The digestive system is a very important part of our body. Nutrients are required for normal body functions. Nutrients which include carbohydrates, proteins, lipids, vitamins, and minerals. The food we eat are to big to pass into the blood, so the nutrients we need can not get into our blood. That is where the digestive system comes into place. The major function of the digestive system is the digestion of food and absorption of nutrients.
The digestive system consist of the alimentary canal, which is the long tube food passes through, and the accessory organs. The major parts of the alimentary canal is the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. The major parts of the accessory organs are the teeth, salivary glands, liver, gallbladder, and pancreas.
The digestive system starts in the mouth. Our salivary glands are located under our tongue in our mouth. When we smell, taste, or imagine a tasty meal our salivary glands produce saliva. The saliva is set in motion by a brain reflex that is triggered when we sense food. The brain sends impulses through the nerves to the salivary glands, letting them know to prepare for a meal. The teeth in the mouth tear and chop up the food and the saliva moistens the food for easy swallowing.
Swallowing, which is done by muscles in the tongue and mouth, move the food into the pharynx(throat). The pharynx is a passageway for air and food to pass through. Also, when we swallow the epiglottis reflexively closes over the windpipe to keep us from choking.
After the throat, the food goes down into a muscular tube in the chest called esophagus. The food travels through the esophagus to the stomach by muscle contractions called peristalsis.
Once in the stomach the food is churned and mixed, by the stomach muscles, with acids and enzymes. This breaks the food into much smaller, digestible pieces. The food stays in the stomach until it is at the right consistency to enter into the small intestine. When the food is at the right consistency it has been processed into a thick liquid called chyme. Chyme is squirted down into the small intestine.
The small intestine consist of three major parts. The duodenum, the jejunum, and the ileum. This is where the liver, gallbladder, and pancreas come into play. The liver produces bile. Bile helps the body absorb fat. This bile is stored in the gallbladder until it is needed. The pancreas produces the enzymes. Enzymes help to digest proteins, fats, and carbohydrates. The enzymes and the bile travel through ducts, which is special channels, directly into the small intestine. This is where they help to break down food. After this process the undigested food then travels to the large intestine.
The large intestine's major function is to remove water from undigested matter and make solid waste that can be excreted. The large intestine has three parts the cecum, the colon, and the rectum. The cecum is a pouch that joins the small intestine to the large intestine. After the cecum, is the colon. The colon extends from the cecum up the right side of the abdomen, across the upper abdomen, and then down the left side of the abdomen, and then finally to the rectum. The rectum is where feces are stored until they leave the digestive system. They leave the digestive system through the anus as a bowel movement.