an essay on digestive system

Essay on Digestive System

Students are often asked to write an essay on Digestive System in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Digestive System

Introduction to digestive system.

The digestive system is a group of organs that work together to change the food we eat into energy for our bodies. It’s like a food processing factory. It includes the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.

Process of Digestion

Digestion starts in the mouth when we chew food. It then travels down the esophagus to the stomach. In the stomach, food is mixed with stomach acids to break it down into a liquid. This liquid then moves to the small intestine.

Role of Small Intestine

The small intestine plays a major role in digestion. Here, nutrients from the liquid food are absorbed into the bloodstream. The blood then carries these nutrients to all parts of the body. The leftover food, which the body can’t use, moves to the large intestine.

Role of Large Intestine

The large intestine is the last part of the digestive process. It absorbs water from the leftover food and turns it into waste. This waste then leaves the body through the rectum and anus. This whole process is known as digestion.

Also check:

• Paragraph on Digestive System
• Speech on Digestive System

250 Words Essay on Digestive System

What is the digestive system.

The digestive system is a group of organs that work together to change the food you eat into energy and basic nutrients to power your body. It is like a food processing plant that takes in raw materials (food) and turns them into something the body can use.

Parts of the Digestive System

The digestive system is made up of several parts. It starts with the mouth, where you chew and swallow your food. Then there’s the esophagus, a tube that carries food to your stomach. The stomach is like a mixer, churning and breaking down food into a liquid.

How Food Travels

From the stomach, the liquid food then goes into the small intestine. Here, it is broken down even more so your body can absorb the nutrients. Finally, what’s left goes into the large intestine, and then out of your body as waste.

The Role of the Liver and Pancreas

The liver and the pancreas also play important roles in digestion. The liver makes a juice called bile that helps to break down fats. The pancreas makes juices that help to break down carbohydrates, fats, and proteins.

Importance of the Digestive System

The digestive system is very important. Without it, our bodies wouldn’t get the nutrients they need. It keeps us healthy and gives us energy. So, remember to eat a balanced diet to keep your digestive system happy and healthy.

500 Words Essay on Digestive System

The digestive system: an introduction.

The digestive system is a group of organs that work together to change the food we eat into energy our bodies can use. It’s like a food processing factory inside our body. It includes the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus. The liver and pancreas also play a big role in digestion.

Starting Point: The Mouth

Digestion begins in the mouth. When we eat, our teeth break down the food into smaller pieces. Our saliva, a liquid made by the salivary glands, mixes with these pieces, making them easier to swallow. Saliva also starts the process of breaking down the food chemically.

The Esophagus: The Food Pipe

The esophagus is a long tube that connects the mouth to the stomach. It uses a process called peristalsis to move food. This process is like a wave of muscle contractions that pushes the food down into the stomach.

The Stomach: The Mixing Pot

The stomach is like a mixing pot. Here, the food is mixed with stomach acid and enzymes, which break it down into a liquid. This liquid is then sent to the small intestine.

The Small Intestine: The Nutrient Absorber

The small intestine is where most of the digestion happens. It is a long, coiled tube where nutrients from the food are absorbed into the bloodstream. The liver and pancreas help in this process. The liver makes bile, a substance that helps break down fats. The pancreas makes enzymes, which assist in breaking down proteins and carbohydrates.

The Large Intestine: The Water Saver

The large intestine, also known as the colon, is the final part of the digestive system. Its job is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body.

The End of the Journey: The Rectum and Anus

The rectum and anus are the last parts of the digestive system. The rectum stores the waste until it’s ready to leave the body. Then, it passes through the anus and out of the body as feces.

Conclusion: The Importance of the Digestive System

The digestive system is vital for our survival. It turns the food we eat into nutrients that our body needs for energy, growth, and cell repair. Without it, we wouldn’t be able to live. So, next time when you are eating your favorite food, remember the amazing journey it takes through your body!

Remember, eating a balanced diet and drinking plenty of water can help keep your digestive system healthy and working well. Regular exercise is also important as it helps keep food moving through the digestive system, reducing the risk of constipation.

That’s it! I hope the essay helped you.

If you’re looking for more, here are essays on other interesting topics:

• Essay on Different Religions
• Essay on Diet And Nutrition
• Essay on Diet And Health

Apart from these, you can look at all the essays by clicking here .

Happy studying!

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons
• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

18.2: Introduction to the Digestive System

• Last updated
• Save as PDF
• Page ID 16831

• Suzanne Wakim & Mandeep Grewal
• Butte College

If you’re a dessert lover, then just the sight of this flan dish may make your mouth water. The “water” in your mouth is actually saliva, a fluid released by glands that are part of the digestive system. Saliva contains digestive enzymes among other substances important for digestion. When your mouth waters at the sight of a tasty treat, it’s a sign that your digestive system is preparing to digest food.

What Is the Digestive System?

The digestive system consists of organs that break down food, absorb its nutrients, and expel any remaining waste. Organs of the digestive system are shown in Figure \(\PageIndex{2}\). Most of these organs make up the gastrointestinal (GI) tract. Food actually passes through these organs. The rest of the organs of the digestive system are called accessory organs. These organs secrete enzymes and other substances into the GI tract, but food does not actually pass through them.

Functions of the Digestive System

The digestive system has three main functions relating to food: digestion of food, absorption of nutrients from food, and elimination of solid food waste. Digestion is the process of breaking down food into components the body can absorb. It consists of two types of processes: mechanical digestion and chemical digestion. Mechanical digestion is the physical breakdown of chunks of food into smaller pieces. This type of digestion takes place mainly in the mouth and stomach. Chemical digestion is the chemical breakdown (bonds are broken) of large, complex food molecules into smaller, simpler nutrient molecules that can be absorbed by body fluids (blood or lymph). This type of digestion begins in the mouth and continues in the stomach but occurs mainly in the small intestine.

