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  1. DIGESTION By Erin and Courtney 

  2. Evolution • Two types of digestion • Intracellular: Break down of macromolecules takes place within the cell. • Extracellular: Break down of macromolecules takes place outside of the cell • Advantages of extracellular digestion with evolution • Allowed organisms to break down larger molecules, and gave a wider variety of food choices.

  3. So who does what? Protists : Obtain their food by filter feeding, or absorbing there food by engulfing it to form a food vacuole. Food is then taken within the cell through endocytosis. • Arthropods: Complete gut with regional specialization. The foregut, Midgut, and Hindgutwhich use extracellular digestion in order to be completed Echinoderms: They exhibit a wide range of feeding habits including; suspension feeders, deposit feeders, carnivores, browsers and parasites. They mostly digest their food externally. Worms: Have a sac-like gut, in which they take in their food and digest extracellular Mollusks: Have a gut into which is also used to digest their food

  4. DIGESTION IS COOL! • The digestion system has one goal in mind… it wants to convert food into energy the body can use to grow and maintain itself. It has evolved to be more efficient by taking as many nutrients out of the food as possible, and leaving the rest to be excreted. • It’s important because in order for the cells to absorb all the important nutrients, that slice of pizza, must be converted into the smallest particle possible so that it can be transferred into the blood stream and carried throughout the body to help build and nourish cells, as well as provide energy.

  5. Pharynx Mouth Salivary Glands Tongue Esophagus Liver Stomach Pancreas Gallbladder Small Intestine Appendix Large Intestine Rectum Anal Canal

  6. How does it work? • Digestion starts the moment food gets into the mouth, through mechanical digestion. Saliva aids in digestion with the help of enzymes, by breaking down the chemicals in food, to make it mushy enough to swallow. The tongue aids in this process by pushing the food around to various teeth, and then eventually toward the back of your throat into the opening of the esophagus, the second part of your digestive tract. • The esophagus is about 10 inches wide. As food travels down, the epiglottis (a small flap) covers the windpipe, or trachea. This allows the food to continue down the right path, toward the stomach. This process is done through muscles that move the food in a wave like motion to push it down. It takes about 2-3 seconds.

  7. STOMACH • 3 main function • Store food • Break down the food, liquefy • Empty liquid into small intestine This is all done through a somewhat simple process. Gastric juices that come from the stomach walls and the wall muscles, help churn the food and break it down. The gastric juices also aid in killing any harmful bacteria that may be in the food.

  8. Chemical Digestion • Chemical digestion of fats, proteins, and carbohydrates is completed in the small intestine by intestinal enzymes and, pancreatic enzymes. Alkaline pancreatic juice neutralizes acid chyme and provides the proper environment for the operation of enzymes. Both pancreatic Juice and bile are necessary for normal fat breakdown and absorption. Bile acts as a fat emulsifier. Secretin and cholecystokinin, hormones produced by the small intestine, stimulate release of bile and pancreatic juice. Segmental movements mix foods; peristaltic movements move foodstuffs along the small intestine. Most nutrient absorption occurs by active transport into the capillary blood of the villi. Fats are absorbed by diffusion into both capillary blood and lacteals in the villi.

  9. Small intestine..well kinda • Once in the small intestine, the absorption of vitamins, minerals, proteins, carbohydrates, and fats takes place. • With the help of the pancreas, liver, and gallbladder. • With the help of the juices produced, the food is able to be digested, and nutrients absorbed. • Function of Juices: • Pancreas-> helps digest fats and proteins. • Liver-> (called bile) help absorb fats into bloodstream. • Gallbladder-> warehouse for bile, houses it until needed. • This process takes 4 hours, ends up as thin watery mixture, and it’s nutrients are able to be absorbed into the bloodstream. I don’t know about you, but that time is worth it to me! * The small intestine is actually 22 feet long…that’s 22 notebooks lined up!

  10. Last but not least • The final steps to digestion. • The nutrient rich blood enters the liver, where it goes through a processing similar to email. • Determines the junk mail, or wastes. • Either will be excreted or turned into more bile. • Determines what nutrients are to carried throughout the body, or to be stored for later use as energy. • Where do the wastes go? • To the large intestine! • Once in the large intestine, it has one final place to absorb any sort of nutrition by the colon. • All other wastes are pushed through the large intestine until it becomes a solid and reaches the rectum, and then comes out of the anus.

  11. Buddy System • Circulatory SystemThe Digestive system works with the Circulatory system because the Digestive system makes nutrients to give to the cells. The cells turn it into energy. The body, needs energy, so the Circulatory system is like a delivery system. The Circulatory system meets with the cells and the blood stream dellivars the energy to the other parts of the body. • Skeletal SystemThe Digestive system needs the food to be grind into tiny mushy piece called pulp, so it is easier to swallow and digest. Also the ribs cover the digestive system’s organs and protect them. • Muscular SystemThe Digestive system works with the Muscular system when you need to chew your food. Muscles move your jaw bone to chew up the food. Also there are muscles called the sphincter muscles, which lets food into one organ to another. There are two intestinal muscles, that makes the ntestines move the food from the small intestine to the large intestine. There is an other muscle called the esophagus muscle which moves food down the esophagus to the stomach. • Respiratory SystemThe Digestive system works with the Respiratory system for example, when you gulp too much air and it goes down the esophagus and into your stomach the lungs give air and you burp, so too much air won’t hurt your stomach.

