Digestive System Overview Quiz

Digestive System Overview

The digestive system is responsible for processing food you eat into nutrients your body can absorb. It's divided into several organs, each with its own unique role in breaking down and absorbing nutrients. Let's explore how this process unfolds from the moment you take a bite until the leftovers become waste.

Mouth

When you put food in your mouth, it starts its journey through the digestive tract. The first step involves chewing the food, which mixes saliva with the food to form a bolus. Saliva contains enzymes like amylase that help break down carbohydrates. As you swallow, the muscles of the throat push the bolus down the esophagus.

Esophagus

Your esophagus connects your mouth to your stomach. When you swallow, the muscle that makes up the lower esophageal sphincter opens temporarily, allowing the bolus to pass into the stomach. This opening prevents the contents of the esophagus and stomach from mixing unless there is an abnormal condition known as gastroesophageal reflux disease (GERD).

Stomach

Once the bolus reaches your stomach, it gets mixed with gastric juices containing hydrochloric acid and enzymes such as pepsin. These substances aid in breaking down proteins and killing off any bacteria present in the food. Muscular contractions within the stomach further grind the food into a thick liquid called chyme. The lining of the stomach secretes mucus to protect itself against the corrosive acids.

Small Intestine

Chyme moves from the stomach into the small intestine via the pyloric sphincter, a ringed muscle that controls the passage from the stomach to the duodenum, the first portion of the small intestine. In the small intestine, more digestive juices are added to the chyme from the liver and pancreas. Bile enters from the gallbladder, helping to emulsify fats so enzymes can break them down.

The surface area of the small intestine, made up of finger-like projections called villi, increases absorption efficiency. Nutrients like glucose, amino acids, vitamins, and minerals are absorbed into the bloodstream through the walls of the villi, while water and electrolytes move into the cells lining the intestines.

Large Intestine

After most of the nutrient absorption has taken place, what remains—mainly water, salt, some undigested material, and bacteria—moves into the large intestine. Here, friendly bacteria break down the remaining matter, producing substances like fatty acids, vitamin K, and short-chain fatty acids. Water is absorbed back into the bloodstream, and the remaining waste is expelled as feces.