Chapter 2

2.1 Digestive Process Begins

The Digestive Process Begins A.Functions Of the Digestive System 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

Digestion A.Digestion- the process in which your body breaks down food into small nutrient molecules B.Two kind of Digestion 1.Mechanical- foods are physically broken down into smaller pieces a. examples-

2. Chemical- chemicals are produced by the body, break foods in there smaller chemical building blocks a. Example-

Absorbsion A.Absorption – the process by which nutrient molecules pass through the wall of your digestive system into your blood 1. Materials that are not absorbed are eliminated from the body such as wastes

The Mouth A.Both mechanical and chemical digestion begin in the mouth 1. Saliva- a fluid release when your mouth waters

The Esophagus A.“It went down the wrong pipe” 1. meaning- 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

The Stomach A.Stomach-the J-shaped muscular pouch located in the abdomen 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.

2.2 Final Digestion and Absorption

Small Intestine A.Small Intestine- the part of the digestive system where most of the chemical digestion takes place B.6 meters long C.Almost all chemical digestion takes place in the small intestine

Liver A.Located in the upper portion of the abdomen B.Largest and heaviest organ of the body C.breaks down medicines, and it helps eliminate nitrogen from the body. D.The role of the liver in the digestive system is to produce bile.

E. Bile- 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.

Pancreas A.Pancreas- a triangular organ that lies between the stomach and the first part of the small intestine B.plays a role in many body processes. C.As part of the digestive system, the pancreas produces enzymes that flow into the small intestine and help break down starches, proteins, and fats.

A.Absorption in the Small Intestine 1. The structure of the small intestine makes it well suited for absorption. B.Millions of tiny finger-shaped structures called villi cover the surface. C.Vili 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.

The Large Intestine A.the last section of the digestive system. B.It is about 1.5 meters long C.it runs up the right-hand side of the abdomen, across the upper abdomen, and then down the left-hand side. D.The large intestine contains bacteria that feed on the material passing through. E.These bacteria normally do not cause disease.

… 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.

… I

… I.Rectum 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 J. Anus a. A muscular opening at the end of the rectum through which waste material is eliminated from the body.

Time for a Test!!!!!