When you have hunger pangs, the first thing one does is get hold of some food. So you move towards the fridge and make yourself a delicious sandwich or eat a leftover slice of pizza or cake, even though digestive problems might be a concern. Once you have eaten, you go back to doing whatever it was that you were doing, and in a while, you forget about that food. But the food is in your stomach, which is silently doing its work of digesting that food. The digestive system, which comprises several organs, breaks down food into simpler nutrients like carbohydrates, proteins, and fats.
What is Digestion and the Human Digestive System
The human digestive system is helped by other organs like the liver, gallbladder and pancreas to digest food. Together they break down the food into simpler nutrients — carbohydrates, proteins and fats as well as minerals and vitamins. They then proceed to further break them into even simpler substances like sugar and amino acids which are easily absorbed by the body. These are absorbed into the bloodstream and used for energy, growth and repair of the body. Digestion is the mechanical and biochemical breakdown of food into simpler substances. This helps in the easy absorption of nutrients by the body.
The digestive system begins its work even before you take the first bite of food. This is because we start salivating at the sight or smell of food when we are hungry. Digestion continues for the next few hours depending on what you’ve eaten. This process helps our body to get the nutrients and energy it needs to function normally.
A simple digestive system definition is that it is a group of organs that break down the food into simpler components in order to absorb the nutrients which are used as fuel to keep all our systems working. The main organs of the human digestive system are,
- Small intestine
- Large intestine
Functions of Digestive System
- Ingestion of food which enters through the mouth and goes into the alimentary canal.
- Secretion of various acids, enzymes and hormones which help the body to digest food.
- Digestion of nutrients by breaking them down into smaller molecules for energy.
- Absorption of vitamins and fatty acids by the lymph system for use by the small intestine.
Parts of Digestive System
- Small Intestine
- Large Intestine
The digestion process starts at the mouth itself even before you have actually put the food in your mouth. As soon as you smell, see or think about something tasty, saliva is secreted in your mouth. The moment you start chewing food, the enzymes in the saliva or spit break down some of the starch in the food which makes the food soft and thus easy to swallow. Your tongue too plays its role as it pushes the food around in your mouth while you chew. When you want to swallow, it is the tongue that pushes the chewed food to the back of your throat and into the oesophagus.
The oesophagus is behind the windpipe and is like a 10 inches long stretchy pipe. The strong muscles of its walls propel the chewed food from the back of your throat to your stomach. The windpipe is also located at the back of the throat and whenever we swallow, a special flap called the epiglottis closes over the opening of the windpipe. This prevents the food from entering the windpipe so that one doesn’t choke. The muscles in the walls of the oesophagus squeeze the food down its length into the stomach. This process takes all of 2 or 3 seconds.
In the stomach the food gets churned with various acids and enzymes that are secreted by its walls. The stomach has a rather interesting shape and looks like a J-shaped sack. It produces hydrochloric acid which helps in the activation of enzymes that facilitate digestion. The stomach stores the food you have eaten, breaks it down into a liquid mixture and slowly empties that mixture into the small intestine. The stomach churns the chewed food into smaller and smaller pieces with the help of its strong muscles and gastric juices and also kills the bacteria that might be in the food.
The small intestine is all of 22 feet long and is shaped like a long tube with a circumference of about 1.5 to 2 inches. It is coiled and packed beneath the stomach. Most of the vitamins and minerals from the digested food are absorbed into the blood in the small intestine. The enzymes produced by the small intestine break down the food even further so that the body can absorb all the nutrients. The small intestine is aided in this process by the pancreas, liver and gallbladder which secrete different juices to help in digestion and allow the body to absorb nutrients. The pancreas produce enzymes that help to digest fats and protein. Bile from the liver helps to absorb fats. The gallbladder is an organ that stores the bile till the body needs it.
Food can stay up to 4 hours in the small intestine where it gradually turns into a very thin, watery mixture. After that, the nutrients from your food pass from the intestine into the blood. The nutrients then travel to the liver while the leftover waste goes on to the large intestine. The nutrient-rich blood flows to the liver where it is processed and filtered to remove the waste and harmful substances. Some of the waste is also converted into more bile by the liver. Some of these nutrients then travel to the rest of the body and the rest is stored in the liver.
The last of the water from the waste material is absorbed in the large intestine. The large intestine has a circumference of 3 to 4 inches and is about 5 feet long.
Before the waste material goes into the rectum, it passes through the colon which is the last chance to absorb water and minerals into the blood. As the water is absorbed, the waste product gets harder and harder and forms stool or faecal matter.
This is where the stool or faecal matter is stored till it is passed out from the body. The large intestine pushes the stool into the rectum which is the last stop on the digestive tract. The solid waste stays there till it is expelled when you pass stool through the anus.
The main digestive system function is to break down food and absorb nutrients from the stomach and small intestine. It also removes toxins and waste products through the rectum and anus. The enzymes and acids soften the food which acts as fuel for our body. Complex nutrients like carbohydrates, proteins and fats are converted into simpler substances like sugar and amino acids so that they can be easily absorbed. For more information on the digestive system, do contact the EuroKids website.