  12. HOMEOSTASIS • Maintaining Homeostasis: pH Balance • Although the digestive system may seem simple, it is complex. Maintenance relies on a balance of pH and helpful bacteria to maintain homeostasis. Both acidic and basic pHs are required at various points in digestion to maintain balance during the process. Saliva in the mouth, the starting point of digestion, is only mildly acidic for the purpose of initially breaking down the food without damaging the teeth or delicate throat tissue. The stomach, on the other hand, needs to be highly acidic to jump-start the breakdown process as well as act as a defense for the body against any harmful bacteria or other intruders. To balance things out on the basic side, it is important that the small intestine has a high pH, because most of the enzymes used in digestion can't function properly in an acidic environment. • Maintaining Homeostasis: Helpful Bacteria • Helpful bacteria also are needed to maintain homeostasis in the digestive system. These bacteria aid in digestion, help produce vitamins, help formulate excrement and guard against harmful bacteria. When the bacteria population in a digestive tract is off the host will notice a change in the pace and quality of digestion.

  13. Nutrition~ • Proteins - essential to growth and repair of muscle and other body tissues • Fats - one source of energy and important in relation to fat soluble vitamins • Carbohydrates - our main source of energy • Minerals - those inorganic elements occurring in the body and which are critical to its normal functions • Vitamins - water and fat soluble vitamins play important roles in many chemical processes in the body • Water - essential to normal body function - as a vehicle for carrying other nutrients and because 60% of the human body is water • Roughage - the fibrous indigestible portion of our diet essential to health of the digestive system • 57% Carbohydrates (sugar, sweets, bread, cakes) • 30% Fats (dairy products, oil) • 13% Protein (eggs, milk, meat, poultry, fish)

  14. Problems? Celiac disease: Celiac disease is a digestive disease that damages the small intestine and interferes with absorption of nutrients from food. People who have celiac disease cannot tolerate gluten, a protein in wheat, rye, and barley. • Lactose intolerance: is the inability or insufficient ability to digest lactose, a sugar found in milk and milk products. Lactose intolerance is caused by a deficiency of the enzyme lactase, which is produced by the cells lining the small intestine. Gastroesophageal reflux disease (GERD) is a more serious form of gastroesophageal reflux (GER), which is common. GER occurs when the lower esophageal sphincter (LES) opens spontaneously, for varying periods of time, or does not close properly and stomach contents rise up into the esophagus. AKA: acid reflux or acid regurgitation

  15. MOVIEEEEEEEE!!!! • http://www.youtube.com/watch?v=Z7xKYNz9AS0&feature=related • http://youtu.be/Z7xKYNz9AS0

  16. Cool…and your point? • It is the largest and most evolved system in our bodies • With it the body is able to break down important molecules, and well…dispose of the useless ones. • Without it you wouldn’t have the energy to be here listening to this.

  17. Works Cited • Anatomy and Physiology Homepage. Web. 15 Apr. 2011. <http://www.lrn.org/Content/Lessons/digestive.html>. • Carson, Nacie. "How Does the Digestive System Maintain Homeostasis? | EHow.com." EHow | How to Videos, Articles & More - Trusted Advice for the Curious Life | EHow.com. Web. 15 Apr. 2011. <http://www.ehow.com/how-does_4565570_digestive-system-maintain-homeostasis.html>. • "Celiac Disease." National Digestive Diseases Information Clearinghouse. Web. 15 Apr. 2011. <http://digestive.niddk.nih.gov/ddiseases/pubs/celiac/index.htm>. • "Digestion System." Biology Questions. Web. 15 Apr. 2011. <http://www.biology-questions-and-answers.com/digestion-system.html>. • "Echinoderms." ReefED - Educate to Keep It Great. Web. 15 Apr. 2011. <http://www.reefed.edu.au/home/explorer/animals/marine_invertebrates/echinoderms>. • "Protist." Wikipedia, the Free Encyclopedia. Web. 15 Apr. 2011. <http://en.wikipedia.org/wiki/Protist>. • Taggart, Starr, comp. Biology The Unity and Diversity of Life. 11th ed. Belmont: Thomson Brooks/Cole, 2006. Print. • Web. • "Work with Other Systems." Web. 15 Apr. 2011. <http://homepage.mac.com/seisenelem/bodysystems/Digestive/othersystems.html>. • "Your Digestive System." KidsHealth - the Web's Most Visited Site about Children's Health. Web. 15 Apr. 2011. <http://kidshealth.org/kid/htbw/digestive_system.html>.