The Digestive System. Chapter 2. 2.1. Digestive Process Begins. The Digestive Process Begins. Functions Of the Digestive System 1. Three Main Functions a. Breaks down food into molecules the body can use
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Digestive Process Begins
1. Three Main Functions
a. Breaks down food into molecules the body can use
b. Then molecules are absorbed into the blood and are carried throughout the body
c. Finally wastes leave the body
1.Mechanical- foods are physically broken down into smaller pieces
2. Chemical- chemicals are produced by the body, break foods in there smaller chemical building blocks
1. Materials that are not absorbed are eliminated from the body such as wastes
1. Saliva- a fluid release when your mouth waters
2. Two openings
a. one opening leads to wind pipe which carries air to the lungs
b. a flap of tissue called the epiglottis seals off your windpipe preventing food from entering
c. food goes through the esophagus. A musclular tube that connects the mouth to the stomach, lined with mucus
mucus -a thick slippery substance produced by the body, makes food easier to swallow
3. after the food enters the esophagus contractions of smooth muscles push the food towards the stomach
a. peristalsis- involuntary waves of muscle contraction
1. All Mechanical and most chemical digestion occurs in the stomach
2. The reason is that cells in the stomach lining produce a thick coating of mucus, which protects the stomach lining. Also, the cells that line the stomach are quickly replaced as they are damaged or worn out.
3. Food remains in the stomach until all of the solid material has been broken down into liquid form.
4. A few hours after you finish eating, the stomach completes mechanical digestion of the food. By that time, most of the proteins have been chemically digested into shorter chains of amino acids.
5. The food, now a thick liquid, is released into the next part of the digestive system. That is where final chemical digestion and absorption will take place.
Final Digestion and Absorption
E. Bile- material has been broken down into liquid form.
1. Bile flows from the liver into the gallbladder, the organ that stores bile.
2. After you eat, bile passes through a tube from the gallbladder into the small intestine.
3. not an enzyme
4. physically break up large fat particles into smaller fat droplets.
5. Bile mixes with the fats in food to form small fat droplets.
6. The droplets can then be chemically broken down by enzymes produced in the pancreas.
1. The structure of the small intestine makes it well suited for absorption.
1. absorb nutrient molecules
2. Nutrient molecules pass from cells on the surface of a villus into blood vessels.
3. The blood carries the nutrients throughout the body for use by body cells.
F. The material entering the large intestine contains water and undigested food.
G. As the material moves through the large intestine, water is absorbed into the bloodstream.
H. The remaining material is readied for elimination from the body.
a. -The end of the large intestine where waste material is compressed into a solid form before being eliminated.
b. waste material is compressed into a solid form
a. A muscular opening at the end of the rectum through which waste material is eliminated from the body.