After food is digested, the resulting nutrients are absorbed. Absorption is the process in which substances pass into the bloodstream or lymph system to circulate throughout the body. The absorption of nutrients occurs mainly in the small intestine. Any remaining matter from food that is not digested and absorbed passes out of the body through the anus in the process of elimination.

Gastrointestinal Tract

The gastrointestinal (GI) tract is basically a long, continuous tube that connects the mouth with the anus. If it were fully extended, it would be about 9 meters (30 feet) long in adults. It includes the mouth, pharynx, esophagus, stomach, and small and large intestines. Food enters the mouth and then passes through the other organs of the GI tract where it is digested and/or absorbed. Finally, any remaining food waste leaves the body through the anus at the end of the large intestine. It takes up to 50 hours for food or food waste to make the complete trip through the GI tract.

Tissues of the GI Tract

The walls of the organs of the GI tract consist of four different tissue layers, which are illustrated in Figure \(\PageIndex{3}\): mucosa, submucosa, muscularis externa, and serosa.

• The mucosa is the innermost layer surrounding the lumen, or open space within the organs of the GI tract. This layer consists mainly of the epithelium with the capacity to secrete and absorb substances. For example, the epithelium can secrete digestive enzymes and mucus, and it can absorb nutrients and water.
• The submucosa layer consists of connective tissue that contains blood and lymph vessels and also nerves. The vessels are needed to absorb and carry away nutrients after food is digested, and nerves help control the muscles of the GI tract organs.
• The muscularis externa layer contains two types of smooth muscle: longitudinal muscle and circular muscle. The longitudinal muscle runs the length of the GI tract organs and circular muscle encircles the organs. Both types of muscles contract to keep food moving through the track by the process of peristalsis (Figure \(\PageIndex{4}\).
• The serosa layer is the outermost layer of the walls of GI tract organs. This is a thin layer that consists of connective tissue and separates the organs from surrounding cavities and tissues.

Peristalsis in the GI Tract

The muscles in the walls of GI tract organs enable peristalsis, which is illustrated in Figure \(\PageIndex{4}\). Peristalsis is a continuous sequence of involuntary muscle contraction and relaxation that moves rapidly along an organ like a wave, similar to the way a wave moves through a spring toy. Peristalsis in organs of the GI tract propels food through the tract.

Divisions of the GI Tract

The GI tract is often divided into an upper GI tract and a lower GI tract. For medical purposes, the upper GI tract is typically considered to include all the organs from the mouth through the first part of the small intestine, called the duodenum. For instructional purposes, it makes more sense to include the mouth through the stomach in the upper GI tract and all of the small intestine as well as the large intestine in the lower GI tract. The latter approach is followed here. All organs of GI which are discussed in the text are illustrated in Figure \(\PageIndex{2}\).

Upper GI Tract

The mouth is the first digestive organ that food enters. The sight, smell, or taste of food stimulates the release of digestive enzymes and other secretions by salivary glands inside the mouth. The major salivary gland enzyme is amylase. It begins the chemical digestion of carbohydrates by breaking down starches into sugar. The mouth also begins the mechanical digestion of food. When you chew, your teeth break, crush, and grind food into increasingly smaller pieces. Your tongue helps to mix the food with saliva and also helps you swallow.

A lump of swallowed food is called a bolus. The bolus passes from the mouth into the pharynx and from the pharynx into the esophagus. The esophagus is a long, narrow tube that carries food from the pharynx to the stomach. It has no other digestive functions. Peristalsis starts at the top of the esophagus when food is swallowed and continues down the esophagus in a single wave, pushing the bolus of food ahead of it.

From the esophagus, food passes into the stomach, where both mechanical and chemical digestion continue. The muscular walls of the stomach churn and mix the food, thus completing mechanical digestion as well as mixing the food with digestive fluids secreted by the stomach. One of these fluids is hydrochloric acid. As well as killing pathogens in food, it gives the stomach the low pH needed by digestive enzymes that work in the stomach. One of these enzymes is pepsin, which chemically digests proteins. The stomach stores the partially digested food until the small intestine is ready to receive it. Food that enters the small intestine from the stomach is in the form of a thick slurry (semi-liquid) called chyme.

Lower GI Tract

The small intestine is a narrow but very long tubular organ. It may be almost 7 meters (23 feet) long in adults. It is the site of most chemical digestion and virtually all absorption of nutrients. Many digestive enzymes are active in the small intestine, some of which are produced by the small intestine itself, and some of which are produced by the pancreas, an accessory organ of the digestive system. Much of the inner lining of the small intestine is covered by tiny finger-like projections called villi, each of which in turn is covered by even tinier projections called microvilli. These projections, shown in Figure \(\PageIndex{5}\), greatly increase the surface area through which nutrients can be absorbed from the small intestine.

The small intestine is made up of three parts:

• The duodenum is the first part of the small intestine. It is also the shortest part. This is where most chemical digestion takes place.
• The jejunum is the second part of the small intestine. This is where most nutrients are absorbed into the blood.
• The ileum is the last part of the small intestine. A few remaining nutrients are absorbed in the ileum. From the ileum, any remaining food waste passes into the large intestine.

From the small intestine, any remaining nutrients and food waste pass into the large intestine. The large intestine is another tubular organ like the small intestine, but it is wider and shorter than the small intestine. It connects the small intestine and the anus. Waste that enters the large intestine is in a liquid state. As it passes through the large intestine, excess water is absorbed from it. The remaining solid waste, called feces, is eventually eliminated from the body through the anus.

