DIGESTIVE �SYSTEM

Prepared by :

Name : Rachana.R.

USN : 4MC21CV070

INTRODUCTION

The digestive system is used for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.Digestion is important because our body needs nutrients from the food we eat and the liquids you drink in order to stay healthy and function properly. Nutrients include carbohydrates, proteins, fats, vitamins, minerals and water.

FUNCTIONS OF THE DIGESTIVE SYSTEM

• Ingest food

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• Break down food into nutrient molecules

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• Absorb molecules into the bloodstream

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• Rid the body of indigestible remains

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There are four stages to food processing:

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1. Ingestion: taking in food.

2. Digestion: breaking down food into nutrients.

3. Absorption: taking in nutrients by cells.

4. Egestion: removing any leftover wastes.

MOUTH

• The mouth is the beginning of the digestive tract. In fact, digestion starts before we even take a bite.Saliva mixes with the food to begin to break it down into a form your body can absorb and use. When we swallow, the tongue passes the food into the throat and then into esophagus.

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ESOPHAGUS

• Located in the throat near trachea, the esophagus receives food from the mouth when swallow. A series of muscular contractions within the esophagus called peristalsis delivers food to your stomach.

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Stomach

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The stomach is a hollow organ, or "container," that holds food while it is being mixed with stomach enzymes. These enzymes continue the process of breaking down food into a usable form. Cells in the lining of stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are processed enough, they’re released into the small intestine.

SMALL INTESTINE

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• Made up of three segments — the duodenum, jejunum, and ileum — the small intestine is muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also works in this organ, moving food through and mixing it with digestive juices from the pancreas and liver.
• The duodenum is the first segment of the small intestine. It’s largely responsible for the continuous breaking-down process. The jejunum and ileum lower in the intestine are mainly responsible for the absorption of nutrients into the bloodstream.
• Contents of the small intestine start out semi-solid and end in a liquid form after passing through the organ. Water, bile, enzymes and mucus contribute to the change in consistency. Once the nutrients have been absorbed and the leftover-food residue liquid has passed through the small intestine, it then moves on to the large intestine.

Pancreas

The pancreas secretes digestive enzymes into the duodenum that break down protein, fats and carbohydrates. The pancreas also makes insulin, passing it directly into the bloodstream. Insulin is the chief hormone in the body for metabolizing sugar.

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Liver

• The liver has many functions, but its main job within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat and some vitamins.
• The liver is body's chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals in body needs to function.
• The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs that can be toxic to body.

Gallbladder

• The gallbladder stores and concentrates bile from the liver, and then releases it into the duodenum in the small intestine to help absorb and digest fats.

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Colon

• The colon is responsible for processing waste so that emptying your bowels is easy and convenient. It’s a 6-foot long muscular tube that connects the small intestine to the rectum.
• The colon is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum.

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Rectum

The rectum is a straight, 8-inch chamber that connects the colon to the anus. The rectum's job is to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not.

Anus

The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is able to detect rectal contents. It lets you know whether the contents are liquid, gas or solid.

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Digestion Process

The digestion process takes place in the following steps.

• Ingestion

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.

• Mixing and Movement

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

• Secretion

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.

• Digestion

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

• Absorption

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.

• Excretion

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

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Functions of the Human Digestive System

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

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

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• 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

Disorders of the Human Digestive System

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

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

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

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• 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.

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