Content Writer-SME | Updated On - Aug 31, 2024
The human digestive system is a complex system involving biochemical processes that begin as soon as food is ingested through the mouth. The main purpose of digestion in human beings is to convert the food we eat into simplest form. Several organs work together to break down food, extract nutrients, and remove excretory products from the body. The food we eat contains complex compounds like carbohydrates, proteins, etc., which are broken down into simpler substances for complete digestion of food.
Ingestion, mixing, secretion, digestion, absorption, and excretion are the main processes of the human digestive system. In Human Digestive System Class 10, we have covered the complete process of human digestion and the functions of organs involved in digestion in humans.
Human Digestive System
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Gastrointestinal tract (GI tract), and accessory organs together constitute a human digestive system. The GI tract is a long, continuous tube that starts from the mouth and goes to the anus.The human digestive system works in the coordination with other organ system in the body, including the neural and circulatory systems.
- The food we eat is first processed and then converted into simpler substances.
- After intaking food through mouth, it usually takes six to eight hours to pass through stomach and reach small intestine.
- The process of digestion in human play a vital role in obtaining energy from various food sources.
Complex and Simple Food ComponentsOrganic compounds, including carbohydrates, fats, and proteins, are considered complex compounds. For complete digestion, they are broken down into digestible or simple compounds such as sugar or glucose by the action of enzymes secreted by organs associated with human digestive system.
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Human Digestive System Diagram
Food passes through different parts of the digestive tract including the mouth, esophagus, stomach, small intestine, large intestine, and anus. The diagram of Human Digestive System with different parts is shown below with the help of figure:
Human Digestive System Diagram
Parts of Human Digestive System
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The different parts of the human digestive system, along with their functions are mentioned below in detail:
Mouth
The process of human digestion is started in mouth. The salivary glands already sense the taste and smell of the food that we eat. With the help of teeth, our food is broken down into small particles. The tongue helps in mixing of food particles, and the food molecules are later transferred to the throat for further digestion.
Pharynx
Pharynx is a muscular organ, also called a fibromuscular organ, located at the mouth's terminal. It works as a bridge between the mouth and the oesophagus; it transfers food molecules to the oesophagus through a y-shaped tube.
Esophagus
The esophagus is located near the windpipe or trachea. It is a muscular tube measuring about 5m long. It is responsible for the transfer of food that you swallow to the stomach.
- Muscular contractions will help with the transfer of food into the stomach.
- There is a ring-like muscle that allows the food into the esophagus.
- The muscular contractions of the esophagus also help the food not to flow back into the mouth.
Stomach
It is the main organ of the digestive system where important parts of digestion take place. It is a hollow U-shaped muscular organ that is situated at the left side of the abdominal cavity and below the diaphragm. It wraps over the edges of the small intestine.
- The stomach has separate enzymes which break down the food into very minute particles.
- It has a lining of hydrochloric acid which breaks down the food particles.
- The contents of the food molecules from the stomach are later transferred to the small intestine for further process.
Small Intestine
Major separation of food molecules takes place at this stage. It is a thin long tube-like structure that is about 9-10 feet long located just behind the stomach. It is the lower part of the gastrointestinal tract. It is completely coiled and again this small intestine is divided into:
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Duodenum
The main duty of this duodenum is to break the food molecules continuously. The digestive juices and enzymes which are released from the liver and pancreas help break down food molecules.
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Jejunum and Ileum
These are responsible for the nutrient absorption from the food directly into blood. This absorption of nutrients and transferring them to blood gives energy to the body. Later on, the remaining waste particles from the small intestine are transferred to the large intestine for evacuation.
Large Intestine
Large Intestine is responsible for transferring waste materials outside the body. It is a long tube-like structure that is 10-15 feet long, situated below the stomach, wrapped by a small intestine. It clears the bowel by evacuating the waste particles with the help of the rectum and anus.
Rectum
It is a long tube that connects the large intestine and anus. When the large intestine is full, the waste is temporarily placed in the rectum until the anus evacuates it.
Anus
When the rectum is full, it starts an urge by contracting muscles and finally relaxes and releases the content.
Accessory Organs of Human Digestive System
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Pancreas and Liver are considered as accessory organs of the human digestive system as they play a supporting role in human digestion.
Pancreas
Digestive Enzymes from the pancreas are released to the duodenum. The pancreas is the producer of insulin in our body. The enzymes released by the pancreas are responsible for the digestion of fats, proteins, and carbohydrates in the food molecules. The insulin produced is responsible for maintaining the sugar level in the body.
