach but prevents its backward flow.

 

  • Stomach:

Located lower to Diaphragm on left side of Abdominal Cavity is a muscular sac called Stomach. This is the major organ of Digestive System and stores the food inside so that it can be digested properly. It contains gastric juices containing Hydrochloric Acid and Pepsin, which aids in digestion process.

 

  • Small Intestine:

Connected to the terminal part of Stomach and taking up most of the Abdominal Cavity space is Small Intestine. It is a structure coiled like hose with many ridges and folds inside. These folds (called villi and microvilli) maximize the digestion of food and nutrient absorption. By the time food leaves the Small intestine 90% of nutrients have already been absorbed from it.

 

  • Liver :

Located at right of Stomach, lower of Diaphragm and upper to Small Intestine is an accessory Digestive System organ called Liver. The main function of Liver is assistance in digestion, production of Bile and its secretions into the Small Intestine.

 

  • Gallbladder:

Located on to undersurface of Liver is  a small pear shaped organ called Gallbladder. Its main function is the storage of excess Bile.

  • Pancreas:

Located on the lower and posterior side of the Stomach is a large gland, Pancreas. It has two parts i.e.

  • Head: connected to Duodenum

  • Tail: directed towards the left wall of Abdominal Cavity

It completes the chemical digestion of food by secreting digestive enzymes into the Small Intestine.

 

  • Large Intestine:

Located in the lower portion of Stomach and lateral side of Small Intestine is a long thick tube called Large Intestine. It absorbs the water and extracts small amounts of nutrients by breaking down wastes with the help of residing Symbiotic Bacteria in it.

Feces from the Large Intestine exit through Anal Canal.

 

FUNCTION:

Digestive System takes in whole food and turns into the basic constituents (proteins, carbohydrates and fats). The Nutrients and Energy generated from the food is essential for body function, growth and repair. Digestive System is the only way for the intake of nutrients in the human body that is why this system alone fulfils the nutrient requirement of body.

 

CLINICAL SIGNIFICANCE:

Among many known diseases of Digestive System, the most common condition is Colon Cancer. If diagnosed early it can be controlled, as it is a slow growing cancer.

Many conditions of Digestive System are chronic and difficult to diagnose and treat. These conditions are as follows.

  • Irritable Bowel Syndrome

  • Lactose Intolerance

  • Diverticulitis

  • Crohn’s Disease

  • Celiac Disease

  • Peptic Ulcer

  • Hiatal Hernia

Diagnosis of Digestive System disorders is carried out through a procedure called Colonoscopy.  The technique makes use of flexible, fiberoptic viewing instrument called Colonoscope.

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