Accessory Organs of the Digestive System

Accessory organs of the digestive system are not part of the GI tract, so they are not sites where digestion or absorption take place. Instead, these organs secrete or store substances that are needed for the chemical digestion of food. The accessory organs include the liver, gallbladder, and pancreas. They are shown in Figure \(\PageIndex{6}\) and described in the text:

• The liver is an organ that has a multitude of functions. Its main digestive function is producing and secreting a fluid called bile, which reaches the small intestine through a duct. Bile breaks down large globules of lipids into smaller ones that are easier for enzymes to chemically digest. Bile is also needed to reduce the acidity of food entering the small intestine from the highly acidic stomach because enzymes in the small intestine require a less acidic environment in order to work.
• The gallbladder is a small sac below the liver that stores some of the bile from the liver. The gallbladder also concentrates the bile by removing some of the water from it. It then secretes the concentrated bile into the small intestine as needed for fat digestion following a meal.
• The pancreas secretes many digestive enzymes and releases them into the small intestine for the chemical digestion of carbohydrates, proteins, and lipids. The pancreas also helps to lessen the acidity of the small intestine by secreting bicarbonate, a basic substance that neutralizes the acid.

• What is the digestive system?
• What are the three main functions of the digestive system? Define each function.
• Describe the GI tract.
• Distinguish between the upper and lower GI tracts.
• Relate the tissues in the walls of GI tract organs to the functions the organs perform.
• Identify accessory organs of digestion and their general function in digestion.
• Identify the points in the GI tract where food becomes a bolus, chyme, and feces, respectively.
• Does food pass through the pancreas? Why or why not?
• True or False. Absorption mainly occurs in the stomach.
• True or False. Some chemical digestion occurs in the mouth.

A. Gall bladder

C. Small intestine

D. Large intestine

b. Describe one way in which carbohydrates are at least partially chemically digested in the digestive system.

• If the villi in your small intestine were damaged and could not function normally, what effect might this have on your body? Explain your reasoning.

A. An accessory organ of the digestive system

B. Part of the upper GI tract

C. Part of the lower GI tract

D. The longitudinal muscle

Explore More

Check out this 3D animation video to see peristalsis in the Large Intestine:

Why do we feel hungry? Check out this video to learn more:

Attributions

• Caramel cream flan by RitaE via Pixabay license
• Digestive system diagram by Mariana Ruiz, Public Domain via Wikimedia Commons
• Mucosa by National Institute of Health, Public Domain via Wikimedia Commons
• Peristalsis by Zachary Wilson , CC BY NC 3.0 via CK12.org
• Small Intestines from Microbiology by Open Stax CC BY 3.0
• Gallbladder-Liver-Pancreas Location by Blausen.com staff (2014). " Medical gallery of Blausen Medical 2014 ". WikiJournal of Medicine 1 (2). DOI : 10.15347/wjm/2014.010 . ISSN 2002-4436 . licensed CC BY 3.0 via Wikimedia Commons
• Text adapted from Human Biology by CK-12 licensed CC BY-NC 3.0

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons
• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

21.3: Digestive System Processes and Regulation

• Last updated
• Save as PDF
• Page ID 22410

• Whitney Menefee, Julie Jenks, Chiara Mazzasette, & Kim-Leiloni Nguyen
• Reedley College, Butte College, Pasadena City College, & Mt. San Antonio College via ASCCC Open Educational Resources Initiative

By the end of the section, you will be able to:

• Discuss seven fundamental activities of the digestive system, giving an example of each
• Describes the functions of each digestive organs
• Describe the difference between mechanical digestion and chemical digestion
• Describe the difference between peristalsis and segmentation

The digestive system uses mechanical and chemical activities to break food down into absorbable substances during its journey through the digestive system. Table \(\PageIndex{1}\) provides an overview of the basic functions of the digestive organs.

Digestive Processes

The processes of digestion include seven activities: ingestion, propulsion, mechanical or physical digestion, chemical digestion, secretion, absorption, and defecation.

The first of these processes, ingestion , refers to the entry of food into the alimentary canal through the mouth. There, the food is chewed and mixed with saliva secreted by salivary glands, which contains enzymes that begin breaking down the carbohydrates in the food plus some lipid digestion via lingual lipase. Chewing increases the surface area of the food and allows an appropriately sized bolus (chunk) to be produced.

Food leaves the mouth when the tongue and pharyngeal muscles propel it into the esophagus. This act of swallowing, the last voluntary act until defecation, is an example of propulsion , which refers to the movement of food through the digestive tract. It includes both the voluntary process of swallowing and the involuntary process of peristalsis. Peristalsis consists of sequential, alternating waves of contraction and relaxation of of circular and longitudinal layers of the muscularis externa (alimentary wall smooth muscles), which act to propel food along (Figure \(\PageIndex{1}\)). These waves also play a role in mixing food with digestive juices. Peristalsis is so powerful that foods and liquids you swallow enter your stomach even if you are standing on your head.

Digestion includes both mechanical and chemical processes. Mechanical digestion is a purely physical process that does not change the chemical nature of the food. Instead, it makes the food smaller to increase both surface area and mobility. It includes mastication , or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva. Although there may be a tendency to think that mechanical digestion is limited to the first steps of the digestive process, it occurs after the food leaves the mouth, as well. The mechanical churning of food in the stomach serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme . Segmentation , which occurs mainly in the small intestine, consists of localized contractions of circular muscle of the muscularis layer of the alimentary canal. These contractions isolate small sections of the intestine, moving their contents back and forth while continuously subdividing, breaking up, and mixing the contents. By moving food back and forth in the intestinal lumen, segmentation mixes food with digestive juices and facilitates absorption.