Liver
The liver comprises an important part of the digestive process; it releases bile juice, which is responsible for the digestion of vitamins in food molecules. It is a large reddish, browned, triangular-shaped organ which is located at the right of the stomach.
Gall Bladder
Gall Bladder is a pear-shaped organ located under the liver. It is again divided into three parts: Fundus, Body, and Neck. It stores the bile juice produced by the liver until it is ejected to the duodenum.
Human Digestive System Process
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The Human Digestive System process starts from the mouth and ends in the small intestine. The digestion process in the human body is completed in five major steps which are discussed below in detail:
Ingestion
Ingestion is the first step of digestion, which involves chewing of food particles. The food particles are complex molecules which need to be broken down into simpler substances by certain enzymes for it to digest.
- The salivary glands found in the tongue help moisten the food. This process of chewing the food is often termed as mastication.
- The food is lubricated before being pushed into the food pipe.
Secretion
Secretion involves the release of enzymes, hormones, and other chemical substances in the body. The hormones in the body help release the digestive juices, which will signal the brain whether the person is empty stomach or full stomach. The enzymes are released by the stomach, liver, and small intestine to make the process of digestion easier.
Digestion
Digestion is a mechanical and a chemical process which involves the conversion of food particles into smaller and finer substances. This process takes place in the presence of enzymes. Proteins, carbohydrates, vitamins, lipids, minerals, and water are some of the food particles broken down into fine molecules. Glycerol and fatty acids are broken down into fatty molecules.
Absorption
Absorption involves the movement of carbohydrates from the gut to the required circulatory system. The process is initiated in the small intestine, where most of the minerals and nutrients are absorbed.
Excretion
Excretion involves the removal of unwanted substances from the human digestive system by the process of defecation. The undigested food materials enter the colon where most of the water is reabsorbed.
Functions of Human Digestive System
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The important functions of the human digestive system are as follows:
- The process starts with breaking food in the mouth by teeth and enzymes.
- Next, partially digested food is transferred through the esophagus.
- The food is then mixed with various digestive juices in the digestive system.
- Digestion and absorption are primary functions of the human digestive system.
- Food absorbed in the small intestine is assimilated.
- Finally, the absorption of food and water takes place in the large intestine.
Things to Remember
- Human digestive system is the key to survival, as all organs are interconnected.
- The digestive system structures form the alimentary canal and other essential organs of digestion.
- Human digestive system consists of six significant activities.
- The six activities include Ingestion, Propulsion, Mechanical Breakdown, Chemical Digestion, Absorption, and Elimination.
- The alimentary canal is a tube that comprises the oral cavity, pharynx, esophagus, stomach, and intestines.
- Alimentary canal is also called the digestive tract or the gastrointestinal (GI) tract.
- The stomach is divided into four parts: Cardia, Fundus, Body, and Pylorus.
- The longitudinal and circular layers pass food using peristaltic contractions.
Sample Questions
Ques. What is mastication or chewing, and where does it occur? (2 Marks)
Ans. Mastication (chewing), in which food is crushed and mixed with saliva to form a bolus for swallowing, is a complex mechanism involving opening and closing the jaw, secretion of saliva, and mixing food with the tongue. It is the first step in food digestion, breaking large food particles into small pieces.
Ques. What is the use of Bile juice? (3 Marks)
Ans. The liver generates bile juice and helps digest vitamins and minerals in food molecules.
Bile contains:
- Mostly cholesterol
- Bile acids (also called bile salts)
- Bilirubin (a breakdown product or red blood cells)
- Water
- Body salts (such as potassium and sodium)
- Copper and other metals
Ques. Write down the functions involved in the Digestion process? (3 Marks)
Ans. The function of the digestive system is digestion and absorption. Digestion is the breakdown of food into small molecules, which are then absorbed into the body. The digestive system is divided into two major parts:
- The digestive tract (alimentary canal) is a continuous tube with two openings: the mouth and the anus.
- It includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
- Food passing through the internal cavity, or lumen, of the digestive tract does not technically enter the body until it is absorbed through the walls of the digestive tract and passes into blood or lymphatic vessels.
- Accessory organs include teeth, tongue, salivary glands, liver, gallbladder, and pancreas.
Ques. What food should we take for proper digestion? (3 Marks)
Ans. The digestive system breaks food into nutrients and energy that the body can use. Some types of food, including vegetables and yoghurt, can help this digestion process. High-fibre foods are also beneficial for proper digestion.
