Digestion 101

Maybe it’s just me, but I love talking about digestion. No it doesn’t spur the thought of the most beautiful of images and to be honest the vocabulary needed to discuss the topic is…unique. I mean one doesn’t usually throw around terms like bolus, sphincter, and chyme on a daily basis. None the less digestion is process our body is going through multiple times a day and many times the process is misconstrued. Haven’t we all heard something like sugar is like glass shards in the blood stream? I actually did hear someone say that. So today, I’m going to explain the biological process of digestion. It may not be the most glamorous of reads, but I will try to keep things appealing…

image from here

We eat with our eyes…

This is true and this is where digestion begins. When we see something appetizing the process of digestion is set in motion. Immediately our mouth starts watering which means it is releasing saliva into the mouth; saliva is the key component to the chemical digestion of food. Try it for yourself by putting a cracker into your mouth – do not chew it but let the saliva break it down. You may be surprised how quickly it goes to work. Your teeth are the key players of mechanical digestions. Teeth grind and chew food to increase the surface area for more chemical reactions to take place. Food should be chewed to the consistency of applesauce for maximum nutrient absorption.

Down the Hatch

Once you swallow the food, it passes into the esophagus which in my opinion is the unsung hero of the digestive system. Our esophagus is a thin muscular tube that attaches our mouth to our stomach. Peristalsis are the involuntary, wave like, muscle contractions that occur that push our food, called a bolus at this point, into our stomach. They are strong enough that we can even eat food while upside down! The base of the esophagus has an esophageal sphincter that closes keeping food from entering back into the stomach.

The Stomach

The stomach is a muscular pouch that can hold up to 6 cups of food but both chemical and mechanical digestion takes place. So if you have ever felt your stomach moving and grooving after a meal, it probably is by moving, crushing, and churning your partially digested food. At this point our food is called chyme and is a thick liquid that will travel into the small intestine. Different foods take different amounts of time to digest in the stomach. Carbohydrates digest the fastest (why a sugar high happens) in 1-2 hours, protein is next at 3-5 hours, and finally fat can take up to 12 hours to digest!

The Small Intestine

From the stomach, the chyme enters the small intestine where digestive juices such as bile, pancreatic juice, and intestinal juice help break down nutrients. The surface area of the small intestine is as large as a tennis court. (There is your fun fact for the day!) This is the case because the inner walls are covered in billions of finger like projections called villi. They increase the surface area of the small intestine so maximum nutrient absorption can take place. After absorption in the small intestine, dietary fiber and waste are left.

Waste Management

Our body’s waste management is regulated by the Large Intestine and it is very resourceful. In the large intestine, all the water is removed from the digestion process and what is left is flushed down the toilet.

Pretty fascinating right? Now, I promise I won’t say pancreatic juices in any future articles.