Chemical digestion is aided by secretion of enzymes. Starting in the mouth, digestive secretions break down complex food molecules into their chemical building blocks (for example, proteins into separate amino acids). These secretions vary in composition, but typically contain water, various enzymes, acids, and salts. The process is completed in the small intestine.

Food that has been broken down is of no value to the body unless it enters the bloodstream and its nutrients are put to work. This occurs through the process of absorption , which takes place primarily within the small intestine. There, most nutrients are absorbed from the lumen of the alimentary canal into the bloodstream through the epithelial cells that make up the mucosa. Lipids are absorbed into lacteals and are transported via the lymphatic vessels to the bloodstream (the subclavian veins near the heart). The details of these processes will be discussed later.

In defecation , the final step in digestion, undigested materials are removed from the body as feces.

AGING AND THE...

Digestive System: From Appetite Suppression to Constipation

Age-related changes in the digestive system begin in the mouth and can affect virtually every aspect of the digestive system. Taste buds become less sensitive, so food isn’t as appetizing as it once was. A slice of pizza is a challenge, not a treat, when you have lost teeth, your gums are diseased, and your salivary glands aren’t producing enough saliva. Swallowing can be difficult, and ingested food moves slowly through the alimentary canal because of reduced strength and tone of muscular tissue. Neurosensory feedback is also dampened, slowing the transmission of messages that stimulate the release of enzymes and hormones.

Pathologies that affect the digestive organs—such as hiatal hernia, gastritis, and peptic ulcer disease—can occur at greater frequencies as you age. Problems in the small intestine may include duodenal ulcers, maldigestion, and malabsorption. Problems in the large intestine include hemorrhoids, diverticular disease, and constipation. Conditions that affect the function of accessory organs—and their abilities to deliver pancreatic enzymes and bile to the small intestine—include jaundice, acute pancreatitis, cirrhosis, and gallstones.

In some cases, a single organ is in charge of a digestive process. For example, ingestion occurs only in the mouth and defecation from the anus. However, most digestive processes involve the interaction of several organs and occur gradually as food moves through the alimentary canal (Figure \(\PageIndex{2}\)). Figure 21.3.2 shows the digestive tract with the locations of propulsion, chemical digestion, mechanical digestion, and absorption in different organs.

While most chemical digestion occurs in the small intestine, some occurs in the mouth (carbohydrates and lipids) and stomach (proteins). Absorption, also largely carried out by the small intestine, some can occur in the mouth, stomach, and large intestine. For example, alcohol and aspirin are absorbed by the stomach and water and many ions are absorbed by the large intestine.

Regulatory Mechanisms

Neural and endocrine regulatory mechanisms work to maintain the optimal conditions in the lumen needed for digestion and absorption. These regulatory mechanisms, which stimulate digestive activity through mechanical and chemical activity, are controlled both extrinsically and intrinsically.

Neural Controls

The walls of the alimentary canal contain a variety of sensors that help regulate digestive functions. These include mechanoreceptors, chemoreceptors, and osmoreceptors, which are capable of detecting mechanical, chemical, and osmotic stimuli, respectively. For example, these receptors can sense when the presence of food has caused the stomach to expand, whether food particles have been sufficiently broken down, how much liquid is present, and the type of nutrients in the food (lipids, carbohydrates, and/or proteins). Stimulation of these receptors provokes an appropriate reflex that furthers the process of digestion. This may entail sending a message that activates the glands that secrete digestive juices into the lumen, or it may mean the stimulation of muscles within the alimentary canal, thereby activating peristalsis and segmentation that move food along the intestinal tract.

The walls of the entire alimentary canal are embedded with nerve plexuses (enteric nervous system, submucosal and myenteric plexuses) that interact with the central nervous system and other nerve plexuses—either within the same digestive organ or in different ones. These interactions prompt several types of reflexes. Extrinsic nerve plexuses orchestrate long reflexes, which involve the central and autonomic nervous systems and work in response to stimuli from outside the digestive system. Short reflexes, on the other hand, are orchestrated by intrinsic nerve plexuses within the alimentary canal wall. These two plexuses and their connections were introduced earlier as the enteric nervous system. Short reflexes regulate activities in one area of the digestive tract and may coordinate local peristaltic movements and stimulate digestive secretions. For example, the sight, smell, and taste of food initiate long reflexes that begin with a sensory neuron delivering a signal to the medulla oblongata. The response to the signal is to stimulate cells in the stomach to begin secreting digestive juices in preparation for incoming food. In contrast, food that distends the stomach initiates short reflexes that cause cells in the stomach wall to increase their secretion of digestive juices.

Hormonal Controls

A variety of hormones are involved in the digestive process. The main digestive hormone of the stomach is gastrin, which is secreted in response to the presence of food. Gastrin stimulates the secretion of gastric acid by the parietal cells of the stomach mucosa. Other GI hormones are produced and act upon the gut and its accessory organs. Hormones produced by the duodenum include secretin, which stimulates a watery secretion of bicarbonate by the pancreas; cholecystokinin (CCK), which stimulates the secretion of pancreatic enzymes and bile from the liver and release of bile from the gallbladder; and gastric inhibitory peptide, which inhibits gastric secretion and slows gastric emptying and motility. These GI hormones are secreted by specialized epithelial cells, called enteroendocrine cells, located in the mucosal epithelium of the stomach and small intestine. These hormones then enter the bloodstream, through which they can reach their target organs.

