THE DIGESTIVE SYSTEM

LEARNING OBJECTIVES

• Students will be able to identify and describe the main organs of the digestive system and their function Students will explain the step by step process of how food is broken down, absorbed, and eliminated by the body.

WHAT IS THE DIGESTIVE SYSTEM?

• The digestive system is a group of organs that work together to turn the food you eat into energy and nutrients your body can use. It starts in your mouth and ends in your anus, with many steps in between. This system breaks food down into smaller parts, absorbs the nutrients into your blood, and gets rid of the waste. Every time you eat, your digestive system jumps into action!

CHEWING AND SALIVA START DIGESTION

• Digestion begins in the mouth. Your teeth break down food into smaller pieces through chewing, while your saliva adds moisture and contains special enzymes that start breaking down carbohydrates. Your tongue helps move the food around and forms it into a soft ball called a bolus for easy swallowing.

THE STOMACH

• Once in the stomach, food is mixed with stomach acid and enzymes that help break it down even more. The stomach muscles churn the food into a thick liquid called chyme. The acid kills most harmful bacteria and starts digesting proteins. This process takes several hours and prepares the food for the small intestine.

THE SMALL INTESTINE

• The small intestine is a long, coiled tube where most digestion and nutrient absorption happens. As chyme passes through, enzymes from the pancreas and bile from the liver help break down fats, proteins, and carbohydrates. The walls of the small intestine are lined with tiny finger-like projections called villi that absorb nutrients into the bloodstream.

HELPER ORGANS: LIVER, GALLBLADDER, AND PANCREAS

• The liver, gallbladder, and pancreas don’t directly touch the food, but they help digestion in big ways. The liver makes bile, which breaks down fat. The gallbladder stores that bile and sends it to the small intestine when needed. The pancreas makes enzymes that break down sugar, fat, and protein.

THE LARGE INTESTINE

• The liver, gallbladder, and pancreas don’t directly touch the food, but they help digestion in big ways. The liver makes bile, which breaks down fat. The gallbladder stores that bile and sends it to the small intestine when needed. The pancreas makes enzymes that break down sugar, fat, and protein.

THE RECTUM AND ANUS

• The final part of the digestive system is the rectum and anus. The rectum stores the waste until your body is ready to get rid of it. When it's time to go, muscles around the anus relax and let the waste pass out of the body—this is called a bowel movement.