The Digestive System

I am a sandwich which has an important role. As a food, I know I have to be bitten by someone. Now, I need to enter a body and join his digestive system. I know why he eats me because he has to give something important to his body.
Anyways, what is digestion? Digestion is the breaking down of food into forms that human bodies can use. The bodies use food as fuel to provide energy for work, play and growth. The digestive system is responsible for converting the foods that human eat into energy for bodies to use.

Mouth
Ouch!!! I am bitten off by his teeth. I am in his mouth and he starts chewing me now. The digestion begins by breaking down of food into small molecules. The teeth help to break the food apart, saliva helps to soften the food and his tongue helps to push the food into his throat when he ready to swallow. It means I am in the mechanical breakdown, plus some chemical (because it uses ptyalin, enzyme in saliva).

Swallowing
After being chewed, food is forced into the rest of the digestive tract by swallowing me. The tongue and the floor of the mouth rise, squeezing food into a muscular tube called the esophagus. I slide down the esophagus with the help of mucle contraction, peristalsis. Peristalsis is the name given to the wave-like contraction. If human tries to talk while swallowing food may enter the respiratory passages and a cough reflex expels.

Stomach
After moving through the 25 cm length of the esophagus, the bites of me reach the stomach. It is J- shaped bag, left side, just below the heart. Here, I temporarily stored. The principal activity is to begin the digestion of protein. The stomach makes digestive juices (acids and enzymes) that help to break me down into a thick liquid or paste. This thick liquid or paste is called chyme. The stomach is a muscular organ that is able to move in order to mix the food with digestive juices. I remain in the stomach for about two hours.

The small intestine
After leaving the stomach the piece of me enters the small intestine. It is a 20-25 foot tube that is coiled up in human abdomen. The most important part of digestion takes place in the small intestine. As the thick liquid food paste travels through small intestine, the nutrients (vitamins, minerals, proteins, carbohydrates and fats) are absorbed by millions of tiny finger-like objects called villi and sent into bloodstream where the nutrients can travel to all the body cells. The liver and gallbladder help digest fats in foods. Liver also helps body store extra food that it cannot use right away. Pancreas creates the chemical insulin to help body use sugar. There†are†some†leftovers that get to the end of small intestine. The leftovers go into your large intestine.

Large Intestine
The undigested food enters the large intestine as a liquid paste. In the large intestine water is removed from the liquid paste turning what is left into solid waste. The solid waste then collects in the rectum at the end of the large intestine and will finally leave the body through an opening called the anus.

The Fact

1. Biting into a sandwich and chewing it begins its physical breakdown. Chewing not only makes the sandwich easier to swallow, but also increases the surface area of the food so that digestive enzymes can come into contact with more of the food.

2. As the food travels through our digestive system, a journey of more than 8 m.

3. The liver stores and regulates the levels of food molecules in the blood.

4. The oesophagus is a long tube that runs from the mouth to the stomach.

5. Peristalsis is the name given to the wave-like contraction, which also happen in the stomach and the rest of the digestive tract.

6. Saliva is produced by salivary glands that lying in and near the mouth.

7. The salivary glands increase their saliva production before we eat.

8. Saliva plays an important role in digestion; to moisten and lubricates food, making it easier to swallow.

9. HOW LONG ARE OUR INTESTINES? At least 25 feet in an adult.

10. When we eat, our body digests the food so our cells can use it to make energy.

Bibliography

http://training.seer.cancer.gov/module_anatomy/images/illu_dige_tract.jpg
http://hes.ucf.k12.pa.us/gclaypo/digestive_system.html
http://www.mayoclinic.com/health/digestive-system/DG00049
http://personal.nbnet.nb.ca/kvhs/biology/digest.html