Concept Review

The digestive system ingests and digests food, absorbs released nutrients, and excretes food components that are indigestible. The six activities involved in this process are ingestion (mouth), motility (GI tract), mechanical digestion (mouth, stomach, small intestine), chemical digestion (mouth, stomach, small intestine), absorption (mouth, stomach, small and large intestines), and defecation (anus). Contractions of smooth muscles (muscularis externa) result in peristalsis to push contents along in the GI tract and segmentation to mix the content with enzymes. These processes are regulated by neural and hormonal mechanisms.

Review Questions

Q. Which of these processes occurs in the mouth?

A. ingestion

B. mechanical digestion

C. chemical digestion

D. all of the above

Q. Which of these processes occurs throughout most of the alimentary canal?

B. propulsion

C. segmentation

D. absorption

Q. Which of the following occur(s) in the mouth?

A. mechanical digestion

B. chemical digestion

C. mastication

Q. Which of these statements about the colon is false?

A. Chemical digestion occurs in the colon.

B. Absorption occurs in the colon.

C. Peristalsis occurs in the colon.

D. Diverticular disease occurs in the colon.

Critical Thinking Questions

Q. Offer a theory to explain why segmentation occurs and peristalsis slows in the small intestine.

A. The majority of digestion and absorption occurs in the small intestine. By slowing the transit of chyme, segmentation and a reduced rate of peristalsis allow time for these processes to occur.

Q. Which organ is mostly responsible for diarrhea and constipation and why?

A. The colon absorbs water. If it absorbs too much water, then the remaining contents (stool) may be hard and constipation may result. If it absorbs very little water or even secretes water, then the remaining contents will be loose and watery, resulting in diarrhea.

Contributors and Attributions

OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at  https://openstax.org/books/anatomy-and-physiology

• Biology Article

Human Digestive System

Digestive system of humans.

The digestive tract of humans starts with the mouth and ends with the anus. It includes different structures such as the mouth, oesophagus, pancreas, stomach, small intestine, large intestine, liver, gall bladder, and anus.

Table of Contents

Introduction Structure Parts

• Small Intestine

Large Intestine

Accessory organs, digestion process.

• Mixing and Movement

Disorders Functions  Notes

The Human Digestive System

The digestive system of the human body comprises a group of organs working together to convert food into energy for the body. Anatomically, the digestive system is made up of the gastrointestinal tract, along with accessory organs such as the liver, pancreas and gallbladder. The hollow organs that make up the gastrointestinal tract (GI tract) include the mouth, stomach, oesophagus, small intestine and large intestine that contains the rectum and anus.

Human Digestive System and Nutrition involve the intake of food by an organism and its utilization for energy. This is a vital process which helps living beings to obtain their energy from various sources. The food which we eat undergoes much processing before the nutrients present in them are utilized to generate energy. This processing is known as digestion. Humans and other animals have specialized organs and systems for this process.

The digestion process involves the alimentary canal along with various accessory organs and organ systems. In humans, the process is quite simple due to our monogastric nature. This means that we have a one-chambered stomach, unlike other animals such as cows, which have four chambers.

Some parts of nervous and circulatory systems also play a significant role in the digestion process. A combination of nerves, bacteria, hormones, blood and other organs of the digestive system completes the task of digestion.

Let us have a detailed look at the human digestive system, its parts and functions. Also provided at the end of the chapter are digestive system notes.

Also Read:  Alimentary Canal

Diagram Of The Human Digestive System

The diagram given below represents different parts of the human digestive system that convert food into essential nutrients absorbed by the body.

Parts of the Human Digestive System

The digestive system of the human body comprises a group of organs that work together in converting food into energy and other basic nutrients to power the body. The food we take in is digested and utilized by our body, and the unused parts of the food are defecated.

The digestive system of the human body is the sum of the gastrointestinal tract (GIT; also called alimentary canal) and accessory organs (tongue, liver, pancreas, etc.). These two parts together help in the digestion process.

The alimentary canal is the long tube through which the food that we eat is passed. It begins at the mouth (buccal or oral cavity), passes through the pharynx, oesophagus or food pipe, stomach, small intestines, large intestines, rectum and finally ends at the anus. The food particles gradually get digested as they travel through various compartments of the alimentary canal.

Accessory organs are organs which participate in the digestion process but are not actually a part of GIT. They stimulate the digestion by releasing certain enzymes that help in breaking down the food.

Let us have a detailed look at the digestive system of the human body, along with its parts and functions:

Food starts its journey from the mouth or the oral cavity. There are many other organs that contribute to the digestion process, including teeth, salivary glands, and tongue. Teeth are designed for grinding food particles into small pieces and are moistened with saliva before the tongue pushes the food into the pharynx.

A fibromuscular y-shaped tube attached to the terminal end of the mouth. It is mainly involved in the passage of chewed/crushed food from the mouth through the oesophagus. It also has a major part in the respiratory system, as air travels through the pharynx from the nasal cavity on its way to the lungs.

This is a muscular tube that connects the pharynx, which is a part of an upper section of the gastrointestinal tract. It supplies swallowed food along with its length.

Also Read:  Food Pipe

It serves as a muscular bag which is situated towards the left side of the abdominal cavity, beneath the diaphragm. This vital organ acts as a storage for the food and provides enough time to digest meals. The stomach also produces digestive enzymes and hydrochloric acid that maintains the process of digestion.

Mucous : It is an aqueous secretion produced by the mucous membranes. It functions by protecting the stomach lining and gastric pits from the acid, which is produced by the glands to destroy the bacteria that entered along with the food particles.

Digestive enzymes : They are the group of enzymes which functions by breaking down polymeric macromolecules like biopolymers into their smaller and simpler substances.

