What is Digestion of Food?
Digestion is a process in which large insoluble food molecules are broken down to small water-soluble molecules that can be absorbed by the blood plasma. Digestion can be categorized into two forms: Mechanical Digestion and Chemical Digestion.
The breaking down of large pieces of food into smaller ones so that the digestive enzymes can work on them is known as mechanical digestion.
In chemical digestion, the enzymes are broken down into smaller molecules so that the body can use them.
If you are looking forward to how long does it take to digest food, you can read below:
There are several steps in digestion.
Mouth to Stomach to Digest Food:
After putting the food inside the mouth, we grind and tear the food by chewing and reducing the bigger pieces to smaller ones. That’s where mechanical digestion starts. Inside the mouth, the salivary enzymes such as amylase and lipase chemically break down the food particles into the elementary components like proteins, fats, starches. The food forms a ball called bolus which is pushed down the esophagus by the muscular contractions of the tongue. It takes about 5-8 seconds to swallow.
From the esophagus, it takes another 5-8 second to reach the stomach. This process is known as Peristalsis.
Stomach to Small Intestine to Digest Food:
From the esophagus, a ring-like muscle called the sphincter links with the stomach. It opens and lets the bolus pass through and closes right after that to prevent digestive acids and juices from flowing back up. Inside the stomach, the food is subjected to gastric juices and enzymes. This reduces the bolus to a thick milky material called chyme.
The small intestine consists of the duodenum and the jejunum. In the duodenum, the acidic juices are neutralized by pancreatic juices. The substance is broken down into smaller particles so that it can be absorbed into the bloodstream. It is then passed into the jejunum where the primary absorption of nutrients take place. It takes 2-6 hours to empty the stomach.
 Large Intestine to Rectum to Digest Food:
The large intestine is 1.5 – 1.8 m long and is divided into three parts – caecum, colon, and rectum. Substances like fiber, which are not absorbed out of the small intestine move to the large intestine along with water. A sphincter prevents its back flow. The resulting substance is considered as waste, and it can remain in the large intestine for as long as about 36 hours.
The undigested food that is passed to the colon mixes with the resident bacteria. The bacteria ferment some of the food. Important chemicals like Vitamin-K are also produced in this stage.
Then the large intestine removes the water content from the waste material and passes it from the colon to the rectum. The residual mass is called stool.
 Rectum to Anus to Digest Food:
The external opening of the rectum is called the anus. During elimination of the stool, the sphincter, and pelvic muscles relax. If it is inhibited, the desire to defecate subsides but it returns hours later. This process is known as Egestion.
Thus, digestion takes 24-72 hours for an average adult and 33 hours for children.
Through the above mentioned steps, you now know how long it takes to digest food.
Factors That Affect Digestion:
- If the fiber intake is more then fiber binds with the stool which makes the elimination process easier. Fruits, vegetables, and whole grains contain fiber and should regularly be taken as a part of the diet.
- Some prescription drugs, caffeine, and nicotine products may slow down the digestive process.
- Physical activities can speed up the digestion process. Such activities make the muscles more flexible and thus stimulate the muscular movement required for moving the stool through the intestines.