High-fiber foods include:
- Apple with skin
- Artichokes
- Baked beans
- Barley
- Black beans
- Bran flakes
- Broccoli
Ques. What is the cause of heartburn? How does heartburn occur? (3 Marks)
Ans. Heartburn occurs when stomach contents flow back into the esophagus—the muscular tube carrying food and liquids from the mouth to the stomach. Also called acid indigestion, heartburn is an uncomfortable, burning feeling in the mid-chest, behind the breastbone, or in the upper part of the abdomen—the area between the chest and the hips. This feeling occurs because the stomach’s digestive juices contain acid. Sometimes, people with this problem can taste food or acidic fluid in the back of the mouth.
Ques. How does food poisoning affect digestion? (4 Marks)
Ans. Food poisoning is a common infectious condition affecting millions globally. Most commonly, people complain of vomiting, diarrhoea, and cramping abdominal pain.
- People seek medical care if they have a fever, rectal bleeding, or experience symptoms of dehydration.
- Treatment for food poisoning focuses on keeping the affected person well-hydrated.
- Most cases of food poisoning resolve on their own.
- Prevention is key and depends upon keeping food preparation areas clean, proper hand washing, and cooking foods thoroughly.
Ques. Which cells of the stomach secrete hydrochloric acid? (4 Marks)
Ans. Parietal cells or oxyntic or delomorphous cells secrete hydrochloric acid (HCl). They contain canaliculi, from which the chemical is secreted. It is then transported to the stomach. The enzyme hydrogen-potassium ATPase is exclusive to the parietal cells. It transports the hydrogen ions.
- HCL is formed with water and carbon dioxide combined within the parietal cell cytoplasm.
- It leads to the production of carbonic acid, which is catalyzed by carbonic anhydrase.
- Carbonic acid dissociates into a hydrogen ion and a bicarbonate ion.
- Eventually, both hydrogen and chloride ions are present within the stomach lumen.
- Opposite charges form hydrochloric acid (HCl).
Ques. What steps must be taken to keep the human digestive system healthy? (3 marks)
Ans. The steps taken to keep the human digestive system healthy are as follows:
- Drink large quantities of water at regular intervals.
- Eat fibrous substances that help regulate the bowel movement.
- Include probiotic substances in your diet that will help nourish your gut.
- Avoid smoking and drinking alcohol.
- While eating your food, chew your food thoroughly.
Ques. Explain the function of mouth, gall bladder and esophagus? (3 marks)
Ans. The function of mouth, gall bladder and esophagus are as follows:
- Mouth: Mouth is the initial part of the human digestive system. It senses the taste and smell of the material. The food is broken down into small particles with the help of teeth.
- Gall Bladder: Gall Bladder is a pear-shaped organ which divided into three parts: fundus, body, and neck. It is responsible for storing the bile juice produced by the liver until it is ejected to the duodenum.
- Esophagus: Esophagus is a muscular tube measuring that is responsible for the transfer of food that you swallow to the stomach. It will help with the transfer of food into the stomach. The muscular contractions of the esophagus also help the food not to flow back into the mouth.
Ques. Expain the process of human digestive system? (5 marks)
Ans. The process of human digestive system includes
- Ingestion: It is the first step of human digestive system. Ingestion involves chewing of food particles. The salivary glands found in the tongue help moisten the food. The food is finally pushed into the food pipe.
- Secretion: Secretion involves the release of enzymes, hormones, and other chemical substances in the body during the process of digestion. The hormones are responsible for releasing the digestive juices, which will signal the brain whether the brain is empty stomach or not.
- Digestion: Digestion is the important function of human digestive function. It involves the conversion of food particles into smaller and finer molecular substances. The process takes place in the presence of enzymes.
- Absorption: Another important function of human digestive system is absorption. It involves the movement of carbohydrates from the gut for the process of circulation in the circulatory system. The process is initiated in the small intestine, where most of the minerals and nutrients are absorbed.
- Excretion: It involves the removal of unwanted substances from the human digestive system by the process of defecation.
Ques. Mention some of the disorders of human digestive system? (3 marks)
Ans. Some of the dosorders of human digestive system are as follows:
- Vomiting: Vomiting is defined as the ejection of food substances found in the stomach through the mouth.
- Ulcers: Ulcers involve the development of a thin lining on the wall of esophagus, stomach or small intestine. The most common bacteria responsible for ulcers include Helicobacter pylori (H. pylori).
- Constipation: Constipation is the most common problem encountered in the human digestive system. In this, the poop cycle of an individual is disturbed, which in turn disturbs the bowel movement of the stomach.
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