Hydrochloric acid : It is the digestive fluid formed by the stomach during the process of digestion. It functions by destroying harmful microorganisms present in the food particles.

The small intestine is a thin, long tube of about 10 feet long and a part of the lower gastrointestinal tract. It is present just behind the stomach and acquires a maximum area of the abdominal cavity. The complete small intestine is coiled and the inner surface consists of folds and ridges.

This is a thick, long tube measuring around 5 feet in length. It is present just beneath the stomach and wraps over the superior and lateral edges of the small intestine. It absorbs water and consists of bacteria (symbiotic) that support the breakdown of wastes to fetch small nutrients.

Also Read:  Large Intestine

Waste products are passed into the end of the large intestine called the rectum and eliminated out of the body as a solid matter called stool. It is stored in the rectum as semi-solid faeces which later exits from the body through the anal canal through the process of defecation.

It is a large gland present just behind the stomach. It is short with its anterior connected to the duodenum and posterior pointing towards the left part of the abdominal cavity. The pancreas releases digestive enzymes to complete the process of chemical digestion.

Read More:  Pancreas

The liver is a roughly triangular, reddish-brown accessory organ of the digestive system located to the right of the stomach. It produces bile , which helps in the digestion of fat in the small intestine. The bile is stored and recycled in the gallbladder. It is a small, pear-shaped organ which is located just next to the liver.

Also Read:  Cellulose in Digestion

The process of digestion begins from the mouth and ends in the small intestine – the large intestines’ main function is to absorb the remaining water from the undigested food and enable bacterial fermentation of materials that can no longer be digested.

The alimentary canal or the gastrointestinal tract is a series of hollow organs and tubes that begins from the mouth cavity and continues into the pharynx, through the stomach, small intestines, large intestines, and finally ending at the anus. Food particles gradually get digested as they travel through various compartments of the gastrointestinal tract.

The digestion process takes place in the following steps.

The very first step involves mastication (chewing). The salivary glands, along with the tongue, helps to moisten and lubricate food, before being pushed down into the food pipe.

It involves the process of lubricating and manipulating food and pushing it down the food through the food pipe (using peristalsis ), and into the stomach.

The stomach, small intestine, liver, and pancreas secrete enzymes and acids to aid the process of digestion. It functions by breaking down food particles into simple components and easily absorbable components.

Also Read:  What is Liver

The process of converting complex food particles into simpler substances in the presence of enzymes and acids secreted by different digestive organs.

Read more: What are digestive juices?

This process begins in the small intestine where most of the nutrients and minerals are absorbed. The excess water in the indigestible matter is absorbed by the large intestines.

The process of removing indigestible substances and waste by-products from the body through the process of defecation.

In a nutshell, the digestion process consists of the six following steps:

Ingestion  ⇒ Mixing and Movement  ⇒  Secretion  ⇒  Digestion  ⇒ Absorption  ⇒ Excretion

Also Read:  Gastrointestinal Tract

Disorders of the Human Digestive System

Vomiting : It is the ejection of stomach contents through the mouth.

Diarrhoea : It is the abnormal watery bowel movement. Prolonged diarrhoea eventually leads to dehydration.

Constipation : A condition in which the faeces are clutched within the rectum due to an irregular bowel movement.

Indigestion : A pain or discomfort in the stomach which is caused when food is not digested properly, resulting in the feeling of fullness.  Indigestion is mainly caused due to inadequate enzyme secretion, food poisoning, anxiety, overeating and eating spicy foods.

Also Read:  Difference between trachea and oesophagus

Functions of the Human Digestive System

Digestion and absorption are the two main functions of the digestive system.

Digestion is necessary for breaking down food particles into nutrients that are used by the body as an energy source, cell repair and growth.

Food and drink need to be converted into smaller molecules of nutrients before it is absorbed by the blood and carried to the cells throughout the body. The body breaks the nutrients present in the drinks and food into carbohydrates, vitamins, fats and proteins.

Human Digestive System Notes

• The human digestive system breaks down food to release energy essential for the body to carry out its activities.
• The process of digestion takes place in 6 major steps.
• The food is ingested by the alimentary canal and is propelled through the body for further processing.
• The autonomous nervous system controls the peristalsis, contraction and relaxation of muscles within the alimentary canal wall.
• The food is passed to the small intestine where it is digested, and the nutrients are absorbed.
• Water, electrolytes and vitamins are absorbed by the large intestine and the waste is defecated.

Also Read:  Mouth and Buccal Cavity

To learn more about the human digestive system parts and functions, as well as related topics such as the digestion process and disorders of the digestive system, keep visiting  BYJU’S Biology or download the BYJU’S app, for further reference.

Frequently Asked Questions

Deduce the function of the human digestive system..

The digestive system consists of the alimentary canal and the accessory organs. Their main function is to break down the ingested food into its components and produce vital nutrients and energy required to sustain life.

What are accessory organs?

Accessory organs are organs which are not part of the digestive system; however, they aid in the digestion process by performing many secondary functions. The main accessory organs of the digestive system are the tongue, liver, pancreas and gall bladder.

Outline the process of digestion, step by step.

The process of digestion involves the following steps, namely:

List out the parts of the digestive system.

• Mouth & Buccal Cavity

Explain the role of the tongue as an accessory organ.

The tongue is not a part of the digestive system, but it provides support functions such as moving and manipulating the food within the buccal cavity. Furthermore, moistening food also helps to swallow and pass through the oesophagus without much resistance.

Register at BYJU’S to explore digestive system notes and more.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

Visit BYJU’S for all Biology related queries and study materials

Your result is as below

Request OTP on Voice Call

Leave a Comment Cancel reply

Your Mobile number and Email id will not be published. Required fields are marked *

Post My Comment

Excellent notes

its good thing for learning

Its very good article and for learning

It is important for everybody because after knowing it anybody could become able to care of his or her health.

