The Human Digestive System

The Digestive Process

The human digestive system is an incredible journey that turns food into the energy and nutrients our bodies need to function. 

Different parts work together to break down food, absorb nutrients, and eliminate waste.

Mouth: Digestion begins in the mouth, where teeth break down food into smaller pieces. Saliva, produced by the salivary glands, contains enzymes that start breaking down carbohydrates.

Esophagus: After chewing, food is swallowed and travels down the esophagus—a muscular tube that pushes food into the stomach through a series of contractions called peristalsis.

Stomach: In the stomach, food is mixed with gastric juices, including acid and enzymes that further break down proteins. The stomach muscles churn the food into a thick liquid called chyme.

Small Intestine: The chyme moves into the small intestine, where most digestion and nutrient absorption occur. The liver and pancreas help out by releasing bile and enzymes, which break down fats, proteins, and carbohydrates.

Large Intestine: Any leftover material not absorbed in the small intestine moves into the large intestine. Here, water is absorbed, and the remaining waste is prepared for elimination.

Rectum and Anus: The waste is stored in the rectum until it’s ready to be expelled through the anus during a bowel movement.

 

Timing Of Digestive Juices

The body uses signals from the brain and hormones to know when to release the right digestive juices!

• When you think about or smell food, your brain signals the digestive system to get ready.
• When you take a bite, the brain tells the salivary glands to produce saliva, which begins breaking down food in the mouth.
• As food moves to the stomach, cells release gastric juices, including enzymes and acid, to break it down further. The stomach then signals the small intestine to release more enzymes and bile from the pancreas and liver.
• Nerves and hormones help your body communicate throughout digestion, ensuring each part acts at the right time like a well-coordinated team.

 

Fun Facts

Here are some interesting facts about the digestive system:

• Despite its name, the small intestine is about 20 feet long—around four times your height!
• Your stomach produces a new layer of mucus every two weeks to prevent it from digesting itself.
• Food passes through the stomach and small intestine in about 6 to 8 hours, but it can take up to a day or more to pass through the entire digestive system.
• The rumbling noises you hear when you’re hungry are called “borborygmi” and are caused by gas moving through your intestines.

Review

Let’s quickly recap what we learned about the digestive system:

• What is the tube that connects the mouth to the stomach? Esophagus
• What liquid forms in the stomach after food is mixed with gastric juices? Chyme
• Which organ absorbs the most nutrients from food? Small Intestine
• What organ releases bile to help digest fats? Liver