Human Digestive System
Digestion is the process in which ingested food is broken down into simpler compounds that are later absorbed by the body in the form of nutrients. The digestive system is the system of the body that involves various organs of the body carrying out the process of digestion.
The major parts of the digestive system are:
- Salivary glands
- Small Intestine
- Large Intestine
- Accessory digestive organs: liver, gallbladder, pancreas
Role and Importance of Human Digestive System
- Motility of the food.
- Digestion or breakdown of food.
- Secretion and absorption of nutrients, vitamins, minerals, and water to finally assimilate in the blood to provide energy.
- Elimination of waste and undigested food.
- It provides the nutrition to the body to work.
- It balances the pH value of the blood by secreting certain enzymes while digestion.
- It’s also supplies the body with the extra amount of energy when it needs it. It converts the glucagon into glucose which provides instant energy.
- It detoxifies the food you eat and it is very important for your health.
The major layers of the gastrointestinal tract:
- Mucosa which is the inner layer which lines completely the gastrointestinal tract. It is the simple columnar epithelium.
- Submucosa which is this layer having blood vessels, glands, and nerve plexuses.
Food undergoes many different processes to reach the anus ultimately. These processes extract every bit of nutrition from the intake of food and finally throw the waste material from the anus. In this section, we will discuss how your food starts its journey from the mouth to the anus.
Different Parts of a Human Digestive System
Mouth and Salivary Glands:
The mouth is the place where the digestion process begins. First, the food enters the mouth and the teeth break down the food into smaller pieces. Then the saliva secreted by the salivary glands gets the food to transform it into a semi-liquid mass known as “Bolus” with the help of tongue. The saliva has enzymes called as amylase and lipase which breaks down of carbohydrates present in the food. Saliva also kills germs present in food and mouth. From the mouth, the food enters the esophagus
This is also known as the “Food Pipe”. In this pipe food just travels and reaches the stomach through a movement called as a peristaltic movement. The Lower Oesophageal sphincter (LOS or LES) present at the junction of the esophagus and stomach prevent the backflow of food (vomiting). The food pipe takes the bolus from the lower cavity of the mouth to the first stage of the stomach.
It is the major organ of the digestive system where the digestion of proteins takes place in a bulk. The stomach produces a juice known as “Gastric Acid”. It mainly contains hydrochloric acid and sodium chloride. These two chemicals digest most of the bolus and act on proteins to break them down. The Chief G cells in the stomach produce an enzyme pepsinogen. The gastric acid acts on that enzyme to produce pepsin which breaks down the protein to amino acids. These chemicals can easily damage the inner cells of the stomach, so to protect them, there is mucus secreted all around the stomach walls. Gastric juice also helps to kill the germs which have entered inside the body through food.
Being the second largest organ in the human body, it also does very vital work while digestion. The most important purpose of the liver is to detoxify the food that you eat. Then, it also produces glucose from glycogen whenever the body needs energy. At the connecting point, there is the gallbladder which produces bile juice. Bile or bile juice has bilirubin. It emulsifies the fats and reduces the surface tension between liquids or solids.
This is the hub where all the chemicals are secreted that helps in every nutrient to get digested. It works both as an endocrine gland and exocrine gland. It secretes chemicals like insulin, glucagon and the pancreatic juice. The pancreas has a pancreatic duct that joins the stomach to the duodenum (part of the small intestine).
From the stomach, the bolus after going through so many processes reaches the small intestine. The small intestine is divided into three parts called as
- Duodenum ( Upper part)
- Jejunum (Middle part)
- Ileum (Lower Part)
The food here is called “Chyme”. The small intestine produces alkaline enzymes that act on the acidic food coming from the stomach. Apart from that the pancreatic juice from the pancreas, bile juice from the liver are secreted inside the small intestine to digest proteins, fats and rest of carbohydrates.
In the small intestine, the digestion of carbohydrates, proteins, and fats is complete.
Carbohydrates finally break down to glucose, proteins to amino acids and fats to fatty acids in the small intestine which has then absorb through various hairs like structures called as villi. They increase the surface area for absorption.
Finally, the digestion and absorption of the food are complete the small intestine.
This is a pouch-like structure that separates the large intestine and the small intestine. It slows down the flow of the chyme which helps in more absorption.
The first part of the large intestine is the colon. It is the place where a large amount of water has absorb from the feces. This water helps the body when it needs the most. The process is very slow and takes around 12-50 hours before it is released through defecation. Apart from the absorption of certain vitamins and minerals also takes place in the large intestine.
It is the part where the undigested food or the waste material has the store in the form of feces or stools.
This is the part where the feces get out of our body. It is an opening of the rectum.
Conclusion of the Human Digestive System:
Digestion is really necessary for every living body on this planet. The above section briefly explains how the digestive system in human works. Digestion is like the ink inside the pen without which no human body will exist.
Written By Mansi Mandal
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