Have you ever been so hungry that your mouth starts to water at the sight of a home cooked lasagna, or the smell of bread baking in the oven? This sensory response is your digestive system preparing to receive something delicious. Even before you take your first bite it’s preparing to go to work!
The digestive system spans the length of your entire upper body, from mouth to anus, and is responsible for turning what we eat into building blocks our body needs to grow, function and repair itself.
To best understand how the digestive system works, let’s follow a bite of that mouth watering lasagna as it passes through the four main phases of digestion.
As soon as the lasagna enters your mouth manual laborers, also known as your teeth, begin to break it down. Simultaneously saliva is released to moisten and soften the lasagna so it can travel more easily down the esophagus. Through a process called peristalsis, esophageal muscles gently move the masticated mass into the stomach. As food enters the stomach it begins to churn and releases a mixture of enzymes, acids and mucus. The stomach metabolizes and warehouses the food mass until it’s ready to pass into the small intestine.
The real action begins once your food has left the stomach. Digestion is a coordinated effort between the small and large intestines with an assist from the pancreas, liver and gallbladder. Each organ contributes vital materials to the nearly four liters of ‘digestive juices’ that will be used to further process the lasagna. Some of the key components in the mixture include:
By the time the lasagna leaves the small intestines about 90% of its nutrients have been extracted and absorbed into the bloodstream - but the essential digestive organs are still at work! The liver stores some of the nutrients, including iron and fat-soluble vitamins A, D, E and K, and releases them back into the blood when needed. It also detoxifies potentially harmful or toxic chemicals from the body and secretes them. The pancreas makes insulin, the hormone needed for metabolizing sugar for energy. The gallbladder is the gatekeeper of bile. It supplies bile for digestion and then recycles the excess, storing it for use during the next meal. Any remaining food residue from this stage is released into the large intestine.
The large intestine, or colon, is approximately 5 feet of muscular intestinal tubing. This is where the final stage of digestion occurs. The colon reabsorbs water from undigested food, forming a compact mass of waste and bacteria. The ‘good’ bacteria support this process and protect against harmful or ‘bad’ bacteria. When the colon becomes full it empties into the rectum; waste exits through the anal canal. It can take up to 36 hours for waste to pass through your colon and exit your body.
Next time you take a bite of something delicious (like lasagna) take a minute to appreciate the incredibly complex bit of digestive chemistry that is about to take place. Also notice how different foods affect your system. Most importantly, take your time and don’t forget to chew thoroughly!