BY: NICKY AND GIGI The Digestive System

Food The digestive system starts when you take a bite of food. The minute you swallow a bite of food, the digestive system starts. Why do you even eat food? You eat food to feed the trillions of living cells that make up your body. Different cells do different things to keep your body alive and working. Just like any time you work, your cells get hungry. The kind of food cells require are energy and raw materials for building. Cells get this energy and raw materials from three groups of nutrients called fats, carbohydrates, and proteins. The process of breaking your own food into nutrients for your cells is called digestion. Pretend you just ate an apple. Once you swallow a bite of it, your apple goes through the digestive system. Let’s follow it!

The Esophagus Your apple is no longer that juicy red apple. In fact, it isn’t really an apple at all. It is a mashed up wad of food called a bolus. The bolus leaves your mouth and heads down the esophagus. Muscles along the esophagus contract to push the bolus along the esophagus. The bolus is headed towards the stomach.

The Stomach Once inside the stomach, digestive juices, including acid, are added to the food. Muscles inside your stomach squeeze and mash the food. The food changes into a gross, runny liquid. Yuck!

The Small Intestine After being in the stomach, the food goes into the small intestine. The small intestine can be 6 meters(20 feet) long. Even more digestive juices are added to the food. At the small intestine, the food changes into nutrients that cells need. The small intestine is lined with millions of capillaries, which are small blood vessels. Nutrients flow through the sides of the small intestine and into the capillaries. After that, the blood which is now nutrient-rich, flows through your body. It provides food for cells.

Undigested Leftovers The undigested leftovers of food enter the large intestine and colon. At this stage in the digestive system, the nutrients have left the food and fed the cells. The bacteria that lives in the colon breaks down the remaining food that is still able to be used. Water is taken out of the food. The remaining stuff is made up of fiber, indigestible material, and dead bacteria. This is called feces. This material can then exit the body through the anus.

Cleaning Blood Food is still not finished with the breakdown process. Remember that still usable food? Well, that needs to get broken up. At this stage, all that is left are waste chemicals. Waste chemicals, bits of salts, acids, and dead cells all end up in your blood flow. This stuff needs to get out of your blood and your kidneys are the perfect blood cleaners! Kidneys are next to your back bone and right below your ribs. Your kidneys clean your blood 20 to 25 times a day. They separate cellular wastes from the blood. The salts, acids, dead cells, and waste materials are taken away from the blood and converted to urine. Then, they are stored in a tube in the bladder. The bladder and kidneys make up the excretory system.

Kidneys In the previous slide, you learned how kidneys help clean blood. But why do people need kidneys? People need kidneys to keep your blood clean. If you didn’t have kidneys, waste would be added to your blood and eventually your blood would be so full of waste that it couldn’t do its job. You would die. How do kidneys work? Kidneys act as filters that separate cellular wastes from blood. They also keep a balance between salts, fluids, and more in your body. Kidneys come in sets of two.