The Digestive System

What’s Good for Your Gut?

The Digestive System—“The Food Tube”:

They digestive system consists of several organs connected in a long path that allows food into the body and excretes excess waste from the body. The digestive system consists of the mouth, esophagus, stomach, small intestine, and large intestine with accessory organs such as the liver, gallbladder, pancreas, and kidneys.

Mouth:

-        Food is chewed and mixed with saliva.

-        Salivary amylase (an enzyme that breaks down carbohydrates) begins breaking down starch.

Esophagus:

-        Long muscular tube connecting the mouth to the stomach.

-        The lower esophageal sphincter (LES) at the base of the esophagus acts as a door between the esophagus and the stomach. When the door opens, food is allowed into the stomach to be churned around. This door also prevents food and stomach acid from moving back up into the esophagus.

Stomach:

-        Digestion occurs!

-        Stretchable organ, can hold more than 4 cups of food but when it’s empty it is about the size of a baked potato.

-        Hydrochloric acid (HCl) in the stomach mixes with food to form something we call “chyme” and is pronounced K-EYE-M. When the stomach acid mixes with food to form chyme it all becomes a big blob of liquid goop that can move easily through the intestines.

-        Proteins start to digest when they meet an enzyme called pepsin.

-        The stomach also has a bottom door that allows chyme into the small intestine and prevents it from coming back into the stomach—this is a one way street! This door is called the pyloric sphincter.

Small intestine (~20 feet in length):

-        The small intestine is made up of 3 parts—the duodenum (upper portion), jejunum (mid-section), and ileum (base).

-        The pancreas and gallbladder send substances to the duodenum to break down fats from big globs into tiny droplets.

-        Absorption occurs!

o   Duodenum—iron, calcium, magnesium, zinc

o   Jejunum—glucose (energy!), galactose, fructose, vitamin C, and B vitamins

o   Ileum—protein, vitamins A, D, E, K, fat, cholesterol

§  Fun fact! Vitamins A, D, E & K are fat-soluble vitamins which means they need to hold hands with a fat molecule in order to cross the intestinal wall into our bodies.

-        Absorption area is large due to the many folds inside the intestine giving it a larger surface area.  These folds are called villi, and on each villi are microvilli that give even more surface area!

-        At the bottom of the small intestine is the ileocecal valve (the door between the small intestine and the large intestine).

Large intestine (~10 feet in length):

-        Everything that wasn’t absorbed in the small intestine moves on to the large intestine.

-        The large intestine absorbs water, sodium, and potassium into the body from the remaining contents.

-        Once the body pulls out all the water needed, the chyme turns into feces and is excreted from the body.

Learn from your poop!!

-        On average, it takes about 40-45 hours for food to travel the entirety of the digestive tract.

-        An ideal poop looks like a torpedo—it should be large, fluffy, and easy to pass.

-        Hard and dry poop—this poop has been in the digestive tract for longer than 45 hours and has had more water pulled out as it slowly moves along which makes it harder and drier. Being dehydrated can lead to hard and dry feces because the body is lacking water and will take back as much as it can out of the food in your gut.

-        Little lumps (deer or bunny poops)—this poop has also been in the digestive tract for longer than average. Little lumpy poops usually means that your diet is lacking in fiber (something you get from fruits, veggies, and whole grains!). The body is not able to digest fiber and fiber holds on to water as it is going through our gut, so without it we end up with pellet-like poops.

-        Too liquid—your body secretes about 2 gallons of fluid each day into your gut to help you break down food. When food passes too quickly through the digestive tract the intestines don’t have enough time to absorb all of that fluid back into the body. Quick transit usually is caused by a sudden increase of fiber in the diet, or a bacterial or viral infection.

-        Looking pale or gray—poop varies in color depending on what you eat and what medications you’re taking. However, if your poop has a hue of gray or is looking pale it could be due to a problem further up in your digestive tract like a problem with your liver or pancreas.

-        Bright red—as we just said, poop can vary in color depending on what we eat. Sometimes eating red popsicles or bright red beets can change our poop to look red as well. However, it is possible for there to be blood in the stool—if you know you haven’t eaten any red foods recently, it may be wise to talk to your doctor.

-        It floats (and stinks!)—healthy poop (those torpedoes we talked about) should sink. When the body doesn’t properly absorb fat in the intestines it ends up in the stool. What is the result? Poop that is yellowish, greasy, smelly, and floats. Certain medical conditions like celiac disease can cause these problems, so it is good to see your doctor if you notice this occurring.

-        Not going—constipation can occur for many reasons and can present differently as well. Maybe you’re not going very often, or maybe there isn’t a lot coming out when you do go. A good approach to help aid constipation is to increase your fluid and fiber intake—these can both give the gut the necessary boost to help get you back on track.

Adapted from “What Your Bowel Movements are Telling You About Your Helath” by Sally Wadyka and Medically Reviewed by: Pat F. Bass III, M.D., M.S., M.P.H. March 4, 2011