The Digestive System of the Human Body

The Digestive System of = the Human Body

The Digestive= System starts in your mouth to change the food you eat into substances your body c= an use. This is called digestion= which is the process of getting the nutrients and energy from the food you eat. Mechanical digestion is the chewin= g of food and the churning of food in the stomach. Chemical digestion is the changing= of food molecules into other nutrient molecules with the aid of enzymes. This occurs in the mouth, stomach = and small intestine. The digestive tract is also called the alimentary canal.

Digestion begins in the mouth by tearing, ripping, mashing, and chewing food mixed with saliva from the salivary glands. Saliva contains a chemical substan= ce that changes starches into sugars. <= /span>

= = &nb= sp;

Time to swallow...&nb= sp; The food travels down the e= sophagus. The epiglottis closes over your wi= ndpipe so that no food enters the windpipe. When this does not work properly and food or liquid enters the windp= ipe and you cough violently as we say it went down the wrong pipe. A wave like motion called peristalsis moves the food down t= he esophagus.

On to the sto= mach...food mixes, churns, and mashes as stomach muscles twist and turn. Stomach acid (HCl) mixes with the = food to break the molecules into smaller molecules the body can use. The partially broken down food in = the stomach is a thin dark liquid called chyme. Chemical substances in the stomach= also break down protein molecules into amino acid molecules. Fats are broken down into fatty ac= ids and glycerol.

It is time for the new nutrient molecules to travel to= the small intestine. This is a long tube about 20= feet long. The new molecules are b= roken down even more. The small int= estine needs some help from the pancreas<= /b>, liver, and gallbladder. The pancreas makes juices that help digest fats and proteins. The liver produces bile which is s= tored in the gallbladder. The gallb= ladder squirts the bile into the small intestine to help absorb fats into the bloodstream. The inner wall o= f the small intestine is covered with millions of microscopic, finger-like projections called villi. The villi are the vehicles through which nutrients can be absorbed into the body.&n= bsp; The nutrients now leave the small intestine and enter the blood stre= am to be carried to the liver which filters out waste and then the nutrients a= re sent to every cell in your body.

The small intestine is made up of three parts:

the large intestine which is also a tube about five feet long. Most of the water is absorbed back= into the body making the waste material solid.&= nbsp; Yes, you are right. It’s poop. The l= ast stop is out of the body from the r= ectum to the anus. With a flush the waste material fr= om the food you ate is gone, gone, gone.

The digestive system works with other systems. The circulatory system carries the nutrients and chemical signals from the endocrine sy= stem to control the speed of digestion. The excretory system wo= rks with the digestive system to filter substances from the blood stream and collects them in the urine.

= &nb= sp; =

Projects:

1. Think of something you eat, and tell the story of i= ts travels from beginning to end.

2. Resea= rch a stomach disorder and write three paragraphs explaining the symptoms, causes, treatment and cure.

3. Resea= rch carbohydrates, proteins, fats, minerals and vitamins. Prepare a chart showing the differ= ent nutrients and what foods they come from.

4. Compa= re and contrast a nutritious meal and a no nutritious meal. Give a detailed explanation why th= e meal is nutritious or why it is not nutritious.