Transcript Document
Learning Objectives I can explain the overall importance of the digestive system in animals. I know what an enzyme is and what it does during digestion. I can list the different kinds of nutrients found in food and I know what each is used for in the body. I can explain how the food pyramid works and/or how to read it. NOTE • There are a few differences in text on this PowerPoint slide show (compared to the student notes). These differences are in red italics. You are not expected to write these down on your notes, but listen and ask questions if it doesn’t make sense! Digestion is… o The process of breaking food into small molecules o Absorbing those small molecules/nutrients into the body. . Nutrients… • Nutrients are substances in food that provide ENERGY and materials for cell development, GROWTH and REPAIR • The food pyramid suggests what food groups to eat and the size of the serving (the larger the slice = the bigger the serving you should eat). • The new pyramid also emphasizes the importance of getting EXERCISE. • Nutrition by Brainpop There are Two Types of Digestion • Mechanical digestion: breaking down food using physical force • Examples: chewing, mixing and churning. There are Two Types of Digestion • Chemical digestion: breaking down food into smaller molecules through chemical reactions. • Examples: Enzymes Acids Bile Enzymes o …are molecules that speed up the rate of chemical reactions Enzymes • amylase is secreted in the mouth (in saliva). This enzyme breaks down STARCHES. Starches = foods like bread, pasta, potatoes, rice Enzymes • PEPSIN is found in the stomach. It breaks complex proteins into less complex proteins protein= foods like meat, eggs, nuts, legumes/beans Enzymes • Amylase only works on STARCHES • Pepsin only works on PROTEINS Enzymes are also responsible for MANY chemical reactions in your body---not just the ones involved in digestion! Mouth • First place food enters your body • Begins chemical & mechanical digestion • Different kinds of teeth do different kinds of job. Made of bone. Mouth • Which jaw belongs to a carnivore? (meat eater) ________ • Which jaw belongs to an herbivore? (plant eater) _______ • What kind of teeth do humans have? Touch or examine yours! • What kind of eater are we? • OMNIVORES (we eat all kinds of foods) Mouth • Glands in the mouth produce saliva which contains amylase, which breaks down starch. • SALIVA = 98% water + amylase + mucus, etc. Mouth • Tongue: used for chewing, tasting food (with taste buds) and talking CLIPS & ACTIVITIES • Teeth by Brainpop • In the Mouth—Mechanical & Chemical Digestion Clip Amylase observation • Place one marshmallow in the center of your tongue. DO NOT CHEW IT, ROLL IT AROUND OR SUCK ON IT. Just let the marshmallow sit on the middle of your tongue. Time how long it takes to dissolve in your mouth. • Which kind of digestion is this? • Which enzyme is at work on this marshmallow? • Why is it important that your mouth do both kinds of digestion? Learning Objectives I can explain the function of each digestive organ in the human body. I can identify the major parts of the digestive tract from a diagram. I know what an enzyme is and what it does during digestion. I understand how my digestive system helps me maintain homeostasis. I know which part(s) of the digestive system help to regulate my body’s internal environment. Esophagus • Muscular tube that connects throat to stomach • Moves food down by squeezing (peristalsis) Peristalsis (pear-a-stal-sis): the squeezing of muscles and organs as food moves through the digestive tract Esophagus • The epiglottis seals off your windpipe when you swallow so that food doesn’t get into your lungs Other things “back there” What are these things for?? Any ideas? Stomach • muscular bag where chemical and mechanical digestion continue Stomach • Mechanical digestion occurs through churning/ peristalsis STomach • Stomach acid and enzymes (pepsin) perform chemical digestion STomach • food stays here ~4 hours; • changes to chyme • (pronounced kime) Yes, sometimes astronauts throw up! Small Intestine • tube nearly 7 meters long where digestive juices from the liver and pancreas are added to chyme It is divided into 3 sections Small Intestine • Villi absorb molecules from chyme (increases surface area for absorption • Food molecules enter blood stream Small Intestine • CHYME = partially broken down food • Duodenum = upper part of small intestine where food is still being broken down Pancreas • a small, yellowish organ that produces substances that stop the action of stomach acid • makes enzymes that break down carbohydrates • food does NOT pass through the pancreas Liver • Large reddish organ that filters the nutrient-rich blood (it is the largest internal organ—has 4 lobes); has many other jobs • Produces a greenish substance called bile. • Bile breaks up large particles of fat into smaller particles. • FOOD DOES NOT PASS THROUGH THE LIVER! Gall bladder • small sac that stores bile produced by liver • FOOD DOES NOT PASS THROUGH THE GALL BADDER! Large intestine • ALSO KNOWN AS COLON • absorbs water from undigested food • unabsorbed materials become more solid Large intestine • shorter but larger diameter tube • appendix is offshoot of large intestine • helps the body maintain fluid balance (homeostasis) Rectum • where muscles control the release of waste from the body. ANus • opening where solid waste leaves the body mouth esophagus liver Gall bladder stomach pancreas Large intestine Small intestine rectum Digestive System by Brainpop Digestive System by Brainpop 1) Where does digestion begin? 2) What connects your mouth to your stomach? 3) What is the duodenum? 4) What is one organ that food doesn’t pass through, that is still important in digestion? Related Clips • Body Weight by Brainpop • Metabolism by Brainpop • Eating Disorders by Brainpop • The Process of Digestion Clip (13 minutes) Animations • http://www.kitses.com/animation/swf s/digestion.swf