Thursday, December 17, 2009

Digestive System

All living things need food to survive, but why? Food provides both a source of energy, as well as the building blocks to help your body grow, develop, and repair itself

Through the process of digestion, your body breaks the food down into the basic blocks of life, and than rebuilds them by incorporating them into your body. Just like if you were to take apart a Lego dinosaur so that you could use the blocks to build your castle. Your body is constantly breaking food down, and then using the pieces to build, repair, and grow your body.

There are many parts or organs utilized by your digestive system. The job of each of these organs is to break food down into smaller pieces or smaller blocks, so that by the time that this food reaches the cells of your body, they are nothing more than tiny molecules.

How Is Food Broken Down?

All though it smells really good, in its current form, that hot dog will not do your body much good. It is much too large to squeeze into your tiny cells. Even if you could get it into one of your cells, that cell would not be able to use it. What do we need to do to the hot dog before we put it into your cells? That’s right!! We need to break it down into smaller pieces.

Your Mouth Is The Chomping Champ
As you lift the hotdog up towards your mouth, what is the first thing you do, to begin breaking it down into smaller pieces? That is right, you bite it. The hotdog is too big to swallow in one giant gulp, so you bite the end off. Already you have begun breaking it down haven’t you. But wait! Now what are you doing? You are still breaking it down into smaller pieces. You are squishing it, and grinding it, and cutting it using your teeth. Something else very important is also happening.

Your mouth produces a chemical called saliva, which is more commonly referred to as spit. Saliva is produced by your salivary glands, and is released as you begin to chew. It can also be released when you smell something yummy. Saliva has a couple of important jobs to perform. First, it moistens your food. This makes it easier to chew, and helps lubricate it, so that it can travel through your body more easily. Saliva also contains chemicals that begin to break your food down into smaller pieces through the process of chemical digestion.

Now you are holding a hotdog in your hand, with a bite missing out of it. In your mouth you have a small wet ball of mashed up hotdog, bun, ketchup, mustard, and saliva. So what is next?

The Esophagus, The Waterside of The Body

Ought Oh!! Here it comes. Wait… you swallow it. That wet ball of broken up hotdog begins a long journey towards the cells of your body. At this point it is still much too big to fit inside of your tiny cells. Even the smallest pieces would be far too large to do your cells any good.

After swallowing your hotdog bite, it enters into your esophagus. The esophagus is like a long slippery water slide. Muscles within your esophagus squeeze the food down towards your stomach. Whether you are standing up, laying down, or hanging upside down, you can safely swallow a bite of food, because the muscles within your esophagus know that their job is to send food in only one direction… towards your stomach.

Imagine sliding down a water slide. Now suppose that you stick out your arms and legs to stop yourself. You then turn around, and start to climb back up the slide. If the water slide were like your esophagus, it would squeeze down, closing in front of you. It would then squeeze closer and closer to you, forcing your to start sliding down again.

Your Stomach

As that hotdog bite falls into the stomach, a round muscle called a sphincter closes behind it. This protects the esophagus from having food or other chemicals splash back into it. The single hotdog bite is soon joined by other bites as you continue eating. After a few minutes your stomach is completely full. Because you feel full, you stop eating, and run off to play with your friends. As you play, you don’t think about the food, or what it is doing inside of you. But your body does not forget about it. Deep within you, your body continues the process of breaking your food down into smaller and smaller pieces.

For the next couple of hours your stomach muscles churn and grind the food in your stomach, causing it to roll over and over again. Glands within your stomach release a variety of powerful chemicals which help to further break down the food within you. The two most important chemicals are hydrochloric acid and pepsin. Together these chemicals break the hotdog down into a slush known as chyme.

Your Small Intestine

Once the chyme is ready, a valve opens in your stomach and releases the chyme into your small intestine. The small intestine is where most of the digestion process takes place. All though the slushy chyme is much more broken down than the original hotdog, the small pieces floating in the chyme are still too large to fit inside your cells. They must be broken down even further.
As the chyme enters your small intestine it is mixed with a variety of chemicals, whose job it is to further break down the hotdog. Your liver adds a liquid known as bile which helps to neutralize the acids from your stomach, so that digestion can continue to take place.

By now, you are done playing with your friends, and are back at home watching television. The chyme is slowly moving further along in your small intestine. As it moves along, the process of digestion is almost complete. Your small intestine is lined with tiny folds called Villi.
The muscles within your small intestine squeeze and roll the food about. As it sloshes around, these villi quickly absorb the nutrients from the chyme, leaving behind the materials that are not nutritious.

Your Large Intestine