The Digestive System

 Digestion  The process by which the digestive system breaks down food into molecules that the body can use.  2 types of digestion  Mechanical digestion-foods are physically broken down into smaller pieces.  Chemical digestion-chemicals produced by the body break larger molecules into smaller ones.

 Enzymes  The chemicals involved in breaking down food molecules.  Absorption  The process by which nutrients pass through the lining of the digestive system into the blood.

 Elimination  Materials not absorbed are eliminated from the body as waste.

 The beginning of digestion  Mechanical digestion  The Jaw  Teeth tear, crush, and grind food  Tongue pushes food around

 Chemical digestion  Enzymes in saliva begin to breakdown starches in food.  Saliva also moistens the bite of food into a slippery mass called a bolus that can be easily swallowed  Approximately 1.5 L of saliva is secreted daily

 Location  3 main parts  Nasopharynax  Oropharynax  Laryngopharynx  Behind nasal and oral cavity  Nasopharynax- behind the nasal cavity

 Oropharynx- part you can see through the mouth

 Laryngopharynx- the bottom part of the Pharynx  Back part of pharynx continues downward into the esophagus  The front part leads to the larynx (voice box)  During swallowing the entrance of the larynx is covered by the epiglottis

 Connects throat (pharynx) with the stomach  Muscular tube  10 inches long  Lined moist pink tissue called Mucosa  Runs behind windpipe (trachea) and heart, but in front of the spine.  Passes through diaphragm

 Mechanical Digestion  Three layers of stomach muscle cause a “churning motion”  Chemical Digestion  Pepsin ▪ Breaks down proteins ▪ Works well with hydrochloric acid ▪ Stomach is protected by a lining of mucus to aid in protection of itself from the acid

 Digestion normally occurs over a few hours  Most proteins have been chemically digested into shorter chains of amino acids  Peristalsis moves food along into the small intestine  Food becomes a thick liquid called chyme

 20 feet long, 1 inch diameter  Where most of the chemical digestion and nutrient absorption takes place  Fingerlike projections along the lining called villi which absorb nutrient molecules  Nutrients pass onto the blood vessels on the villi and pass on into the blood stream and throughout the body

 Liver, Gallbladder, and Pancreas also help in digestion  Liver  Produces bile which breaks up large fat droplets that clump together  Gallbladder  Storage for bile. As food leaves your stomach, the gallbladder releases the bile  Pancreas  Releases enzymes into the small intestine for the breakdown of carbohydrates, proteins and fats

 5 ft long, 3 inches in diameter  Vitamin production through the natural bacteria living in the lining of the large intestine  Most of body’s requirements of Vit K  Most nutrients have been absorbed when food enters large intestine  As it moves through the large intestine, most of the remaining water is absorbed into the bloodstream  It ends at the rectum, a short tube where waste material is compressed into solid form known as feces or stool and eliminated through the anus

 t2mw

1. What is the process that physically broken down into smaller pieces? 2. What are the Chemicals involved in breaking down food molecules 3. What is the beginning of digestion 4. The average person produces 1.5 liters of this per day 5. What is the name of the thick liquid that moves along into the small intestines

6) What is the muscle flap called that covers the opening of the larynx during swallowing 7) What are the fingerlike projections that absorb nutrient molecules 8) What Stores Bile 9) Muscular tube that connects the throat with the stomach 10) The wave like function that moves food along to the intestines