Human digestive system

Introduction

The food that we eat enters the mouth. But what happens from there. Do you think that it will directly go to stomach and come out as waste. No that is wrong. Our human body is very very very very very cool. It has so much things. After food goes to the mouth it then enters to the esophagus and then it goes to so much body parts. We will study all about where the food that we eat goes to. It will be an interesting journey.

Human digestive system

Some important facts:

In the human digestive system, there is only 1 stomach. Because of this we are called as monogastric animals.

• Mono- 1
• Gastric- relating to the stomach
  
  
  

Digestion starts from Mouth and ends in Anus. In the mouth the action of saliva takes place. Saliva is created from the 3 salivary glands

• Parotid
• Submandibular
• Sublingual
  
  
  

Saliva breaks down the starch in food. This is done by help of enzymes. The name of the enzyme in saliva is amylase. The tongue helps mix saliva with the food. The end result is Bolus.

• Bolus is a mixture of the grinded, crushed food and with saliva. It is in a round shape 

The bolus passes to an tube like structure called as food pipe or esophagus. 

When the food goes in the esophagus, it expands a particular section of the esophagus. The esophagus will then try to contract on the part where there is expansion. This causes food to go down. This is called peristalsis. 

The food from esophagus then goes to the stomach. The Sphincter muscle helps in pushing the food from the esophagus to stomach. The stomach contains H.C.L which kills the bacteria in food. The H.C.L is produced in the inner-lining of stomach.

• PH level of H.C.L in stomach is 1.5 to 2.5
• There is an acidic nature in the stomach
  
  
  

Some people may think "H.C.L will burn through the stomach and damage our body." Nice question, but that is unlikely to happen. It is because the inner-lining of the stomach also produces mucous. The mucous together forms the mucous layer which helps in protecting the stomach from burning of H.C.L. When ever we eat food, the stomach produces H.C.L. So that is why people say it is bad to eat bubblegum. Because eating bubblegum can cause unnecessary formation of H.C.L. This can cause acid reflex. The inner-lining of the stomach also produces gastric juices which partially digest protein in food. This partially digested food is called as chyme.

The food then goes to the small intestine. The Small intestine is a long tube which helps in digestion and absorption. It is divided into 3 parts.

• Duodenum- Place where the bile juice from the liver and pancreatic juice from the pancreas will join and act on the chyme, the food then changes to chyle (Pronounced as "Kile")
• Jejunum- Helps in digestion and absorption
• lleum- Helps in digestion and absorption
  
  
  

The liver produces bile juice as I said before. The bile juice helps in digestion of fat in food. The pancreas produces pancreatic juice. It turns complex substances into simpler substances.

For example: It turns

• Proteins to amino acids
• Carbohydrates to glucose
• Fat to fatty acids
  
  
  

 

There are small finger like structures in the small intestine. These are called as villi. Villi:

• Increases surface area
• It is highly supplied with blood vessels
• It helps in absorption of food materials

The food then goes to the cells and the cells break the food down. Then glucose is released. Cells take the glucose for energy. If we eat to much, the food will go to the cells. The cells will take the amount that it needs and the extra food is stored as glycogen in our body.

This process of utilization is called as assimilation.

But once the small intestine finishes digestion and absorption there may be some undigested food. So the undigested food alone goes to the large intestine. The large intestine will absorb the water, salts and minerals. The remaining things is released to through anus as faeces. Before faeces are released it is stored in the rectum.

• Large intestine's other name is colon
• There are 4 parts of the colon:

• Ascending colon
• Transversal colon
• Descending colon
• Sigmoid colon

The small intestine and the large intestine is connected by an body part called as caecum.

In here, the thin curly tube is appendix.

The thick tube, right side of the very big tube is the small intestine.