Thanks a lot. It really helped me

Year it really helped I passed my exam

Thank you byjus it really help me a lot

Notes are very good 👍👌

Thank u so much for your help! Byjus is really doing great work.

Thanks a lot for helping me with my biology project

Thanks for your help.

Thank you for helping students especially for those who want to write the exam

It helps me a lot. Awesome notes. Very good

Helpful 👍🏻👍🏻👍🏻👍🏻

Thanks a lot, very good

Thanks for your help great😊

Thank you for your help👍👍👍

Thank you BYJUS because of you only I got full marks in my exams and trust me because each and every single thing is described so nicely and in so simple language. (VERY HELPFUL MUST DOWNLOAD BYJUS TO GET GOOD AND EVEN EXTRA MARKS : ) ^_^ )

Thanks for this brief notes which help me to cover my digestion topics

Thanks a lot for this such an informative notes It’s really helpful for me👍keep growing

Thank you so much sir. It’s such an informative note great efforts.

I understood the digestion process more nicely.

Thanks for these brief notes which help me to cover my digestion topics

It helps us in study

• Share Share

Register with BYJU'S & Download Free PDFs

Register with byju's & watch live videos.

Home — Essay Samples — Nursing & Health — Digestive System — Organs of Digestive system

Organs of Digestive System

• Categories: Digestive System Human Anatomy

About this sample

Words: 1435 |

Published: Dec 18, 2018

Words: 1435 | Pages: 3 | 8 min read

Table of contents

Small intestine.

Cite this Essay

Let us write you an essay from scratch

• 450+ experts on 30 subjects ready to help
• Custom essay delivered in as few as 3 hours

Get high-quality help

Prof. Kifaru

Verified writer

• Expert in: Nursing & Health

+ 120 experts online

By clicking “Check Writers’ Offers”, you agree to our terms of service and privacy policy . We’ll occasionally send you promo and account related email

No need to pay just yet!

Related Essays

2 pages / 858 words

2 pages / 774 words

2 pages / 1178 words

1 pages / 668 words

Remember! This is just a sample.

You can get your custom paper by one of our expert writers.

121 writers online

Still can’t find what you need?

Browse our vast selection of original essay samples, each expertly formatted and styled

The digestive system is a complex network of organs and tissues that work together to break down and absorb nutrients from the food we consume. This system exemplifies the interdependency and interconnectivity between structure [...]

Ehrlich, S. D. (2013). Microbes in the gut: probiotics, prebiotics, symbionts to control inflammatory conditions. Immunity, inflammation, and disease, 1(2), 109-123.Ensminger, A. H. (2018). Foods & Nutrition Encyclopedia, 2nd [...]

Achlorhydria occurs when there’s an absence of hydrochloric (HCl) acids in the stomach. It’s a more severe form of a hypochlorhydria, a deficiency of stomach acids. Both conditions can impair the digestive process and lead to [...]

The esophagus or gullet is a muscular canal, about 23 to 25 cm. long, extending from the pharynx to the stomach. It begins in the neck at the lower border of the cricoids cartilage, opposite the sixth cervical vertebra, descends [...]

Abstract This paper includes the studies of techniques used to prevent, treat and nutritional or surgical therapies used for Coronary artery disease. This paper also outlines some of the causes and possible threats of having [...]

Hemostasis is the process that occurs when a blood vessel ruptures and large amounts of plasma and formed elements may escape (Bostwick and Wingerd, 2013). It can be divided into primary and secondary hemostasis. Primary [...]

Related Topics

By clicking “Send”, you agree to our Terms of service and Privacy statement . We will occasionally send you account related emails.

Where do you want us to send this sample?

By clicking “Continue”, you agree to our terms of service and privacy policy.

Be careful. This essay is not unique

This essay was donated by a student and is likely to have been used and submitted before

Download this Sample

Free samples may contain mistakes and not unique parts

Sorry, we could not paraphrase this essay. Our professional writers can rewrite it and get you a unique paper.

Please check your inbox.

We can write you a custom essay that will follow your exact instructions and meet the deadlines. Let's fix your grades together!

Get Your Personalized Essay in 3 Hours or Less!

We use cookies to personalyze your web-site experience. By continuing we’ll assume you board with our cookie policy .

• Instructions Followed To The Letter
• Deadlines Met At Every Stage
• Unique And Plagiarism Free

The Digestive System and Its Functions Essay

One of the most significant components of human life is digestion, because namely during this process, the necessary proteins, fats, carbohydrates, vitamins, minerals, and other useful ingredients enter the body. That is why the proper functioning of the human digestive system serves as the basis for full-fledged life support during the main processes in the digestive tract. Moreover, the digestive system is also responsible for the water-electrolytic balance, regulating the rate of fluid intake from food. The functions of the gastrointestinal tract can be summarized as follows (Hoffman 9-14):

• Motor function. Due to the middle (muscle) membrane of the digestive tract, muscle contraction-relaxation, food taking is carried out, following chewing, swallowing, mixing, and moving food along the digestive canal.
• Secretory function is carried out due to the digestive juices, that are produced by the glandular cells located in the mucous membrane (inner) of the canal. These secrets contain enzymes (reaction accelerators) that carry out the chemical processing of food (hydrolysis of food substances).
• Excretory function provides the secretion of metabolic products by the digestive glands in the gastrointestinal tract.
• Absorption function ‑ the process of assimilation of nutrients through the wall of the gastrointestinal tract into the blood and lymph.

The gastrointestinal tract is a convoluted tube that begins with the mouth and ends with the anus. The digestive system includes the following: the oral cavity with organs located in it and the adjacent large salivary glands; pharynx; esophagus; stomach; small and large intestine; liver; pancreas (Rogers 15).

The oral cavity, pharynx, and esophagus located in the area of the human head, neck, and chest cavity have a relatively straight direction. In the oral cavity, food enters the throat, where there is a cross of digestive and respiratory tracts. Then the esophagus comes, through which food mixed with saliva enters the stomach. In the oral cavity, the primary processing of food occurs, which consists of its mechanical grinding with the help of the tongue and teeth and turning into a food lump.

The salivary glands secrete saliva, the enzymes of which start the breakdown of carbohydrates in food (Smith and Morton 29). Then, through the throat and esophagus, food enters the stomach, where it is digested under the influence of gastric juice.

The stomach is a thick-walled muscle sac located under the diaphragm in the left half of the abdominal cavity. By reducing the walls of the stomach, its contents are mixed. Many glands concentrated in the mucous wall of the stomach secrete gastric juice containing enzymes and hydrochloric acid. After this, partially digested food enters the anterior part of the small intestine ‑ the duodenum.

The small intestine consists of the duodenum, jejunum, and ileum. In the duodenum, food is exposed to the action of pancreatic juice, bile, and also the juice of the glands located in its wall. In the jejunum and ileum, the final digestion of food and absorption of nutrients into the blood occurs. Undigested residues enter the colon. Here they are accumulated and are subject to removal from the body in the form of feces. The initial part of the colon is called the blind, and the appendix is following it.

Digestive glands include salivary glands, microscopic glands of the stomach and intestines, pancreas, and liver. The liver is the largest gland in the human body. It is located on the right under the diaphragm (Rogers 42). Bile is produced in the liver, which flows through the ducts into the gall bladder, where it accumulates and enters the intestine as needed. The liver retains toxic substances and protects the body from poisoning. The pancreas also belongs to the digestive glands that secrete juices and turn complex nutrients into simpler and more soluble in water. It is located between the stomach and the duodenum. Pancreatic juice contains enzymes that break down proteins, fats, and carbohydrates; 1–1.5 liters of pancreatic juice is secreted per day (Hoffman 30).

The correct sequential operation of the elements of the digestive system in time and space is ensured by regular processes of various levels. Enzymatic activity is characteristic of each section of the digestive tract and is maximum at a certain pH value of the medium. For example, in the stomach, the digestive process is carried out in an acidic environment.

Acidic content passing into the duodenum is neutralized, and intestinal digestion occurs in a neutral and slightly alkaline environment created by secrets secreted into the intestine ‑ bile, pancreatic juices, and intestinal secretions, which inactivate gastric enzymes (Smith and Morton 24). Intestinal digestion occurs in a neutral and slightly alkaline environment, first in the type of abdominal and then parietal digestion, ending with the absorption of hydrolysis products ‑ nutrients.

The degradation of nutrients by the type of cavity and parietal digestion is carried out by hydrolytic enzymes, each of which has specificity expressed to one degree or another. A set of enzymes in the secretions of the digestive glands has specific and individual characteristics, adapted to the digestion of the food that is characteristic of this region, and those nutrients that prevail in the diet.

Each digestion department has its internal environment, which serves as the basis for the functions assigned to it. The organs of the gastrointestinal tract, together with the auxiliary glands, gradually break down each component of the food, separating what the body needs and sending the rest of the absorbed food to waste. If at any of these stages a malfunction occurs, the organs and systems do not receive enough energy resources and, therefore, cannot fully perform their functions, causing an imbalance of the whole organism. Violations of the normal functioning of the digestive system can lead to the development of several diseases.

Works Cited

Hoffman, Gretchen. Digestive System . Benchmark Books, 2008.

Rogers, Kara. The Digestive System . Rosen Education Service, 2010.

Smith, Margaret E., and Dion G. Morton. The Digestive System: Systems of the Body Series . Churchill Livingstone, 2011.

• Chicago (A-D)
• Chicago (N-B)

IvyPanda. (2021, June 27). The Digestive System and Its Functions. https://ivypanda.com/essays/the-digestive-system-and-its-functions/

"The Digestive System and Its Functions." IvyPanda , 27 June 2021, ivypanda.com/essays/the-digestive-system-and-its-functions/.

IvyPanda . (2021) 'The Digestive System and Its Functions'. 27 June.

IvyPanda . 2021. "The Digestive System and Its Functions." June 27, 2021. https://ivypanda.com/essays/the-digestive-system-and-its-functions/.

1. IvyPanda . "The Digestive System and Its Functions." June 27, 2021. https://ivypanda.com/essays/the-digestive-system-and-its-functions/.

Bibliography

IvyPanda . "The Digestive System and Its Functions." June 27, 2021. https://ivypanda.com/essays/the-digestive-system-and-its-functions/.

• The Anatomy of the Pancreas
• Digestion of a Cheeseburger
• Digestive Journey of Cheeseburger
• Esophagus Anatomy and Physiology
• Development of the Chimpanzee Pancreas
• Human Digestion
• The Digestive System in the Human Body
• The Digestive System Analysis
• The Digestive System and Peptic Ulcers in Nursing
• "Salivary Gland Involvement..." Article by Liu et al.
• Microbial Biotechnology and Pharmaceutical Impact
• Bloodborne Infections: Human Immunodeficiency Virus
• Viruses: Are They Living or Non-Living?
• Animal, Plant, and Bacterial Cells' Cycles
• Eukaryotic and Prokaryotic Cells: Key Differences